Molecular Interactions of Saccharides and Their Derivatives with

Article Cite This: J. Chem. Eng. Data XXXX, XXX, XXX−XXX

pubs.acs.org/jced

Molecular Interactions of Saccharides and Their Derivatives with Thiamine HCl and Pyridoxine HCl Vitamins in Aqueous Solutions: Calorimetric, Viscometric, and NMR Spectroscopic Studies Mousmee Sharma, Tarlok S. Banipal, and Parampaul K. Banipal* Department of Chemistry, Guru Nanak Dev University, Amritsar-143005, Punjab, India S Supporting Information *

ABSTRACT: Limiting standard enthalpies of dilution (ΔdilH°) and Jones−Dole viscosity B-coefficients of various polyhydroxy solutes, viz., saccharides, their methyl and deoxy derivatives, and sugar alcohol in 0.05, 0.15, 0.25, and 0.35 mol·kg−1 thiamine HCl(aq) and pyridoxine HCl(aq) solutions have been determined from heat change (q) and viscosity (η) data at T = 288.15−318.15 K and pressure p = 0.1 MPa. The corresponding transfer parameters (ΔtrΔdilH°, ΔtrB), change in heat capacity (ΔdilC°p,2,m), and enthalpic (hAB and hABB) and viscometric (ηAB and ηABB) pair and triplet interaction coefficients have also been derived. The dB/dT coefficients have been calculated and discussed in terms of the kosmotropic or chaotropic nature of solutes in aqueous solutions of vitamins. The present results have also been compared with previously reported studies carried out in L-ascorbic acid.17 Further, NMR spectroscopy has been employed to understand the nature of interactions occurring in ternary solution {polyhydroxy solute + vitamins + 9:1 (w/w) H2O−D2O} at molality mB = 0.15 mol·kg−1 and T = 300.15 K. The results have been explained in terms of contributions due to hydrophilic−hydrophilic/hydrophobic interactions and H-bonding between solute−solute/cosolute molecules. The effect of stereochemistry and molecular conformations of both polyhydroxy solutes and cosolutes (vitamins) have also been discussed.

1. INTRODUCTION The understanding about the solvation behavior of saccharides and their derivatives in aqueous solutions is very essential due to their recognition in various biological processes like protein/ enzyme stability, cellular interactions, protective efficacy, etc. Saccharides are appropriate models to study the hydration characteristics of proteins and nucleic acids, as these stabilize the protein conformations and impede denaturation due to reagents.1−6 Sugar alcohols have low caloric contents and are considered high value added products mainly in the biorefinery. Xylitol is considered as an alternative sugar for diabetics and broadly used as a sweetener in dietary drinks, food, as well as pharmaceutical applications. Therefore, measurements of the solution properties of these compounds have become a subject of increasing interest because of their multidimensional applications in the medicinal and biological systems.7,8 Vitamin B complexes are essential nutrients which play an important role in nerve conduction, carbohydrate metabolism, cell growth, the digestive system, and normal heart activity.9 It is known that vitamins are not produced within the body; thus, they must be taken through the diet and have been used as nutrient supplements in feed industries, medicines, cosmetics, as well as additives to enhance the nutritional values of different food products. Important vitamins such as thiamine HCl (vitamin B1) and pyridoxine HCl (vitamin B6) are known to cure diseases like tuberculosis and beriberi. Thiamine HCl, a © XXXX American Chemical Society

water-soluble vitamin, plays a pivotal biological role in the metabolic process of the carbohydrate in the human body.10 Pyridoxine HCl is one of the most essential ingredients and participates in many vital metabolic activities of living cells, i.e., for the production of red blood cells (RBCs) and cells of the immune system, and it maintains proper functioning of nerves. Pyridoxine HCl is an important vitamin for greater than 100 enzyme reactions in the body related to the metabolism of amino acids and proteins.11,12 Due to the complex nature of the vitamins, the thermodynamic, transport, and spectroscopic data are quite informative in understanding the molecular interactions occurring in fluids. The hydration characteristics of saccharides are the key model for understanding interactions between hydrophilic groups and interfacial water molecules. In this context, several attempts have been made to gain a more fundamental insight into the molecular level understanding of sugar hydration.13 Some workers reported10,14,15 the physiochemical properties of some vitamins only in water and in dilute HCl or aqueous NaCl solutions. We have reported16,17 volumetric, UV absorption, calorimetric, and viscometric studies to understand the solvation behavior of monosaccharides, their methoxy and Received: October 30, 2017 Accepted: April 3, 2018

A

DOI: 10.1021/acs.jced.7b00937 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

Article

Table 1. Description of the Chemicals Used C, H, N, S analysis compound (abbreviation) [molecular formula] thiamine HCl [C12H17ClN4OS·HCl]

pyridoxine HCl [C8H11NO3·HCl]

molar mass (g·mol−1)

source

337.27

Sigma Chemical Co.

205.64

Sigma Chemical Co.

CAS number 67-03-8

58-56-0

mass fraction puritya

calculated %

observed %

≥0.99

C = 42.73

C = 42.75

≥0.99

H = 5.38 N = 16.62 S = 9.51 C = 46.73

H = 5.35 N = 16.64 S = 9.53 C = 46.75 H = 5.90 H = 6.84 C = 39.97

(+)-D-xylose (Xyl) [C5H10O5]

150.13

Sigma Chemical Co.

58-86-6

≥0.99

H = 5.88 H = 6.81 C = 40.00

xylitol (Xyol) [C5H12O5]

152.15

Sisco Research Lab.

87-99-0

≥0.99

H = 6.71 C = 39.43

H = 6.69 C = 39.45

(+)-D-glucose (Glc) [C6H12O6]

180.16

Sigma Chemical Co.

50-99-7

≥0.99

H = 7.89 C = 40.00

H = 7.87 C = 40.03

2-deoxy-D-glucose (2-de-Glc) [C6H12O5]

164.16

Sisco Research Lab.

154-17-6

0.99

H = 6.71 C = 43.90

H = 6.69 C = 43.88

(+)-methyl-α-D-glucopyranoside (Me-α-Glc) [C7H14O6]

194.18

Sigma Chemical Co.

97-30-3

≥0.99

H = 7.37 C = 43.30

H = 7.39 C = 43.27

(+)-maltose monohydrate (Mal) [C12H22O11·H2O]

360.31

Sigma Chemical Co.

6363-53-7

0.99

H = 7.27 C = 40.00

H = 7.25 C = 40.02

H = 6.71 4.5−6.5%b

H = 6.69

a

As reported by supplier bWater content as reported by the supplier.

analyzer (FLASH 2000), USA. The carbon and hydrogen contents obtained in the analysis are similar to expected values from the molecular formulas, hence suggesting that the samples were completely dried and the water content was negligible for anhydrous samples (Table 1). 2.2. Isothermal Titration Calorimetry. The heat change (q) was measured using an isothermal titration microcalorimeter (MicroCal iTC200, USA) having temperature stability within ±0.01 K. An automated instrument controlled syringe having a volume capacity of 40 μL with 0.25 mol·kg−1 solute (saccharide/derivative/polyol) solution and stirring at a speed of 500 rpm was used for carrying out titrations into the sample cell containing 200 μL of the respective solvent (thiamine HCl/pyridoxine HCl). The reference cell was filled with pure water. Each titration experiment had 20 consecutive injections of 2 μL each with 4 s duration and an interval of 120 s between the consecutive injections. Control experiments of the titration of water with water and water with aqueous cosolute solutions were performed, and appropriate corrections were applied to the main experiment. The microcalorimeter was calibrated by performing a complexation reaction between CaCl2 (5 mM) and EDTA (0.4 mM) solution in MES buffer (10 mM) at pH 5.6 provided by the company, along with the iTC kit. The titration experiment was carried out by taking CaCl2 solution in the syringe and the sample cell filled with EDTA solution at a stirring speed of 500 rpm at 298.15 K. The enthalpy of binding (ΔH = −17.34 kJ·mol−1) was compared with the data (ΔH = −17.40 kJ·mol−1) provided with the iTC kit that confirmed the validation and proper working of the instrument (Figure S1).

deoxy derivatives, disaccharides, and sugar alcohols in Lascorbic acid(aq) (vitamin C) solutions at T = 288.15−318.15 K. Further, in continuation to earlier reported18 volumetric and UV spectroscopic studies of these solutes in thiamine HCl (vitamin B1) and pyridoxine HCl (vitamin B6), we report here the limiting standard enthalpies of dilution and Jones−Dole viscosity B-coefficients at different molalities of thiamine HCl and pyridoxine HCl (cosolutes) in aqueous solutions over the temperature range T = 288.15−318.15 K under pressure p = 0.1 MPa. Other parameters like limiting standard enthalpies of dilution of transfer, change in heat capacity, viscosity Bcoefficients of transfer, interaction coefficients, and change in chemical shifts have also been evaluated and discussed in terms of various molecular interactions occurring in the ternary systems. The results have been compared with the previously reported17 studies carried out in L-ascorbic acid(aq).

2. EXPERIMENTAL SECTION 2.1. Materials. The chemicals along with their abbreviations, mass fraction purity, source of procurement, and CAS number are given in Table 1. These chemicals with highest available purity were used without further purification but stored in a vacuum desiccator over anhydrous CaCl2 before use. The solutions were prepared fresh on the mass basis using a Mettler-Toledo balance (model: AB 265-S) with a precision of ±0.01 mg. Pure water with a specific conductance less than 1.29 × 10−4 S·m−1 was procured from a Rions lab water (Ultra UV/ UF) system and degassed before use to avoid microbubbles in solutions. The purity of the chemicals used was analyzed with the C, H, N, S analysis method by using an organic elemental B



Article

Table 2. Heat Change q at Temperature T and Molality m for the System Polyhydroxy Solute (1) in Solutions of Water (2) + Thiamine HCl/Pyridoxine HCl (3) at Pressure p = 0.1 MPa Thiamine HCl qd (J·mol−1)

qd (J·mol−1)

T (K) 10

·mAa

3

−1

(mol·kg )

−1

10 ·m′ (mol·kg ) 3

c

288.15

298.15

T (K) 308.15

318.15

−1

10 ·m′ (mol·kg ) 3

c

288.15

298.15

308.15

318.15

(+)-D-Xylose (M = 150.13 g·mol−1) 2.6907 5.1114 7.5079 9.8803 12.2284 14.5523 16.8521 19.1276 21.3789 23.6061 25.8090 27.9878 30.1424 32.2727 34.3789 36.4609 38.5187 40.5522 42.5616 2.6907 5.1114 7.5079 9.8803 12.2284 14.5523 16.8521 19.1276 21.3789 23.6061 25.8090 27.9878 30.1424 32.2727 34.3789 36.4609 38.5187 40.5522 42.5616

2.6907 5.1114 7.5079 9.8803 12.2284 14.5523 16.8521 19.1276 21.3789 23.6061 25.8090 27.9878 30.1424 32.2727 34.3789

mB = 0.05 mol·kg−1 b −70.17 −69.34 −68.52 −66.62 −65.98 −64.48 −63.23 −61.70 −60.54 −60.39 −59.20 −57.99 −57.07 −56.13 −55.43 −54.67 −54.06 −53.29 −51.34 mB = 0.25 mol·kg−1 247.3092 62.63 244.8880 59.30 242.4903 56.02 240.1157 50.83 237.7639 46.04 235.4346 43.09 233.1274 39.11 230.8420 35.39 228.5782 32.61 226.3355 28.08 224.1138 24.72 221.9127 20.84 219.7320 18.03 217.5713 14.08 215.4304 10.43 213.3090 7.45 211.2069 4.56 209.1238 1.85 207.0594 0.10 49.4618 48.9776 48.4980 48.0231 47.5528 47.0869 46.6255 46.1684 45.7156 45.2671 44.8228 44.3825 43.9464 43.5143 43.0861 42.6618 42.2414 41.8248 41.4119

49.4618 48.9776 48.4980 48.0231 47.5528 47.0869 46.6255 46.1684 45.7156 45.2671 44.8228 44.3825 43.9464 43.5143 43.0861

mB = 0.05 mol·kg−1 −4.56 −4.97 −5.20 −5.45 −5.89 −6.51 −6.87 −7.12 −7.44 −7.93 −8.24 −8.68 −9.13 −9.49 −9.80

−62.70 −60.56 −59.92 −57.12 −56.16 −55.52 −53.88 −51.91 −50.19 −49.46 −48.47 −47.01 −45.35 −44.89 −43.36 −42.93 −41.09 −39.91 −38.05 87.37 85.20 82.64 80.15 77.84 76.81 74.57 72.10 70.28 67.47 65.20 63.07 60.73 58.53 57.02 55.27 52.14 49.95 47.72

−8.69 −9.01 −9.28 −9.71 −9.92 −10.29 −10.64 −10.91 −11.28 −11.45 −11.65 −12.02 −12.26 −12.72 −13.06

−53.34 −52.52 −50.99 −49.32 −47.87 −46.87 −46.08 −44.27 −43.77 −41.61 −40.69 −38.98 −37.84 −37.04 −35.95 −34.65 −33.86 −32.57 −32.32

−45.85 −44.61 −43.01 −41.25 −40.47 −39.33 −37.94 −36.39 −34.72 −33.22 −31.72 −30.25 −29.35 −27.93 −26.31 −24.93 −23.70 −23.47 −22.00

111.78 132.12 110.41 128.46 108.71 125.52 105.25 122.77 103.90 119.16 100.56 116.19 98.16 114.54 94.38 111.47 92.46 107.51 90.82 104.22 88.99 102.61 86.93 100.97 85.18 97.90 83.00 95.16 79.32 91.37 76.52 89.09 73.51 86.79 72.80 84.41 70.90 82.77 Xylitol (M = 152.15 g·mol−1) −10.84 −11.11 −11.53 −11.64 −11.84 −12.25 −12.61 −12.84 −13.44 −13.60 −13.74 −14.11 −14.18 −14.48 −14.69

−13.71 −14.06 −14.31 −14.57 −14.74 −15.05 −15.40 −15.53 −16.04 −16.35 −16.71 −17.05 −17.17 −17.63 −17.93 C

346.2329 342.8432 339.4864 336.1620 332.8695 329.6084 326.3783 323.1788 320.0094 316.8697 313.7593 310.6778 307.6248 304.5998 301.6026 298.6326 295.6897 292.7733 289.8831

mB = 0.15 mol·kg−1 −22.66 −3.77 −23.94 −5.06 −25.39 −6.08 −26.83 −7.36 −28.26 −8.73 −29.46 −9.78 −31.03 −11.27 −12.56 −32.19 −33.26 −13.49 −35.07 −14.80 −35.75 −16.11 −36.84 −17.06 −37.83 −17.97 −39.81 −19.38 −20.85 −40.81 −41.46 −21.81 −43.71 −23.29 −44.64 −24.53 −45.72 −24.95 mB = 0.35 mol·kg−1 101.97 144.59 95.41 137.14 90.89 130.19 82.76 122.75 75.92 113.83 70.92 105.58 62.31 97.37 55.25 90.75 48.89 85.18 45.06 77.48 35.18 70.18 24.57 65.16 22.81 55.31 16.29 48.29 8.64 42.41 5.60 35.45 1.29 31.56 −6.01 27.50 −9.31 18.68

148.3855 146.9328 145.4942 144.0694 142.6583 141.2607 139.8764 138.5052 137.1469 135.8013 134.4683 133.1476 131.8392 130.5428 129.2582

mB = 0.15 mol·kg−1 93.27 102.81 89.60 99.52 85.29 94.34 81.22 91.17 75.90 86.16 71.75 82.63 67.57 78.44 64.64 75.49 59.45 70.85 55.05 67.05 51.10 64.04 46.57 57.78 42.62 53.35 38.68 51.87 35.82 47.39

148.3855 146.9328 145.4942 144.0694 142.6583 141.2607 139.8764 138.5052 137.1469 135.8013 134.4683 133.1476 131.8392 130.5428 129.2582 127.9854 126.7241 125.4743 124.2356

11.24 9.81 8.79 7.17 5.87 4.41 3.58 2.01 0.99 −0.67 −1.78 −2.97 −4.24 −5.49 −7.04 −8.47 −9.12 −10.43 −11.74

25.45 24.01 22.44 20.34 18.19 15.96 14.29 12.08 10.67 8.60 7.20 5.77 3.26 1.01 −0.65 −2.44 −4.41 −6.23 −7.49

184.81 176.26 166.82 158.60 150.57 143.43 136.22 131.82 123.76 114.44 107.89 97.94 91.55 77.90 71.35 67.45 60.37 50.80 42.88

236.78 230.01 221.41 213.57 206.72 200.59 195.08 185.85 178.99 171.89 166.51 160.35 150.21 141.84 134.75 129.63 121.56 115.27 109.56

116.04 113.77 109.11 104.06 100.27 95.59 92.05 88.44 84.56 80.30 76.03 73.64 69.10 62.95 59.06

128.77 123.48 118.06 113.82 109.92 106.50 101.61 98.77 95.53 89.75 85.00 80.83 75.52 71.63 68.95



Article

Table 2. continued Thiamine HCl qd (J·mol−1)

qd (J·mol−1)

