Measurement and Correlation of the Solubility of Azoxystrobin in

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

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Measurement and Correlation of the Solubility of Azoxystrobin in Seven Monosolvents and Two Different Binary Mixed Solvents Haiyan Yang,†,‡ Teng Zhang,†,‡ Shijie Xu,†,‡ Dandan Han,†,‡ Shiyuan Liu,†,‡ Yang Yang,†,‡ Shichao Du,†,‡ Mingchen Li,†,‡ and Junbo Gong*,†,‡ †

School of Chemical Engineering and Technology, State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, China ‡ The Co-Innovation Center of Chemistry and Chemical Engineering of Tianjin, Tianjin 300072, China ABSTRACT: A gravimetric method was used to determine the solubility of azoxystrobin in seven monosolvents (methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and ethyl acetate) and two binary mixed solvents (n-propanol + ethyl acetate and methanol + ethyl acetate) at different temperatures from 288.15 to 328.15 K. The solubility of azoxystrobin is positively related with temperature in all selected solvents. Moreover, the solubility of azoxystrobin in methanol + ethyl acetate binary mixed solvent reaches a maximum when the mole fraction of ethyl acetate is 0.8, differing from that in n-propanol + ethyl acetate binary mixed solvent. The Apelblat, λh, combined nearly ideal binary solvent/ Redlich−Kister, and nonrandom two-liquid model (NRTL) equations were applied to correlate the solubility of azoxystrobin, and all of the equations provided good fitting results to the data. In addition, the mixing thermodynamic properties of azoxystrobin in binary mixed solvents were calculated based on the NRTL equation. The results demonstrate that the mixing process in the experimental binary mixed solvents is endothermic and spontaneous. enormous growth potential.8,9 The amorphous solid and two polymorphic forms (form A, the more thermodynamically stable form, and form B) of azoxystrobin have been reported by some patents.1,10 It is well-known that the purity, mobility, and size distribution of the crystallization products play important roles in the treatment effect of products. To a great extent, crystallization serves as the final unit operation to separate and purify solid state agrichemical products. The quality of product significantly depends on the operation parameters of crystallization. To measure and correlate the solubility, thermodynamic basis data will benefit the design of purification methods and the preparing processes. By employing the solubility data, one can calculate the mixing thermodynamic properties of drugs, which could take further insight into the mixing process and help to choose appropriate crystallization technological conditions. The solubility of azoxystrobin in seven monosolvents (methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and ethyl acetate) and two binary mixed solvents (n-propanol + ethyl acetate and methanol + ethyl acetate) was measured from 288.15 to 328.15 K by applying a gravimetric method. The experimental solubility value in monosolvents was correlated by the Apelblat, λh, and nonrandom two-liquid model (NRTL) equations. Moreover, the combined nearly ideal binary

1. INTRODUCTION Azoxystrobin (C22H17N3O5, chemical name: methyl (E)-2-{2[6-(2-cyanophenoxy) pyrimidin -4-yloxy] phenyl}-3-methoxypropenoate, CAS registry no.: 131860-33-8, shown in Figure 1),

Figure 1. Chemical structure of azoxystrobin.

as a broad-spectrum fungicide with protectant and curative properties, is profoundly beneficial to the growth of cereals, fruits, and vegetables such as rice, citrus, potatoes, and tomatoes.1,2 It shows excellent efficacy in controlling anthracnose disease of chili and many other plant diseases.3,4 From the statistical data listed in Phillips’ paper, azoxystrobin is used as fungicide for more than 85 different crops over the world, which is considered as the most popular (ranked as the number 1) agricultural fungicide on the global fungicides market.5,6 Azoxystrobin is useful for controlling and combating fungi grown on agricultural and horticultural crops.1 As a commercial agrichemical product, it resists major groups of plant pathogenic fungi, including Ascomcetes and Basidiomycetes.7 Many studies focus on the resistance mechanism of azoxystrobin against diseases and the residue behaviors of azoxystrobin in plants. It was found that azoxystrobin has low acute and chronic toxicity to humans and mammals, giving azoxystrobin © XXXX American Chemical Society

Received: July 20, 2017 Accepted: September 28, 2017

A

DOI: 10.1021/acs.jced.7b00669 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

Article

Table 1. Sources and Mass Fraction Purity of the Materials

a

chemical name

source

mass fraction purity

molecular mass

analysis method

azoxystrobin methanol ethanol n-propanol isopropanol n-butanol isobutanol ethyl acetate

Changshuhengrong Commercial and Trading Co., Ltd. Jiangtian Chemical Technology Co., Ltd., Tianjin, China Tianjin Fuyu Fine Chemical Co., Ltd. Tianjin Fuyu Fine Chemical Co., Ltd. Tianjin Fuyu Fine Chemical Co., Ltd. Jiangtian Chemical Technology Co., Ltd., Tianjin, China Jiangtian Chemical Technology Co., Ltd., Tianjin, China Hengshan Chemical Science and Technology Co., Ltd., Tianjin, China.

≥0.998 ≥0.995 ≥0.997 ≥0.998 ≥0.997 ≥0.995 ≥0.995 ≥0.995

403.39 32.04 46.07 60.06 60.06 74.12 74.12 88.11

HPLCa GCb GCb GCb GCb GCb GCb GCb

High performance liquid chromatography. bGas chromatography.

Figure 2. PXRD patterns of raw azoxystrobin and excess azoxystrobin from selected solvents (T = 288.15 K, methanol).

solvent/Redlich−Kister (CNIBS/R−K) and NRTL equations were employed to correlate the experimental solubility in binary mixed solvents. Additionally, the mixing thermodynamic properties of azoxystrobin in binary mixed solvents, including enthalpy, entropy and Gibbs energy, were calculated based on the experimental solubility data using the NRTL equation.

2. EXPERIMENTAL SECTION 2.1. Materials. A detailed description of the chemicals used in this work is given in Table 1. All chemical materials were used without any further purification. The raw azoxystrobin was supplied by Changshuhengrong Commercial and Trading Co., Ltd. with purity of larger than 0.998 (mass fraction purity). Methanol, n-butanol, and isobutanol were purchased from Jiangtian Chemical Technology Co., Ltd., Tianjin, China. Ethanol, n-propanol, and isopropanol were provided by Tianjin Fuyu Fine Chemical Co., Ltd. Ethyl acetate was offered by Hengshan Chemical Science and Technology Co., Ltd., Tianjin, China. 2.2. X-ray Powder Diffraction Analysis. X-ray powder diffraction (XRPD) was used to analyze the polymorph of the azoxystrobin in this experiment, including raw azoxystrobin and excess azoxystrobin. The condition of data collection was on Rigaku D/max-2500 (Rigaku, Japan) using Cu Kα radiation (0.15405 nm) in the 2θ range of 2−35° and scanning rate of 8°/min. The excess azoxystrobin in seven monosolvents and different ratios (x02 = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 0.9) of

Figure 3. Thermal analysis DSC/TGA curve of azoxystrobin.

binary mixed solvents were tested at fixed temperatures (T = 288.15, 308.15, and 328.15 K). The XRPD patterns of azoxystrobin show that all the samples used in this experiment have a good stability. Figure 2 indicates that the raw azoxystrobin and excess azoxystrobin (T = 288.15 K as an example, methanol) in the conical flask did not have any solvates, polymorphism, or amorphous forms during our experiments. It is worth mentioning that the form of azoxystrobin in all experimental solvents is form A by comparing the XRPD patterns with the corresponding pattern in the patent.1 B



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Table 2. Mole Fraction Solubility (x1) of Azoxystrobin in Seven Monosolvents at Different Temperatures from 288.15 to 328.15 K (p = 0.1 MPa)a T/K

100 xexp 1

288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15 328.15

0.1345 0.1648 0.2053 0.2704 0.3682 0.4970 0.6833 0.9599 1.4365

288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15 328.15

0.0747 0.0923 0.1184 0.1711 0.2196 0.2961 0.4216 0.5605 0.7857

288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15 328.15

0.0654 0.0829 0.1080 0.1621 0.2067 0.2771 0.3874 0.5268 0.7202

288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15 328.15

0.0339 0.0476 0.0649 0.1016 0.1336 0.1827 0.2602 0.3583 0.4519

100 xcal A methanol 0.1381 0.1671 0.2091 0.2698 0.3582 0.4885 0.6830 0.9773 1.4292 ethanol 0.0717 0.0937 0.1237 0.1650 0.2220 0.3012 0.4117 0.5665 0.7845 n-propanol 0.0632 0.0846 0.1136 0.1533 0.2077 0.2823 0.3849 0.5260 0.7207 isopropanol 0.0301 0.0455 0.0672 0.0972 0.1375 0.1908 0.2598 0.3474 0.4569

