Nearest-Neighbor and Non-Nearest-Neighbor Interactions between

Article pubs.acs.org/JPCA

Nearest-Neighbor and Non-Nearest-Neighbor Interactions between Substituents in the Benzene Ring. Experimental and Theoretical Study of Functionally Substituted Benzamides Sergey P. Verevkin,*,† Vladimir N. Emel’yanenko,†,‡ and Ruslan N. Nagrimanov‡ †

Department of Physical Chemistry and Department of Science and Technology of Life, Light and Matter, University of Rostock, Dr-Lorenz-Weg 1, D-18059 Rostock, Germany ‡ Department of Physical Chemistry, Kazan Federal University, Kremlevskaya str. 18, 420008 Kazan, Russia S Supporting Information *

ABSTRACT: Standard molar enthalpies of formation of 2- and 4-hydroxybenzamides were measured by combustion calorimetry. Vapor pressures of benzamide and 2-hydroxybenzamide were derived by the transpiration method. Standard molar enthalpies of sublimation or vaporization of these compounds at 298 K were obtained from vapor pressure temperature dependence. Thermochemical data on benzamides with hydroxyl, methyl, methoxy, amino, and amide substituents were collected, evaluated, and tested for internal consistency. The high-level G4 quantum-chemical method was used for mutual validation of the experimental and theoretical gas-phase enthalpies of formation. Sets of nearest-neighbor and non-nearest-neighbor interactions between substituents in the benzene ring have been evaluated. A simple incremental procedure has been suggested for a quick appraisal of the vaporization and gas-phase formation enthalpies of the substituted benzamides.

1. INTRODUCTION The study of nonbonding interactions between various functional groups on benzenes rings is very popular in physical chemistry.1 Perturbation of the electron density on the benzene ring due to interactions between the substituents is usually responsible for the distribution of ortho-, meta-, and paraisomers synthesized. Numerically, the substituent effects are often described by various constants related to the substituents X and Y, which are generally divided into electron-withdrawing and electron-donating groups. The concept of substituent effects in the benzene ring is not straightforward, but it is successfully realized in organic and inorganic chemistry.2 Also in thermochemistry, pairwise nearest-neighbor and non-nearestneighbor interactions between substituents in the benzene ring are also responsible for the distribution of the ortho-, meta-, and para-isomers, e.g., in the case of production of the industrially important antioxidant p-tert-butylphenol via alkylation of phenol with isobutene.3 Moreover, knowledge about pairwise interactions in the benzene ring is essential for prediction of thermochemical properties of the benzene derivatives based on the group-additivity procedure.3−6 Admittedly, the reaction ° , of a general distribution reaction, (1), with enthalpy, ΔrHm participation of a benzamide, as calculated according to Hess’s law, can be considered as evidence of the pairwise interaction of substituent R1 and carboxamide substituent in the 2-, 3-, and 4positions on the benzene ring. In comparison to classical values © 2016 American Chemical Society

of enthalpies of formation, ΔfHm° (g), which are mostly responsible for the overall energetics of a molecule, the energetics of the ortho-, meta-, and para-pairwise interactions are more demonstrative for interpretation by using ΔrHm ° values derived for the disproportionation reaction 1. From our experiences,3−6 the pairwise meta- and para-interactions of different substituents R1 are usually weak, hardly exceeding a few kJ mol−1. In contrast, the ortho-interactions can be strongly destabilizing, due to steric interactions, or stabilizing, due to intramolecular hydrogen bonding. The ortho-repulsions are unique, and they are usually dependent on the nature and size of the substituents. However, a general quantification of ortho-, meta-, and para-pairwise interactions is required for the optimization of synthesis and for a quick appraisal of the distribution of positional isomers in the reaction mixtures. Moreover, quantitative knowledge of the intensity of pairwise interactions is crucially important for validation and evaluation Received: October 12, 2016 Revised: November 17, 2016 Published: November 17, 2016 9867

DOI: 10.1021/acs.jpca.6b10332 J. Phys. Chem. A 2016, 120, 9867−9877

Article

The Journal of Physical Chemistry A

(±0.1 K), a nitrogen stream was slowly passed through the saturator. The certain amount of transported material was collected in a cold trap. Gas chromatography was used to determine the amount of condensed sample. The absolute vapor pressure was calculated from the amount of the product collected within a definite period of time by using eq 2:

of experimental or theoretical data. Especially for thermochemical data of different amides and benzoic acid derivatives, where a dramatic disagreement among available experimental data is often discussed,7−9 the determination and discussion of ortho-, meta-, and para-pairwise interactions is one possible way to establish the reliability and consistency of the experimental data. Benzoic acid derivatives, especially 2-hydroxybenzamide (salicylamide) and 2-hydroxybenzoic acid (salicylic acid), have received much attention in the recent thermochemical literature,10−18 mainly due to their biological, antibacterial, and fungicidal activity. Thermochemical data for this chemical family, like standard molar enthalpies of formation, ΔfHm °, standard molar enthalpies of sublimation, ΔgcrH°m, standard molar enthalpies of vaporization, Δg1H°m, and standard molar enthalpies of fusion, Δ1crHm ° , are of practical importance for optimization of synthetic procedures. This work complements and extends our previous knowledge on the thermochemistry of amides and benzoic acid derivatives7−9 with experimental and theoretical studies on the ortho-, meta-, and para-substituted benzamides presented in Figure 1. We have carefully collected all available thermochem-

pi = miRTa /VMi ;

V = VN2 + Vi

(VN2 ≫ Vi )

(2)

where R is the molar gas constant, mi is the mass of the transported compound, Mi is the molar mass of the compound, Vi is its volume contribution to the gaseous phase, VN2 is the volume of the carrier gas, and Ta is the temperature of the soap bubble meter used for measurement of the gas flow. The volume of the carrier gas VN2 was determined from the flow rate and the time measurement. Detailed results from transpiration experiments are given in Table S2. 2.3. High-Precision Combustion Calorimetry. The standard molar energies of combustion of 2-hydroxybenzamide and 4-hydroxybenzamide were measured by an isoperibolic calorimeter with a static bomb. The procedure was described in detail previously.22,23 The samples pellets of mass ∼0.5−0.7 g were placed in a platinum crucible together with the auxiliary material (polyethylene cut in small pieces) and were burned in products were examined for the carbon monoxide (Dräger tube) and unburned carbon, but neither was detected. The energy equivalent of the calorimeter, εcalor, was determined with a standard reference sample of the benzoic acid (sample SRM 39j, NIST). Correction for nitric acid formation was based on titration with 0.1 mol dm−3 NaOH(aq). Conventional procedures24 were used for the reduction of the data to standard conditions. Auxiliary data are given in Table S3. Primary results and details of combustion experiments are collected in Tables S4 and S5. 2.4. Computational Details. Quantum-chemical calculations of benzamides were performed with the Gaussian 09 series software.25 Energies of molecules involved in this study were calculated by using the G4 method.26 Computational details for this approach are reported elsewhere.27,28 We used the values of H298 directly available from the output, which were obtained according to the rigid rotor harmonic oscillator approach embedded in Gaussian 09.