T (K) 10

·mAa

3

−1

(mol·kg )

−1

10 ·m′ (mol·kg ) 3

c

36.4609 38.5187 40.5522 42.5616

42.6618 42.2414 41.8248 41.4119

2.6907 5.1114 7.5079 9.8803 12.2284 14.5523 16.8521 19.1276 21.3789 23.6061 25.8090 27.9878 30.1424 32.2727 34.3789 36.4609 38.5187 40.5522 42.5616

247.3092 244.8880 242.4903 240.1157 237.7639 235.4346 233.1274 230.8420 228.5782 226.3355 224.1138 221.9127 219.7320 217.5713 215.4304 213.3090 211.2069 209.1238 207.0594

2.6907 5.1114 7.5079 9.8803 12.2284 14.5523 16.8521 19.1276 21.3789 23.6061 25.8090 27.9878 30.1424 32.2727 34.3789 36.4609 38.5187 40.5522 42.5616

49.4618 48.9776 48.4980 48.0231 47.5528 47.0869 46.6255 46.1684 45.7156 45.2671 44.8228 44.3825 43.9464 43.5143 43.0861 42.6618 42.2414 41.8248 41.4119

2.6907 5.1114 7.5079 9.8803 12.2284 14.5523 16.8521 19.1276 21.3789 23.6061 25.8090 27.9878

247.3092 244.8880 242.4903 240.1157 237.7639 235.4346 233.1274 230.8420 228.5782 226.3355 224.1138 221.9127

288.15

mB = 0.05 mol·kg−1 −10.35 −10.68 −10.91 −11.03 mB = 0.25 mol·kg−1 180.20 178.93 175.33 169.31 164.10 159.83 155.72 152.20 147.37 142.95 137.67 134.46 128.37 125.08 118.78 115.66 111.88 106.14 101.72 mB = 0.05 mol·kg−1 −61.44 −60.43 −59.43 −59.21 −58.84 −57.51 −57.24 −56.05 −55.06 −54.27 −53.20 −52.05 −51.00 −51.09 −50.25 −49.23 −48.09 −47.23 −46.96 mB = 0.25 mol·kg−1 129.76 123.52 119.18 114.69 108.86 102.64 97.70 92.19 88.95 82.83 78.60 72.85

298.15 −13.19 −13.42 −14.04 −14.33

T (K) 308.15

318.15

−14.97 −15.14 −15.53 −15.76

−18.28 −18.73 −18.92 −19.02

c

127.9854 126.7241 125.4743 124.2356

202.44 220.88 233.03 346.2329 198.03 215.44 230.74 342.8432 194.66 211.65 227.46 339.4864 189.51 208.90 225.23 336.1620 184.42 205.24 218.89 332.8695 182.28 201.50 216.87 329.6084 178.99 201.56 214.48 326.3783 175.97 197.24 209.68 323.1788 170.82 191.93 205.68 320.0094 167.70 188.34 200.10 316.8697 161.10 184.42 195.12 313.7593 157.55 180.79 191.81 310.6778 155.13 177.93 187.14 307.6248 152.27 174.80 183.22 304.5998 148.54 168.37 180.01 301.6026 142.04 165.01 175.89 298.6326 139.00 162.39 172.25 295.6897 135.81 158.54 168.64 292.7733 131.68 155.30 166.63 289.8831 (+)-D-Glucose (M = 180.16 g·mol−1) −54.35 −53.03 −52.35 −50.94 −50.06 −48.98 −47.77 −46.88 −45.98 −44.99 −44.39 −43.63 −43.13 −42.46 −41.05 −40.14 −39.02 −37.88 −37.25

−46.92 −46.02 −45.57 −44.21 −43.23 −41.83 −41.08 −40.25 −38.91 −37.43 −36.88 −35.90 −35.56 −34.27 −33.90 −33.17 −32.99 −31.26 −30.92

−40.75 −39.78 −38.60 −37.88 −37.03 −36.01 −35.03 −34.08 −32.94 −31.22 −30.52 −29.49 −28.89 −28.16 −27.77 −27.12 −26.09 −25.24 −24.02

148.3855 146.9328 145.4942 144.0694 142.6583 141.2607 139.8764 138.5052 137.1469 135.8013 134.4683 133.1476 131.8392 130.5428 129.2582 127.9854 126.7241 125.4743 124.2356

151.17 146.50 140.62 135.55 128.62 121.65 116.67 110.08 105.27 99.25 94.70 90.40

178.18 172.18 164.24 160.03 151.28 148.57 143.16 137.84 134.19 125.94 120.53 116.05

196.21 193.23 187.01 184.05 179.51 172.21 165.50 160.02 155.11 150.78 145.56 140.63

346.2329 342.8432 339.4864 336.1620 332.8695 329.6084 326.3783 323.1788 320.0094 316.8697 313.7593 310.6778

D

−1

10 ·m′ (mol·kg ) 3

288.15

298.15

mB = 0.15 mol·kg−1 31.56 45.63 28.32 41.49 25.31 39.24 22.44 36.80 mB = 0.35 mol·kg−1 198.65 239.53 189.30 232.30 182.43 224.98 172.32 216.34 164.78 210.16 156.57 202.46 146.20 195.58 136.59 189.15 130.81 181.61 125.22 173.83 117.99 168.27 111.20 158.51 102.16 151.82 90.75 146.09 87.99 137.66 79.34 125.83 73.85 119.04 66.11 114.48 60.85 112.30 mB = 0.15 mol·kg−1 52.68 65.25 48.23 60.27 43.10 57.99 38.21 52.92 34.20 48.29 29.08 42.77 25.43 38.22 21.84 35.67 14.47 30.08 9.62 26.24 6.49 21.21 3.00 17.57 −1.13 14.63 −3.88 10.45 −7.74 8.68 −10.92 5.35 −15.85 1.08 −19.22 −3.85 −23.37 −7.85 mB = 0.35 mol·kg−1 155.76 215.57 152.36 211.96 148.78 208.35 143.14 200.99 138.41 197.97 133.51 192.97 129.12 188.08 125.04 182.13 121.86 180.70 118.15 175.26 114.73 172.26 111.11 165.03

308.15

318.15

56.17 53.37 50.33 47.32

64.13 61.06 58.00 54.91

280.62 274.10 266.02 262.20 252.33 245.72 237.26 230.74 220.01 210.03 202.55 193.15 191.20 181.69 173.89 167.60 162.57 158.39 147.87

332.99 324.93 317.00 309.00 300.99 287.92 280.02 277.26 267.98 257.82 251.24 248.21 236.90 233.92 228.55 219.29 208.36 205.61 197.72

73.14 68.67 65.07 60.47 55.51 50.57 46.68 43.22 38.20 34.59 30.40 26.80 23.11 19.12 14.76 12.31 8.99 4.62 1.05

81.51 75.41 70.44 64.98 60.01 55.59 52.53 48.77 44.01 41.80 38.03 34.09 31.56 26.18 22.66 19.42 15.91 11.46 8.14

279.63 275.90 272.34 268.79 265.98 262.89 259.46 257.16 255.64 251.88 245.31 241.17

334.78 327.48 323.12 314.40 311.56 302.46 296.53 290.12 286.83 280.93 272.33 268.10



Article


qd (J·mol−1)

T (K) 10

·mAa

3

−1

(mol·kg )

30.1424 32.2727 34.3789 36.4609 38.5187 40.5522 42.5616

−1

10 ·m′ (mol·kg ) 3

c

219.7320 217.5713 215.4304 213.3090 211.2069 209.1238 207.0594

288.15

mB = 0.25 mol·kg−1 69.15 65.61 58.57 51.63 46.78 45.95 38.51

2.6907 5.1114 7.5079 9.8803 12.2284 14.5523 16.8521 19.1276 21.3789 23.6061 25.8090 27.9878 30.1424 32.2727 34.3789 36.4609 38.5187 40.5522 42.5616

49.4618 48.9776 48.4980 48.0231 47.5528 47.0869 46.6255 46.1684 45.7156 45.2671 44.8228 44.3825 43.9464 43.5143 43.0861 42.6618 42.2414 41.8248 41.4119

2.6907 5.1114 7.5079 9.8803 12.2284 14.5523 16.8521 19.1276 21.3789 23.6061 25.8090 27.9878 30.1424 32.2727 34.3789 36.4609 38.5187 40.5522 42.5616

247.3092 244.8880 242.4903 240.1157 237.7639 235.4346 233.1274 230.8420 228.5782 226.3355 224.1138 221.9127 219.7320 217.5713 215.4304 213.3090 211.2069 209.1238 207.0594

mB = 0.05 mol·kg−1 −135.21 −132.11 −129.76 −125.81 −122.17 −121.05 −117.00 −116.94 −113.91 −110.71 −108.70 −107.49 −104.58 −103.18 −102.20 −99.68 −96.75 −96.02 −93.19 mB = 0.25 mol·kg−1 74.79 70.68 63.21 55.89 48.53 43.18 35.03 28.94 24.02 16.12 6.77 −0.49 −5.70 −7.55 −16.16 −21.37 −30.25 −34.95 −41.03

2.6907 5.1114 7.5079 9.8803 12.2284 14.5523 16.8521 19.1276

49.4618 48.9776 48.4980 48.0231 47.5528 47.0869 46.6255 46.1684

mB = 0.05 mol·kg−1 −283.51 −281.52 −278.95 −273.74 −268.25 −266.57 −262.05 −257.26

298.15

T (K) 308.15

318.15

c

86.67 109.94 138.83 307.6248 81.99 105.73 134.13 304.5998 78.70 100.78 130.37 301.6026 73.71 98.72 126.51 298.6326 70.57 92.49 122.00 295.6897 66.24 89.79 120.88 292.7733 60.72 83.83 117.35 289.8831 2-Deoxy-D-glucose (M = 164.16 g·mol−1) −113.47 −110.78 −109.86 −107.54 −104.33 −103.34 −100.63 −96.88 −96.09 −94.70 −92.16 −89.41 −88.64 −86.25 −84.63 −83.81 −81.83 −79.65 −75.89

−82.25 −81.51 −79.29 −77.28 −75.19 −72.74 −70.20 −68.21 −66.10 −63.07 −61.89 −59.80 −57.86 −57.56 −55.03 −54.26 −51.05 −49.67 −48.15

−57.19 −54.68 −52.83 −49.49 −47.98 −44.75 −40.97 −39.90 −38.89 −36.06 −34.69 −30.98 −28.07 −26.42 −22.77 −21.58 −18.56 −16.31 −14.07

148.3855 146.9328 145.4942 144.0694 142.6583 141.2607 139.8764 138.5052 137.1469 135.8013 134.4683 133.1476 131.8392 130.5428 129.2582 127.9854 126.7241 125.4743 124.2356

100.06 135.88 160.65 346.2329 92.70 127.83 155.13 342.8432 88.02 120.52 148.86 339.4864 79.09 114.70 145.15 336.1620 73.51 105.40 139.35 332.8695 68.30 100.09 129.89 329.6084 60.48 92.11 123.33 326.3783 50.24 85.33 120.32 323.1788 45.55 79.42 116.91 320.0094 39.09 70.01 106.73 316.8697 30.04 62.62 99.33 313.7593 25.43 58.59 96.64 310.6778 20.58 52.36 89.94 307.6248 16.15 44.68 84.37 304.5998 10.10 39.14 79.95 301.6026 −0.71 35.05 75.41 298.6326 −5.22 28.52 70.84 295.6897 −15.79 22.32 67.63 292.7733 −20.94 18.21 62.90 289.8831 (+)-Methyl-α-D-glucopyranoside (M = 194.18 g·mol−1) −235.44 −232.15 −229.68 −223.40 −218.08 −216.24 −211.69 −206.77

−202.75 −199.41 −197.15 −194.66 −191.29 −187.51 −182.78 −180.06

−183.53 −181.74 −178.94 −172.55 −171.09 −165.80 −164.14 −161.07 E

−1

10 ·m′ (mol·kg ) 3

148.3855 146.9328 145.4942 144.0694 142.6583 141.2607 139.8764 138.5052

288.15

298.15

mB = 0.35 mol·kg−1 105.10 164.12 104.36 160.18 101.05 155.66 97.35 152.45 92.59 148.77 90.28 142.56 85.24 138.54 mB = 0.15 mol·kg−1 −80.39 −58.46 −83.78 −61.56 −87.71 −65.00 −89.55 −69.09 −94.30 −73.00 −94.88 −75.42 −98.17 −78.52 −100.38 −80.91 −105.39 −84.81 −107.81 −88.27 −109.36 −91.07 −112.05 −94.71 −114.86 −96.50 −115.89 −99.64 −117.00 −102.07 −121.95 −105.51 −125.68 −109.33 −129.11 −112.87 −132.75 −116.55 mB = 0.35 mol·kg−1 122.62 190.90 118.35 182.98 114.16 178.77 108.45 170.04 104.03 165.14 98.68 156.72 94.90 150.48 88.03 139.94 83.72 130.81 79.54 121.96 77.43 118.55 73.88 111.75 68.55 102.96 66.43 95.65 62.28 90.53 58.65 85.26 55.25 81.56 51.56 75.25 46.35 65.14 mB = 0.15 mol·kg−1 −108.07 −87.11 −112.05 −91.45 −116.05 −95.36 −119.01 −99.50 −122.83 −102.76 −124.97 −106.95 −126.76 −110.57 −131.52 −112.43

308.15

318.15

238.60 235.06 233.13 229.71 222.00 217.89 216.32

261.58 259.23 252.71 244.94 242.34 235.93 231.66

−27.99 −34.55 −40.05 −45.02 −46.82 −53.08 −58.81 −60.01 −65.05 −70.56 −73.22 −77.30 −82.02 −85.96 −89.43 −92.69 −97.95 −100.73 −104.39

−5.26 −8.22 −12.76 −16.22 −21.05 −24.53 −27.77 −31.75 −35.61 −38.78 −42.81 −45.62 −50.16 −53.27 −56.07 −58.67 −62.87 −67.24 −71.06

253.84 245.89 235.82 227.49 219.27 210.84 202.93 193.86 187.89 181.08 175.26 166.84 160.90 152.98 145.85 142.72 132.90 125.75 116.29

307.20 298.41 290.07 282.34 272.17 267.30 261.64 255.75 245.49 237.00 233.23 229.26 219.20 211.12 206.65 199.55 192.55 186.52 178.52

−67.09 −69.69 −73.31 −77.52 −81.89 −86.14 −88.63 −93.61

−43.47 −48.02 −51.30 −56.02 −58.95 −63.14 −65.18 −70.16



Article


qd (J·mol−1)

T (K) 10

·mAa

3

−1

(mol·kg )

−1

10 ·m′ (mol·kg ) 3

c

21.3789 23.6061 25.8090 27.9878 30.1424 32.2727 34.3789 36.4609 38.5187 40.5522 42.5616

45.7156 45.2671 44.8228 44.3825 43.9464 43.5143 43.0861 42.6618 42.2414 41.8248 41.4119

2.6907 5.1114 7.5079 9.8803 12.2284 14.5523 16.8521 19.1276 21.3789 23.6061 25.8090 27.9878 30.1424 32.2727 34.3789 36.4609 38.5187 40.5522 42.5616

247.3092 244.8880 242.4903 240.1157 237.7639 235.4346 233.1274 230.8420 228.5782 226.3355 224.1138 221.9127 219.7320 217.5713 215.4304 213.3090 211.2069 209.1238 207.0594

2.6907 5.1114 7.5079 9.8803 12.2284 14.5523 16.8521 19.1276 21.3789 23.6061 25.8090 27.9878 30.1424 32.2727 34.3789 36.4609 38.5187 40.5522 42.5616

49.4618 48.9776 48.4980 48.0231 47.5528 47.0869 46.6255 46.1684 45.7156 45.2671 44.8228 44.3825 43.9464 43.5143 43.0861 42.6618 42.2414 41.8248 41.4119

2.6907 5.1114 7.5079 9.8803 12.2284

247.3092 244.8880 242.4903 240.1157 237.7639

288.15

mB = 0.05 mol·kg−1 −255.47 −252.60 −248.40 −244.59 −242.36 −238.69 −235.28 −233.88 −229.81 −225.57 −220.44 mB = 0.25 mol·kg−1 135.60 131.93 128.27 123.81 117.51 113.31 107.74 99.19 92.90 87.34 82.72 79.09 73.17 69.88 66.40 62.22 55.75 51.66 48.40 mB = 0.05 mol·kg−1 −226.06 −223.92 −220.34 −216.17 −213.83 −213.30 −211.94 −207.26 −205.65 −201.90 −200.03 −197.44 −195.30 −191.95 −187.21 −185.40 −183.24 −181.64 −177.01 mB = 0.25 mol·kg−1 0.12 −4.85 −8.83 −11.06 −17.18

298.15 −203.08 −200.64 −196.15 −192.59 −189.79 −185.67 −182.55 −179.23 −176.27 −173.26 −171.75

T (K) 308.15

318.15

−174.29 −169.97 −166.15 −162.58 −160.34 −156.48 −154.21 −152.53 −149.57 −144.84 −142.29