100 xcal λ

100 xcal N

T/K

100 xexp 1

0.1146 0.1584 0.2169 0.2942 0.3958 0.5284 0.7009 0.9244 1.2137

0.1191 0.1595 0.2126 0.2840 0.3811 0.5120 0.6949 0.9601 1.3892

288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15 328.15

0.0514 0.0733 0.0955 0.1490 0.1849 0.2462 0.3396 0.4764 0.6352

0.0664 0.0921 0.1267 0.1725 0.2329 0.3121 0.4156 0.5502 0.7252

0.0714 0.0942 0.1244 0.1671 0.2208 0.2961 0.4083 0.5592 0.8006

288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15 328.15

0.0441 0.0628 0.0840 0.1293 0.1701 0.2309 0.3238 0.4407 0.5707

0.0598 0.0835 0.1155 0.1582 0.2149 0.2896 0.3876 0.5157 0.6829

0.0627 0.0846 0.1138 0.1552 0.2073 0.2791 0.3817 0.5237 0.7300

288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15 328.15

2.4619 2.8262 3.1918 4.1461 4.7326 5.8951 7.5599 8.7949 10.810

0.0333 0.0480 0.0683 0.0962 0.1342 0.1855 0.2543 0.3462 0.4687

0.0346 0.0480 0.0662 0.0937 0.1288 0.1794 0.2558 0.3659 0.5069

100 xcal A n-butanol 0.0538 0.0733 0.0999 0.1362 0.1856 0.2529 0.3443 0.4687 0.6374 isobutanol 0.0417 0.0609 0.0876 0.1239 0.1728 0.2378 0.3230 0.4332 0.5742 ethyl acetate 2.3449 2.8033 3.3661 4.0581 4.9103 5.9612 7.2589 8.8633 10.849

100 xcal λ

100 xcal N

0.0509 0.0718 0.1002 0.1384 0.1894 0.2572 0.3468 0.4647 0.6194

0.0528 0.0728 0.0990 0.1369 0.1839 0.2490 0.3401 0.4705 0.6479

0.0437 0.0624 0.0882 0.1233 0.1707 0.2344 0.3194 0.4322 0.5817

0.0459 0.0635 0.0870 0.1209 0.1648 0.2260 0.3139 0.4368 0.6020

2.2747 2.7941 3.4131 4.1484 5.0192 6.0486 7.2636 8.6968 10.388

2.2747 2.7917 3.4078 4.1425 5.0100 6.0416 7.2713 8.7081 10.429

a exp cal cal x1 is the experimental solubility; xcal A , xλ and xN are the calculated solubility by the Apelblat equation, λh equation and the NRTL equation, respectively. The standard uncertainty of temperature is u(T) = 0.1 K. The relative standard uncertainty of the solubility measurement is ur(x) = 0.06. The relative uncertainty of pressure is ur(p) = 0.05.

Figure 3, we defined the onset temperature (387.67 ± 0.5 K) as the melting temperature of azoxystrobin (form A), which is in agreement with the literature.1 The fusion enthalpy measured in this work is 32.65 kJ·mol−1. 2.4. Solubility Measurements. The solubility of azoxystrobin in seven monosolvents and two binary mixed solvents from 288.15 to 328.15 K was investigated under atmospheric pressure by a gravimetric method.11 In the experiments, all measurements of mass were performed on an analytic balance (AB204-N, Mettler-Toledo, Switzerland) with uncertainty of ±0.0001 g. In this method, excess amount of azoxystrobin was added into a 50 mL capped conical flask containing 25 mL of preheated/cooled solvent. Then, the (solid + liquid) mixture was put into a thermostat shaker (type 501A, Shanghai Laboratory Instrument Works Co., Ltd., China, with the precision of

2.3. Differential Scanning Calorimetry. A differential scanning calorimeter (DSC 1/1500, Mettler Toledo, Switzerland) calibrated by indium and zinc under a nitrogen atmosphere was used to get the melting temperature (Tm) and enthalpy of fusion (ΔfusH) of azoxystrobin (the standard uncertainty of the melting temperature is u(Tm) = 0.5 K; the relative standard uncertainty of the enthalpy is ur(ΔfusH) = 0.005). In this experiment, 5−10 mg of azoxystrobin was transferred into standard DSC aluminum pan, and an empty pan was used as reference. Then, the sample was heated from 398.15 to 433.15 K with a rate of 10 K/min under the protection of nitrogen. We chose a differential scanning calorimeter to analyze the solid state samples before and after the dissolution of azoxystrobin in experimental solvents to ensure the samples keep stable and do not go through any transformations. As shown in C



Article

Figure 5. Experimental solubility data of azoxystrobin in n-propanol + ethyl acetate binary mixed solvent at different temperatures from 288.15 to 328.15 K (p = 0.1 MPa).

Figure 4. Experimental solubility data of azoxystrobin in 7 monosolvents at different temperatures from 288.15 to 328.15 K (p = 0.1 MPa).

T = ±0.1 K) at 220 rpm for about 12 h to reach the solid−liquid equilibrium. The equilibrium was confirmed by repeating concentration analysis at an interval of 30 min. After this, the shaker was stopped, and the solution was kept still for 2 h under the corresponding experimental temperature to allow the undissolved particles to settle. Syringes (10 mL) and syringes filters (0.45 μm) were preheated/cooled to the temperature equivalent to that of the solution. After that, about 5 mL of upper saturated solution was filtered by the prepared syringe filters and poured into preweighted glass dishes. Then, the total weight was measured immediately by the balance. Subsequently the weighed glass dishes were placed into a vacuum oven (type DZ-1BCII, Yichuan Appearance of Bearing Co., Ltd., China) at T = 323.15 K to evaporate the solutions, and the mass of the dishes was recorded periodically until the total weight remained constant. Each experiment was repeated three times under the same condition to minimize the experimental errors, and the mean value was used as the final result to calculate the mole fraction solubility. The experimental mole fraction solubility of azoxystrobin (x1) in monosolvents was calculated by eq 1:

Figure 6. Experimental solubility data of azoxystrobin in methanol + ethyl acetate binary mixed solvents at different temperatures from 288.15 to 328.15 K (p = 0.1 MPa).

x1 =

m1/M1 m1/M1 + m2 /M 2

(1)

In this equation, m1 represents the mass of azoxystrobin in saturated solution; m2 represents the mass of monosolvent (methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, or ethyl acetate), and M1 and M2 are the molecular mass of azoxystrobin and the corresponding monosolvents, respectively. The initial composition of the binary mixed solvents (x02) can be calculated by eq 2: x 20 = D

m2 /M 2 m2 /M 2 + m3 /M3

(2) DOI: 10.1021/acs.jced.7b00669 J. Chem. Eng. Data XXXX, XXX, XXX−XXX


Article

Table 3. Mole Fraction Solubility (x1) of Azoxystrobin in n-Propanol + Ethyl Acetate Binary Mixed Solvent at Different Temperatures from 288.15 to 328.15 K (p = 0.1 MPa)a x02

100 xexp 1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0.0688 0.1572 0.3100 0.5340 0.8317 1.1228 1.5479 1.9258 2.2566 2.4983 2.4619

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0.0843 0.2014 0.3826 0.6157 0.9327 1.3389 1.6673 2.0923 2.4385 2.6535 2.8262

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0.1031 0.2345 0.4619 0.7514 1.1127 1.6107 2.0236 2.5116 2.9123 3.1794 3.1861

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0.1726 0.2935 0.5307 0.9042 1.3247 1.7593 2.5020 3.0899 3.6395 3.9343 4.1481

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0.2067 0.4103 0.7071 1.1213 1.5461 1.9680 2.8948 3.7523 4.1933 4.7035 4.7326