Figure 1. Compounds studied in this work: 2-R-benzamide, 3-Rbenzamide, and 4-R-benzamide, with R = OH, CH3, OCH3, NH2, or C(O)NH2.

ical data for this chemical family, aiming at analysis and evaluation of reliable and consistent thermochemical data useful for practical applications as well as for testing of a high-level quantum-chemical method. Admittedly, the thorough evaluation of available thermochemical data is possible when consistent experimental results are independently measured at least twice by using different techniques or in different laboratories.9 This requirement prompted some additional experimental measurements to be performed in this work. As a rule, a joint treatment of consistent thermochemical results for the compound of interest provides a set of benchmark quality data, and the compound can be recommended as an “anchoring” molecule for different thermochemical calculations.

3. RESULTS AND DISCUSSION 3.1. Vapor Pressures Measured with the Transpiration Method. Vapor pressures for benzamide and 2-hydroxybenzamide were determined over the crystalline phase. The temperature dependence of absolute vapor pressures pi was fitted with the following equation:19

2. MATERIALS AND METHODS 2.1. Materials. Samples of benzamide derivatives were of commercial origin (Table S1) with an initial purity of 98−99% as stated by the manufacturer; they were additionally purified by fractional sublimation in a vacuum. No discernible impurities were detected in samples for thermochemical studies by using a gas chromatograph (GC) with an HP-5 capillary column with a column length of 30 m, an inside diameter of 0.32 mm, and a film thickness of 0.25 μm. The standard temperature program of the GC was T = 333 K for 180 s followed by heating at a rate of 0.167 K·s−1 to T = 523 K. 2.2. Vapor Pressure Measurements: Transpiration Method. The transpiration method19−21 was used for absolute vapor pressure measurements of benzamide and 2-hydroxybenzamide. Glass beads were covered with the sample of benzamide and placed in a saturator. At a constant temperature

R ln pi = a +

⎛T ⎞ b ◦ + Δcrg Cp,m ln⎜ ⎟ T ⎝ T0 ⎠

(3)

where a and b are adjustable parameters and ΔgcrCp,m ° is the difference of the molar heat capacities of the gaseous and crystalline phases, respectively. T0 in eq 3 is arbitrarily chosen to be T = 298 K, and R is the molar gas constant. Values of ΔgcrCp,m ° in eq 3 were estimated (see Table S7) according to the procedure suggested by Chickos and Acree29 based on the isobaric molar heat capacities C°p,m(cr, 298 K) estimated by the group-additivity procedure.30 Experimental absolute vapor pressures for benzamide and 2-hydroxybenzamide measured by the transpiration method are given in Table S2. Vapor 9868


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The Journal of Physical Chemistry A Table 1. Enthalpies of Sublimation, ΔgcrHm ° , of Benzamides (in kJ mol−1) compound

Ma

ΔgcrHm ° /Tav

T range

± ± ± ± ±

ref 31 32 14 14 this work averagec

(99.3 ± 2.3) (101.9 ± 0.4) 107.0 ± 1.1 108.8 ± 1.0 108.3 ± 1.2 108.1 ± 0.6

11 13 33 this work this work averagec

K C K S T

328.4−341.9 323−349 324.1−346.2 344.8−394.3 318.3−370.6 298

2-OH-benzamide (cr)

DC DC T T T

386.0 398.4 320.2−345.2 377.7−413.2 343.7−376.5 298

3-OH-benzamide (cr)

T

367.7−396.2 298

119.6 ± 1.3

(121.7 ± 1.6) 129.4 ± 3.1d

33 this work

4-OH-benzamide (cr)

T T DC

360.2−420.7 362.2−420.7 398.4 298

115.6 ± 0.6 115.5 ± 0.6

(118.2 ± 0.8) (118.2 ± 0.8) 129.7 ± 1.6 126.9 ± 2.1d

34 33 11 this work

2-NH2-benzamide (cr)

K

335.1−357.2

105.7 ± 0.3

106.9 ± 1.0

17


K

358.1−380.1 298

123.3 ± 0.3

128.5 ± 1.2d 125.3 ± 2.3d

17 this work


K T

389.1−411.2 373.2 ± 403.2 298 298

128.5 ± 0.4 128.8 ± 1.2

131.1 ± 1.4 131.1 ± 1.5 131.1 ± 1.0 127.5 ± 2.6d

17 35 averagec this work

298 298 298

150.3 ± 6.2d 153.9 ± 3.6e 153.0 ± 3.1

averagec

298 298 298

149.2 ± 7.4d 153.3 ± 3.7e 152.5 ± 3.3

averagec

4-CONH2-benzamide(cr)

1.0 1.0 0.4 0.1 0.4

99.6 ± 1.7 101.5 ± 1.2 103.1 ± 1.0 102.6 ± 0.6 103.2 ± 0.6 102.7 ± 0.4

benzamide (cr)

3-CONH2-benzamide (cr)

98.7 100.6 102.5 100.9 102.1

ΔgcrHm ° /298 Kb

106.0 ± 0.7 106.1 ± 0.4 106.6 ± 0.9

a

Methods: K = Knudsen effusion method; C = calorimetry; T = transpiration method; S = static method; DC = drop microcalorimetry. Uncertainties of sublimation enthalpies are expressed in this table as standard deviations. Vapor pressures available in the literature were treated using eqs 3 and 4 in order to evaluate enthalpy of sublimation at 298 K in the same way as our own results. cAverage values were calculated using the uncertainty as a weighting factor. Recommended values are given in bold. dFrom Table S8, column 4, calculated as the sum of enthalpy of vaporization calculated by group-additivity and fusion enthalpy adjusted to the reference temperature 298 K. eFrom Table 2, column 3, calculated as the difference between the G4 gas-phase enthalpy of formation and the experimental crystal-phase enthalpy of formation. b

3.2. Thermodynamics of Sublimation. Standard molar enthalpies of sublimation of benzamides at temperature T were calculated by using the following equation:

pressures of 2-hydroxybenzamide were additionally measured above the melting point (see Table S2), and they also were ° values (difference approximated by eq 3 by using the Δg1Cp,m between the molar heat capacities of the gaseous and liquid phases, given in Table S7). Comparisons of vapor pressures available for benzamide and hydroxybenzamides are presented in Figures S1 and S2. Vapor pressures measured in this study for benzamide are in very good agreement with all available results measured with the Knudsen effusion method,14,31 as well as with the static method14 (see Figure S1). Absolute vapor pressures of 2hydroxybenzamide measured in this study are in agreement with results from a recent transpiration study.33

◦ Δcrg Hm◦ (T ) = −b + Δcrg Cp,m T

(4)