161.69 157.70 152.86 146.55 139.50 135.31 130.53 123.09 118.89 116.55 110.89 103.95 99.93 95.34 90.46 83.80 82.64 78.27 73.69 (+)-Maltose

−158.70 −157.64 −154.85 −150.79 −147.99 −146.15 −142.51 −139.99 −135.50 −133.51 −129.34

c

137.1469 135.8013 134.4683 133.1476 131.8392 130.5428 129.2582 127.9854 126.7241 125.4743 124.2356

185.65 217.53 346.2329 181.12 210.64 342.8432 175.28 205.68 339.4864 171.25 200.32 336.1620 163.42 191.87 332.8695 157.71 185.52 329.6084 154.57 179.69 326.3783 149.59 168.90 323.1788 141.58 165.65 320.0094 139.03 157.10 316.8697 132.84 152.52 313.7593 128.22 148.32 310.6778 125.06 141.89 307.6248 120.41 138.09 304.5998 115.66 133.31 301.6026 112.75 127.16 298.6326 109.48 118.46 295.6897 102.39 116.86 292.7733 97.38 114.36 289.8831 Monohydrate (M = 360.31 g·mol−1)

−189.75 −186.12 −183.47 −182.01 −178.33 −177.76 −176.13 −175.70 −171.74 −169.28 −167.28 −165.87 −163.72 −162.09 −160.06 −156.53 −153.89 −152.97 −150.20

−168.92 −166.74 −164.83 −161.90 −160.29 −156.82 −153.56 −149.94 −148.30 −145.67 −143.27 −141.55 −138.82 −136.93 −136.18 −134.38 −132.11 −129.88 −128.05

−154.82 −154.23 −151.01 −148.36 −145.55 −143.07 −139.86 −136.23 −133.19 −130.88 −127.65 −124.69 −121.13 −118.17 −116.58 −114.19 −113.81 −110.83 −108.88

148.3855 146.9328 145.4942 144.0694 142.6583 141.2607 139.8764 138.5052 137.1469 135.8013 134.4683 133.1476 131.8392 130.5428 129.2582 127.9854 126.7241 125.4743 124.2356

35.34 29.83 26.49 20.21 15.05

68.60 62.49 56.65 51.34 42.57

89.43 82.21 77.49 72.46 65.23

346.2329 342.8432 339.4864 336.1620 332.8695

F

−1

10 ·m′ (mol·kg ) 3

288.15

298.15

mB = 0.15 mol·kg−1 −133.03 −116.32 −136.52 −116.90 −138.08 −121.09 −144.46 −125.22 −145.79 −126.89 −147.94 −129.61 −151.04 −133.00 −155.13 −137.85 −158.81 −140.98 −160.42 −141.52 −162.27 −143.62 mB = 0.35 mol·kg−1 188.09 238.30 179.06 226.18 169.63 215.00 158.08 205.94 144.73 196.11 130.67 185.82 122.97 171.72 108.34 161.23 99.81 151.00 90.98 140.59 82.56 130.50 69.77 120.44 58.59 105.89 44.47 95.99 35.64 85.35 22.83 71.01 11.38 66.07 1.16 57.83 −2.72 43.31 mB = 0.15 mol·kg−1 −113.49 −95.82 −109.37 −93.70 −109.34 −93.40 −105.27 −90.74 −102.62 −88.13 −101.35 −86.97 −98.76 −84.56 −95.88 −82.37 −93.47 −81.38 −92.15 −80.73 −89.61 −78.30 −87.47 −75.76 −85.65 −76.08 −84.36 −72.72 −82.40 −72.02 −80.47 −70.92 −79.28 −68.97 −77.90 −66.99 −75.14 −64.66 mB = 0.35 mol·kg−1 −1.12 40.51 −8.40 33.35 −15.03 25.33 −23.24 20.44 −28.34 11.21

308.15

318.15

−95.48 −97.41 −100.63 −105.13 −109.05 −111.11 −113.01 −116.12 −119.42 −122.21 −127.98

−73.16 −77.43 −83.55 −84.48 −88.25 −94.95 −97.12 −100.52 −104.64 −108.19 −112.72

291.89 286.99 270.81 263.38 255.39 246.86 239.95 231.91 217.95 208.42 202.58 187.36 182.71 173.04 165.90 162.93 152.36 144.57 138.14

338.10 328.05 324.11 316.93 311.13 310.51 300.04 292.02 283.28 280.12 275.77 269.34 265.01 263.83 255.70 249.98 241.91 239.53 230.12

−82.81 −80.51 −79.40 −77.16 −75.25 −73.24 −71.29 −69.94 −68.17 −65.26 −63.70 −62.85 −60.36 −59.10 −56.11 −55.24 −54.14 −53.43 −52.33

−74.34 −71.93 −70.25 −68.45 −67.08 −64.90 −62.64 −61.42 −59.37 −57.98 −56.25 −54.30 −52.01 −50.41 −49.87 −47.57 −46.05 −45.72 −43.67

78.33 71.01 62.75 55.18 46.89

113.99 105.52 100.90 92.55 85.74



Article


qd (J·mol−1)

T (K) 10

·mAa

3

−1

(mol·kg )

−1

10 ·m′ (mol·kg ) 3

14.5523 16.8521 19.1276 21.3789 23.6061 25.8090 27.9878 30.1424 32.2727 34.3789 36.4609 38.5187 40.5522 42.5616

c

235.4346 233.1274 230.8420 228.5782 226.3355 224.1138 221.9127 219.7320 217.5713 215.4304 213.3090 211.2069 209.1238 207.0594

288.15

mB = 0.25 mol·kg−1 −21.11 −24.35 −28.55 −33.12 −34.35 −40.73 −41.36 −43.71 −48.95 −51.26 −57.05 −60.36 −62.63 −68.18

298.15

T (K) 308.15

9.78 7.22 3.69 −2.12 −4.64 −8.85 −14.66 −19.26 −21.76 −25.29 −32.43 −37.30 −41.02 −45.32

318.15

−1

10 ·m′ (mol·kg ) c

3

38.99 62.64 32.99 57.40 28.98 52.25 21.80 45.26 19.43 40.66 12.47 35.80 7.10 31.24 1.45 26.21 −2.65 21.23 −4.36 16.40 −12.49 12.51 −20.49 9.09 −24.11 5.21 −30.34 1.95 Pyridoxine HCl

288.15

298.15

mB = 0.35 mol·kg−1 −35.93 2.61 −42.90 −1.81 −49.00 −5.57 −55.26 −15.08 −62.98 −22.27 −67.57 −32.13 −72.61 −38.17 −78.13 −46.00 −86.09 −51.20 −90.77 −59.47 −95.91 −68.09 −100.83 −72.49 −108.72 −78.66 −112.90 −85.53

329.6084 326.3783 323.1788 320.0094 316.8697 313.7593 310.6778 307.6248 304.5998 301.6026 298.6326 295.6897 292.7733 289.8831

qd (J·mol−1) −1

10 ·mA (mol·kg ) a

−1

10 ·m′ (mol·kg ) 3

c

288.15

298.15

318.15

37.13 31.05 21.60 12.81 8.50 1.04 −8.09 −12.13 −21.95 −31.06 −35.18 −40.21 −44.26 −50.52

79.18 68.31 61.34 51.36 47.50 40.63 37.79 31.47 20.71 13.87 8.65 1.85 −2.80 −10.85

qd (J·mol−1)

T (K) 3

308.15

T (K) 308.15

318.15

−1

10 ·m′ (mol·kg ) 3

c

288.15

298.15

308.15

318.15

22.55 22.03 21.16 20.54 20.03 19.23 18.75 18.09 17.37 16.76 16.03 15.41 14.29 13.68 12.94 12.10 11.32 10.70 9.73

28.97 28.24 27.30 26.57 25.97 24.82 24.09 23.45 22.60 22.15 20.65 20.50 19.63 18.99 18.19 17.00 16.12 15.74 14.66

201.08 196.16 192.00 185.19 179.05 173.03 167.57 163.88 159.43 151.01 149.09 141.03 137.45 132.07 128.90 124.04 121.46

233.81 229.02 224.21 217.04 211.42 206.19 201.91 196.08 191.26 184.10 177.59 173.82 167.47 161.96 155.71 150.70 148.57

(+)-D-Xylose (M = 150.13 g·mol−1) 2.6907 5.1114 7.5079 9.8803 12.2284 14.5523 16.8520 19.1276 21.3789 23.6061 25.8090 27.9878 30.1423 32.2727 34.3789 36.4609 38.5186 40.5522 42.5616

49.4618 48.9776 48.4980 48.0231 47.5528 47.0869 46.6255 46.1684 45.7156 45.2671 44.8228 44.3825 43.9464 43.5143 43.0861 42.6618 42.2414 41.8248 41.4119

2.6907 5.1114 7.5079 9.8803 12.2284 14.5523 16.8521 19.1276 21.3789 23.6061 25.8090 27.9878 30.1424 32.2727 34.3789 36.4609 38.5187

247.3092 244.8880 242.4903 240.1157 237.7639 235.4346 233.1274 230.8420 228.5782 226.3355 224.1138 221.9127 219.7320 217.5713 215.4304 213.3090 211.2069

mB = 0.05 mol·kg−1 −77.22 −74.91 −73.45 −73.02 −71.57 −69.21 −68.15 −66.97 −66.10 −63.88 −63.14 −61.06 −59.58 −58.04 −56.45 −54.75 −54.71 −54.01 −52.38 mB = 0.25 mol·kg−1 51.81 50.07 48.52 47.50 45.50 44.22 42.96 41.48 39.92 38.29 36.21 34.66 33.78 32.09 30.23 28.73 26.70

−62.61 −62.32 −61.04 −60.12 −59.16 −57.90 −57.64 −56.56 −56.47 −55.31 −55.04 −54.46 −53.80 −53.01 −51.79 −51.50 −51.28 −49.77 −48.87

−43.52 −42.08 −41.59 −40.60 −39.27 −38.71 −37.49 −36.82 −36.30 −35.27 −34.72 −33.95 −33.56 −32.88 −31.90 −31.35 −31.08 −30.38 −29.45

−40.84 −39.75 −38.60 −37.67 −36.10 −34.53 −33.59 −33.09 −32.29 −31.16 −29.98 −29.20 −27.99 −26.11 −25.02 −24.18 −22.73 −21.70 −21.27

148.3855 146.9328 145.4942 144.0694 142.6583 141.2607 139.8764 138.5052 137.1469 135.8013 134.4683 133.1476 131.8392 130.5428 129.2582 127.9854 126.7241 125.4743 124.2356

59.44 57.94 55.64 54.63 53.18 51.90 48.43 46.99 44.81 42.73 41.26 38.54 37.15 34.24 33.85 31.43 29.02

82.08 81.66 79.86 76.54 75.52 73.83 72.51 70.95 69.52 68.51 67.46 66.37 65.10 62.54 62.07 59.98 59.57

90.66 89.88 88.85 88.13 87.39 86.62 85.55 84.68 83.84 83.18 82.57 82.02 81.24 80.62 79.23 78.40 77.85

346.2329 342.8432 339.4864 336.1620 332.8695 329.6084 326.3783 323.1788 320.0094 316.8697 313.7593 310.6778 307.6248 304.5998 301.6026 298.6326 295.6897

G

mB = 0.15 −16.16 −16.58 −16.91 −17.20 −17.80 −18.77 −19.26 −19.82 −20.14 −20.54 −21.04 −21.28 −21.82 −22.40 −22.83 −23.29 −23.72 −24.69 −24.69 mB = 0.35 112.86 107.32 103.94 99.29 94.33 91.25 88.14 84.17 81.38 78.18 74.18 71.86 66.44 63.66 59.48 55.42 52.28

mol·kg−1 −8.49 −8.84 −9.35 −9.65 −10.10 −10.47 −10.81 −11.21 −11.40 −11.66 −12.01 −12.52 −12.76 −13.19 −13.70 −14.17 −14.55 −14.98 −15.23 mol·kg−1 138.73 134.94 130.70 128.78 123.82 120.44 116.43 115.00 112.48 108.79 104.96 100.78 97.08 92.68 91.80 87.70 83.02



Article

Table 2. continued Pyridoxine HCl qd (J·mol−1)

qd (J·mol−1)

T (K) −1

10 ·mA (mol·kg ) 3

a

40.5522 42.5616

−1

10 ·m′ (mol·kg ) 3

c

288.15

mB = 0.25 mol·kg−1 209.1238 24.94 207.0594 24.21

2.6907 5.1114 7.5079 9.8803 12.2284 14.5523 16.8520 19.1276 21.3789 23.6061 25.8090 27.9878 30.1423 32.2727 34.3789 36.4609 38.5186 40.5522 42.5616

49.4618 48.9776 48.4980 48.0231 47.5528 47.0869 46.6255 46.1684 45.7156 45.2671 44.8228 44.3825 43.9464 43.5143 43.0861 42.6618 42.2414 41.8248 41.4119

2.6907 5.1114 7.5079 9.8803 12.2284 14.5523 16.8521 19.1276 21.3789 23.6061 25.8090 27.9878 30.1424 32.2727 34.3789 36.4609 38.5187 40.5522 42.5616

247.3092 244.8880 242.4903 240.1157 237.7639 235.4346 233.1274 230.8420 228.5782 226.3355 224.1138 221.9127 219.7320 217.5713 215.4304 213.3090 211.2069 209.1238 207.0594

mB = 0.05 mol·kg−1 −22.23 −21.75 −21.18 −20.64 −20.06 −19.43 −18.98 −18.09 −17.37 −17.08 −16.33 −15.71 −14.81 −13.97 −13.61 −12.47 −12.31 −11.95 −11.60 mB = 0.25 mol·kg−1 52.57 51.99 51.34 50.84 49.66 48.11 47.71 47.30 46.06 45.20 44.17 43.25 41.67 40.99 39.85 38.73 37.85 37.51 36.68

2.6907 5.1114 7.5079 9.8803 12.2284 14.5523 16.8520 19.1276 21.3789 23.6061 25.8090 27.9878 30.1423

49.4618 48.9776 48.4980 48.0231 47.5528 47.0869 46.6255 46.1684 45.7156 45.2671 44.8228 44.3825 43.9464

mB = 0.05 mol·kg−1 −45.98 −45.49 −44.62 −44.18 −43.21 −42.41 −41.77 −40.44 −39.41 −38.84 −38.49 −37.45 −36.45

298.15 27.64 25.54

−7.77 −7.52 −7.18 −6.90 −6.69 −6.51 −6.24 −5.87 −5.54 −5.25 −5.05 −4.81 −4.40 −3.98 −3.60 −3.27 −3.15 −2.79 −2.55

T (K) 308.15

318.15

57.66 77.29 56.61 76.71 Xylitol (M = 152.15 g·mol−1) −2.61 −2.45 −2.25 −2.11 −1.96 −1.79 −1.66 −1.51 −1.33 −1.24 −1.04 −0.92 −0.76 −0.63 −0.44 −0.36 −0.32 −0.11 −0.07

0.50 0.56 0.78 0.96 1.13 1.25 1.47 1.62 1.75 1.94 2.12 2.30 2.40 2.54 2.70 2.79 2.92 3.11 3.20

64.80 78.04 85.36 64.68 77.75 83.98 63.76 76.48 83.37 62.05 75.31 82.45 61.74 75.03 80.98 61.12 73.63 80.17 59.10 72.17 78.91 58.17 71.11 77.89 57.00 69.93 76.35 56.37 69.00 75.75 55.61 68.04 74.62 54.71 67.28 73.28 53.15 66.07 71.88 51.73 64.65 70.08 50.95 63.00 69.53 49.81 62.49 68.25 49.14 61.77 67.71 47.62 60.94 66.88 46.80 59.81 65.69 (+)-D-Glucose (M = 180.16 g·mol−1) −42.23 −41.80 −41.11 −40.00 −38.97 −38.29 −37.38 −36.26 −35.95 −35.30 −34.20 −33.71 −32.89

−34.45 −33.67 −32.79 −32.19 −31.86 −31.39 −30.98 −30.26 −29.39 −29.22 −28.29 −27.72 −27.16

−27.58 −27.02 −26.52 −26.03 −25.84 −25.26 −24.98 −24.60 −24.28 −24.16 −23.75 −23.23 −22.74 H

−1

10 ·m′ (mol·kg ) 3

c

292.7733 289.8831

288.15

298.15

mB = 0.35 mol·kg−1 50.25 79.06 47.54 75.19

308.15

318.15

116.37 111.93

145.83 139.28

mol·kg−1 36.32 35.34 34.65 34.28 33.15 32.81 31.97 31.09 30.33 28.83 27.57 27.02 26.19 25.66 24.26 24.07 23.13 22.22 21.17 mol·kg−1 112.43 108.29 106.01 103.11 100.59 97.76 95.22 93.06 90.34 88.33 85.06 82.26 77.84 74.64 73.46 71.09 67.26 64.56 62.49

43.03 42.35 41.15 40.72 40.59 39.33 38.78 37.88 37.52 36.51 35.92 35.52 35.17 34.37 33.88 33.33 32.95 31.72 30.71