100 xcal R T = 288.15 K 0.0661 0.1588 0.3132 0.5334 0.8156 1.1521 1.5295 1.9208 2.2711 2.4896 2.4639 T = 293.15 K 0.0936 0.1998 0.3730 0.6216 0.9403 1.3105 1.7030 2.0837 2.4177 2.6727 2.8211 T = 298.15 K 0.1023 0.2358 0.4529 0.7563 1.1358 1.5729 2.0430 2.5095 2.9150 3.1749 3.1877 T = 303.15 K 0.1795 0.3155 0.5326 0.8557 1.2983 1.8504 2.4698 3.0846 3.6097 3.9726 4.1357 T = 308.15 K 0.2514 0.4227 0.6778 1.0398 1.5269 2.1428 2.8622 3.6156 4.2820 4.7021 4.7237

100 xcal N

x02

100 xexp 1

0.0618 0.1520 0.2776 0.4623 0.7082 1.0040 1.3289 1.6477 1.9249 2.1282 2.2747

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0.2771 0.5522 0.9702 1.5233 1.8495 2.5833 3.6107 4.9398 5.4396 5.8513 5.8951

0.0842 0.2006 0.3608 0.5933 0.9001 1.2682 1.6663 2.0581 2.3978 2.6466 2.7917

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0.3874 0.7606 1.1715 1.9637 2.6418 3.5797 4.6575 6.0450 6.8444 7.1372 7.5599

0.1140 0.2623 0.4654 0.7568 1.1375 1.5921 2.0804 2.5587 2.9726 3.2764 3.4078

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0.5268 1.0251 1.8431 2.6184 3.7895 5.2741 6.5164 7.3428 8.0196 8.3507 8.7949

0.1558 0.3405 0.5953 0.9589 1.4286 1.9815 2.5841 3.1651 3.6684 4.0367 4.1425

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0.7202 1.3570 2.4286 3.9070 5.4663 6.8559 8.1644 9.9334 10.3573 10.7896 10.8102

100 xcal R T = 313.15 K 0.3769 0.5757 0.8788 1.3237 1.9431 2.7466 3.6939 4.6725 5.4961 5.9451 5.8501 T = 318.15 K 0.4635 0.7464 1.1816 1.8104 2.6511 3.6760 4.7971 5.8742 6.7517 7.3090 7.5020 T = 323.15 K 0.5972 1.0210 1.6968 2.6671 3.8935 5.2293 6.4584 7.3969 7.9937 8.3679 8.7887 T = 328.15 K 0.6974 1.4117 2.4692 3.8270 5.3699 6.9451 8.3990 9.5998 10.4446 10.8555 10.7775

100 xcal N 0.2816 0.5647 0.9644 1.5218 2.2140 3.0369 3.9220 4.7866 5.5034 6.0374 6.0416 0.3837 0.7218 1.2135 1.9056 2.7627 3.7614 4.8184 5.8475 6.7104 7.3397 7.2713 0.5238 0.9188 1.5458 2.3864 3.4538 4.6852 5.9452 7.1194 8.1281 8.8740 8.7081 0.7236 1.1653 1.9489 3.0262 4.3425 5.7943 7.2812 8.7282 9.8825 10.7654 10.4297

0.2073 0.4399 0.7591 1.2087 1.7826 2.4527 3.1870 3.8945 4.4951 4.9446 5.0100 E



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Table 3. continued a 0 x2 is the initial mole fraction of ethyl cal xexp 1 is the experimental solubility; xR ,

acetate in n-propanol + ethyl acetate binary mixed solvent; the relative standard uncertainty is ur(x02) = 0.005. and xcal N are the calculated solubility by the CNIBS/R−K equation and the NRTL equation, respectively. The standard uncertainty of temperature is u(T) = 0.1 K. The relative standard uncertainty of the solubility measurement is ur(x) = 0.06. The relative uncertainty of pressure is ur(p) = 0.05.

C are equation parameters. A and B are constants which are in accordance with the nonideality of the real solution, and C reveals the effect of temperature on the fusion enthalpy.14 3.2. λh Equation. λh equation was proposed by Buchowski et al.15,16 Like the Apelblat equation, λh equation also reflects the relationship between the mole fraction solubility x1 and temperature T. It can be shown as follows: ⎡1 ⎡ λ(1 − x1) ⎤ 1 ⎤ ln⎢1 + ⎥ ⎥ = λh⎢ − x1 Tm ⎦ ⎣T ⎦ ⎣

(5)

Similar to the Apelblat equation, x1 in this equation refers to the mole fraction solubility of the solute; T and Tm are the absolute experimental temperature and melting temperature of the solute, and λ and h are the parameters of the equation. 3.3. CNIBS/R−K Equation. Compared to that for monosolvents, the CNIBS/R−K equation is generally used to calculate the solubility of substance in binary solvent systems at a fixed temperature and was first proposed by Acree et al.17 The CNIBS/R−K equation is suitable to predict the connection of isothermal solubility with solvent composition. This equation can be shown as follows:

Figure 7. Experimental solubility data of azoxystrobin in n-propanol + ethyl acetate binary mixed solvent at different mole fractions of ethyl acetate (x02) from 0.1 to 0.9 (p = 0.1 MPa).

n

ln x1 = xA ln XA + x B ln XB + xAx B ∑ Si(xA − x B)i

The mole fraction solubility (x1) of azoxystrobin in binary mixed solvents can be calculated based on eq 3: x1 =

m1/M1 m1/M1 + m2 /M 2 + m3 /M3

i=0

(6)

where x1 refers to the mole fraction solubility of the solute; xA and xB refer to the initial mole fraction of the binary mixtures, and XA and XB are the saturated mole solubility of solute in corresponding monosolvents. Si is the equation parameter, and n is the number of “curve-fit” parameter. If n = 2, eq 6 can be simplified as

(3)

In the above two equations, x02 refers to the mole fractions of ethyl acetate in binary mixed solvents (the composition of binary mixed solvents remained unchanged because there was little leakage before and after experiment, which could be ignored). x1 is the mole fraction solubility of azoxystrobin; m1 is the mass of azoxystrobin, and m2 and m3 refer to the mass of organic solvents. M1, M2, and M3 represent the corresponding molecular masses.

ln x1 = xA ln XA + (1 − xA )ln XB + (1 − xA )xA [S0 + S1(2xA − 1) + S2(2xA − 1)2 ]

(7)

Eq 7 can be simplified as

3. THERMODYNAMIC EQUATIONS The determination and correlation of solubility play a vital role in the design and optimization of the crystallization. One main purpose of this work is to provide necessary data about solid− liquid equilibrium for industrial applications. Various proposed equations such as the Apelblat, CNIBS/R−K, λh, and NRTL equations were developed to correlate the solubility data. In this work, the Apelblat, λh, and NRTL equations were applied to correlate the solubility of azoxystrobin in monosolvents; the CNIBS/R−K and NRTL equations were used to correlate the solubility of azoxystrobin in binary mixed solvents. 3.1. Apelblat Equation. As a semiempirical equation, the Apelblat equation obtained from the Clausius−Clapeyron equation12,13 is frequently used to correlate the solubility with temperature. The equation can be shown as follows: B ln x1 = A + + C ln(T /K) (4) T /K

ln x1 = B1 + B2 xA + B3xA2 + B4 xA3 + B5xA4

(8)

where B1, B2, B3, B4, and B5 in this equation are equation parameters. They can be obtained by least-squares regression.18 3.4. NRTL Equation. The NRTL equation19 can be used to calculate the properties of solutions with multicomponents. The equation can be described as follows: ⎛ Δ H ⎞⎛ 1 1⎞ ln x1 = ⎜ fus ⎟⎜ − ⎟ ⎝ R ⎠⎝ Tm T⎠ ⎞ ⎛ ΔC P ⎞⎛ T T ⎟⎜ln −⎜ − + 1⎟ − ln γi ⎝ R ⎠⎝ Tm Tm ⎠

(9)

In this equation, x1 represents the mole fraction solubility of the solute; ΔfusH, Tm, and R stand for the enthalpy of fusion, melting temperature of the solute, and gas constant, respectively, and γi refers to the activity coefficient of solute in the saturated solution. ΔCp refers to the molar heat capacity difference between the solid and liquid state of the solute at the melting temperature.