Entropies of sublimation at temperature T were also derived from the temperature dependence of vapor pressures using eq 5: Δcrg Sm◦ (T ) = Δcrg Hm◦ /T + R ln(pi /p◦ )

(5)

Values of absolute vapor pressures, coefficients a and b of eq 3, as well as values of ΔgcrHm ° (T) and ΔgcrSm ° (T) are given in Table S2 (primary data), and final results are collected in Table 1. 9869


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The Journal of Physical Chemistry A Table 2. Thermochemical Data for Substituted Benzamides at T = 298 K (in kJ mol−1)a ΔfHm ° (g) compound

ΔfH°m(cr)

ΔgcrH°mb

exp

col 2

col 3

col 4

col 1 benzamide

2-OH-benzamide

3-OH-benzamide 4-OH-benzamide

2-CH3-benzamide 3-CH3-benzamide 4-CH3-benzamide 2-CH3O-benzamide 3-CH3O-benzamide 4-CH3O-benzamide 2-NH2-benzamide 3-NH2-benzamide 4-NH2-benzamide 3-CONH2-benzamide 4-CONH2-benzamide

−204.0 ± 3.039 −202.6 ± 1.140 −208.5 ± 3.841 −204.8 ± 2.942 −202.1 ± 0.643 −202.5 ± 0.5e

102.7 ± 0.4

−99.8 ± 0.6

−402.7 ± 2.2f,10 −407.8 ± 1.811 −406.7 ± 1.413 −407.6 ± 1.5 [this work] −407.3 ± 0.9e

108.1 ± 0.6

−299.2 ± 1.1

129.4 ± 3.1

−408.1 ± 1.813 −409.2 ± 1.9 [this work] −408.6 ± 1.3e ± ± ± ± ± ± ± ± ± ± ±

1.644 1.544 1.444 1.344 1.644 1.744 1.517 1.517 1.517 1.045 1.346

exp − QC

col 5

col 6

col 5

(−407.1 ± 4.7)g

−235.4 −239.9 −245.8 −366.5 −375.5 −376.3 −219.9 −227.5 −231.3 −436.9 −433.1

QCc

129.7 ± 1.6 106.7 107.1 109.1 111.0 120.2 118.9 106.9 128.5 131.1 (153.0 (152.5

± ± ± ± ± ± ± ± ± ± ±

0.544 0.544 0.644 0.744 0.644 0.644 1.0 1.2 1.0 3.1)i 3.3)i

−98.9d

−309.3

−0.9

−10.1

−277.7

−278.9 ± 2.1

−281.0

−128.7 −132.8 −136.7 −255.5 −255.3 −257.4 −113.0 −99.0 −100.3

−127.8 −132.8 −133.1 −256.6 −256.5 −256.5 −108.9 −97.4 −99.6 −283.0h −279.8h

± ± ± ± ± ± ± ± ±

1.7 1.6 1.5 1.5 1.7 1.8 1.8 1.9 1.8

2.1 −0.9 0.0 −3.6 1.1 1.2 −0.9 −4.1 −1.6 −0.7

a

All uncertainties in this table are expressed as twice the standard deviation. Values given in bold are recommended for thermochemical calculations. From Table 1. cCalculated by G4 by using eq 1. dCalculated according to the atomization procedure. eWeighted average value. fResult was disregarded by averaging. gCalculated as the difference between columns 5 and 3 from this table. hResults from Dorofeeva et al.47 iValues given in parentheses were calculated as the difference between columns 5 and 2 from this table.

b

compound ΔgcrH°m(298 K) = 102.7 ± 0.4 kJ mol−1 (see Table 1) using uncertainties as the weighting factor and recommend it for thermochemical calculations. As a matter of fact, the new sublimation enthalpy of 2hydroxybenzamide derived from vapor pressures measured by the transpiration method in this work (ΔgcrH°m(298 K) = 108.3 ± 1.2 kJ mol−1 in the range 318−371 K (with the mass m determination by the gas-chromatography, see Table S2) is in good agreement with the previous results also measured by the transpiration method in ref 33 (see Table 1). However, these results are in a significant disagreement with two direct calorimetric measurements.11,13 In order to ascertain the sublimation enthalpy of 2-hydroxybenzamide, we repeated the transpiration measurements on this compound in a second series of experiments but this time by using a saturator of significantly different geometry and the significantly higher temperature range 378−413 K, as well as determination of the mass m by weighing of the condensate (see Table S2). However, in spite of significantly different experimental conditions, the value of ΔgcrH°m(298 K) = 108.8 ± 1.0 kJ mol−1 for 2-hydroxybenzamide was indistinguishable from our result from the first series (see Table 1). Having established agreement of three independent values on sublimation enthalpy

Transpiration experiments with 2-hydroxybenzamides were additionally performed above the melting temperature. However, eqs 3 and 4 are also used for the treatment of vapor pressures measured over the liquid sample, giving the standard molar enthalpy of vaporization Δg1H°m(T) and the standard molar vaporization entropy Δg1S°m(T). In this case in eqs 3 and 4, we used the value Δg1Cp,m ° (see Table S7) instead of ΔgcrCp,m ° . The combination of uncertainties in the vaporization/ sublimation enthalpies includes uncertainties in experimental conditions for transpiration, uncertainties in vapor pressure, and uncertainties in the adjustment of vaporization/sublimation enthalpies to T = 298 K as described elsewhere.20,21 The enthalpies of sublimation ΔgcrHm ° of the benzamides available in the literature33−35 were also adjusted to T = 298 K in the same way as our own results using eqs 3 and 4, with the heat capacity differences listed in Table S7, and we calculated ΔgcrHm ° (298 K) for comparison with our results (see Table 1). Sublimation enthalpies of the benzamide derived from vapor pressures measured with the mass loss Knudsen effusion method14,31 and with the static method14 are in good agreement (see Table 1). These indirect results are also in a good agreement with the direct calorimetric measurements32 on the benzamide. We calculated the average value for this 9870


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The Journal of Physical Chemistry A Table 3. Thermodynamics of Phase Transitions in Substituted Benzamides (in kJ mol−1) at 298 K compound 1 benzamide