50.34 48.34 47.91 46.75 45.95 45.05 44.13 43.69 41.82 40.94 40.13 39.29 39.19 38.53 37.84 37.06 36.09 35.05 34.14

346.2329 342.8432 339.4864 336.1620 332.8695 329.6084 326.3783 323.1788 320.0094 316.8697 313.7593 310.6778 307.6248 304.5998 301.6026 298.6326 295.6897 292.7733 289.8831

mB = 0.15 25.89 25.29 24.69 23.97 23.44 22.70 21.33 20.66 20.52 19.65 19.18 17.98 17.01 16.42 15.80 15.34 14.37 13.59 12.60 mB = 0.35 77.88 75.35 72.50 68.87 66.55 63.96 62.30 59.36 56.75 55.13 52.88 50.99 48.18 45.46 42.87 40.52 39.03 38.24 35.85

171.36 169.67 164.01 159.21 158.23 151.80 146.55 144.21 141.04 140.17 137.10 132.79 127.01 125.12 119.30 114.99 112.95 108.90 103.64

205.98 199.80 195.92 190.67 185.43 181.25 177.42 172.80 168.77 163.00 158.14 153.08 146.61 141.38 139.11 134.50 132.37 130.06 125.61

148.3855 146.9328 145.4942 144.0694 142.6583 141.2607 139.8764 138.5052 137.1469 135.8013 134.4683 133.1476 131.8392

mB = 0.15 mol·kg−1 22.16 27.41 21.76 26.76 21.19 26.40 21.01 25.90 20.59 25.46 19.76 25.26 19.27 24.91 18.52 24.19 18.03 23.90 17.59 23.49 17.04 23.00 16.21 22.23 15.79 21.90

32.60 31.99 31.77 31.56 31.38 30.77 30.41 30.27 29.90 29.61 28.99 28.86 28.42

42.19 41.58 41.24 40.71 40.24 39.88 39.41 39.01 38.41 38.21 37.86 37.45 37.05

148.3855 146.9328 145.4942 144.0694 142.6583 141.2607 139.8764 138.5052 137.1469 135.8013 134.4683 133.1476 131.8392 130.5428 129.2582 127.9854 126.7241 125.4743 124.2356



Article


qd (J·mol−1)

T (K) −1

10 ·mA (mol·kg ) 3

a

−1

10 ·m′ (mol·kg ) 3

c

32.2727 34.3789 36.4609 38.5186 40.5522 42.5616

43.5143 43.0861 42.6618 42.2414 41.8248 41.4119

2.6907 5.1114 7.5079 9.8803 12.2284 14.5523 16.8521 19.1276 21.3789 23.6061 25.8090 27.9878 30.1424 32.2727 34.3789 36.4609 38.5187 40.5522 42.5616

247.3092 244.8880 242.4903 240.1157 237.7639 235.4346 233.1274 230.8420 228.5782 226.3355 224.1138 221.9127 219.7320 217.5713 215.4304 213.3090 211.2069 209.1238 207.0594

2.6907 5.1114 7.5079 9.8803 12.2284 14.5523 16.8520 19.1276 21.3789 23.6061 25.8090 27.9878 30.1423 32.2727 34.3789 36.4609 38.5186 40.5522 42.5616

49.4618 48.9776 48.4980 48.0231 47.5528 47.0869 46.6255 46.1684 45.7156 45.2671 44.8228 44.3825 43.9464 43.5143 43.0861 42.6618 42.2414 41.8248 41.4119

2.6907 5.1114 7.5079 9.8803 12.2284 14.5523 16.8521 19.1276 21.3789 23.6061

247.3092 244.8880 242.4903 240.1157 237.7639 235.4346 233.1274 230.8420 228.5782 226.3355

288.15

mB = 0.05 mol·kg−1 −36.16 −35.47 −34.68 −33.76 −33.19 −32.73 mB = 0.25 mol·kg−1 117.57 116.11 114.61 111.32 108.66 107.41 104.62 97.62 96.99 92.17 90.55 86.87 84.07 80.53 78.94 75.05 73.31 71.00 67.30 mB = 0.05 mol·kg−1 −118.12 −116.62 −115.36 −112.92 −110.75 −107.95 −106.61 −103.44 −101.83 −99.86 −98.07 −95.77 −95.45 −93.67 −91.86 −91.20 −88.77 −87.08 −83.60 mB = 0.25 mol·kg−1 15.21 14.06 13.00 12.22 11.55 10.91 9.94 9.42 8.84 8.02

298.15 −32.33 −31.66 −31.28 −30.54 −29.05 −28.65

T (K) 308.15

318.15

−26.43 −25.64 −24.81 −24.61 −23.85 −23.43

−22.48 −22.22 −21.59 −21.03 −20.67 −20.42

133.34 150.30 130.78 146.29 127.89 145.10 123.39 142.05 121.24 139.69 116.82 135.34 113.96 133.91 110.44 129.71 107.47 128.97 104.25 124.46 100.34 123.96 97.28 121.09 94.64 115.59 92.07 113.82 87.26 112.99 83.86 108.85 82.36 106.57 79.22 103.42 77.80 99.61 2-Deoxy-D-glucose (M =

c

130.5428 129.2582 127.9854 126.7241 125.4743 124.2356

161.92 346.2329 159.21 342.8432 155.50 339.4864 155.10 336.1620 152.32 332.8695 146.76 329.6084 145.22 326.3783 143.28 323.1788 141.97 320.0094 139.11 316.8697 135.25 313.7593 133.76 310.6778 129.42 307.6248 129.02 304.5998 127.79 301.6026 123.56 298.6326 121.61 295.6897 118.68 292.7733 117.51 289.8831 164.16 g·mol−1)

−112.19 −110.13 −108.74 −107.08 −104.97 −102.83 −101.35 −98.47 −96.77 −95.76 −93.51 −92.03 −89.76 −88.98 −87.07 −85.84 −84.02 −82.20 −79.47

−98.24 −96.91 −94.53 −91.90 −90.26 −88.91 −86.42 −84.53 −82.56 −79.73 −78.11 −74.68 −73.91 −72.34 −70.59 −67.88 −66.55 −65.59 −65.05

−88.56 −85.92 −83.42 −82.09 −79.73 −76.89 −75.47 −73.89 −71.67 −69.90 −67.73 −66.13 −64.86 −62.68 −60.56 −57.94 −56.82 −55.55 −53.57

148.3855 146.9328 145.4942 144.0694 142.6583 141.2607 139.8764 138.5052 137.1469 135.8013 134.4683 133.1476 131.8392 130.5428 129.2582 127.9854 126.7241 125.4743 124.2356

16.96 16.32 15.49 14.57 13.75 12.95 12.62 12.03 11.18 10.47

19.68 19.10 18.22 17.13 16.57 15.59 14.83 14.31 13.34 13.10

21.54 21.02 20.29 19.26 18.36 17.54 17.00 16.44 15.78 15.22

346.2329 342.8432 339.4864 336.1620 332.8695 329.6084 326.3783 323.1788 320.0094 316.8697

I

−1

10 ·m′ (mol·kg ) 3

288.15

298.15

mB = 0.15 15.29 14.56 13.83 13.77 13.44 12.93 mB = 0.35 313.56 302.85 287.86 276.52 266.48 256.57 242.30 228.12 220.74 207.53 201.27 187.85 182.39 170.28 160.96 154.40 144.62 138.05 128.95

mol·kg−1 21.59 20.64 20.37 19.87 19.40 19.06 mol·kg−1 343.08 332.27 317.55 304.92 296.87 287.54 275.19 265.92 251.72 242.78 231.98 224.10 217.88 205.71 195.52 186.16 184.06 172.89 166.08

mB = 0.15 −63.78 −62.81 −61.90 −60.25 −59.29 −58.41 −57.31 −56.09 −55.26 −53.96 −52.85 −51.83 −51.43 −50.67 −49.94 −48.73 −48.51 −46.83 −45.43 mB = 0.35 76.77 73.93 69.74 65.73 58.51 55.46 51.75 48.00 44.28 37.55

mol·kg−1 −56.69 −55.72 −54.64 −53.27 −52.44 −51.26 −50.69 −49.97 −48.92 −48.19 −46.80 −46.37 −46.04 −45.46 −44.13 −42.69 −41.84 −41.65 −41.20 mol·kg−1 107.96 104.01 101.10 95.51 93.60 89.45 87.22 84.53 78.13 75.68

308.15

318.15

28.07 27.98 27.76 27.51 26.80 26.63

36.70 36.17 35.66 35.42 34.87 34.54

383.63 371.79 357.55 344.65 334.32 324.97 310.96 299.91 291.93 279.98 270.45 261.17 252.69 239.01 235.45 226.05 218.48 207.83 195.91

402.50 395.33 381.56 370.73 362.52 354.69 342.02 335.68 322.30 315.91 309.05 299.56 287.68 279.27 274.97 265.25 257.73 249.83 240.12

−45.03 −44.51 −43.50 −41.93 −41.54 −39.32 −37.73 −36.88 −36.32 −34.51 −33.57 −32.63 −32.04 −30.53 −29.60 −28.92 −28.34 −27.12 −26.49

−40.46 −39.18 −38.07 −37.12 −35.51 −33.45 −31.60 −29.99 −28.99 −28.06 −26.49 −26.39 −24.55 −23.36 −22.65 −20.98 −20.57 −19.06 −18.11

151.48 146.24 139.73 133.43 131.09 128.19 122.08 119.32 113.59 110.58

170.59 161.55 158.06 151.98 146.64 142.93 138.65 136.06 132.70 125.43



Article


qd (J·mol−1)

T (K) −1

10 ·mA (mol·kg ) 3

a

25.8090 27.9878 30.1424 32.2727 34.3789 36.4609 38.5187 40.5522 42.5616

c

224.1138 221.9127 219.7320 217.5713 215.4304 213.3090 211.2069 209.1238 207.0594

2.6907 5.1114 7.5079 9.8803 12.2284 14.5523 16.8520 19.1276 21.3789 23.6061 25.8090 27.9878 30.1423 32.2727 34.3789 36.4609 38.5186 40.5522 42.5616

49.4618 48.9776 48.4980 48.0231 47.5528 47.0869 46.6255 46.1684 45.7156 45.2671 44.8228 44.3825 43.9464 43.5143 43.0861 42.6618 42.2414 41.8248 41.4119

2.6907 5.1114 7.5079 9.8803 12.2284 14.5523 16.8521 19.1276 21.3789 23.6061 25.8090 27.9878 30.1424 32.2727 34.3789 36.4609 38.5187 40.5522 42.5616

247.3092 244.8880 242.4903 240.1157 237.7639 235.4346 233.1274 230.8420 228.5782 226.3355 224.1138 221.9127 219.7320 217.5713 215.4304 213.3090 211.2069 209.1238 207.0594

2.6907 5.1114 7.5079 9.8803 12.2284 14.5523

−1

10 ·m′ (mol·kg ) 3

49.4618 48.9776 48.4980 48.0231 47.5528 47.0869

288.15

298.15

T (K) 308.15

318.15

c

mB = 0.25 mol·kg−1 7.23 9.25 12.28 14.64 313.7593 6.34 9.03 11.76 14.12 310.6778 5.54 8.12 11.06 13.07 307.6248 4.50 7.49 10.24 12.25 304.5998 4.05 6.39 9.26 12.03 301.6026 3.10 5.36 8.64 11.08 298.6326 2.50 4.64 7.73 10.25 295.6897 1.32 4.10 7.29 9.86 292.7733 0.58 3.33 6.98 9.25 289.8831 (+)-Methyl-α-D-glucopyranoside (M = 194.18 g·mol−1) mB = 0.05 mol·kg−1 −199.83 −178.94 −160.58 −141.87 148.3855 −197.01 −175.57 −154.59 −136.74 146.9328 −195.17 −171.44 −151.37 −136.10 145.4942 −192.08 −166.55 −148.14 −133.05 144.0694 −190.00 −163.55 −146.24 −129.14 142.6583 −188.28 −160.56 −143.61 −125.52 141.2607 −185.88 −157.14 −140.07 −123.97 139.8764 −182.89 −153.94 −135.09 −121.80 138.5052 −178.47 −151.26 −134.16 −118.67 137.1469 −175.85 −148.37 −132.38 −118.12 135.8013 −169.90 −143.35 −127.19 −114.54 134.4683 −167.17 −142.73 −123.38 −109.30 133.1476 −165.59 −140.30 −122.41 −107.74 131.8392 −161.86 −136.95 −121.26 −104.91 130.5428 −158.42 −134.41 −114.80 −102.53 129.2582 −155.26 −132.37 −112.70 −98.85 127.9854 −154.47 −130.05 −110.54 −96.36 126.7241 −152.10 −127.41 −107.38 −93.78 125.4743 −147.42 −122.38 −104.63 −91.28 124.2356 mB = 0.25 mol·kg−1 62.32 82.53 108.71 134.46 346.2329 60.62 79.89 106.50 132.61 342.8432 58.96 78.92 104.60 128.92 339.4864 57.87 77.18 102.19 126.67 336.1620 55.79 75.47 100.11 122.93 332.8695 54.89 74.19 98.10 119.59 329.6084 53.90 72.11 92.89 114.13 326.3783 52.36 69.06 90.88 112.08 323.1788 49.85 67.34 88.45 108.64 320.0094 48.70 65.25 84.28 104.63 316.8697 47.15 63.22 82.74 102.85 313.7593 45.25 62.05 79.78 98.94 310.6778 44.32 60.25 77.47 94.97 307.6248 43.40 57.52 75.04 92.24 304.5998 42.46 56.40 70.96 90.59 301.6026 41.98 54.51 69.08 89.02 298.6326 40.46 53.70 67.81 87.54 295.6897 38.39 51.52 67.30 85.58 292.7733 36.47 48.88 64.12 84.57 289.8831 (+)-Maltose Monohydrate (M = 360.31 g·mol−1) mB = 0.05 mol·kg−1 −99.36 −77.65 −58.59 −50.62 148.3855 −99.16 −76.03 −57.31 −50.11 146.9328 −97.72 −75.59 −56.30 −48.63 145.4942 −95.32 −73.84 −55.39 −47.25 144.0694 −92.86 −71.85 −53.56 −45.16 142.6583 −91.65 −71.23 −52.99 −44.42 141.2607 J

−1

10 ·m′ (mol·kg ) 3

288.15

298.15

mB = 0.35 mol·kg−1 33.28 71.30 30.92 69.30 25.58 66.79 22.09 63.32 20.46 59.23 16.68 57.68 13.75 56.75 11.00 52.56 4.70 46.84 mB = 0.15 −60.73 −59.48 −58.46 −56.99 −56.89 −56.14 −55.46 −54.68 −53.76 −52.92 −52.22 −50.71 −50.17 −49.58 −48.38 −47.87 −47.21 −45.33 −45.30 mB = 0.35 235.70 230.83 222.82 212.59 202.73 195.22 187.25 179.43 169.78 162.47 157.24 149.18 141.68 138.49 129.66 125.06 115.30 112.33 105.61

mol·kg−1 −52.45 −50.87 −50.39 −49.23 −48.71 −48.23 −47.34 −45.88 −45.69 −44.82 −43.69 −43.06 −42.04 −41.62 −41.00 −40.41 −39.87 −39.22 −38.04 mol·kg−1 277.87 268.55 263.16 257.80 251.10 244.06 234.15 228.44 218.08 213.09 204.01 195.06 192.03 181.97 176.32 169.93 160.84 156.68 145.41

mB = 0.15 −55.59 −53.72 −52.78 −51.18 −50.04 −48.60

mol·kg−1 −53.83 −52.36 −51.07 −49.61 −47.77 −46.92

308.15

318.15

103.64 97.33 93.79 88.85 85.17 78.30 76.24 76.23 70.52

122.19 119.19 112.20 106.16 103.51 96.54 94.01 91.91 84.35

−44.46 −43.92 −43.51 −42.82 −41.77 −41.00 −40.37 −39.52 −38.72 −37.99 −37.28 −36.78 −36.07 −35.68 −35.40 −34.97 −34.27 −33.35 −32.45

−41.30 −40.25 −39.00 −38.08 −37.10 −36.12 −35.23 −34.53 −33.86 −33.11 −33.03 −31.82 −30.64 −30.23 −29.59 −29.28 −28.62 −27.45 −26.32

320.62 310.45 304.47 296.65 287.79 276.69 270.29 265.87 255.77 242.80 236.81 225.37 220.93 219.95 209.65 202.10 196.85 192.17 187.25

355.54 344.61 337.72 328.01 321.17 312.23 303.47 294.22 288.42 278.74 272.50 262.77 251.10 245.24 232.97 226.83 222.38 215.96 214.11

−41.84 −41.12 −39.98 −39.39 −38.58 −37.90

−38.53 −37.57 −36.68 −35.91 −35.03 −33.74



Article


qd (J·mol−1)

T (K) −1

10 ·mA (mol·kg ) 3

a

−1

10 ·m′ (mol·kg ) 3

c

16.8520 19.1276 21.3789 23.6061 25.8090 27.9878 30.1423 32.2727 34.3789 36.4609 38.5186 40.5522 42.5616