In this equation, x1 refers to the mole fraction solubility of the solute; T is the absolute experimental temperature, and A, B, and F



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Table 4. Mole Fraction Solubility (x1) of Azoxystrobin in Methanol + Ethyl Acetate Binary Mixed Solvent at Different Temperatures from 288.15 to 328.15 K (p = 0.1 MPa)a x02

100 xexp 1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0.1345 0.3567 0.6364 1.0485 1.4689 1.9004 2.1933 2.5884 2.7680 2.6388 2.4551

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0.1648 0.4200 0.7726 1.2050 1.7759 2.2319 2.6086 2.8708 3.1105 3.1030 2.8262

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0.2051 0.5048 0.9417 1.5305 2.0993 2.6937 3.1507 3.4598 3.6144 3.4968 3.1861

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0.2704 0.6681 1.2611 1.9993 2.8109 3.4787 3.9437 4.3483 4.3815 4.2878 4.1481

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0.3682 0.8594 1.6871 2.5978 3.6398 4.4175 5.1191 5.2659 5.5250 5.2391 4.7326

100 xcal R T = 288.15 K 0.1482 0.3461 0.6503 1.0366 1.4621 1.8828 2.2603 2.5557 2.7205 2.6967 2.4359 T = 293.15 K 0.1569 0.3988 0.7788 1.2511 1.7465 2.2093 2.6064 2.9134 3.0939 3.0896 2.8344 T = 298.15 K 0.2126 0.5005 0.9474 1.5126 2.1189 2.6859 3.1505 3.4671 3.5984 3.5107 3.1817 T = 303.15 K 0.2866 0.6641 1.2551 2.0046 2.7918 3.4853 3.9944 4.2879 4.3822 4.3173 4.1362 T = 308.15 K 0.3530 0.8691 1.6674 2.6389 3.6117 4.4394 5.0399 5.3831 5.4575 5.2477 4.7363

100 xcal N

x02

100 xexp 1

0.1191 0.3059 0.6044 0.9769 1.3576 1.7057 1.9808 2.1948 2.3159 2.3440 2.2747

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0.4970 1.2249 2.2832 3.7661 4.8644 5.7788 6.3492 6.7629 6.8903 6.4680 5.8951

0.1595 0.4007 0.7838 1.2471 1.7370 2.1636 2.5064 2.7506 2.9018 2.9425 2.7917

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0.6833 1.7260 3.0935 4.8868 6.3628 7.2842 8.1180 8.4597 8.5908 7.9916 7.5599

0.2126 0.5233 1.0136 1.6124 2.2069 2.7443 3.1649 3.4590 3.6270 3.6630 3.4078

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0.9599 2.5591 4.4557 6.7322 8.5104 9.5065 10.1575 10.3476 10.5212 9.9801 8.7949

0.2840 0.6917 1.3327 2.0977 2.8647 3.5131 4.0051 4.3576 4.5324 4.5692 4.1425

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

1.4365 3.5575 6.2324 9.1952 11.0522 12.1568 12.6790 12.9997 13.0274 12.2200 10.8102

100 xcal R T = 313.15 K 0.4634 1.2203 2.3701 3.6779 4.8690 5.7866 6.4033 6.7442 6.8114 6.5502 5.8698 T = 318.15 K 0.6988 1.7015 3.1684 4.8136 6.2985 7.4139 8.1139 8.4434 8.4537 8.1538 7.5062 T = 323.15 K 0.9441 2.4638 4.5911 6.7349 8.4164 9.5169 10.1521 10.4553 10.4420 9.9715 8.8114 T = 328.15 K 1.3763 3.5266 6.3891 9.0835 11.0223 12.1664 12.7570 13.0034 12.9205 12.2967 10.7930

100 xcal N 0.5120 1.2335 2.3517 3.7019 4.8430 5.7653 6.4199 6.8596 7.0733 7.0437 6.0416 0.6949 1.6912 3.1735 4.8845 6.3170 7.3503 8.1304 8.5853 8.8011 8.7160 7.2713 0.9601 2.4139 4.4488 6.6242 8.3146 9.4492 10.2315 10.6753 10.8930 10.7760 8.7081 1.3892 3.4271 6.2500 8.9934 10.8292 12.0536 12.8290 13.2999 13.4655 13.2519 10.4297

0.3811 0.9104 1.7609 2.7343 3.7040 4.4845 5.0932 5.4491 5.6720 5.6785 5.0100 G



Article

Table 4. continued a 0 x2

is the initial mole fraction of ethyl acetate in methanol + ethyl acetate binary mixed solvent, and the relative standard uncertainty is ur(x02) = cal cal 0.005. xexp 1 is the experimental solubility; xR and xN are the calculated solubility by the CNIBS/R−K equation and the NRTL equation, respectively. The standard uncertainty of temperature is u(T) = 0.1 K. The relative standard uncertainty of the solubility measurement is ur(x) = 0.06. The relative uncertainty of pressure is ur(p) = 0.05. 2 ⎡ ⎤ τ21G21 τ12G21 ⎥ ln γ1 = x 22⎢ + (x 2 + x1G12)2 ⎦ ⎣ (x1 + x 2G21)2

G12 = exp( −α12τ12) G21 = exp( −α12τ21)

g12 − g22

τ12 =

RT g21 − g11

τ21 =

ln γi =

Table 5. Parameters of the Apelblat Equation for Azoxystrobin in Seven Monosolvents C

ARD%

methanol

−916.9749

36918.7809

138.1246

1.4355

ethanol

−445.2820

15240.0111

68.0062

2.2289

n-propanol isopropanol n-butanol isobutanol ethyl acetate

A

B

−326.5369

9731.8827

50.3925

2.1306

243.2597

−16890.5773

−34.0342

3.9103

−235.2300

5477.0707

36.8490

2.6938

94.7651

−9898.4254

−12.0413

2.6439

−235.5347

7535.7104

36.3080

2.5711

+

+

λ

h

ARD%

methanol ethanol n-propanol isopropanol n-butanol isobutanol ethyl acetate

0.1436 0.0884 0.0881 0.0782 0.0865 0.0909 0.4445

37 816.9838 62 214.2928 63 713.4188 78 376.9046 66 720.9693 65 962.1282 7576.7201

7.6355 4.6221 3.8345 2.6772 3.2314 2.0141 3.7029

RT

(12)

(Gjixj + Gkixk)(τjiGjixj + τkiGkixk) (xi + xjGji + xkGki)2 [τijGijxj 2 + GijGkjxjxk(τij − τkj)] (xj + xiGij + xkGkj)2

[τijGik xk 2 + Gik Gjk xjxk(τik − τjk)] (xk + xiGik + xjGjk )2

(13)

τji = (gji − gii)/RT = Δgji /RT αji = αij , i , j = 1, 2, 3

(14)

where Δgji is the parameter and is related to the cross interaction energy. It is independent of the temperature and composition. αji is an adjustable empirical constant and can be adjusted from 0 to 1, which reveals the nonrandomness of the solution.21 In this work, the applicability and accuracy of the above equations can be determined by the average relative deviation (ARD). ARD is defined as the following equation: Table 7. Parameters of the NRTL Equation for Azoxystrobin in Seven Monosolvents

Because the value of ΔCp is relatively low and can be neglected at the melting temperature, eq 9 can be simplified as Δ H⎛ 1 1⎞ ln x1 = fus ⎜ − ⎟ − ln γi R ⎝ Tm T⎠

RT Δg21

Gji = exp( −αjiτji)

Table 6. Parameters of the λh Equation for Azoxystrobin in Seven Monosolvents solvent name

=

Δg12

where Δg12 and Δg21 are the parameters of this equation, which represent the cross interaction energy and α12 is the parameter adjusted from 0 to 1 and is related to the nonrandomness and nonideality of the solution.20 3.4.2. Calculation in Binary Mixed Solvents. In binary mixed solvents, the activity coefficient of solute (γi) in the saturated solution can be calculated as follows:

Figure 8. Experimental solubility data of azoxystrobin in methanol + ethyl acetate binary mixed solvent at different mole fractions of ethyl acetate (x02) from 0.1 to 0.9 (p = 0.1 MPa).

solvent name

RT

=

(11)

(10)