2-OH-benzamide

a

Tfus, K

Δ1crH°m at Tfus

ref

Δ1crH°m a

ΔgcrH°m b

Δg1H°m c

4

5

6

18.5 ± 1.6 (13.2 ± 1.9) (13.9 ± 1.9) 17.9 ± 1.6 18.2 ± 1.1d

102.7 ± 0.4

84.5 ± 1.2e

22.2 ± 2.3 20.2 ± 2.2 20.3 ± 2.1 20.6 ± 2.2 20.8 ± 1.1d

108.1 ± 0.6

87.3 ± 1.3

2

3

403.0 402.3 402.1 401.3

23.8 ± 0.1 (18.5 ± 1.0) (19.2 ± 1.0) 23.2 ± 0.1 23.5 ± 0.1d

43 48 49 14

29.0 ± 1.0 27.0 ± 0.5 27.1 ± 0.2 27.4 ± 0.5 27.2 ± 0.2d

12 50 13 33

411.9 413.0 414.7 438.0

3-OH-benzamide

440.7

28.8 ± 0.5

33

20.1 ± 2.6

131.2 ± 1.0

111.1 ± 2.8

4-OH-benzamide

433.2 433.8 433.1

25.2 ± 0.5 25.4 ± 0.2 25.2 ± 0.5 25.2 ± 0.2d

34 13 33

17.5 ± 2.4 17.7 ± 2.3 17.5 ± 2.4 17.6 ± 1.4d

129.7 ± 1.6

112.1 ± 2.1

± ± ± ± ± ± ± ±

44 44 44 18 18 18 17 17

16.0 17.6 17.7 21.6 22.7 21.3 15.5 18.0

20.0 ± 3.0 20.4 ± 3.0 20.2 ± 2.1d

131.1 ± 0.7

110.9 ± 2.2

13.4 ± 5.8

150.3 ± 6.2h

136.9 ± 2.1g

12.3 ± 7.1

149.2 ± 7.4h

2-CH3-benzamide 3-CH3-benzamide 4-CH3-benzamide 2-CH3O-benzamide 3-CH3O-benzamide 4-CH3O-benzamide 2-NH2-benzamide 3-NH2-benzamide

415.1 366.7 433.2 401.7 407.2 440.6 384.4 387.5

22.7 21.5 24.5 27.2 28.6 29.0 20.9 23.6

0.2 0.2 0.2 0.3 0.2 0.3 0.2 0.3f

4-NH2-benzamide

457.6 455.5

30.0 ± 0.2 30.4 ± 0.2 30.2 ± 0.1d

17 35

3-CONH2-benzamide

559.1

32.6

45

4-CONH2-benzamide

618.2

35.8

46

Δ1crHm °

± ± ± ± ± ± ± ±

1.4 0.8 1.6 1.7 1.8 2.3 1.6 1.7

106.7 107.1 109.1 111.0 120.2 118.9 106.9 128.6

± ± ± ± ± ± ± ±

0.5 0.5 0.6 0.7 0.6 0.6 1.0 1.2[17]

b

90.7 89.5 91.4 89.4 97.5 97.6 91.4 110.5

± ± ± ± ± ± ± ±

1.5 0.9 1.7 1.8 1.9 2.4 1.9 2.1

136.9 ± 2.1g c

Experimental values measured at Tfus and adjusted to 298 K (see SI). Recommended values taken from Table 1. Calculated as the difference between columns 5 and 4 in this table. dWeighted average value. eFor comparison, the experimental value Δg1H°m(298 K) = 85.4 ± 1.5 kJ mol−1 was measured by the static method.14 fResult related to the thermodynamically stable phase, crII, at T = 298 K.17 gFrom Table S8, column 3. h From Table S8, column 4.

Δcu°(cr) of the 2-hydroxy- and 4-hydroxybenzamide have been measured with high-precision combustion calorimetry, and they are given in Tables S4 and S5. These values have been used to obtain the standard molar enthalpies of combustion ΔcHm ° (cr) and the standard molar enthalpies of formation in the crystalline state ΔfHm ° (cr) (see Table 2). Values of Δcu°(cr) and ΔcH°m of both isomers were referenced to the reaction,

of 2-hydroxybenzamide, we calculated the average value for this ° (298 K) = 108.1 ± 0.6 kJ mol−1 (see Table compound, ΔgcrHm 1), using uncertainties as the weighting factor and recommended it for further thermochemical calculations. The two indistinguishable results of ΔgcrH°m(298 K) = 118.2 ± 0.8 kJ mol−1 (see Table 1) for the sublimation enthalpy of 4hydroxybenzamide were reported by the same working group33,34 from the transpiration measurements. It should be mentioned, however, that both reported p−T data sets were essentially identical, except for one point in the lowtemperature range. The direct calorimetric result reported by ° (298 K) = 129.7 ± 0.6 kJ mol−1 (see Bernardes et al.,13 ΔgcrHm Table 1), was significantly different from those reported from transpiration by Perlovich et al.33,34 This discrepancy has prompted a careful evaluation of both indirect and direct results, which will be shown below (see Section 3.4.2). 3.3. Enthalpies of Formation from Combustion Calorimetry. Standard specific energies of combustion

C7H 7NO2 (cr) + 7.75O2 (g) = 7CO2 (g) + 3.5H 2O(l) + 0.5N2(g)

(6)

Values of ΔfH°m(cr) of the 2-hydroxy- and 4-hydroxybenzamide were calculated according to Hess’s law applied to eq 6, using the reference values of standard molar enthalpies of formation of CO2(g), ΔfH°m(g) = −393.51 ± 0.13 kJ mol−1, and H2O(l), ΔfH°m(l) = −285.830 ± 0.042 kJ mol−1, assigned by CODATA.36 A well-established procedure37 was used to estimate the uncertainties of combustion experiments. The 9871


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The Journal of Physical Chemistry A uncertainties of the standard molar energy of combustion correspond to expanded uncertainties of the mean (0.95 confidence level). The uncertainty of the molar enthalpy of combustion and the uncertainty of the molar enthalpy of formation are twice the overall standard deviation. They include the uncertainties of the enthalpies of formation of the reaction products H2O and CO2, the uncertainties from calibration, the uncertainties from the combustion energies of the auxiliary materials, and the uncertainty due to the specific intervals of atomic masses reported by IUPAC.38 The ΔfHm ° (cr) value for the 2-hydroxybenzamide measured in this work (see Table 2) is in disagreement with the earlier result reported by Ryskalieva et al.,10 but it is in very good agreement (see Table 2) with the results of more recent studies.11,13 For 4-hydroxybenzamide the ΔfHm° (cr) value measured in this work (see Table 2) is in very good agreement with that measured by Bernardes et al.13 For both 2- and 4hydroxybenzmides we have calculated the weighted average values of ΔfHm ° (cr) (see Table 2) based on the uncertainties taken as the weighting factor. For benzamide, the solid-state enthalpies of formation, ΔfH°m(cr), available in the literature are in very good agreement. The average value for this compound, ΔfHm ° (cr, 298 K) = −202.5 ± 0.5 kJ mol−1 (see Table 2), was calculated by using the uncertainties as the weighting factor, and it is recommended for thermochemical calculations. 3.4. Enthalpies of Vaporization. 3.4.1. Consistency Check of Phase Change Enthalpies. Significant disagreement between enthalpies of sublimation for 2-hydroxybenzamide derived indirectly from vapor pressure temperature dependence and those measured directly by calorimetry has prompted our additional efforts for validation of our new experimental data as follows. The general thermochemical relationship Δgl Hm◦ = Δcrg Hm◦ − Δcrl Hm◦