46.6255 46.1684 45.7156 45.2671 44.8228 44.3825 43.9464 43.5143 43.0861 42.6618 42.2414 41.8248 41.4119

2.6907 5.1114 7.5079 9.8803 12.2284 14.5523 16.8521 19.1276 21.3789 23.6061 25.8090 27.9878 30.1424 32.2727 34.3789 36.4609 38.5187 40.5522 42.5616

247.3092 244.8880 242.4903 240.1157 237.7639 235.4346 233.1274 230.8420 228.5782 226.3355 224.1138 221.9127 219.7320 217.5713 215.4304 213.3090 211.2069 209.1238 207.0594

288.15

mB = 0.05 mol·kg−1 −88.64 −88.30 −87.13 −85.13 −82.91 −81.70 −80.21 −78.22 −75.71 −75.17 −73.90 −73.28 −71.92 mB = 0.25 mol·kg−1 −45.05 −42.06 −39.35 −36.05 −33.19 −30.14 −27.15 −24.24 −21.31 −18.75 −15.53 −12.45 −10.15 −8.41 −6.02 −2.83 −0.70 1.44 3.18

298.15

T (K) 308.15

318.15

−1

10 ·m′ (mol·kg ) 3

c

−70.42 −68.33 −66.98 −65.81 −65.04 −63.29 −62.33 −60.71 −59.79 −58.88 −57.29 −55.88 −54.24

−52.65 −51.38 −50.12 −48.70 −47.86 −47.16 −46.43 −45.19 −44.61 −44.23 −42.83 −41.81 −40.77

−42.80 −42.09 −41.60 −40.54 −38.69 −37.94 −37.08 −35.80 −34.48 −33.37 −31.98 −31.30 −29.82

139.8764 138.5052 137.1469 135.8013 134.4683 133.1476 131.8392 130.5428 129.2582 127.9854 126.7241 125.4743 124.2356

−40.20 −37.62 −35.26 −31.84 −28.84 −26.43 −24.87 −21.66 −18.82 −16.56 −13.80 −10.39 −8.74 −5.89 −4.39 −0.93 1.53 3.68 5.10

−23.94 −21.29 −17.48 −15.18 −12.39 −10.05 −7.55 −5.09 −1.88 0.35 2.95 6.09 8.01 10.81 12.63 16.96 19.57 20.06 22.40

−5.57 −3.27 1.00 3.68 5.75 8.48 10.62 14.50 16.44 20.20 23.07 24.06 27.25 29.96 31.95 36.00 38.71 38.79 42.57

346.2329 342.8432 339.4864 336.1620 332.8695 329.6084 326.3783 323.1788 320.0094 316.8697 313.7593 310.6778 307.6248 304.5998 301.6026 298.6326 295.6897 292.7733 289.8831

288.15

298.15

mB = 0.15 −48.15 −46.33 −45.91 −44.94 −43.10 −42.21 −41.90 −39.98 −38.65 −37.42 −36.61 −35.90 −34.50 mB = 0.35 14.72 13.85 12.93 11.92 10.49 9.66 8.98 7.94 6.56 5.58 4.20 3.39 2.26 1.79 0.58 −0.85 −1.78 −3.07 −3.23

mol·kg−1 −45.11 −44.19 −42.74 −41.79 −40.32 −39.54 −38.04 −36.15 −35.29 −34.13 −33.70 −32.82 −32.52 mol·kg−1 18.63 17.66 16.62 15.45 14.86 13.69 12.93 11.58 10.61 9.79 8.61 7.05 6.22 5.39 4.19 3.13 1.90 0.94 0.08

308.15

318.15

−36.94 −35.66 −34.42 −33.26 −31.99 −31.59 −29.96 −29.17 −28.41 −27.82 −27.24 −26.11 −24.99

−33.20 −31.70 −30.78 −30.25 −29.52 −29.13 −27.90 −27.19 −26.09 −24.66 −22.86 −22.68 −21.85

23.22 21.94 21.05 20.45 19.02 17.57 16.35 15.45 14.68 13.46 12.88 12.07 10.95 10.25 9.14 7.96 6.57 6.27 5.13

33.91 32.88 31.63 29.98 29.17 28.12 26.60 25.70 24.04 23.27 22.25 21.08 19.52 17.92 17.22 16.13 14.67 13.70 12.70

a mA (mol·kg−1) is the molality of solute in (water + thiamine HCl/pyridoxine HCl) solutions. bmB (mol·kg−1) is the molality of (water + thiamine HCl/pyridoxine HCl) solution before first dilution. cm′ (mol·kg−1) is the molality of (water + thiamine HCl/pyridoxine HCl) solution after each dilution. dq (J·mol−1) is the heat change per mole of studied polyhydroxy solute. Standard uncertainties u are u(m) = 2 × 10−4 mol·kg−1, u(q) = 1.49 J·mol−1, u(T) = 0.01 K, and u(p) = 0.5 kPa (the level of confidence is 0.68).

s at 288.15, 298.15, 308.15, and 318.15 K, respectively.20,21 The standard uncertainty in viscosity on average is ±0.01 mPa·s which also includes 1% uncertainty in water used for calibrating the apparatus. 2.4. Nuclear Magnetic Resonance Spectroscopy. Proton (1H) and 13C NMR spectra have been recorded for polyhydroxy solutes in aqueous solutions of vitamins by using a Bruker (AVANCE-III, HD 500 MHz) spectrometer at a probe temperature of 300.15 K. The center of the HDO signal (δ = 4.650 ppm) has been considered as the internal reference (deuterium oxide, D2O, used as lock solvent) for the other nuclei in order to determine the chemical shifts for the studied systems. Proton (1H) and 13C NMR spectra have been recorded for mB = 0.15 mol·kg−1 thiamine HCl and pyridoxine HCl solutions prepared in 9:1 (w/w) H2O−D2O solution. These chemical shifts, δ, were compared with those of ternary systems {polyhydroxy solute + thiamine HCl/pyridoxine HCl + 9:1 (w/w) H2O−D2O}, relative to the solute molality, mA = 0.05 mol·kg−1.

2.3. Viscosity. The viscosities (η) of studied systems in mB = 0.05, 0.15, 0.25, and 0.35 mol·kg−1 thiamine HCl(aq) and pyridoxine HCl(aq) solutions have been calculated from efflux time measurements at T = 288.15, 298.15, 308.15, and 318.15 K by using the equation19 η /ρ = at − b/t

(1)

where ρ is the density of solution (reported earlier18), t is the efflux time, and a and b are the viscometric constants (a = 7.09 × 10−5 mPa·kg−1·m3, b = 0.0675 mPa·kg−1·m3·s2). The solution viscosities were measured by an Ubbelohde type suspended level capillary viscometer at constant temperature using a temperature bath (model: Julabo F-25) within ±0.01 K. The calibration of the viscometer was performed by measuring the efflux time of water from T = 288.15 to 318.15 K. The efflux time was measured using a digital stopwatch having a resolution of ±0.01 s. The average of at least four flow-time readings was used as the final efflux time. The viscosities for pure water taken from the literature are 1.1382, 0.8904, 0.7194, and 0.5963 mPa· K



Article

3. RESULTS AND DISCUSSION 3.1. Limiting Standard Enthalpy of Dilution. The heat change (q) values for saccharides, their derivatives, and sugar

Figure 3. Heat change (q) versus molalities (mA) of solutes: (+)-Dglucose {blue ⧫; red ■; green ▲; purple ×} and 2-deoxy-D-glucose {blue ∗; red ●; blue +; pink -} in mB = 0.15 mol·kg−1 of thiamine HCl at T = 288.15 K {blue ⧫; blue ∗}, 298.15 K {red ■; red ●}, 308.15 K {green ▲; blue +}, and 318.15 K {purple ×; pink -}.

higher molalities of both cosolutes. This may be due to the increase of the dehydration effect of solute molecules caused by an increase in the molality of thiamine HCl and pyridoxine HCl cosolutes. This process is accompanied by endothermic contributions, thus decreasing the overall exothermicity. The heat change for the studied solutes is more exothermic at mB ≈ 0.05 mol·kg−1 in both cosolutes; however, the exothermicity has been observed up to mB = 0.15 mol·kg−1 for 2-de-Glc, Meα-Glc, and Mal. A three-dimensional plot of q versus mA, the molality of (+)-D-glucose, in mB = 0.05 mol·kg−1 thiamine HCl(aq) solutions is given in Figure 1, at T = 288.15, 298.15, 308.15, and 318.15 K. The comparison of q data (Figure 2) shows that the process is accompanied by more exothermicity in the case of thiamine HCl as compared to that of pyridoxine HCl at all of the studied molalities of cosolutes. Me-α-Glc shows more exothermicity as compared to 2-de-Glc and Glc at lower molalities, mB ≈ 0.05 and 0.15 mol·kg−1, of cosolutes, while the process is almost reversed at higher molalities of both cosolutes. Furthermore, higher q values have been found in the case of 2-de-Glc as compared with its parent saccharide, Glc. A comparison of the plot of q values versus mA, the molalities of solutes Glc and 2-de-Glc, in mB = 0.15 mol·kg−1 thiamine

Figure 1. Plot of heat change (q) versus molality (mA) of (+)-Dglucose in mB = 0.05 mol·kg−1 of thiamine HCl at T = (288.15, 298.15, 308.15 and 318.15) K.

alcohol in mB = 0.05, 0.15, 0.25, and 0.35 mol·kg−1 of thiamine HCl(aq) and pyridoxine HCl(aq) solutions at T = 288.15, 298.15, 308.15, and 318.15 K have been obtained from the calorimetric measurements (Table 2). Initially, the process of titration is exothermic, as the heat is released during each injection of added titrant. The exothermicity decreases with increasing molalities of solutes and also with increased temperature (except for Xyol at mB ≈ 0.05 mol·kg−1 thiamine HCl). This may be due to the fact that Xyol, having a linear open-chain structure in the solution, is capable of forming stronger Hbonds and probably interacts more with the hydrophilic (three N, two Cl, one NH2, and one OH) groups present in thiamine HCl at mB = 0.05 mol·kg−1 which contributes more to exothermicity with the rise of temperature. However, the endothermicity has been observed for the studied solutes at the

Figure 2. Heat change (q) versus molalities (mA) of solutes; (+)-D-xylose; blue ⧫, xylitol; red ■, (+)-D-glucose; green ▲, 2-deoxy-D-glucose; purple ×, (+)-methyl-α-D-glucopyranoside; blue ∗, (+)-maltose monohydrate; red ● in mB = 0.05 mol·kg−1 of (a) thiamine HCl and (b) pyridoxine HCl at T = 298.15 K. L



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Figure 4. Plot of limiting standard enthalpies of dilution (ΔdilH°) of (+)-methyl-α-D-glucopyranoside versus molality (mB) in thiamine HCl and pyridoxine HCl as a function of temperature.

endothermic change varies in the following order: L-ascorbic acid < pyridoxine HCl < thiamine HCl. The magnitude of endothermicity is greater at the higher molalities of thiamine HCl due to the presence of an aliphatic (R = −CH2CH2) side chain while lesser in the former cases (L-ascorbic acid, pyridoxine HCl) because of polar −OH groups. However, the exothermicity in the enthalpy change for studied solutes was observed in the presence of L-ascorbic acid(aq) solutions at all molalities and temperatures.17 Furthermore, the ΔdilH° values for the studied sugar alcohol Xyol are less exothermic as compared to those of the respective parent saccharide, Xyl, indicating that Xyl disrupts the water structure to a larger extent as compared to Xyol. In the case of Mal, the ΔdilH° values are less endothermic at the higher molalities of both cosolutes among all of the studied polyhydroxy solutes which may be attributed to the dominance of the hydration process. 3.2. Limiting Standard Enthalpy of Dilution of Transfer. The limiting enthalpies of dilution of transfer (ΔtrΔdilH°) of solutes from water to aqueous solutions of thiamine HCl and pyridoxine HCl were calculated using the following equation:22,23

HCl(aq) is given in Figure 3, over the temperature range 288.15−318.15 K. A linear dependence of heat change was found in almost all cases. Thus, the limiting standard enthalpies of dilution (ΔdilH°) for the studied polyhydroxy solutes have been obtained by least-squares fitting the following equation22,23 to the q data obtained at each temperature as

q = Δdil H ° + mA Sv

(2)

where mA is the molality of the solute in solution and Sv is the empirical slope. The ΔdilH° values for polyhydroxy solutes studied in water are in good agreement with the literature24 values (Table S1). The ΔdilH° values for all of the studied polyhydroxy solutes are negative primarily at mB ≈ 0.05 and 0.15 mol·kg−1 (Table S1), reflecting that the solute−solute/ cosolute interactions are accompanied by an exothermic process.17 The ΔdilH° values tend to be less exothermic and become positive at higher molalities of both cosolutes. Moreover, with an increase in temperature, the ΔdilH° values also become less exothermic, except for Xyol at mB ≈ 0.05 mol· kg−1 thiamine HCl(aq) solutions. An evocative plot of limiting standard enthalpies of dilution, ΔdilH°, of Me-α-Glc versus mB, the molality of thiamine HCl(aq) and pyridoxine HCl(aq) solutions, is given in Figure 4, at all of the investigated molalities and temperatures. The negative values of ΔdilH° at the lower molalities of both cosolutes indicate the predominance of (hydrophilic + hydrophilic) interactions over the (hydrophobic + hydrophilic/hydrophobic) interactions, which are more favorable at low temperatures. The positive ΔdilH° values increase with an increase in the molalities of vitamins (B1 and B6), which may be due to the dominance of the dehydration process over solute−solvent interactions.25 Furthermore, the magnitude of ΔdilH° values is higher at lower molalities of thiamine HCl, which suggests that thiamine HCl containing more hydrophilic (three N, two Cl, one  NH2, and one OH) groups interacts more strongly at these molalities than the pyridoxine HCl containing less hydrophilic (three OH, one N, and one Cl) groups. A similar trend of ΔdilH° values was observed in earlier reported17 calorimetric studies in L-ascorbic acid(aq) where the values were also observed to become less exothermic with increased molality of cosolute and temperature. The comparison of ΔdilH° values for solutes studied in aqueous solutions of vitamins reveals that the exo- to

Δtr Δdil H ° = Δdil H ° {in aqueous cosolute solution} − Δdil H ° {in H 2O(l)}

(3)

The positive ΔtrΔdilH° values of the studied polyhydroxy solutes increase with an increase in molality of both cosolutes as well as with the rise of temperature. In the case of 2-de-Glc (in pyridoxine HCl), the temperature effect is reserved up to mB ≈ 0.25 mol·kg−1 (plots are given in Figure 5). In the case of thiamine HCl, the increase in ΔtrΔdilH° values is more sharp from mB ≈ 0.05 to 0.25 mol·kg−1 in almost all cases of studied solutes (Figure 5a1−f1). The negative ΔtrΔdilH° values have also been observed in some cases at very low molalities of the thiamine HCl. In the case of Me-α-Glc, the ΔtrΔdilH° values are negative at mB ≈ 0.05 mol·kg−1 and T = 288.15 K, while, in Mal, the ΔtrΔdilH° values are negative and show a minimum at mB ≈ 0.05 mol·kg−1 of thiamine HCl (Figure 5e1 and f1). In pyridoxine HCl, the ΔtrΔdilH° values are negative for Xyl, Xyol, and Mal at mB ≈ 0.05 mol·kg−1 and show a dip at this molality and T = 288.15 K (Figure 5a2, b2, and f2). The magnitude of ΔtrΔdilH° values is higher for Me-α-Glc than 2de-Glc and Glc at all of the studied temperatures in the presence of both vitamins. This may be due to the contribution M



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Figure 5. continued

N



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Figure 5. Limiting standard enthalpies of transfer (ΔtrΔdilH°) versus molalities (mB) of (a1,2) (+)-D-xylose, (b1,2) xylitol, (c1,2) (+)-D-glucose, (d1,2) 2-deoxy-D-glucose, (e1,2) (+)-methyl-α-D-glucopyranoside, and (f1,2) (+) maltose monohydrate in thiamine HCl (1) and pyridoxine HCl (2) at ◆, 288.15 K; ■, 298.15 K; ▲, 308.15 K; ×, 318.15 K.