3.4.1. Calculation in Monosolvents. The activity coefficient of solute in the saturated solution (γ1) in monosolvents can be calculated as follows: H

solvent name

Δg12

Δg21

α12

ARD%

methanol ethanol n-propanol isopropanol n-butanol isobutanol ethyl acetate

4982.9542 −4771.9556 −2660.0010 3425.5515 58.9519 574.0336 36993.3039

7091.2460 17870.6887 13594.4570 9905.5798 9768.2708 9698.9565 −31022.5623

0.8350 0.3000 0.4000 0.8450 0.6300 0.7100 0.0100

3.8645 2.1995 2.2555 3.7865 2.2600 3.3153 3.5942



Article

Table 8. Parameters of the CNIBS/R−K Equation for Azoxystrobin in n-Propanol + Ethyl Acetate Binary Mixed Solvent T/K

B1

B2

B3

B4

B5

ARD%

288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15 328.15

−7.3214 −6.9736 −6.8850 −6.3225 −5.9861 −5.5811 −5.3741 −5.1207 −4.9655

9.9424 8.3161 9.4207 5.7971 5.4497 4.1980 4.7889 5.3927 7.8744

−12.8651 −7.7604 −11.5987 −1.3996 −2.6276 0.6064 0.0804 0.3481 −8.7229

11.1053 3.8839 9.1360 −2.1940 1.0899 −2.1675 −3.4154 −6.7648 5.0839

−4.5647 −1.0341 −3.5189 0.9335 −0.9785 0.1055 1.3303 3.7130 −1.4977

1.1913 2.0467 0.8808 2.5405 4.8426 7.7522 3.9607 2.6709 1.9970

Table 9. Parameters of the CNIBS/R−K Equation for Azoxystrobin in Methanol + Ethyl Acetate Binary Mixed Solvent T/K

B1

B2

B3

B4

B5

ARD%

288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15 328.15

−6.5114 −6.4572 −6.1537 −5.8548 −5.6465 −5.3744 −4.9636 −4.6627 −4.2858

9.7298 10.9013 9.8352 9.5468 10.4714 11.5082 10.4826 11.6479 11.5413

−13.8339 −17.1562 −13.6997 −12.1120 −15.7600 −19.8904 −17.1307 −22.5705 −23.4804

11.2212 14.5806 10.1307 6.8096 11.8926 16.9701 13.4286 20.9121 22.4610

−4.3178 −5.4318 −3.5603 −1.5750 −4.0075 −6.0489 −4.4063 −7.7559 −8.4624

2.4748 1.8136 0.7893 1.0806 1.3196 1.5901 1.3605 1.0716 1.0356

At a certain temperature, the solubility order of azoxystrobin in monosolvents can be ranked as ethyl acetate > methanol > ethanol > n-propanol > n-butanol > isobutanol > isopropanol. Azoxystrobin is a methoxyacrylate with −COO− resembling ethyl acetate. This phenomenon is called “like dissolves like”,22 which causes high solubility of solute in ethyl acetate. As for the alcohol solvents methanol, ethanol, n-propanol, and n-butanol, the value of solubility of azoxystrobin is in the same order of polarity of the four solvents because azoxystrobin possesses −CN−, which is a polar group.23 It is interesting to notice that the solubility in isopropanol is lower than that in n-propanol, which may be rationalized by the dual effect of greater steric hindrance of isopropanol and polarity.24 Moreover, the solubility of azoxystrobin in isopropanol and isobutanol is the lowest in those two, which may be ascribed to the possession of greater steric hindrance. The branched chains of isopropanol and isobutanol25,26 make it harder to form hydrogen bonds with the solute compared to n-alkanol. In summary, the solubility ranking of azoxystrobin is in accordance with the polarity. Furthermore, the steric hindrance also has an impact on the solubility of the solute through hindering the formation of hydrogen bonds between the solute and solvents. In this way, the interactions between solute−solute and solvent−solvent will dominate in the dissolution process, hence leading to the decrease in the solubility.27 4.2. Solubility of Azoxystrobin in Binary Mixed Solvents. On the basis of the solubility of azoxystrobin in the above monosolvents, it can be concluded that the solubility of azoxystrobin in alcohols is much lower than that in ethyl acetate at a given temperature. Thus, ethyl acetate was chosen as the good solvent, and n-propanol and methanol were chosen as the antisolvents to study the solubility behavior of azoxystrobin in binary mixed solvents. The solubility of azoxystrobin in two binary mixed solvents varying with temperature is plotted in Figures 5 and 6, which demonstrates that both solubility and temperature are positively related.

Table 10. Parameters of the NRTL Equation for Azoxystrobin in Two Binary Mixed Solvents parameters

n-propanol + ethyl acetate

methanol + ethyl acetate

Δg12 Δg13 Δg21 Δg23 Δg31 Δg32 α12 α13 α23 ARD%

10795.6560 −452.6499 −6118.8498 −4494.4626 9328.7178 7393.8177 0.1000 0.2000 0.0200 7.3560

−2082.5814 927.0716 5003.0568 1865.7998 7428.3190 2357.3711 0.8100 0.4000 0.7000 3.8605

ARD% =

100 N

N

∑ i=1

x1exp − x1cal x1exp

(15)

N represents the number of experimental measurement points. cal xexp 1 and x1 represent the experimental and calculated solubility of azoxystrobin, respectively.

4. RESULTS AND DISCUSSION 4.1. Solubility of Azoxystrobin in Monosolvents. The value of the mole fraction solubility of azoxystrobin in seven monosolvents at different temperatures from 288.15 to 328.15 K is listed in Table 2 and clearly plotted in Figure 4. The result shows that the solubility of azoxystrobin increases with increasing temperature in all selected solvents, which can give a guide to the purification and preparing of azoxystrobin. Cooling crystallization method could be suitable for the recrystallization to purify azoxystrobin. Considering the safety, ethanol may be a better choice for purification. The solubility of azoxystrobin in ethyl acetate is remarkably higher than that in other seven alcohols. Thus, dilution crystallization could be applied as the last step to produce azoxystrobin. I



Article

Table 11. Mixing Thermodynamic Properties of Azoxystrobin in n-Propanol + Ethyl Acetate Binary Mixed Solvent at Different Temperatures from 288.15 to 328.15 K (p = 0.1 MPa)a

a

x02

ΔmixG (J·mol−1)

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

−0.6963 −1.0193 −1.1978 −1.2859 −1.3053 −1.2791 −1.1986 −1.0549 −0.8113

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

−0.7104 −1.0412 −1.2246 −1.3171 −1.3460 −1.3138 −1.2353 −1.0898 −0.8387

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

−0.7239 −1.0636 −1.2550 −1.3534 −1.3899 −1.3641 −1.2888 −1.1445 −0.8926

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

−0.7392 −1.0855 −1.2864 −1.3916 −1.4261 −1.4209 −1.3510 −1.2139 −0.9601

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

−0.7583 −1.1140 −1.3215 −1.4301 −1.4659 −1.4715 −1.4162 −1.2706 −1.0259

ΔmixH (J·mol−1) T = 288.15 K 206.7084 271.181 264.5569 231.8658 201.185 184.7509 180.5567 171.4913 124.2204 T = 293.15 K 213.3274 280.4015 274.2386 241.0692 208.9903 191.2208 185.3551 174.8998 126.5292 T = 298.15 K 219.2427 289.6292 284.4084 250.4686 216.8964 197.0783 189.3234 177.158 126.8316 T = 303.15 K 226.3707 298.4137 294.7237 260.0438 224.9487 203.0861 193.2478 178.8186 126.1000 T = 308.15 K 236.4200 310.0900 305.8872 269.7424 233.0790 209.7234 197.5707 181.7923 125.6074

ΔmixS (J·mol−1·K−1)

x02

ΔmixG (J·mol−1)