Table 4. Experimental and Calculated Enthalpies of Vaporization, Δg1H°m, of Substituted Benzamides (in kJ mol−1) Δg1H°m/Tav

Δg1H°m/298 Kc

benzamide

77.3 ± 1.3

a

85.4 ± 1.5

2-OH-benzamide

76.1 ± 0.4b

87.4 ± 0.9 87.3 ± 1.3 (109.3 ± 1.6)

this work from Table 3 from Table S8

3-OH-benzamide

111.1 ± 2.8 109.3 ± 1.6

from Table 3 from Table S8

4-OH-benzamide

112.1 ± 2.1 109.3 ± 1.6


2-CH3-benzamide

90.7 ± 1.5 89.6 ± 1.6


3-CH3-benzamide

89.5 ± 0.9 89.6 ± 1.6


4-CH3-benzamide

91.4 ± 1.7 89.6 ± 1.6


2-CH3O-benzamide

89.4 ± 1.8 (97.9 ± 1.6)


3-CH3O-benzamide

97.5 ± 1.9 97.9 ± 1.6


4-CH3O-benzamide

97.6 ± 2.4 97.9 ± 1.6


compound

(7)

establishes the relation among phase change enthalpies, and it can be used to prove an internal consistency of the experimental data derived in this work on the sublimation (Table 1), fusion (Table 3), and vaporization enthalpies (Tables 3 and 4). It is important that enthalpies involved in eq 7 are referenced to any common temperature (T = 298 K in this work). Enthalpies of fusion evaluated in Table 3 have been adjusted to T = 298 K by using a well-established procedure29 (see SI). In this work, the sample of 2-hydroxybenzamide has been deliberately studied by the transpiration method in both ranges below and above the melting temperature, Tfus = 414.7 K. These results allow for validation of enthalpies of phase transitions of 2-hydroxybenzamide according to eq 7. Indeed, the value of ΔgcrH°m(298 K) = 108.1 ± 0.6 kJ mol−1 for this compound was evaluated in this work from vapor pressure measurements in the temperature range below the melting point Tm (see Table 1). The vaporization enthalpy for 2hydroxybenzamide, Δg1H°m(298 K) = 87.4 ± 0.9 kJ mol−1, was derived from transpiration measurements in the temperature range above the melting point (see Table 4). The enthalpy of fusion, Δcr1Hm° (298 K) = 20.8 ± 1.1 kJ mol−1, for 2hydroxybenzamide was averaged from available fusion enthalpies collected in Table 3. The enthalpy of vaporization calculated for 2-hydroxybenzamide according to eq 7 as the difference Δg1H°m(298 K) = ΔgcrH°m(298 K) − Δ1crH°m(298 K) = 108.1 − 20.8 = 87.3 ± 1.3 kJ mol−1 is in very good agreement with the value Δg1Hm ° (298 K) = 87.4 ± 0.9 kJ mol−1 measured by the transpiration method above the melting point in this

ref 14

2-NH2-benzamide

91.4 ± 1.9 (107.3 ± 1.6)

from Table 3 additive

3-NH2-benzamide

110.5 ± 2.1 107.3 ± 1.6


4-NH2-benzamide

110.9 ± 2.2 107.3 ± 1.6


a

Measured by the static method between 380.4 and 438.2 K. Measured by the transpiration method between 414.9 and 441.7 K. c Uncertainties of vaporization enthalpies are expressed in this table as standard deviations. Recommended values are given in bold. b

work (see Table 4). Such a good agreement is evidence of the internal consistency of the phase transition data measured in this work for 2-hydroxybenzamide. 3.4.2. Quick Assessment of Vaporization Enthalpies by Group Additivity. It is well known that experimental standard molar sublimation enthalpies, ΔgcrHm ° , are difficult to predict by using group-additivity rules. The main reason is that the value of the sublimation enthalpy encompass the enthalpy of vaporization, Δg1H°m, and the enthalpy of fusion, Δ1crH°m, as two independent contributions. As a consequence, any prediction of sublimation enthalpies suffers from a large ambiguity.51 However, vaporization enthalpies obey the additive rules.6 We used an incremental approach to the halogen-substituted aromatic compounds in our recent work.4,53 9872


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substituted benzamides predicted by the incremental procedure are listed in Table 4. Comparison of the theoretical and experimental Δg1Hm ° (298 K) values in Table 4 shows an agreement (except for ortho-substituted benzamides) within the experimental uncertainties, typically 2−3 kJ mol−1. Such a good agrement renders this simple additive procedure suitable for a quick but ° (298 K) values of substituted reliable assesment of Δg1Hm benzamides with meta- and para-substitution on the benzene ring. As a rule, the ortho-pairwise interactions are unique because of the intense steric repulsions of the bulky nextneighbor substituents or because of intramolecular hydrogen bonding. As a consequence, the ortho-interactions have to be considered as single additional increments, e.g., ortho OH− CONH2, ortho NH2−CONH2, etc., to the vaporization enthalpy due to the specific mutual interactions of the nextneighbor groups (see Table 5) on the benzene ring. Moreover, these specific ortho-pairwise interactions have to be definitely taken into account, at least for assessment of vaporization enthalpies of polysubstituted benzenes. However, for the simple case of disubstituted benzenes, the straightforward incremental procedure based on a very restricted number of parameters (see Table 5) is generally very useful for a quick appraisal of the rationality of experimental vaporization enthalpies of meta- and para-substituted aromatics available, e.g., in a comprehensive compilation by Chickos and Acree.29 This procedure can be useful even for the current work in order to resolve contradictions among sublimation enthalpies available for 4hydroxybenzamide, as described in Section 3.2. Indeed, the theoretical vaporization enthalpy for this compound, Δg1H°m(298 K) = 109.3 ± 1.6 kJ mol−1, is listed in Table 4, and the fusion enthalpy, Δg1H°m(298 K) = 17.6 ± 1.4 kJ mol−1, is given in Table 3. The sum of these values provides the value ° (298 K) = 109.3 + 17.6 = 126.9 ± 2.1 kJ mol−1, which is ΔgcrHm in agreement with the direct calorimetric result reported by Bernardes et al.,13 ΔgcrH°m(298 K) = 129.7 ± 0.6 kJ mol−1 (see Table 1). This agreement was decisive for recommendation of the latter calorimetric result on sublimation enthalpy of 4hydroxybenzamide for further thermochemical calculations (see Table 1). 3.4.3. Validation of Vaporization Enthalpy of 2Hydroxybenzamide. As can be seen in Table 1, the available enthalpies of sublimation of 2-hydroxybenzamide measured directly by drop calorimetry are in close agreement and they can be averaged to the value Δg1Hm ° (298 K) = 101.8 ± 0.5 kJ mol−1. However, this averaged calorimetric result is significantly (by 7 kJ mol−1) lower than those indirectly derived from vapor pressure measurements by the transpiration method (see Table 1). In spite of the successful reconciliation of the phase change enthalpies for 2-hydroxybenzamide (see Section 3.4.1), we are still reticent to make a final decision whether direct or indirect results should be preferred. In order to resolve the current contradiction between two data sets, let us make use of the structure−property relationships. Indeed, all molecules presented in Figure 2, starting with 2-hydroxybenzamide, have a common structural unit: the carbonyl group and the hydroxyl group in the ortho-position on the benzene ring. It is well established in the literature54−56 that all molecules in Figure 2 possess the intramolecular hydrogen bond (intra-HB). Thus, it is rather reasonable to assume that the strength of this intra-HB in the molecules in Figure 2 is mostly determined by the close proximity of CO and OH groups. The consequence of this assumption is that the strength of the intra-HB is expected to