of CH2OCH3 groups leading to high positive ΔtrΔdilH° values as expected for a hydrophobic moiety, that introduces a hydrophobic hydration in the Me-α-Glc derivative.6 In the currently studied ternary systems, the possible types of interactions are (I) (hydrophilic + hydrophilic) interactions between the hydrophilic (OH, CO, and O) polar sites of the solute and hydrophilic (OH, N, S) sites of thiamine HCl and pyridoxine HCl through hydrogen bonding which contribute exothermicity to ΔtrΔdilH° values; (II) (hydrophobic + hydrophobic) interactions between the nonpolar alkyl (R = CH, CH2, CH3) groups of solutes and the nonpolar alkyl chain (R = CH2CH2) of thiamine HCl and the alkyl group (R = CH2) of the pyridoxine HCl molecule, contributing endothermicity to ΔtrΔdilH° values; (III) (hydrophobic + hydrophilic/hydrophobic) interactions between the nonpolar parts of the solute or cosolute molecules and polar/nonpolar parts of both the solute and cosolutes also provide an endothermic contribution to ΔtrΔdilH° values; (IV) partial dehydration of the hydration shells of polar sites of the solute and the hydroxyl (OH) groups of cosolute molecules also contributes endothermicity to ΔtrΔdilH° values. The negative contribution to ΔtrΔdilH° values decreases and becomes positive with increasing molalities of cosolutes as well as temperature, indicating that the (hydrophilic + hydrophilic) or hydrogen bonding interactions are more predominant over the dehydration process at lower molalities and temperatures.7,25 The ΔtrΔdilH° values for the studied solutes follow the order: Mal < Xyl < Xyol < 2-de-Glc < Glc < Me-α-Glc in the case of thiamine HCl and Mal < Xyol < 2-de-Glc < Xyl < Glc < Me-α-Glc in the case of pyridoxine HCl, indicating the significant effects of nature, the molality, mB, of cosolutes, as well as temperature on polyhydroxy solutes. These results indicate that transfer of solutes from water to thiamine HCl(aq) and pyridoxine HCl(aq) solutions is more exothermic and an

energetically favorable process at low molalities of cosolutes and lower temperatures rather than at higher ones. Similar observations for studied solutes were also made from previously reported17 calorimetric studies in L-ascorbic acid(aq) solutions. 3.3. Change in Heat Capacity. The change in heat capacity, ΔdilC°p,2,m, was calculated from the temperature dependence of limiting standard enthalpy of dilution, ΔdilH°, data by using the following equations:22,26 Δdil H ° = A + XT

(4)

Δdil H ° = A + X1T + X 2T 2

(5)

The values of the A, X, X1, and X2 temperature coefficients are given in Table S2. The linear or nonlinear variation of ΔdilH° values with temperature has been chosen by best fit of eqs 4 and 5 to the data with minimum standard deviation. In the case of eq 4, X represents the ΔdilC°p,2,m values, whereas, in the case of eq 5, the differentiation of the equation with respect to temperature gives the ΔdilC°p,2,m (ΔdilC°p,2,m = X1 + 2X2T) values at different temperatures. Overall, the values of A and X2 coefficients are negative and the X and X1 coefficients are positive. The ΔdilC°p,2,m values are positive at all of the investigated temperatures (except for Xyol at mB ≈ 0.05 mol· kg−1 thiamine HCl), leading to a structural increase of polyhydroxy solutes in the presence of both cosolutes (Table 3). The ΔdilC°p,2,m values increase with an increase in the molalities of cosolutes (except in a few cases at mB ≈ 0.05 mol· kg−1) but decrease with the rise of temperature. The decrease in the ΔdilC°p,2,m values with an increase in temperature may be due to the formation of hydrogen bonds by −OH groups of polyhydroxy solutes with water by disrupting the H-bonding network of the solvent molecules.27 Moreover, the positive ΔdilC°p,2,m values indicate that saccharides and their derivatives act as kosmotropes (structure makers), as these enhance the O



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Table 3. Heat Capacity Change ΔdilC°p,2,m at Temperature T and Molality m for the System Polyhydroxy Solute (1) in Solutions of Water (2) + Thiamine HCl/Pyridoxine HCl (3) at Pressure p = 0.1 MPa T (K) mBa (mol·kg−1)

288.15

298.15

T (K) 308.15

mBa (mol·kg−1)

318.15

288.15

298.15

308.15

318.15

−0.26 1.19 1.67 4.44

−0.17 1.19 1.52 4.44

2.57 2.61 2.82 5.69

2.57 2.61 2.82 4.64

1.64 1.09 2.60 3.64

0.31 0.69 1.73 3.16

0.46 0.67 0.97 4.54

−0.14 0.48 0.69 4.54

1.05 0.80 0.21 3.20

1.05 0.80 0.19 3.20

1.31 0.61 1.34 0.62

0.54 0.61 1.34 0.62

Thiamine HCl 0.05b 0.15 0.25 0.35b 0.05b 0.15 0.25b 0.35b 0.05 0.15b 0.25b 0.35

0.05 0.15b 0.25b 0.35b 0.05b 0.15b 0.25b 0.35b 0.05 0.15 0.25b 0.35

(+)-D-Xylose 0.79 0.79 1.73 1.55 2.41 2.18 4.50 4.50 (+)-D-Glucose 0.70 0.70 0.70 1.41 1.05 0.68 2.24 2.24 2.24 6.08 6.08 6.08 (+)-Methyl-α-D-glucopyranoside 5.44 4.05 2.66 2.23 2.23 2.23 2.63 2.63 2.63 5.30 4.86 4.42 0.79 1.90 2.65 4.50

(+)-D-Xylose 1.64 0.94 1.68 1.68 1.32 1.32 4.40 4.40 (+)-D-Glucose 0.66 0.66 0.66 0.63 0.63 0.63 1.39 1.39 1.39 3.10 3.10 3.10 (+)-Methyl-α-D-glucopyranoside 2.57 2.20 1.82 1.04 0.80 0.55 2.51 2.51 2.51 4.61 4.21 3.82 2.33 1.68 1.32 4.40

0.79 1.37 1.94 4.50

0.05 0.15b 0.25 0.35b

0.70 0.32 2.24 6.08

0.05b 0.15b 0.25b 0.35

1.27 0.05 2.23 0.15 2.63 0.25 3.98 0.35 Pyridoxine HCl 0.24 1.68 1.32 4.40

0.05 0.15 0.25 0.35b

0.66 0.63 1.39 3.10

0.05b 0.15b 0.25 0.35b

1.45 0.31 2.51 3.43

0.05 0.15b 0.25b 0.35b

Xylitol −0.43 −0.34 1.19 1.19 1.96 1.81 4.44 4.44 2-Deoxy-D-glucose 2.57 2.57 2.61 2.61 2.82 2.82 7.80 6.74 (+)-Maltose Monohydrate 4.30 2.97 1.89 1.49 4.36 3.48 4.60 4.12 Xylitol 1.67 1.07 1.04 0.85 1.52 1.25 4.54 4.54 2-Deoxy-D-glucose 1.05 1.05 0.80 0.80 0.24 0.22 3.20 3.20 (+)-Maltose Monohydrate 2.86 2.08 0.61 0.61 1.34 1.34 0.62 0.62

mB (mol·kg−1) is the molality of (water + thiamine HCl/pyridoxine HCl) solutions. Standard deviations in the heat capacity change lie in the range 0.36−3.68 J·K−1·mol−1. Standard uncertainties u are u(T) = 0.01 K and u(p) = 0.5 kPa (the level of confidence is 0.68). bValues obtained by using eq 4.

a

(Table S3). The hAB coefficients are higher for Xyol than those of its respective parent saccharide, Xyl. A similar observation for sugar alcohol was made from formerly reported17 calorimetric studies in L-ascorbic acid(aq). The hAB values for Glc increase with the rise of temperature, whereas the reverse effect has been observed in the cases of its deoxy and methoxy derivatives. In the case of Mal, the negative h AB values testify the predominance of the exothermic process mainly at 288.15 and 298.15 K over the endothermic process. Again, the magnitude of hAB values is greater for all of the solutes studied in the case of thiamine HCl(aq) solutions. This trend mainly results from the multiple contributions depending on the nature, concentrations of solute and cosolute, and temperature. Moreover, thiamine HCl having a greater number of hydrophilic groups interacts more with polyhydroxy solutes as compared to pyridoxine HCl and L-ascorbic acid. The observed trend provokes the partial dehydration of the solute’s hydration shells. The dehydration being an endothermic process due to the prevailing release of structured water from the hydration cospheres to the bulk results in the positive pairwise (hAB) enthalpic coefficients, and this effect increases with increasing temperature.31

strength of the H-bonding network of bulk water in the studied cosolutes. However, the negative ΔdilC°p,2,m values in the case of Xyol at mB ≈ 0.05 mol·kg−1 indicate that this sugar alcohol acts as a structure breaker (chaotrope) in thiamine HCl(aq) solutions.22,28 The volumetric studies18 also support the view that saccharides and their derivatives act as kosmotropes in the presence of thiamine HCl(aq) and pyridoxine HCl(aq) solutions. The ΔdilC°p,2,m values for various solutes studied in the presence of various vitamins follow the order L-ascorbic acid < pyridoxine HCl < thiamine HCl, indicating that the water structure enhancing capability of polyhydroxy solutes is more in the presence of thiamine HCl(aq) solutions. 3.4. Enthalpic Interaction Coefficients. The ΔtrΔdilH° values for the studied solutes have been expressed by the McMillan−Mayer theory of solutions29,30 as follows Δtr Δdil H ° {H 2O → cosolute solutions} = 2hABmB + 3hABBmB 2

(6)

where A and B represent the solute and cosolute, respectively. Overall, the pair (hAB) enthalpic interaction coefficients are positive and their values increase with the rise of temperature P



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Table 4. Viscosities η at Temperature T and Molality m for the System Polyhydroxy Solute (1) in Solutions of Water (2) + Thiamine HCl/Pyridoxine HCl (3) at Pressure p = 0.1 MPa η (mPa·s)

η (mPa·s) T (K)

−1

b

mB (mol·kg )

mAa

−1

(mol·kg )

288.15

298.15

308.15

T (K) mBb

318.15

−1

(mol·kg )

mAa

−1

(mol·kg )

288.15

298.15

308.15

318.15

Thiamine HCl 0.0500 0.0500 0.0500 0.0500 0.0500 0.0500 0.0500 0.0500 0.0500 0.1500 0.1500 0.1500 0.1500 0.1500 0.1500 0.1500 0.1500 0.1500 0.2500 0.2500 0.2500 0.2500 0.2500 0.2500 0.2500 0.2500 0.2500 0.3500 0.3500 0.3500 0.3500 0.3500 0.3500 0.3500 0.3500 0.3500

0.0000 0.0410 0.0604 0.0805 0.1004 0.1201 0.1396 0.1598 0.1799 0.0000 0.0408 0.0614 0.0799 0.1004 0.1202 0.1401 0.1600 0.1798 0.0000 0.0404 0.0610 0.0807 0.1005 0.1194 0.1397 0.1601 0.1798 0.0000 0.0408 0.0602 0.0801 0.1002 0.1207 0.1393 0.1602 0.1798

0.0500 0.0500 0.0500 0.0500 0.0500 0.0500 0.0500 0.0500 0.1500 0.1500 0.1500 0.1500 0.1500 0.1500 0.1500 0.1500 0.2500 0.2500

0.0399 0.0597 0.0800 0.0998 0.1199 0.1392 0.1598 0.1796 0.0402 0.0598 0.0795 0.1002 0.1196 0.1400 0.1597 0.1796 0.0401 0.0608

(+)-D-Xylose 1.179 1.203 1.214 1.225 1.240 1.247 1.260 1.272 1.286 1.270 1.299 1.312 1.326 1.341 1.354 1.368 1.379 1.392 1.368 1.398 1.419 1.435 1.449 1.464 1.475 1.492 1.508 1.473 1.514 1.531 1.547 1.563 1.583 1.594 1.616 1.632 (+)-D-Glucose 1.208 1.220 1.235 1.248 1.261 1.274 1.286 1.298 1.300 1.317 1.333 1.349 1.360 1.373 1.388 1.400 1.403 1.420

Xylitol 0.917 0.935 0.944 0.954 0.963 0.970 0.979 0.987 0.996 0.986 1.009 1.020 1.028 1.039 1.047 1.058 1.068 1.078 1.059 1.082 1.093 1.106 1.118 1.129 1.143 1.154 1.164 1.146 1.176 1.188 1.200 1.215 1.228 1.242 1.256 1.265

0.748 0.764 0.771 0.779 0.785 0.792 0.798 0.805 0.811 0.803 0.821 0.829 0.839 0.846 0.855 0.862 0.868 0.876 0.851 0.871 0.880 0.890 0.897 0.906 0.916 0.925 0.935 0.910 0.931 0.942 0.951 0.964 0.974 0.983 0.995 1.006

0.615 0.627 0.632 0.639 0.646 0.650 0.658 0.661 0.667 0.658 0.672 0.679 0.686 0.692 0.697 0.705 0.712 0.719 0.703 0.719 0.728 0.735 0.742 0.748 0.756 0.764 0.771 0.749 0.768 0.775 0.784 0.792 0.801 0.811 0.819 0.827

0.936 0.948 0.959 0.970 0.979 0.988 1.000 1.006 1.010 1.021 1.033 1.042 1.052 1.064 1.074 1.086 1.087 1.097

0.766 0.774 0.781 0.789 0.798 0.805 0.815 0.820 0.822 0.831 0.840 0.851 0.856 0.868 0.874 0.882 0.873 0.883

0.629 0.636 0.642 0.647 0.656 0.663 0.668 0.674 0.673 0.679 0.686 0.695 0.703 0.709 0.716 0.724 0.719 0.728 Q

0.0500 0.0500 0.0500 0.0500 0.0500 0.0500

0.0405 0.0604 0.0797 0.1011 0.1199 0.1401

1.203 1.217 1.227 1.244 1.257 1.269

0.938 0.947 0.956 0.967 0.975 0.982

0.763 0.772 0.779 0.788 0.795 0.801

0.628 0.634 0.640 0.648 0.654 0.659

0.1500 0.1500 0.1500 0.1500 0.1500 0.1500

0.0399 0.0604 0.0801 0.0997 0.1209 0.1385

1.299 1.317 1.329 1.344 1.360 1.373

1.009 1.020 1.031 1.042 1.055 1.063

0.822 0.830 0.840 0.848 0.857 0.866

0.672 0.680 0.687 0.693 0.701 0.708

0.2500 0.2500 0.2500 0.2500 0.2500 0.2500

0.0404 0.0602 0.0800 0.1000 0.1197 0.1400

1.400 1.418 1.438 1.453 1.471 1.486

1.087 1.095 1.111 1.122 1.136 1.149

0.873 0.882 0.892 0.902 0.911 0.920

0.719 0.727 0.735 0.745 0.751 0.759

0.3500 0.3500 0.3500 0.3500 0.3500 0.3500

0.0402 0.0603 0.0801 0.1007 0.1204 0.1401

1.510 1.530 1.553 1.571 1.586 1.606

1.174 1.190 1.206 1.221 1.235 1.248

0.932 0.945 0.955 0.968 0.978 0.989

0.768 0.778 0.787 0.797 0.803 0.812

0.0500 0.0500 0.0500 0.0500 0.0500 0.0500

2-Deoxy-D-glucose 0.0405 1.204 0.0596 1.216 0.0798 1.228 0.1000 1.241 0.1202 1.253 0.1403 1.262

0.934 0.945 0.954 0.961 0.971 0.980

0.764 0.770 0.777 0.784 0.792 0.798

0.627 0.633 0.638 0.645 0.651 0.656

0.1500 0.1500 0.1500 0.1500 0.1500 0.1500

0.0398 0.0603 0.0802 0.1001 0.1201 0.1402

1.298 1.311 1.325 1.339 1.352 1.366

1.006 1.018 1.027 1.036 1.047 1.057

0.818 0.828 0.834 0.844 0.852 0.861

0.671 0.676 0.684 0.691 0.698 0.704

0.2500 0.2500

0.0406 0.0604

1.402 1.417

1.083 1.095

0.869 0.878

0.718 0.726



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Table 4. continued η (mPa·s)

η (mPa·s) T (K)

mBb (mol·kg−1)

mAa (mol·kg−1)

288.15

298.15

308.15

T (K) mBb (mol·kg−1)

318.15

298.15

308.15

318.15

0.2500 0.2500 0.2500 0.2500

2-Deoxy-D-glucose 0.0807 1.431 0.1000 1.446 0.1200 1.462 0.1401 1.476

1.107 1.115 1.127 1.140

0.887 0.896 0.907 0.915

0.733 0.739 0.747 0.755

0.3500 0.3500 0.3500 0.3500 0.3500 0.3500

0.0404 0.0605 0.0798 0.1000 0.1199 0.1402

1.511 1.529 1.545 1.563 1.580 1.597

1.175 1.187 1.200 1.216 1.228 1.239

0.932 0.942 0.952 0.963 0.973 0.984

0.767 0.774 0.782 0.792 0.801 0.809

(+)-Maltose 0.0402 0.0597 0.0797 0.0995 0.1197 0.1391 0.1591 0.1791 0.0401 0.0596 0.0794 0.0993 0.1197 0.1397 0.1593 0.1790 0.0404 0.0599 0.0796 0.0992 0.1196 0.1394 0.1592 0.1791 0.0400 0.0601 0.0795 0.0996 0.1195 0.1395 0.1594 0.1793

(Anhydrous) 1.239 0.966 1.270 0.985 1.295 1.005 1.325 1.029 1.356 1.053 1.379 1.073 1.410 1.092 1.430 1.112 1.338 1.037 1.374 1.063 1.412 1.091 1.442 1.116 1.477 1.137 1.505 1.168 1.543 1.191 1.564 1.214 1.449 1.120 1.493 1.152 1.528 1.178 1.565 1.205 1.605 1.238 1.639 1.270 1.681 1.296 1.714 1.325 1.568 1.222 1.613 1.253 1.658 1.283 1.700 1.324 1.746 1.352 1.786 1.393 1.832 1.419 1.868 1.453