3.1339 4.4786 5.0749 5.2674 5.2280 5.0801 4.7861 4.2562 3.2468

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

−0.7785 −1.1467 −1.3657 −1.4729 −1.5282 −1.5384 −1.5059 −1.3636 −1.1110

3.1512 4.5083 5.1127 5.3152 5.3043 5.1338 4.8463 4.3142 3.2928

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

−0.8018 −1.1756 −1.4101 −1.5388 −1.6056 −1.6181 −1.5859 −1.4579 −1.1986

3.1632 4.5389 5.1631 5.3795 5.3894 5.2361 4.9578 4.4328 3.4190

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

−0.8269 −1.2238 −1.4614 −1.6136 −1.7038 −1.7244 −1.6694 −1.5361 −1.2779

3.1852 4.5651 5.2157 5.4483 5.4462 5.3569 5.0941 4.5941 3.5830

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

−0.8538 −1.2648 −1.5297 −1.6970 −1.7864 −1.8118 −1.7915 −1.6545 −1.4050

ΔmixH (J·mol−1) T = 313.15 K 247.7421 324.2582 319.8167 280.0605 242.1562 216.5976 201.3503 182.6142 122.9240 T = 318.15 K 262.5368 336.6854 334.6393 294.1446 252.9614 224.2536 206.3081 183.4023 119.3914 T = 323.15 K 280.3071 363.1796 353.2066 311.8992 267.1508 233.2362 211.7741 185.7417 116.5633 T = 328.15 K 301.6634 387.4512 382.7143 335.2945 282.6264 243.5882 215.4261 183.3262 103.7859

ΔmixS (J·mol−1·K−1) 3.2772 4.6974 5.3825 5.5980 5.6533 5.6043 5.4518 4.9375 3.9404 3.3454 4.7533 5.4839 5.7611 5.8419 5.7908 5.6331 5.1589 4.1426 3.4263 4.9111 5.6154 5.9585 6.0993 6.0581 5.8213 5.3283 4.3151 3.5212 5.0350 5.8280 6.1932 6.3052 6.2636 6.1158 5.6005 4.5979

3.2280 4.6215 5.2811 5.5164 5.5135 5.4557 5.2368 4.7131 3.7369

The expanding uncertainties are U(ΔmixS)= 0.080ΔmixS and U(ΔmixG)= 0.075ΔmixG (0.95 level of confidence).

The mole fraction solubility of azoxystrobin in n-propanol + ethyl acetate binary mixed solvent versus the mole fraction of ethyl acetate is shown in Table 3 and plotted in Figure 7. The solubility of azoxystrobin in n-propanol + ethyl acetate mixed solvent increases with increasing mole fraction of ethyl acetate, which confirms that the solubility could be enhanced with adding ethyl acetate according to the general rule of like dissolves like.22

While in the binary system of methanol + ethyl acetate, a different dissolution behavior was observed. As shown in Table 4 and Figure 8, at a constant temperature, the solubility of azoxystrobin first increases with increasing mole fraction of ethyl acetate, reaches its maximum point when the mole fraction of ethyl acetate is 0.8, and then decreases with increasing mole fraction of ethyl acetate. Moreover, it is worth noticing that the J



Article

Table 12. Mixing Thermodynamic Properties of Azoxystrobin in Methanol + Ethyl Acetate Binary Mixed Solvent at Different Temperatures from 288.15 to 328.15 K (p = 0.1 MPa)a

a

x02

ΔmixG (J·mol−1)

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

−0.4944 −0.7156 −0.8710 −0.9804 −1.0520 −1.0754 −1.0617 −0.9734 −0.7653

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

−0.5124 −0.7455 −0.9061 −1.0283 −1.1024 −1.1313 −1.1066 −1.0193 −0.8153

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

−0.5320 −0.7776 −0.9530 −1.0769 −1.1610 −1.1949 −1.1719 −1.0759 −0.8597

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

−0.5570 −0.8195 −1.0083 −1.1497 −1.2388 −1.2729 −1.2544 −1.1486 −0.9305

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

−0.5834 −0.8670 −1.0700 −1.2265 −1.3227 −1.3701 −1.3357 −1.2416 −1.0091

ΔmixH (J·mol−1) T = 288.15 K 223.8537 330.4020 376.9314 391.2749 384.8347 363.4004 314.2998 237.1992 120.9486 T = 293.15 K 226.7005 333.1115 379.7353 390.4794 383.8316 360.1533 314.8056 235.4681 115.1425 T = 298.15 K 229.9186 335.6447 378.7883 389.8807 379.8045 354.2857 307.8089 230.4142 111.8258 T = 303.15 K 234.3019 336.6158 375.1107 379.4797 367.9502 342.9700 294.5917 220.2101 100.7483 T = 308.15 K 239.0886 336.5530 369.2224 367.4170 353.7464 323.7826 282.4700 203.2128 87.9376

ΔmixS (J·mol−1·K−1)

x02

ΔmixG (J·mol−1)

2.4926 3.6302 4.3310 4.7602 4.9865 4.9931 4.7754 4.2012 3.0757

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

−0.6198 −0.9229 −1.1608 −1.3216 −1.4256 −1.4655 −1.4453 −1.3424 −1.1011

2.5213 3.6793 4.3864 4.8398 5.0698 5.0876 4.8486 4.2803 3.1741

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

−0.6622 −0.9879 −1.2439 −1.4247 −1.5297 −1.5823 −1.5581 −1.4547 −1.2047

2.5556 3.7337 4.4668 4.9195 5.1679 5.1960 4.9628 4.3814 3.2584

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

−0.7190 −1.0762 −1.3556 −1.5499 −1.6588 −1.7031 −1.6726 −1.5706 −1.3253

2.6103 3.8136 4.5635 5.0441 5.3003 5.3301 5.1098 4.5153 3.4017

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

−0.7801 −1.1765 −1.4839 −1.6804 −1.7938 −1.8338 −1.8094 −1.7020 −1.4487

ΔmixH (J·mol−1) T = 313.15 K 245.7206 334.4197 351.0439 346.9257 330.9748 305.7291 259.2079 183.7864 71.5626 T = 318.15 K 252.7484 329.1398 335.1964 322.0438 307.6016 278.1345 234.7086 160.3233 52.0640 T = 323.15 K 259.3319 314.2076 304.2031 285.1174 271.5759 248.5689 209.6718 135.7136 27.3972 T = 328.15 K 262.4579 290.5289 262.2144 244.5080 232.0161 214.0292 174.4063 104.8033 2.2186

ΔmixS (J·mol−1·K−1) 2.7640 4.0150 4.8279 5.3280 5.6092 5.6562 5.4431 4.8735 3.7446 2.8759 4.1397 4.9635 5.4904 5.7749 5.8476 5.6353 5.0762 3.9501 3.0274 4.3026 5.1365 5.6785 5.9737 6.0396 5.8248 5.2802 4.1861 3.1770 4.4707 5.3211 5.8659 6.1736 6.2405 6.0454 5.5061 4.4216

2.6693 3.9058 4.6705 5.1726 5.4404 5.4970 5.2513 4.6886 3.5601

The expanding uncertainties are U(ΔmixS)= 0.045ΔmixS and U(ΔmixG)= 0.040ΔmixG (0.95 level of confidence).

dielectric constant, and solubility parameter.32−34 The detailed mechanism of this phenomenon can be studied deeply in the future work. 4.3. Thermodynamic Model and Mixing Thermodynamic Properties. The experimental solubility of the azoxystrobin in seven monosolvents was correlated with the Apelblat equation, the λh equation, and the NRTL equation. Relevant parameters

maximum point does not change with temperature. This phenomenon is also called synergistic effect, which was described in previous studies.28,29 The existence of the maximum may owe to the strong intermolecular interactions between the solute and solvent molecules, which contributes to the dissolution of the solute.30,31 Further, there are several factors to affect the solubility of azoxystrobin in the binary mixed solvents, such as viscosity, K



Article

Δmix H id = 0

(22)

On the other hand, the excess mixing properties can be obtained by n

GE = RT ∑ xi ln γi i

(23)

⎡ ∂(GE /T ) ⎤ H E = − T 2⎢ ⎥ ⎣ ∂T ⎦

(24)

SE =

of the three equations and the ARD are listed in Tables 5−7. The value of ARD of the three equations was calculated and shows that those equations have a reasonable fitting efficiency for the experimental solubility of the azoxystrobin. Almost all ARD values are lower than 5%. The CNIBS/R−K and NRTL equations were used to correlate the experimental solubility of the azoxystrobin in binary mixed solvents. The parameters of the two equations are shown in Tables 8−10. The results indicate that the two selected equations also have acceptable accuracy. The thermodynamic properties of mixing process in a nonideal solution play an important role in the research of mixtures. The change of mixing thermodynamic properties of solution is determined by the initial and final states because it is a state function. For a nonideal solution, the mixing thermodynamic properties can be calculated by eq 16:

