Solubility and solution thermodynamics of novel pyrazolo chalcone derivatives in various solvents from 298.15?K to 328.15?K

Article abstract of DOI:10.1016/j.molliq.2018.12.081

Some novel pyrazolo chalcone derivatives have been synthesized and characterization of these synthesized compounds was done by IR, ¹H NMR, ¹³C NMR and mass analysis. The solubility of pyrazolo chalcone derivatives in methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, ethyl acetate and acetonitrile was measured by gravimetric method over a temperature range (298.15 to 328.15) K at atmospheric pressure. The solubility of synthesized compounds is found to increase linearly with temperature. Further, in alcoholic solvents, solubility is maximum in 1-pentanol and minimum in methanol whereas in non-alcoholic solvents, solubility is greater in ethyl acetate and minimum in acetonitrile. The experimental solubility data were correlated with temperature by modified Apelblat and Buchowski-Ksiazczak λh equations. The experimental data and model parameters would be useful for optimizing the process of purification. Some thermodynamic parameters such as dissolution enthalpy, Gibb's free energy and entropy of mixing have also been calculated by Van't Hoff analysis. Further, excess enthalpy of solutions has been calculated using Buchowski-Ksiazczak λh equation.

Full text of DOI:10.1016/j.molliq.2018.12.081

Journal of Molecular Liquids 277 (2019) 692–704
Contents lists available at ScienceDirect
Journal of Molecular Liquids
journal homepage: www.elsevier.com/locate/molliq
Review
Solubility and solution thermodynamics of novel pyrazolo chalcone
derivatives in various solvents from 298.15 K to 328.15 K
⁎
Shipra Baluja , Asmita Hirapara
Physical Chemistry Laboratory, Department of Chemistry, Saurashtra University, Rajkot 360005, Gujarat, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 28 August 2018
Received in revised form 24 November 2018
Accepted 14 December 2018
Available online 18 December 2018
Some novel pyrazolo chalcone derivatives have been synthesized and characterization of these synthesized com-
pounds was done by IR, 1H NMR, 13C NMR and mass analysis. The solubility of pyrazolo chalcone derivatives in
methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, ethyl acetate and acetonitrile was measured by gravimet-
ric method over a temperature range (298.15 to 328.15) K at atmospheric pressure. The solubility of synthesized
compounds is found to increase linearly with temperature. Further, in alcoholic solvents, solubility is maximum
in 1-pentanol and minimum in methanol whereas in non-alcoholic solvents, solubility is greater in ethyl acetate
and minimum in acetonitrile. The experimental solubility data were correlated with temperature by modified
Apelblat and Buchowski-Ksiazczak λh equations. The experimental data and model parameters would be useful
for optimizing the process of purification. Some thermodynamic parameters such as dissolution enthalpy, Gibb's
free energy and entropy of mixing have also been calculated by Van't Hoff analysis. Further, excess enthalpy of
solutions has been calculated using Buchowski-Ksiazczak λh equation.
Keywords:
Pyrazolo chalcone derivatives
Solubility
Apelblat equation
Buchowski-Ksiazczak equation
Thermodynamic parameters
© 2018 Published by Elsevier B.V.
Contents
1.
2.
Introduction
Experimental .
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692
693
693
697
697
697
700
704
704
704
704
704
2.1.
2.2.
Synthesis
Spectroscopy studies .
3.
Solubility measurement . . .
3.1.
3.2.
3.3.
Results and discussion
Thermodynamic parameters .
Excess enthalpy of solutions .
4.
Conclusions.
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Acknowledgments
Appendix A.
References.
Supplementary data .
.
. . . . . . . . . . .
1. Introduction
inflammatory [4], antiherbicidal [5], anti-HIV [6], anti-ulcer [7] and
anti-cancer [8] etc. Due to these biological applications, it was of our in-
terest to study the behaviour of these pyrazolo chalcones in solutions
which may be useful for their further applications in different fields.
The ability of a chemical compound to elicit a pharmacological/ther-
apeutic effect is related to its various physicochemical properties. Solu-
bility is one of the properties which provide preliminary information on
the nature of the tested compound. Solubility behaviour of a compound
is an important factor affecting their bioavailability [9]. Further, solubil-
ity data provides useful information to understanding of intermolecular
Chalcones, considered to be the precursor of flavonoids and
isoflavonoids are abundant in edible plants as well as useful for the syn-
thesis of several derivatives like cyanopyridines [1], pyrazolines
isoxazoles [2] and pyrimidines [3]. These chalcones containing keto eth-
ylenic group demonstrate various biological activities such as anti-
⁎
Corresponding author.
E-mail address: shipra_baluja@rediffmail.com (S. Baluja).
https://doi.org/10.1016/j.molliq.2018.12.081
0167-7322/© 2018 Published by Elsevier B.V.