In this paper, we also apply this simple method for estimation of vaporization enthalpies of substituted benzamides. The procedure is based on a starting basic molecule having well-established data on its vaporization enthalpy. For ° (298 K) of phenol and Δg1Hm ° (298 K) example, using the Δg1Hm of benzene, we calculated the increment ΔH(H→OH) for substitution of a H-atom on the benzene ring by a OH group. ° (298 K) of aniline and Δg1Hm ° (298 K) of benzene, Using Δg1Hm we calculated the increment ΔH(H→NH2) for substitution of a H-atom on the benzene ring by an NH2 group, etc. In the current study, we used the benzamide as the basic molecule for calculation of vaporization enthalpies of R-substituted benz° (298 K) = 85.4 amides (see Table 4). The reliable value Δg1Hm ± 1.5 kJ mol−1 for benzamide was recently measured by using the static method.14 The increments ΔH(H→R) for substitution of a H-atom on the benzene ring by different substituents are compiled in Table 5, and these increments have been used for calculation of theoretical vaporization enthalpies of benzamides. Table 5. Parameters for the Calculation of Enthalpies of Vaporization, Δg1Hm ° , and Enthalpies of Formation, ΔfHm ° , at 298 K (kJ mol−1) groups benzamide ΔH(H→OH) ΔH(H→CH3) ΔH(H→OCH3) ΔH(H→NH2) ΔH(H→CONH2) ortho CONH2−OH ortho CONH2−CH3 ortho CONH2−OCH3 ortho CONH2−NH2 a

Δg1Hm °

ΔfHm ° (g)

85.4a

−99.8b

23.9 4.2 12.5 21.9 51.5 −22.0 1.1 −8.5 −15.9

−179.3 −32.8 −153.6 4.2 −182.7 −20.1 3.9 −2.1 −17.4

From Table 4. bFrom Table 2.

° (298 K) = 85.4 ± For example, using the starting value Δg1Hm 1.5 kJ mol−1 for benzamide and the increment ΔH(H→OH) from Table 5, the theoretical values of vaporization enthalpies for hydroxybenzamides, regardless of the position of substituents on the benzene ring, were calculated (see Table 6). In a similar way, by using increments ΔH(H→R), the theoretical values of vaporization enthalpies for other R-substituted benzamides can be calculated. The theoretical Δg1H°m values of

Table 6. Calculation of Enthalpies of Vaporization, Δg1Hm ° (298 K), of Hydroxybenzamides by Using Group Additivity Δg1Hm ° (298 K)/kJ mol−1 basic molecule ΔH(H→OH) theoretical value experimental value experimental value experimental value

benzamide OH 2-OH-benzamide 3-OH-benzamide 4-OH-benzamide

85.4 ± 1.5a 23.9 ± 0.5b 85.4 + 23.9 = 109.3 ± 1.6 87.4 ± 0.9c 111.1 ± 2.8c 112.1 ± 2.1c

a From ref 14. bDerived as the difference between Δg1Hm ° (298 K, phenol) = 57.8 ± 0.5 kJ mol−1 52 and Δg1H°m(298 K, benzene) = 33.9 ± 0.1 kJ mol−1.53 cFrom Table 4.

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experiment over the liquid sample of 2-hydroxybenzamide. The latter value has been carefully validated in Section 3.4.1 through the consistency of phase transition enthalpies available for the 2-hydroxybenzamide. However, the validation in Section 3.4.1 was successful for the average value taken from transpiration results but not for the results from the direct calorimetric determinations. We believe that the remarkable consistency of intra-HB strengths for parent structures demonstrated in Figure 2 can be also considered as an additional reasoning for recommendation of the indirect values of sublimation and vaporization enthalpies evaluated in this work and not those available from the direct calorimetric measurements. 3.5. Gas-Phase Enthalpies of Formation of Benzamides. 3.5.1. Theoretical Enthalpies of Formation by G4Method. Experimental values of the solid-state enthalpies of formation of substituted benzamides, together with the enthalpies of sublimation of the R-substituted benzamides, have been used for calculation of the gaseous standard molar enthalpies of formation, ΔfHm ° (g) at 298 K (see Table 2, column 4). These experimental values can be used for comparison with theoretical values calculated by any highlevel quantum-chemical methods. In our recent work,5,20,27,44 we have successfully used the high-level composite quantumchemical method G426 for aromatic compounds. Agreement or disagreement between the experimental and theoretical results could provide valuable information for mutual validation for both results and help in evaluation of the quality of thermochemical data for compounds studied in this work. We used the force field method MM358 for an initial search for stable conformers of substituted benzamides. Enthalpies H298 of the most stable conformers (see Table S6) were calculated by the G4 method. The most stable conformations of 2-hydroxy-, 2-methyl-, 2-methoxy-, and 2-aminobenzamides, anticipating the existence of the intra-HB, together with the meta- and para-substituted benzamides, are presented in Figure 3.

Figure 2. Structures of disubstituted benzenes used for validation of vaporization enthalpy of 2-hydroxybenzamide and the strength of the intra-HB (in kJ mol−1) in these molecules.

be of comparable size in all molecules presented in Figure 2. But the question remains of how to obtain the measure for this HB strength from the thermochemical data? There are many different definitions of “hydrogen bond” and its strength in the literature,54−57 and it is not our intention to introduce in this work any new definition. Nevertheless, only for the sake of a structure−property analysis of molecules presented in Figure 2, it is reasonable to assess a “measure” for the intra-HB as a difference between the experimental vaporization enthalpy and the theoretical vaporization enthalpy calculated by the incremental group-additivity procedure described in Section 3.4.2 and demonstrated for hydroxybenzamides in Table 6. It seems to be quite apparent that the theoretical Δg1H°m(298 K) value is collected from general group contributions derived from molecules without hydrogen bonding; thus, comparison with the experimental vaporization enthalpy of the real molecule of 2-hydroxybenzamide with the theoretical Δg1H°m(298 K) value will provide a rough measure for the specific interactions appearing mostly due to the hydrogen bonding of the next-nearest-neighbor substituents in the molecules presented in Figure 2. An example for the estimation of the HB strength in the 2-hydroxybenzamide is shown in Table 7. Similar calculations of the HB strength for 2hydroxy-substituted benzoic acid, methyl benzoate, acetophenone, and benzaldehyde are given in Table S9. Table 7. Calculation of Intra-HB Strength in 2Hydroxybenzamide from Enthalpies of Vaporization, Δg1Hm ° (298 K), by Using Group Additivity Δg1Hm ° /kJ mol−1 basic molecule substituent theoretical value 2-OH-derivative intra-HB