5. CONCLUSION In this work, the solubility of azoxystrobin in seven monosolvents and ethyl acetate + n-propanol/methanol binary mixed solvents from 288.15 to 328.15 K was measured by a gravimetric method. Experimental data show that the changing trend of the solubility of azoxystrobin is associated with solvent type and solvent composition. It can be concluded, along with increasing temperature in all the experimental solvents, that the solubility increases as well. In above seven monosolvents, the solubility value at a fixed temperature can be ranked as ethyl acetate > methanol > ethanol > n-propanol > n-butanol > isobutanol > isopropanol. In addition, in n-propanol + ethyl acetate binary mixed solvent, the solubility of azoxystrobin increases with increasing mole fraction of ethyl acetate. Differing from n-propanol + ethyl acetate mixtures, there exists in the solubility in methanol + ethyl acetate binary mixed solvent a maximum point when the mole fraction of ethyl acetate is 0.8 irrespective of the temperature. It is important to notice that the intermolecular interactions play an irreplaceable role in the dissolution behavior of solute molecules in different solvents and different temperatures. The Apelblat, λh, CNIBS/R−K, and NRTL equations were used to correlate experimental solubility of azoxystrobin in experimental solvents. The results present good correlation with the experimental solubility. Furthermore, the NRTL equation was used to calculate the mixing thermodynamic properties. The value of mixing Gibbs energy in binary mixed solvents is

(16)

ΔmixM stands for mixing thermodynamic properties of an ideal solution; ME refers to the excess properties of a nonideal solution. For the nonideal solution, the three mixing properties (Gibbs energy, enthalpy, and entropy) can be calculated with the following equations: id

Δmix G = GE + Δmix Gid

(17)

Δmix S = S E + Δmix S id

(18)

Δmix H = HE + Δmix H id

(19)

For the ideal solution, in binary mixed solvents, the mixing Gibbs energy, mixing enthalpy, and mixing entropy can be expressed by the following equations. We calculate those thermodynamic properties according to the Lewis−Randall rule. n

Δmix Gid = RT ∑ xi ln xi i

(20)

n

Δmix Sid = − R ∑ xi ln xi i

(25)

where xi represents the mole fraction of component i in real solution; γi represents activity coefficient of component i in real solution. γi can be calculated by the NRTL equation. The calculated mixing thermodynamic properties of azoxystrobin in the two binary mixed solvents are listed in Table 11 and Table 12. First, it is evident that the mixing process of azoxystrobin in binary mixed solvents is a spontaneous process because all values of ΔmixG are negative.22,35 The relation curve of ΔmixG varying with temperature in methanol + ethyl acetate binary mixed solvent is shown in Figure 9. We find that at a certain mole fraction of ethyl acetate in the binary mixed solvent, the value of ΔmixG decreases with the increasing temperature. Contrary to solubility data, ΔmixG is negatively correlated to temperature. That is to say, lower value of ΔmixG always leads to higher value of solubility.36 Second, the value of ΔmixH is positive, indicating that the process of the mixing of azoxystrobin is endothermic in binary mixed solvents. Moreover, the positive ΔmixH expresses the reason why the solubility of azoxystrobin increases with increasing temperature.35 Finally, the positive value of ΔmixS demonstrates that the mixing of azoxystrobin in binary mixed solvents is a process of entropy increment and the mixing process is entropy-driven.37

Figure 9. Calculated mixing Gibbs energy of azoxystrobin in methanol + ethyl acetate binary mixed solvent at different temperatures from 288.15 to 328.15 K (p = 0.1 MPa).

Δmix M = Δmix M id + ME

HE − GE T

(21) L



Article

ΔmixGid ΔmixHid ΔmixSid GE HE SE ΔmixG ΔmixH ΔmixS

negative, which represents that the mixing process is spontaneous. The value of mixing enthalpy is positive, indicating that the mixing process is endothermic. The data and discussions presented in this contribution can provide guidance for purification and new methods for the design and optimization of crystallization of azoxystrobin.

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AUTHOR INFORMATION

Corresponding Author

*Tel.: 86-22-27405754; Fax: +86-22-27374971; E-mail: [email protected].

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ORCID

Shichao Du: 0000-0002-8369-2983 Junbo Gong: 0000-0002-3376-3296

mixing Gibbs energy of an ideal solution (J·mol−1) mixing enthalpy of an ideal solution (J·mol−1) mixing entropy of an ideal solution (J·mol−1·K−1) excess Gibbs energy of a nonideal solution (J·mol−1) excess enthalpy of a nonideal solution (J·mol−1) excess entropy of a nonideal solution (J·mol−1·K−1) mixing Gibbs energy of solution (J·mol−1) mixing enthalpy of solution (J·mol−1) mixing entropy of solution (J·mol−1·K−1)

REFERENCES

(1) MakhtEshtm Chemical Works Ltd. Polymorphs of 3-(E)-2-{2-[6-(2cyanophenoxy) pyrimidin4-yloxy] phenyl}-3-methoxy-acrylate. WO Patent 2008/093325 A2, August 7, 2008. (2) Liu, L.; Zhu, B.; Wang, G. Azoxystrobin-induced excessive reactive oxygen species (ROS) production and inhibition of photosynthesis in the unicellular green algae Chlorella vulgaris. Environ. Sci. Pollut. Res. 2015, 22, 7766−7775. (3) Chen, Y.; Jin, L.; Zhou, M. Effect of Azoxystrobin on Oxygen Consumption and cyt b Gene Expression of Colletotrichum capsici from Chilli Fruits. Agric. Sci. China 2009, 8, 628−631. (4) Jiang, J.; Ding, L.; Michailides, T. J.; Li, H.; Ma, Z. Molecular characterization of field azoxystrobin-resistant isolates of Botrytis cinerea. Pestic. Biochem. Physiol. 2009, 93, 72−76. (5) Rodrigues, E. T.; Lopes, I.; Pardal, M. A. Occurrence, fate and effects of azoxystrobin in aquatic ecosystems: a review. Environ. Int. 2013, 53, 18−28. (6) Phillips, M. AgriService: Products Section; 2014 Market; Midlothian, UK, 2015. (7) Bubici, G.; Amenduni, M.; Colella, C.; D’Amico, M.; Cirulli, M. Efficacy of acibenzolar-S-methyl and two strobilurins, azoxystrobin and trifloxystrobin, for the control of corky root of tomato and verticillium wilt of eggplant. Crop Prot. 2006, 25, 814−820. (8) European Food Safety Authority (EFSA). Peer review report to the conclusion regarding the peer review of the pesticide risk assessment of the active substance azoxystrobin. EFSA J. 2010, 8, 110. (9) Bartlett, D. W.; Clough, J. M.; Godwin, J. R. Review The strobilurin fungicides. Pest Manage. Sci. 2002, 58, 649−662. (10) MakhtEshtm Chemical Works Ltd. Polymorphs of methyl-(E)-2{2-[6-(2- cyanophenoxy) pyrimidin-4-yloxy] phenyl}-3-methoxyacrylate. U.S. Patent 8877767 B2, January 16, 2014. (11) Long, B.; Li, J.; Zhang, R.; Wan, L. Solubility of Benzoic Acid in Acetone, 2-Propanol, Acetic Acid and Cyclohexane: Experimental Measurement and Thermodynamic Modelings. Fluid Phase Equilib. 2010, 297, 113−120. (12) Apelblat, A.; Manzurola, E. Solubilities of L-aspartic, DL-aspartic, DL-glutamic, p-hydroxybenzoic, o-anistic, p-anisic, and itaconic acids in water from T = 278 K to T = 345K. J. Chem. Thermodyn. 1997, 29, 1527−1533. (13) Apelblat, A.; Manzurola, E. Solubilitiesof o-acetylsalicylic, 4aminosalicylic, 3, 5-dinitrosalicylic, and p-toluicacid, and magnesiumDL-aspartate in water from T = (278 to 348) K. J. Chem. Thermodyn. 1999, 31, 85−91. (14) Shi, X.; Zhou, C.; Gao, Y.; Chen, X. Measurement and Correlation for Solubility of (S)-(+)-2, 2-Dimethyl-cyclopropane Carbox Amide in Different Solvents. Chin. J. Chem. Eng. 2006, 14, 547−550. (15) Buchowski, H.; Ksiazczak, A.; Pietrzyk, S. Solvent Activity along a Saturation Line and Solubility of Hydrogen-Bonding Solids. J. Phys. Chem. 1980, 84, 975−979. (16) Buchowski, H.; Khiat, A. Solubility of solids in liquids: oneparameter solubility equation. Fluid Phase Equilib. 1986, 25, 273−278. (17) Acree, W. E.; Zvaigzne, A. I. Thermodynamic properties of nonelectrolyte solutions: Part 4. Estimation and mathematical representation of solute activity coefficients and solubilities in binary solvents using the NIBS and Modified Wilson equations. Thermochim. Acta 1991, 178, 151−167.