0.788 0.802 0.824 0.840 0.857 0.875 0.890 0.906 0.848 0.868 0.889 0.906 0.931 0.948 0.969 0.987 0.903 0.926 0.945 0.970 0.995 1.021 1.038 1.061 0.965 0.992 1.016 1.041 1.078 1.103 1.130 1.154

0.646 0.661 0.672 0.689 0.705 0.717 0.732 0.745 0.691 0.707 0.724 0.740 0.758 0.777 0.793 0.809 0.743 0.764 0.778 0.803 0.821 0.841 0.853 0.870 0.801 0.821 0.837 0.863 0.880 0.904 0.923 0.948

0.751 0.756 0.764 0.772 0.779 0.786

0.619 0.625 0.631 0.636 0.641 0.647

0.892 0.902 0.911 0.920 0.928 0.938 0.933 0.945 0.956 0.968 0.978 0.989 1.000 1.011

0.736 0.743 0.751 0.759 0.767 0.775 0.768 0.778 0.788 0.796 0.807 0.814 0.821 0.831

0.0500 0.0500 0.0500 0.0500 0.0500 0.0500 0.0500 0.0500 0.1500 0.1500 0.1500 0.1500 0.1500 0.1500 0.1500 0.1500 0.2500 0.2500 0.2500 0.2500 0.2500 0.2500 0.2500 0.2500 0.3500 0.3500 0.3500 0.3500 0.3500 0.3500 0.3500 0.3500

(+)-D-Glucose 0.0801 1.438 1.110 0.1006 1.452 1.122 0.1192 1.466 1.134 0.1396 1.482 1.144 0.1599 1.497 1.155 0.1798 1.514 1.171 0.0400 1.512 1.176 0.0601 1.529 1.189 0.0803 1.547 1.205 0.1002 1.571 1.222 0.1205 1.588 1.234 0.1404 1.606 1.246 0.1598 1.622 1.263 0.1800 1.642 1.274 (+)-Methyl-α-D-glucopyranoside 0.0400 1.207 0.935 0.0601 1.222 0.945 0.0797 1.232 0.954 0.0998 1.243 0.964 0.1196 1.257 0.973 0.1397 1.270 0.984 0.1602 1.282 0.994 0.1795 1.294 1.005 0.0403 1.300 1.004 0.0598 1.312 1.017 0.0801 1.329 1.028 0.1004 1.345 1.039 0.1200 1.361 1.051 0.1399 1.370 1.062 0.1599 1.387 1.073 0.1800 1.397 1.082 0.0402 1.403 1.082 0.0607 1.419 1.093 0.0792 1.431 1.107 0.1004 1.451 1.116 0.1200 1.464 1.130 0.1395 1.479 1.145 0.1599 1.496 1.154 0.1799 1.512 1.164 0.0406 1.513 1.171 0.0600 1.525 1.186 0.0797 1.543 1.203 0.0999 1.563 1.214 0.1198 1.581 1.231 0.1404 1.603 1.242 0.1600 1.622 1.255 0.1800 1.636 1.267

0.762 0.770 0.778 0.785 0.794 0.803 0.811 0.817 0.821 0.829 0.838 0.846 0.855 0.862 0.871 0.879 0.870 0.878 0.888 0.897 0.909 0.916 0.926 0.933 0.932 0.941 0.953 0.966 0.975 0.984 0.994 1.004

0.629 0.0500 0.634 0.0499 0.639 0.0499 0.645 0.0499 0.651 0.0499 0.658 0.0499 0.663 0.0499 0.669 0.0498 0.673 0.1499 0.679 0.1498 0.684 0.1498 0.692 0.1497 0.697 0.1497 0.703 0.1496 0.711 0.1495 0.718 0.1495 0.719 0.2498 0.727 0.2497 0.733 0.2496 0.740 0.2495 0.748 0.2494 0.754 0.2493 0.760 0.2492 0.766 0.2491 0.765 0.3497 0.775 0.3496 0.783 0.3494 0.792 0.3493 0.800 0.3492 0.806 0.3490 0.816 0.3489 0.823 0.3487 Pyridoxine HCl

0.0500 0.0500 0.0500 0.0500 0.0500 0.0500 0.0500 0.0500

0.0000 0.0401 0.0605 0.0808 0.1002 0.1200 0.1401 0.1601

(+)-D-Xylose 1.160 1.182 1.194 1.204 1.216 1.227 1.237 1.245

0.736 0.751 0.757 0.764 0.769 0.775 0.782 0.788

0.607 0.618 0.624 0.629 0.634 0.639 0.644 0.651

0.2500 0.2500 0.2500 0.2500 0.2500 0.2500 0.3500 0.3500 0.3500 0.3500 0.3500 0.3500 0.3500 0.3500

mAa (mol·kg−1)

288.15

Xylitol 0.912 0.928 0.936 0.944 0.951 0.959 0.969 0.976

0.0500 0.0500 0.0500 0.0500 0.0500 0.0500

R

0.0405 0.0601 0.0799 0.0999 0.1193 0.1399

1.185 1.196 1.208 1.220 1.234 1.243

0.930 0.939 0.948 0.956 0.967 0.976



Article


η (mPa·s) T (K)

mBb (mol·kg−1)

mAa (mol·kg−1)

0.0500 0.1500 0.1500 0.1500 0.1500 0.1500 0.1500 0.1500 0.1500 0.1500 0.2500 0.2500 0.2500 0.2500 0.2500 0.2500 0.2500 0.2500 0.2500 0.3500 0.3500 0.3500 0.3500 0.3500 0.3500 0.3500 0.3500 0.3500

0.1800 0.0000 0.0406 0.0598 0.0806 0.1005 0.1199 0.1397 0.1598 0.1797 0.0000 0.0408 0.0605 0.0804 0.0992 0.1195 0.1400 0.1599 0.1800 0.0000 0.0407 0.0605 0.0800 0.1002 0.1196 0.1398 0.1597 0.1802

0.0500 0.0500 0.0500 0.0500 0.0500 0.0500 0.0500 0.0500 0.1500 0.1500 0.1500 0.1500 0.1500 0.1500 0.1500 0.1500 0.2500 0.2500 0.2500 0.2500 0.2500 0.2500 0.2500 0.2500 0.3500 0.3500 0.3500 0.3500

0.0401 0.0606 0.0795 0.0996 0.1193 0.1401 0.1599 0.1799 0.0406 0.0600 0.0800 0.1001 0.1201 0.1400 0.1597 0.1802 0.0402 0.0603 0.0801 0.1002 0.1201 0.1401 0.1598 0.1798 0.0401 0.0600 0.0800 0.1001

288.15

(+)-D-Xylose 1.256 1.209 1.233 1.248 1.259 1.271 1.283 1.292 1.302 1.315 1.256 1.282 1.294 1.306 1.321 1.336 1.347 1.362 1.375 1.304 1.335 1.348 1.362 1.375 1.391 1.406 1.421 1.432 (+)-D-Glucose 1.185 1.197 1.209 1.221 1.233 1.246 1.260 1.271 1.238 1.250 1.263 1.276 1.291 1.301 1.320 1.328 1.288 1.302 1.315 1.330 1.344 1.359 1.373 1.386 1.338 1.352 1.369 1.385

298.15

308.15


318.15

mAa (mol·kg−1)

288.15

298.15

308.15

318.15

Xylitol 0.984 0.944 0.963 0.970 0.981 0.990 0.997 1.007 1.017 1.024 0.982 1.003 1.011 1.021 1.030 1.040 1.049 1.060 1.069 1.019 1.040 1.050 1.062 1.071 1.080 1.095 1.106 1.119

0.794 0.761 0.777 0.784 0.791 0.797 0.803 0.810 0.817 0.825 0.791 0.808 0.815 0.823 0.828 0.838 0.845 0.853 0.861 0.820 0.837 0.845 0.854 0.862 0.871 0.881 0.889 0.898

0.654 0.634 0.646 0.653 0.658 0.664 0.668 0.675 0.680 0.686 0.656 0.669 0.675 0.684 0.689 0.695 0.700 0.706 0.712 0.680 0.695 0.703 0.710 0.715 0.722 0.730 0.737 0.744

0.931 0.940 0.949 0.958 0.966 0.975 0.984 0.993 0.967 0.976 0.985 0.994 1.003 1.015 1.025 1.036 1.005 1.014 1.022 1.037 1.047 1.060 1.069 1.079 1.044 1.056 1.067 1.079

0.750 0.759 0.765 0.773 0.780 0.785 0.793 0.800 0.777 0.784 0.791 0.799 0.807 0.815 0.824 0.832 0.809 0.816 0.825 0.833 0.840 0.848 0.860 0.869 0.839 0.847 0.856 0.868

0.618 0.626 0.630 0.635 0.640 0.647 0.652 0.658 0.648 0.654 0.659 0.665 0.672 0.678 0.684 0.688 0.670 0.677 0.683 0.690 0.697 0.704 0.711 0.718 0.693 0.702 0.711 0.719 S

0.1500 0.1500 0.1500 0.1500 0.1500 0.1500

0.0404 0.0602 0.0796 0.0998 0.1201 0.1398

1.235 1.249 1.262 1.273 1.289 1.300

0.964 0.974 0.984 0.995 1.005 1.015

0.778 0.785 0.793 0.799 0.807 0.816

0.646 0.652 0.659 0.666 0.672 0.677

0.2500 0.2500 0.2500 0.2500 0.2500 0.2500

0.0407 0.0599 0.0799 0.1001 0.1201 0.1399

1.285 1.301 1.313 1.329 1.342 1.356

1.002 1.013 1.025 1.038 1.048 1.058

0.808 0.816 0.825 0.835 0.842 0.849

0.671 0.677 0.684 0.691 0.697 0.704

0.3500 0.3500 0.3500 0.3500 0.3500 0.3500

0.0400 0.0601 0.0800 0.0999 0.1197 0.1401

1.336 1.350 1.365 1.384 1.399 1.415

1.040 1.054 1.065 1.080 1.094 1.104

0.839 0.849 0.858 0.867 0.875 0.884

0.696 0.703 0.711 0.719 0.726 0.733

0.0500 0.0500 0.0500 0.0500 0.0500 0.0500

2-Deoxy-D-glucose 0.0404 1.184 0.0603 1.195 0.0796 1.207 0.0998 1.219 0.1195 1.231 0.1398 1.243

0.930 0.939 0.947 0.955 0.963 0.972

0.751 0.758 0.764 0.770 0.777 0.784

0.618 0.624 0.629 0.634 0.640 0.646

0.1500 0.1500 0.1500 0.1500 0.1500 0.1500

0.0402 0.0604 0.0794 0.1001 0.1199 0.1399

1.236 1.249 1.261 1.275 1.286 1.298

0.966 0.973 0.982 0.994 1.002 1.011

0.776 0.784 0.791 0.798 0.806 0.814

0.645 0.651 0.658 0.665 0.670 0.677

0.2500 0.2500 0.2500 0.2500 0.2500 0.2500

0.0402 0.0601 0.0806 0.0999 0.1200 0.1397

1.287 1.299 1.316 1.329 1.341 1.353

1.003 1.014 1.024 1.034 1.045 1.055

0.808 0.816 0.825 0.832 0.840 0.849

0.669 0.677 0.683 0.689 0.697 0.702

0.3500 0.3500 0.3500 0.3500

0.0402 0.0605 0.0796 0.1001

1.335 1.353 1.366 1.382

1.044 1.056 1.066 1.077

0.838 0.849 0.858 0.866

0.695 0.703 0.711 0.719



Article


η (mPa·s) T (K)

mBb (mol·kg−1) 0.3500 0.3500 0.3500 0.3500 0.0500 0.0500 0.0500 0.0500 0.0500 0.0500 0.0500 0.0500 0.1500 0.1500 0.1500 0.1500 0.1500 0.1500 0.1500 0.1500 0.2500 0.2500 0.2500 0.2500 0.2500 0.2500 0.2500 0.2500 0.3500 0.3500 0.3500 0.3500 0.3500 0.3500 0.3500 0.3500

mAa (mol·kg−1)

288.15

298.15

(+)-D-Glucose 0.1201 1.402 1.090 0.1397 1.416 1.102 0.1600 1.431 1.114 0.1799 1.446 1.129 (+)-Methyl-α-D-glucopyranoside 0.0402 1.189 0.933 0.0600 1.199 0.942 0.0799 1.213 0.949 0.0998 1.223 0.959 0.1197 1.236 0.967 0.1398 1.246 0.975 0.1601 1.257 0.984 0.1800 1.271 0.993 0.0400 1.237 0.963 0.0600 1.250 0.976 0.0800 1.264 0.986 0.1001 1.278 0.995 0.1199 1.290 1.005 0.1400 1.303 1.014 0.1601 1.317 1.023 0.1799 1.328 1.032 0.0402 1.290 1.004 0.0601 1.301 1.017 0.0800 1.315 1.026 0.1001 1.331 1.038 0.1199 1.345 1.046 0.1401 1.360 1.057 0.1601 1.371 1.067 0.1800 1.385 1.076 0.0401 1.337 1.045 0.0617 1.354 1.056 0.0798 1.368 1.069 0.0999 1.385 1.079 0.1198 1.402 1.089 0.1402 1.414 1.101 0.1600 1.431 1.113 0.1800 1.442 1.123

308.15


318.15

mAa (mol·kg−1)

288.15

298.15

308.15

318.15

0.875 0.883

0.725 0.733

0.772 0.789 0.806 0.822 0.841 0.857 0.878 0.895 0.801 0.821 0.837 0.860 0.878 0.896 0.911 0.928 0.833 0.856 0.882 0.894 0.921 0.947 0.964 0.988 0.869 0.892 0.913 0.935 0.956 0.977 1.005 1.019

0.635 0.649 0.662 0.674 0.691 0.706 0.722 0.736 0.661 0.679 0.699 0.710 0.727 0.744 0.757 0.774 0.690 0.711 0.725 0.748 0.765 0.783 0.795 0.815 0.720 0.738 0.755 0.778 0.792 0.811 0.827 0.845

0.876 0.883 0.895 0.903

0.725 0.732 0.741 0.748

0.3500 0.3500

2-Deoxy-D-glucose 0.1199 1.398 1.088 0.1398 1.410 1.099

0.752 0.760 0.766 0.773 0.780 0.787 0.794 0.800 0.778 0.785 0.794 0.802 0.808 0.816 0.822 0.831 0.808 0.817 0.825 0.833 0.841 0.849 0.860 0.869 0.839 0.848 0.857 0.865 0.874 0.884 0.895 0.904

0.618 0.624 0.630 0.635 0.642 0.648 0.652 0.658 0.646 0.652 0.658 0.664 0.671 0.676 0.684 0.690 0.669 0.676 0.684 0.689 0.696 0.702 0.711 0.718 0.694 0.703 0.710 0.717 0.724 0.731 0.740 0.746

0.0500 0.0499 0.0499 0.0499 0.0499 0.0499 0.0499 0.0498 0.1499 0.1498 0.1498 0.1497 0.1497 0.1496 0.1496 0.1495 0.2498 0.2497 0.2496 0.2495 0.2494 0.2493 0.2492 0.2492 0.3497 0.3496 0.3495 0.3493 0.3492 0.3491 0.3489 0.3488

(+)-Maltose 0.0395 0.0592 0.0785 0.0975 0.1174 0.1364 0.1552 0.1741 0.0400 0.0591 0.0787 0.0981 0.1174 0.1366 0.1553 0.1744 0.0397 0.0594 0.0785 0.0982 0.1172 0.1366 0.1554 0.1738 0.0397 0.0594 0.0790 0.0982 0.1173 0.1363 0.1555 0.1742

(Anhydrous) 1.221 0.958 1.246 0.982 1.270 1.000 1.298 1.018 1.331 1.049 1.361 1.067 1.385 1.084 1.408 1.103 1.281 0.997 1.303 1.018 1.335 1.041 1.369 1.068 1.394 1.086 1.425 1.105 1.453 1.137 1.484 1.156 1.335 1.035 1.369 1.059 1.396 1.093 1.436 1.114 1.466 1.147 1.505 1.170 1.539 1.204 1.560 1.225 1.383 1.079 1.415 1.106 1.459 1.134 1.489 1.160 1.522 1.193 1.559 1.222 1.597 1.246 1.633 1.269

a mA (mol·kg−1) is the molality of solute in (water + thiamine HCl/pyridoxine HCl) solutions. bmB (mol·kg−1) is the molality of (water + thiamine HCl/pyridoxine HCl) solutions. Standard uncertainties u are u(m) = 2 × 10−4 mol·kg−1, u(η) = 0.010 mPa·s, u(T) = 0.01 K, and u(p) = 0.5 kPa (the level of confidence is 0.68).

where c is the molarity (in mol·dm−3) of the solution, determined from the molality and density data.18 The viscosities (η) for the system (polyhydroxy solutes + water + vitamins) at different temperatures and molalities are given in Table 4. A three-dimensional plot of η versus mA, the molality of (+)-methyl-α-D-glucopyranoside in mB = 0.25 mol·kg−1 pyridoxine HCl, is given in Figure 6 as a function of temperature. The viscosities (η) of polyhydroxy solutes in water show good agreement with the literature values (reported17 earlier). The present values of viscosities (η) for binary (water + thiamine HCl/pyridoxine HCl) and ternary (water + polyhydroxy solutes + thiamine HCl/pyridoxine HCl) systems have been compared with the literature values10,15,36−38 and are given as a part of the Supporting Information in Figures S2 and S3. The viscosity data of thiamine HCl and pyridoxine HCl in water show good agreement with the literature10,15,36,37

However, the values for triplet (hABB) enthalpic interaction coefficients do not follow a specific trend. The irregularities of triplet (hABB) interaction coefficients may be due to the complexity and rare possibility of the three-body interactions as compared to two-body interactions. Hence, the analysis is restricted to the hAB coefficients only, since the higher order hABB coefficients also contain the contributions made by the lower order hAB coefficients and are difficult to explain.17,32−34 3.5. Viscosity and Viscosity B-Coefficients. The viscosity B-coefficients were evaluated by fitting the following Jones− Dole equation35 to relative viscosity, ηr {ηr = η/η0, where η is the viscosity of the solution and η0 is the viscosity of solvent}, data as ηr = 1 + Bc

(7) T



Article

Figure 6. Plot of viscosity (η) versus molality (mA) of (+)-methyl-α-D-glucopyranoside in mB = 0.25 mol·kg−1 of pyridoxine HCl as a function of temperature.