benzamide OH 2-OH-benzamide

85.4 23.9 85.4 87.4 87.4

± 1.5a ± 0.5b + 23.9 = 109.3 ± 0.9c − 109.3 = −21.9 ± 1.8

From Table 4. bDerived as the difference between Δg1H°m(298 K, ° (298 K, benzene) = 33.9 ± phenol) = 57.8 ± 0.5 kJ mol−1 52 and Δg1Hm 0.1 kJ mol−1.53 cExperimental value (see Table 4) from the transpiration experiment over the liquid sample of 2-hydroxybenzamide. a

Measured values of the intra-HB strength derived in this way are presented in Figure 2. As can be seen from the numbers listed in Figure 2, all molecules having intramolecular hydrogen bonding due to the close proximity of CO and OH groups exhibit, as expected, the same level of −20 kJ mol−1 (within their experimental uncertainties) of specific contribution to the vaporization enthalpy. It should be mentioned that calculations given for 2-hydroxybenzamide in Table 7 are based on the experimental vaporization enthalpy, Δg1Hm ° (298 K) = 87.4 ± 0.9 kJ mol−1 (see Table 4), derived from the transpiration

Figure 3. Optimized structures of R-substituted-benzamides obtained with the G4 method. 9874


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The Journal of Physical Chemistry A Values of H298 enthalpies for the most stable conformers of the R-benzamides presented in Figure 3 were calculated by the G4 method, and they were converted to the enthalpies of formation ΔfHm ° (g, 298 K) by using the atomization procedure (AT), as well as with the conventional ring-conserved homodesmic reactions according to eq 1. Using enthalpies of reaction 1 calculated from enthalpies H298 of benzamide derivatives (see Table S6) together with the enthalpies of ° (g), for the benzene, phenol, aniline, toluene, formation, ΔfHm anisole, and benzamide (see Table S11), the theoretical enthalpies of formation of all isomeric R-benzamides have been calculated (see Table 2, column 5). Theoretical enthalpies of formation of R-benzamides (except for 2-hydroxybenzamide) calculated via reaction 1 or via AT (see Table S10) are mostly in good agreement with the experimental values evaluated and presented in Table 2. However, theoretical enthalpies of formation of 2-hydroxybenzamide, −305.4 kJ mol−1 (from AT) and −310.1 kJ mol−1 (from eq 1), are obviously different from the experimental ΔfH°m(g, 298 K) = −299.2 ± 1.1 kJ mol−1 reported in Table 2. Moreover, it also turns out that the disagreement between the theoretical value for 2-aminobenzamide and that from experiment is less profound but quite apparent, in contrast to the very good agreement between theory and experiment for other meta- and para-substituted benzamides listed in Table 2. From our experiences, such disagreement is not surprising, because similar deviations of the theoretical and experimental ΔfH°m(g, 298 K) values for ortho-substituted benzenes were also observed for 1,2-difluorobenzene5 and for 2-methoxybenzoic acid9 recently. We are tracking now the performance of quantum-chemical methods for 1,2-disubstituted benzenes and looking for an explanation for the disagreement observed in our current studies. 3.5.2. Pairwise Interactions of Substituents in the Benzene Ring. Energetics of nearest-neighbor and non-nearest-neighbor interactions of the amide group with different types of substituents are important for understanding and predicting reaction pathways and for modeling of chemical and biochemical processes. These interactions are referenced to reaction enthalpies, ΔrHm° , according to reaction 1 but considered in the reverse way. They can be calculated using the ΔfHm ° (g) values (experimental or theoretical) of the reaction participants, or they can be derived from the enthalpies H298 directly calculated by the G4 method. We collected experimental and theoretical gas-phase enthalpies of formation of R-substituted benzamides in Table 2 and used them for calculations of pairwise interactions of substituents (see Table 8). Comparison of the experimental and theoretical pairwise interactions in Table 8 shows that they are in good agreement (except for 2-hydroxybenzamide), providing confidence for the reliability of both data sets. Further discussion of the nearestneighbor interactions in substituted benzamides is based on the G4 results. First of all, it seems easy to rationalize pairwise interactions in 2-substituted benzamides. Stabilizing interactions in 2-hydroxybenzamide, 2-aminobenzamide, and 2-methoxybenzamide are obviously caused by the intra-HB, with the strength depending on the electron-donating ability of substituents. The weak destabilization of 4.1 kJ mol−1 observed in 2-methylbenzamide is due to the steric repulsion between CH3 and CONH2 substituents. Interpretation of pairwise interactions in 3- and 4-substituted benzamides is less straightforward. The energetics of these

Table 8. Pairwise Intramolecular Interactions of Substituents in R-Substituted Benzamides, in kJ mol−1 compound

ΔrHm °a

ΔrHm °b

2-hydroxybenzamide 3-hydroxybenzamide 4-hydroxybenzamide 2-aminobenzamide 3-aminobenzamide 4-aminobenzamide 2-methoxylbenzamide 3-methoxylbenzamide 4-methoxylbenzamide 2-methylbenzamide 3-methylbenzamide 4-methylbenzamide

−20.1

−31.0 0.6 −2.7 −14.1 −2.6 −4.7 −3.2 −3.1 −3.1 4.1 −0.9 −1.2

0.2 −17.4 −3.4 −4.7 −2.1 −1.9 −4.0 3.9 −0.2 −4.1

Referenced to the reaction benzamide + substituted benzene → ° (g, compound + benzene and calculated using the experimental ΔfHm 298 K) values of reaction participants from Table 2 and Table S11. b Referenced to the reaction benzamide + substituted benzene → compound + benzene and calculated using the H298 values of reaction participants from Table S6. a

interactions are stipulated by the redistribution of the electronic density on the benzene ring system. As a rule, the intensity of the meta- and para-interactions is weak and can lead to either stabilization or destabilization, but it seldom exceeds the level of 5 kJ mol−1. Contributions from pairwise interactions of substituents on the benzene ring compiled in Table 8 can be utilized in physical-organic chemistry as quantitative measures of substituents’ interactions. Moreover, values of reaction enthalpies obtained in this study can be used for prediction of ΔfHm ° (g, 298 K) by the group-additivity method, as was described for the vaporization enthalpy (see Section 3.4.2), but using increments ΔH(H→R) for substitution of the H-atom on the benzene ring by the substituent R listed in Table 5. These increments, in combination with the pairwise interactions given in Table 5, can be useful for a rough assessment of the thermochemical properties of polysubstituted benzenes and aromatics containing substituents R studied in this work.