Funding

The authors are grateful for the financial support of National 863 Program (Grant 2015AA021002), Tianjin Science and Technology Project (Grants 15JCZDJC33200 and KJXH2015-01), and the Major Science and Technology Program for Water Pollution Control and Treatment (Grant 2015ZX07202-013). Notes

The authors declare no competing financial interest.

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NOMENCLATURE initial mole fraction of ethyl acetate in binary mixed solvents (mol·mol−1) T absolute temperature (K) Tm melting temperature of azoxystrobin (K) ΔfusH fusion enthalpy of azoxystrobin (kJ·mol−1) x1 mole fraction solubility of azoxystrobin (mol·mol−1) xexp experimentally determined solubility of azoxystro1 bin (mol·mol−1) cal x1 calculated solubility by thermodynamic equations (mol·mol−1) m1 mass of azoxystrobin (g) m2 mass of n-propanol or methanol (g) m3 mass of ethyl acetate (g) M1 molecular mass of azoxystrobin (g·mol−1) M2 molecular mass of n-propanol or methanol (g·mol−1) M3 molecular mass of ethyl acetate (g·mol−1) A, B, and C constants of the Apelblat equation λh parameter of the λh equation Xi i is A or B, the saturated mole solubility of solute in corresponding monosolvent i Si parameter of the CNIBS/R−K equation n number of “curve-fit” parameters of the CNIBS/ R−K equation Bi i = 1, 2, 3, 4, 5; the parameters of the simplified CNIBS/R−K equation R gas constant (J·K−1·mol−1) ΔCp molar heat capacity difference between the solid and liquid state of azoxystrobin (J·kg1−·K−1) γi activity coefficient of the component i Δgji parameter of the NRTL equation αji adjustable empirical constant between 0 and 1 of the NRTL equation N number of experimental measurement points ARD average relative deviation of solubility ΔmixM change of thermodynamic properties of mixing ΔmixMid change of thermodynamic properties of an ideal solution ME excess properties of a nonideal solution x02

M



Article

(18) Barzegar-Jalali, M.; Jouyban-Gharamaleki, A. A General Model from Theoretical Cosolvency Models. Int. J. Pharm. 1997, 152, 247− 250. (19) Renon, H.; Prausnitz, J. M. Local compositions in thermodynamic excess functions for liquid mixtures. AIChE J. 1968, 14, 135−144. (20) Fan, J.; Xu, X.; Shen, G.; Zhang, X. Measurement and correlation of the solubility of genistin in eleven organic solvents from T = (283.2 to 323.2) K. J. Chem. Thermodyn. 2015, 89, 142−147. (21) Fan, J.; Liao, D.; Zhen, B.; Xu, X.; Zhang, X. Measurement and Modeling of the Solubility of Genistin in Water + (Ethanol or Acetone) Binary Solvent Mixtures at T= 278.2−313.2 K. Ind. Eng. Chem. Res. 2015, 54, 12981−12986. (22) Gantiva, M.; Martínez, F. Thermodynamic analysis of the solubility of ketoprofen in some propylene glycol + water cosolvent mixtures. Fluid Phase Equilib. 2010, 293, 242−250. (23) Zhang, Y.; Wei, S.; Wang, H.; Liu, J.; Wang, W. Solubility Measurement and the Correlation of 1-Naphthaleneacetic Acid in Pure and Methanol + Water Binary Solvents from T = (278.25 to 323.55) K. J. Chem. Eng. Data 2017, 62, 1292−1301. (24) Cai, L.; Xie, T.; Zhao, S.; Zheng, H.; Wu, D. Measurement and correlation of solubility of d-camphor-10-sulfonic acid in pure solvents. Fluid Phase Equilib. 2015, 398, 46−50. (25) Yang, P.; Du, S.; Qin, Y.; Zhao, K.; Li, K.; Hou, B.; Gong, J. Determination and correlation of solubility and thermodynamic properties of pyraclostrobin in pure and binary solvents. J. Chem. Thermodyn. 2016, 101, 84−91. (26) Li, H.; Guo, F.; Hu, G.; Zhao, L.; Zhang, Y. Solubilities and enthalpies of solution for thiourea in ethanol or methanol + water. J. Chem. Eng. Data 2009, 54, 2986−2990. (27) Han, D.; Li, X.; Wang, H.; Wang, Y.; Du, S.; Yu, B.; Liu, Y.; Xu, S.; Gong, J. Determination and correlation of pyridoxine hydrochloride solubility in different binary mixtures at temperatures from (278.15 to 313.15) K. J. Chem. Thermodyn. 2016, 94, 138−151. (28) Ding, Z.; Zhang, R.; Long, B.; Liu, L.; Tu, H. Solubilities of mPhthalic Acid in Petroleum Ether and It’s Binary Solvent Mixture of Alcohol + Petroleum Ether. Fluid Phase Equilib. 2010, 292, 96−103. (29) Domańska, U. Solubility of Benzoyl-Substituted Naphthols in Mixtures of Hexane and 1-Butanol. Ind. Eng. Chem. Res. 1990, 29, 470− 475. (30) Long, B.; Wang, Y.; Yang, Z. Partition Behaviour of Benzoic Acid in (Water + n-Dodecane) Solubilities at T = (293.15 and 298.15) K. J. Chem. Thermodyn. 2008, 40, 1565−1568. (31) Domańska, U. Solubility of Acetyl-Substituted Naphthols in Binary Solvent Mixtures. Fluid Phase Equilib. 1990, 55, 125−145. (32) Zhao, K.; Lin, L.; Li, C.; Du, S.; Huang, C.; Qin, Y.; Yang, P.; Li, K.; Gong, J. Measurement and Correlation of Solubility of γAminobutyric Acid in Different Binary Solvents. J. Chem. Eng. Data 2016, 61, 1210−1220. (33) Zhang, T.; Li, Z.; Wang, Y.; Li, C.; Yu, B.; Zheng, X.; Jiang, L.; Gong, J. Determination and correlation of solubility and thermodynamic properties of l-methionine in binary solvents of water + (methanol, ethanol, acetone). J. Chem. Thermodyn. 2016, 96, 82−92. (34) Cui, C.; Ren, H.; Huang, Y.; Jiao, Q. Solubility Measurement and Correlation for ε-2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane in Five Organic Solvents at Temperatures between 283.15 and 333.15 K and Different Chloralkane + Ethyl Acetate Binary Solvents at Temperatures between 283.15 and 323.15 K. J. Chem. Eng. Data 2017, 62, 1204−1213. (35) Li, J.; Wang, Z.; Bao, Y.; Wang, J. Solid-Liquid Phase Equilibrium and Mixing Properties of Cloxacillin Benzathine in Pure and Mixed Solvents. Ind. Eng. Chem. Res. 2013, 52, 3019−3026. (36) Wang, Y.; Liu, Y.; Xu, S.; Liu, Y.; Yang, P.; Du, S.; Yu, B.; Gong, J. Determination and modelling of Troxerutin solubility in eleven Pure solvents and (1,4-dioxane + 2-propanol) binary solvents at temperatures from 288.15 to 323.15 K. J. Chem. Thermodyn. 2017, 104, 138−149. (37) Feng, S.; Li, T. Predicting Lattice Energy of Organic Crystals by Density Functional Theory with Empirically Corrected Dispersion Energy. J. Chem. Theory Comput. 2006, 2, 149−156.

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Measurement and Correlation of the Solubility of Azoxystrobin in

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