Table 5. dB/dT Coefficients for the System Polyhydroxy Solute (1) in Solutions of Water (2) + Thiamine HCl/Pyridoxine HCl (3) at Pressure p = 0.1 MPaa 103·dB/dT (m3·mol−1·K−1) solute

mB = 0.05

(+)-D-xylose xylitol (+)-D-glucose 2-deoxy-D-glucose (+)-methyl-α-D-glucopyranoside (+)-maltose (anhydrous)

−0.0006 −0.0011 −0.0011 −0.0013 −0.0020 −0.0008

(+)-D-xylose xylitol (+)-D-glucose 2-deoxy-D-glucose (+)-methyl-α-D-glucopyranoside (+)-maltose (anhydrous)

−0.0009 −0.0016 −0.0021 −0.0019 −0.0021 −0.0012

mB = 0.15

mB = 0.25

mB = 0.35

−0.0008 −0.0013 −0.0006 −0.0013 −0.0021 −0.0016

−0.0008 −0.0011 −0.0007 −0.0011 −0.0018 −0.0010

−0.0010 −0.0015 −0.0019 −0.0017 −0.0019 −0.0009

−0.0009 −0.0015 −0.0021 −0.0011 −0.0020 −0.0009

Thiamine HCl −0.0008 −0.0011 −0.0008 −0.0012 −0.0020 −0.0014 Pyridoxine HCl −0.0009 −0.0014 −0.0020 −0.0017 −0.0020 −0.0013

The uncertainty in dB/dT values lies in the range of 0.0001−0.0004 dm−3·K−1·mol−1. Standard uncertainties u are u(T) = 0.01 K and u(p) = 0.5 kPa (the level of confidence is 0.68). a

data (Figure S2). Xu et al.38 have reported the viscosities for the ternary system consisting of 0.2000−1.0006 mol·kg−1 of xylitol in 0.1000−0.4000 mol·kg−1 pyridoxine HCl(aq) over the temperature range from 293.15 to 323.15 K. The qualitative comparison with the current studied 0.0404−0.1398 mol·kg−1 xylitol in 0.0500−0.3500 mol·kg−1 pyridoxine HCl(aq) at T = 288.15−318.15 K shows that the variation of η values with respect to concentration and temperature reported by Xu et al.38 is comparable with the present η values (Figure S3). The viscosity B-coefficients provide direct evidence about the solvation of a solute and structural modifications induced by solute−solute or solute−cosolute interactions. The magnitude of viscosity B-coefficients (Table S4) increases with an increase in the size of saccharide molecules, i.e., from mono- to disaccharides. The B-coefficients increase with an increase in the molalities of cosolutes but decrease with the rise of temperature. The magnitude of B-coefficients for the studied

sugar alcohol in the presence of both cosolutes is higher than those of its parent saccharide. This interesting feature enlightens the fact that Xyol possessing a nonplanar sickle conformation is capable of forming more H-bonds with water than its respective parent saccharide, Xyl.16 The B-coefficients for Mal are higher than the studied monosaccharides. Further, the magnitudes of B-coefficients for the solutes are higher in the presence of thiamine HCl than in pyridoxine HCl. Similar trends of V2° values were observed18 for saccharides, their derivatives, and the sugar alcohol in these vitamins. The temperature dependence of the B-coefficient, i.e., dB/dT, values provides better information about kosmotropic or chaotropic characteristics of the solute.39 The negative dB/dT coefficients (Table 5) suggest that polyhydroxy solutes act as kosmotropes, leading to an increase in the structural order of solutes in aqueous solutions of thiamine HCl and pyridoxine HCl. On the basis of the signs of second-order derivatives, (∂2V2°/∂T2)P, we U



Article

Figure 7. continued

V



Article

Figure 7. Viscosity B-coefficients of transfer (ΔtrB) versus molalities (mB) of (a1,2) (+)-D-xylose, (b1,2) xylitol, (c1,2) (+)-D-glucose, (d1,2) 2-deoxyD-glucose, (e1,2) (+)-methyl-α-D-glucopyranoside, and (f1,2) (+) maltose monohydrate in thiamine HCl (1) and pyridoxine HCl (2) at ◆, 288.15 K; ■, 298.15 K; ▲, 308.15 K; ×, 318.15 K.

0.15 mol·kg−1, the values again increase sharply afterward and further this increase is more in Glc, 2-de-Glc, and Me-α-Glc (Figure 7a1−f1). The ΔtrB values for Glc and its derivatives follow the order Me-α-Glc < 2-de-Glc < Glc, at all temperatures and molalities of thiamine HCl(aq) solutions. The ΔtrB values for solutes studied in pyridoxine HCl(aq) solutions (Figure 7a2−f2) increase sharply from mB ≈ 0 to 0.05 mol kg−1 in all cases, and some level off effect can be observed up to mB ≈ 0.15 mol kg−1 in the cases of Xyl, Xyol, and Mal solutes. However, Glc and its derivatives, 2-de-Glc and Me-αGlc, show a linear increase with an increase in the molality of cosolute. The ΔtrB values for the sugar alcohol are lower as compared to its respective parent saccharide in both cosolutes. The ΔtrB values of the studied solutes vary in the order Me-αGlc < 2-de-Glc < Glc < Xyol < Xyl < Mal in the presence of thiamine HCl(aq) and Me-α-Glc < Glc < 2-de-Glc < Xyol < Xyl < Mal in pyridoxine HCl(aq) solutions. These trends show that Xyl and Xyol (the pentoses) interact strongly with both thiamine HCl and pyridoxine HCl cosolutes. This may offer greater resistance to the movement of solute molecules, hence resulting in higher ΔtrB values for pentoses than hexoses. The comparison of ΔtrB values for solutes studied in various aqueous solutions of vitamins follows the order L-ascorbic acid < pyridoxine HCl < thiamine HCl. The higher magnitude of ΔtrB values in the presence of thiamine HCl(aq) may be due to more strengthening of (hydrophilic + hydrophilic) interactions between polyhydroxy solutes and thiamine HCl than other studied vitamins, as suggested by previous volumetric studies.18 It has been inferred from both transfer parameters (ΔtrΔdilH°, ΔtrB) that Xyl (the pentose) interacts strongly with the cosolutes as compared to its respective sugar alcohol, Xyol. Overall, the transfer values for Glc are higher than its deoxy derivative, 2-de-Glc. The ΔtrΔdilH° and ΔtrB values reveal that the (hydrophilic + hydrophilic) interactions are

Scheme 1. Structure and Labeling of Carbon in (a) Thiamine HCl and (b) Pyridoxine HCl

observed kosmotropic behavior of saccharides but chaotropic behavior of the sugar alcohol in all three vitamins (C, B1, B6).16,18 However, earlier reported17 viscometric studies reveal that all of the polyhydroxy solutes behave as kosmotropes in Lascorbic acid(aq) solutions. The viscosity B-coefficients of transfer, ΔtrB, were calculated using an equation analogous to eq 3. The plots of ΔtrB values versus mB, the molalities of cosolutes, are given in Figure 7. The ΔtrB values of solutes increase with an increase in the molality of cosolutes as well as with the increase of temperature. In the case of thiamine HCl(aq) solutions, the ΔtrB values increase initially sharply in the low concentration range (0−0.05 mol· kg−1) and then, after showing a leveling off effect up to mB ≈ W



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Figure 8. Proton (1H) NMR spectra of (i) pure thiamine HCl (a)/pyridoxine HCl (b), (ii−vii) thiamine HCl (a)/pyridoxine HCl (b) in the presence of (ii) (+)-D-xylose, (iii) xylitol, (iv) (+)-D-glucose, (v) 2-deoxy-D-glucose, (vi) (+)-methyl-α-D-glucopyranoside, and (vii) (+)-maltose monohydrate at T = 300.15 K.

observations are in line with those incurred from volumetric coefficients.18 3.6. NMR Studies. NMR spectral investigations have been performed for the studied solutes (mA = 0.05 mol·kg−1) in mB = 0.15 mol·kg−1 thiamine HCl and pyridoxine HCl solutions made in 9:1 (w/w) H2O−D2O solvent. The labeling of different carbons of thiamine HCl and pyridoxine HCl has been shown in Scheme 1. The chemical shifts, δ, were determined using peak pick facility. The variation in chemical shifts (in ppm) for proton (1H) and 13C NMR spectra has been illustrated in Figures 8 and 9, and data are given in Tables S6 and S7 in the Supporting Information. The 1H and 13C NMR spectral investigations of {polyhydroxy solute + vitamins + 9:1 (w/w) H2O−D2O} ternary solutions show a downfield shift (i.e., deshielding effect) as compared to pure thiamine or pyridoxine hydrochlorides. The observed downfield shift is evidence of stronger H-bonding interactions between solute and cosolute molecules. The hydrogen bonding of the polyhydroxy solutes increases in the presence of thiamine HCl/pyridoxine HCl owing to the hydration of solute and cosolute molecules.40,41 On comparing the chemical shift, δ, data of the studied polyhydroxy solutes, it has been noticed that the deshielding effect is more in Glc (hexose) than in Xyl (pentose). The greater number of −OH groups may lead to an increase in

stronger in the case of Mal; however, these interactions are weaker in the case of Me-α-Glc. It should be noted that the difference in the orders of ΔtrΔdilH° and ΔtrB values from the two different techniques may be due to the nature of properties. Heat change is a quite sensitive thermodynamic property reflecting the solute−solute/cosolute interactions are accompanied either by an exothermic or endothermic process, whereas viscosity is a transport property and the orders of their transfer values are difficult to compare. Viscometric interaction coefficients have been determined by using an equation analogous to eq 6. Overall, the pair (ηAB) viscometric interaction coefficients are positive and their values decrease with an increase of temperature (Table S5), while the triplet (ηABB) interaction coefficients are negative and their values increase with a rise of temperature in both cosolutes. The contributions of ηAB coefficients increase linearly, while ηABB coefficients vary nonlinearly at all temperatures. The greater magnitude of ηAB values as compared to ηABB values reveals the dominance of (hydrophilic + hydrophilic) interactions between solute and cosolute, and it becomes strengthened with an increase in temperature. Again, the magnitudes of ηAB values are higher in the case of thiamine HCl, which supports the previous view that (hydrophilic + hydrophilic) interactions get more strengthened in the presence of thiamine HCl than other studied vitamins. These X



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Figure 9. 13C NMR spectra of (i) pure thiamine HCl (a)/pyridoxine HCl (b), (ii−vii) thiamine HCl (a) /pyridoxine HCl (b) in the presence of (ii) (+)-D-xylose, (iii) xylitol, (iv) (+)-D-glucose, (v) 2-deoxy-D-glucose, (vi) (+)-methyl-α-D-glucopyranoside, and (vii) (+)-maltose monohydrate at T = 300.15 K.

standard enthalpy of dilution (ΔdilH°) values are negative at lower molalities of thiamine HCl(aq) and pyridoxine HCl(aq) solutions and low temperatures, indicating the predominance of (hydrophilic + hydrophilic) interactions over the dehydration effect and (hydrophobic + hydrophilic/hydrophobic) group interactions. The ΔdilC°p,2,m and dB/dT coefficients suggest that saccharides, their derivatives, and the sugar alcohol exhibit a kosmotropic nature in aqueous solutions of vitamins (B1 and B6). The pair (hAB, ηAB) interaction coefficients are higher for Xyol than its respective parent saccharide due to its capability of forming more H-bonds with the water molecules. The higher magnitudes of transfer parameters (ΔtrΔdilH°, ΔtrB) suggest a stronger structure enhancing capability of solutes in the presence of thiamine HCl(aq) than in pyridoxine HCl(aq) and L-ascorbic acid(aq) solutions. The dominance of (hydrophilic + hydrophilic) interactions over the (hydrophobic + hydrophilic/ hydrophobic) interactions interpreted on the basis of volumetric, UV absorption, calorimetric, and viscometric results is further supported by the observed downfield chemical shift (δ) from NMR spectroscopic studies.

hydrogen bonding interactions of Glc with cosolute, which results in a greater deshielding effect than that in Xyl. The chemical shifts for Glc are higher than its derivatives following the order 2-de-Glc < Me-α-Glc < Glc in thiamine HCl and Meα-Glc < 2-de-Glc < Glc in pyridoxine HCl. Further, Xyl shows a greater deshielding effect than Xyol. However, Mal, a disaccharide containing a flexible α (1 → 4) glycosidic bond, is less deshielded as compared to Glc. The downfield shift in ternary solutions in comparison to pure thiamine HCl and pyridoxine HCl suggests the predominance of (hydrophilic + hydrophilic) interactions over the (hydrophobic + hydrophilic/ hydrophobic) interactions. These results are in line with aforementioned viscometric studies and earlier reported18 volumetric and UV absorption studies. However, the limiting standard enthalpy of dilution (ΔdilH°) and their corresponding transfer (ΔtrΔdilH°) values indicate the predominance of (hydrophilic + hydrophilic) interactions at low molalities and temperatures. The ternary solutions of saccharides in Lglycine(aq)42 and CTAB(aq)43 solutions also suggested the predominance of (hydrophilic + hydrophilic) interactions.

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4. CONCLUSION The heat change (q) and viscosities (η) were measured for the ternary solutions {polyhydroxy solute + thiamine HCl/ pyridoxine HCl + H2O} at different temperatures. The limiting

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jced.7b00937. Y



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Article

Table S1: Limiting standard enthalpies of dilution ΔdilH° at temperature T and molality m for the system polyhydroxy solute (1) in solutions of water (2) + thiamine HCl/pyridoxine HCl (3) at pressure p = 0.1 MPa. Table S2: Values of temperature coefficients A, X, X1, and X2 in eqs 4 and 5. Table S3: Pair hAB and triplet hABB enthalpic interaction coefficients at temperature T for the system polyhydroxy solute (1) in solutions of water (2) + thiamine HCl/pyridoxine HCl (3) at pressure p = 0.1 MPa. Table S4: Viscosity B-coefficients at temperature T and molality m for the system polyhydroxy solute (1) in solutions of water (2) + thiamine HCl/pyridoxine HCl (3) at pressure p = 0.1 MPa. Table S5: Pair ηAB and triplet ηABB viscometric interaction coefficients at temperature T for the system polyhydroxy solute (1) in solutions of water (2) + thiamine HCl/pyridoxine HCl (3) at pressure p = 0.1 MPa. Table S6: Proton (1H) NMR chemical shifts δ at temperature T = 300.15 K for pure thiamine HCl/ pyridoxine HCl (1) and polyhydroxy solutes (2) in aqueous thiamine HCl/pyridoxine HCl solutions (3) at pressure p = 0.1 MPa. Table S7: 13C NMR chemical shifts δ at temperature T = 300.15 K for pure thiamine HCl/pyridoxine HCl (1) and polyhydroxy solutes (2) in aqueous thiamine HCl/pyridoxine HCl solutions (3) at pressure p = 0.1 MPa. (PDF)

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AUTHOR INFORMATION

Corresponding Author

*Phone: +91 183 2451357. Fax: +91 183 2258819/20. E-mail: [email protected]. ORCID

Tarlok S. Banipal: 0000-0002-6239-2543 Parampaul K. Banipal: 0000-0001-5467-843X Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS The authors are thankful to the University Grants Commission, New Delhi, India, for the financial assistance under the Research Scheme No. MRP-MAJOR-CHEM-2013-37407. The authors are also thankful to Guru Nanak Dev University, Amritsar, for providing the facilities of ITC under the DSTPURSE program and the Bruker Ascend 500 MHz NMR spectrometer under “University with Potential for Excellence”, UGC scheme, New Delhi, India.

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