4. CONCLUSIONS Thermochemical properties of isomeric R-substituted benzamides have been carefully evaluated on the basis of additional experimental results. Experimental values of ΔgcrH°m(298 K), Δ1crHm ° (298 K), Δg1Hm ° (298 K), and ΔfHm ° (cr, 298 K) were evaluated and tested for internal consistency. Sets of nearestneighbor and non-nearest-neighbor interactions between substituents on the benzene ring have been evaluated. A simple incremental procedure for a quick appraisal of the vaporization enthalpies and the gas-phase formation enthalpies of substituted benzamides has been suggested.

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jpca.6b10332. Information on provenance of the compound under study (Table S1), experimental vapor pressures from transpiration method (Table S2), auxiliary information for combustion calorimetry (Table S3), results for combustion calorimetry of 2- and 4-hydroxybenzamide (Tables S4 and S5), results for quantum-chemical 9875


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(9) Verevkin, S. P.; Zaitsau, D. H.; Emel’yanenko, V. N.; Stepurko, E. N.; Zherikova, K. V. Benzoic acid derivatives: evaluation of thermochemical properties with complementary experimental and computational methods. Thermochim. Acta 2015, 622, 18−30. (10) Ryskalieva, A. K.; Abramova, G. V.; Erkasov, R.; Sh; Nurakhmetov, N. N. Enthalpies of combustion and formation of salicylic acid derivatives. Russ. J. Phys. Chem. (Engl. Transl.) 1992, 66, 421−423. (11) Ribeiro da Silva, M. D. M. C.; Araújo, N. R. M. Thermochemical studies on salicylaldehyde and salicylamide. J. Chem. Thermodyn. 2007, 39, 1372−1376. (12) Nordström, F. L.; Rasmuson, A. C. Solubility and Melting Properties of Salicylamide. J. Chem. Eng. Data 2006, 51, 1775−1777. (13) Bernardes, C. E. S.; Minas da Piedade, M. E. Energetics of the O−H Bond and of Intramolecular Hydrogen Bonding in HOC6H4C(O)Y (Y = H, CH3, CH2CHCH2, CCH, CH2F, NH2, NHCH3, NO2, OH, OCH3, OCN, CN, F, Cl, SH, and SCH3) Compounds. J. Phys. Chem. A 2008, 112, 10029−10039. (14) Almeida, A. R. R. P.; Monte, M. J. S. Thermodynamic Study of Benzamide, N-Methylbenzamide, and N,N-Dimethylbenzamide: Vapor Pressures, Phase Diagrams, and Hydrogen Bond Enthalpy. J. Chem. Eng. Data 2010, 55, 3507−3512. (15) Almeida, A. R. R. P.; Monte, M. J. S. Thermodynamic Study of the Three Fluorobenzamides: Vapor Pressures, Phase Diagrams, and Hydrogen Bonds. J. Chem. Eng. Data 2010, 55, 5230−5236. (16) Almeida, A. R. R. P.; Matos, M. A. R.; Monte, M. J. S.; Morais, V. M. F. Experimental and computational thermodynamic study of ortho-, meta-, and para-methylbenzamide. J. Chem. Thermodyn. 2012, 47, 81−89. (17) Almeida, A. R. R. P.; Monte, M. J. S.; Matos, M. A. R.; Morais, V. M. F. Experimental and computational thermodynamic study of ortho- meta- and para-aminobenzamide. J. Chem. Thermodyn. 2013, 59, 222−232. (18) Almeida, A. R. R. P.; Monte, M. J. S.; Matos, M. A. R.; Morais, V. M. F. The thermodynamic stability of the three isomers of methoxybenzamide: An experimental and computational study. J. Chem. Thermodyn. 2014, 73, 12−22. (19) Verevkin, S. P.; Emel’yanenko, V. N. Transpiration method: Vapor pressures and enthalpies of vaporization of some low-boiling esters. Fluid Phase Equilib. 2008, 266, 64−75. (20) Verevkin, S. P.; Sazonova, A. Y.; Emel’yanenko, V. N.; Zaitsau, D. H.; Varfolomeev, M. A.; Solomonov, B. N.; Zherikova, K. V. Thermochemistry of halogen-substituted methylbenzenes. J. Chem. Eng. Data 2015, 60, 89−103. (21) Emel’yanenko, V. N.; Verevkin, S. P. Benchmark thermodynamic properties of 1,3-Propanediol: comprehensive experimental and theoretical study. J. Chem. Thermodyn. 2015, 85, 111−119. (22) Verevkin, S. P.; Schick, C. Substituent effects on the benzene ring. Determination of the intra-molecular interactions of substituents in tert-alkyl substituted catechols from thermochemical measurements. J. Chem. Eng. Data 2000, 45, 946−952. (23) Emel’yanenko, V. N.; Verevkin, S. P.; Heintz, A. The gaseous enthalpy of formation of the ionic liquid 1-butyl-3-methylimidazolium dicyanamide from combustion calorimetry, vapor pressure measurements, and ab initio calculations. J. Am. Chem. Soc. 2007, 129, 3930− 3937. (24) Hubbard, W. N.; Scott, D. W.; Waddington, G. Standard States Corrections for Combustions in a Bomb at Constant Volume. In Experimental Thermochemistry; Rossini, F. D., Ed.; Interscience: New York, 1956; pp 75−127. (25) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; et al.. Gaussian 09, Revision A.02; Gaussian Inc.: Wallingford, CT, 2009. (26) Curtiss, L. A.; Redfern, P. C.; Raghavachari, K. Gaussian-4 Theory. J. Chem. Phys. 2007, 126, 084108. (27) Verevkin, S. P.; Emel’yanenko, V. N.; Notario, R.; Roux, M. V.; Chickos, J. S.; Liebman, J. F. Rediscovering the wheel. Thermochem-

calculations of benzamides (Table S6), auxiliary information for adjusted enthalpies of phase transitions of benzamides (Table S7), information on thermodynamics of phase transitions (Table S8), information on calculation of intramolecular hydrogen bonds (Table S9), information on quantum chemical calculations of enthalpies of formation of stable conformation of substituted benzamides (Table S10), information on thermochemical data of reference compounds for determination of pairwise intramolecular interactions of substituents in R-substituted benzamides (Table S11), atomic values for H, C, N, and O used by G4 atomization calculations (in hartrees) (Table S12), experimental vapor pressures of the benzamide (Figure S1), and experimental vapor pressures of the 2-hydroxybenzamide (Figure S2) (PDF)

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. ORCID

Sergey P. Verevkin: 0000-0002-0957-5594 Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work has been supported by the German Science Foundation (DFG) in the frame of the priority program SPP 1708 “Material Synthesis Near Room Temperature”. This work has been partly supported by the Russian Government Program of Competitive Growth of Kazan Federal University.

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