S. Baluja, A. Hirapara / Journal of Molecular Liquids 277 (2019) 692–704
693
Fig. 1. Reaction Scheme for synthesized pyrazolo chalcone derivatives.
forces-solution and structure property relationship [10]. By using this
data one can design process pharmaceutical dosage form and drug dis-
covery process [11,12]. It is also important for synthesis and evaluation
of the separation process [13,14]. Study of temperature dependence sol-
ubility data provides the explanation of molecular mechanisms in-
volved in the respective drug dissolution process [15]. The data has
been useful in drug design, formulation, production, distillation and
crystallization based on separation [16] etc. Solubility data may be use-
ful to understand various biological processes [17,18].
purchased from Spectochem Pvt. Ltd. (Mumbai, India) as well as LOBA
Chemie Pvt. Ltd. and the mole fraction purities of these chemicals
were of 98.5–99.5%. The solvents used in solubility determination
were of Analytical Reagent (AR) grade and were further purified accord-
ing to reported method [19]. All the distilled solvents were stored over
dry molecular sieves. The purity of solvents was checked by GC–MS
(SHIMADZU Model-QP- 2010).
Because of the continuing interest and marvellous biological activity
of chalcone derivatives, the solubility of synthesized compounds has
been studied in different solvents and temperatures. These data were
correlated with a modified Apelblat and Buchowski-Ksiazczak λh
models. Further, using solubility data, some thermodynamic parameters
such as dissolution enthalpy, Gibb's free energy and entropy of mixing
were also evaluated.
2.1. Synthesis
A methanolic solution of different 1‑(1H‑benzo[d]imidazole‑2‑yl)
ethan‑1‑one (0.01 mol), pyrazolo aldehyde (0.008–0.007 mol) and po-
tassium hydroxide (0.04 mol) was stirred at room temperature for
1 h. The completion of reaction was confirmed by analytical thin layer
chromatography (TLC) (Performed on aluminium coated plates Gel
60F254 (E. Merck)) using (0.6:0.4-Hexane: Ethyl acetate) as mobile
phase. After completion of reaction, the reaction mass was poured in
to crushed ice and the resultant solid was filtered, washed with metha-
nol to remove unreacted reagents and dried under vacuum to give
crude product.
2. Experimental
The chemicals used in the synthesis of different chalcone com-
pounds are o-phenyledine diamine, glacial acetic acid, phenyl hydrazine
and different substituted acetophenones etc. These chemicals were
The reaction scheme is given in Fig. 1.
Table 1
Physical properties of synthesized chalcone derivatives.
⁎
Compound
-R
3‑methoxy
-H
4‑chloro
3, 4‑dimethoxy
4‑flouro
2‑chloro
Molecular formula
C26H20N4O2
Average molar mass
Yield (%)
Rf value
T
fus/K
Electro-negativity
AH-1
AH-2
AH-3
AH-4
AH-5
AH-6
AH-7
AH-8
420.158
390.446
424.880
450.169
408.440
424.110
420.158
436.136
80
80
80
81
85
86
89
83
0.84
0.84
0.80
0.71
0.88
0.80
0.88
0.83
504.28
543.65
540.90
524.11
555.43
554.67
535.64
523.01
2.26
–
C25H18N4O
C
25H17ClN4O
3.00
2.25
4.00
2.97
2.24
≈2.8
C
27H22N4O3
25H17FN4O
C25H17ClN4O
C
4‑methoxy
3‑nitro
C
C
26H20N4O2
25H17N5O3
⁎
Rf - Retention factor.
fus - Melting point.
a 0.6:0.4-Hexane: Ethyl acetate.
T

694
S. Baluja, A. Hirapara / Journal of Molecular Liquids 277 (2019) 692–704
Table 2
Experimental mole fraction solubilities (xi) and relative deviation (RD) of chalcone derivatives in selected solvents at different temperatures at experimental pressure p = 0.1 MPa.
T(K)
xi·103
xcia·103
100·RDa
xcib·103
100·RDb
xi·103
xcia·103
100·RDa
xcib·103
100·RDb
Methanol
AH-1
AH-2
298.15
303.15
308.15
313.15
318.15
323.15
328.15
AH-3
0.0271
0.0315
0.0363
0.0412
0.0462
0.0515
0.0581
0.0272
0.0315
0.0361
0.0411
0.0464
0.0519
0.0577
−0.4431
0.1268
0.5235
0.0275
0.0315
0.0359
0.0408
0.0462
0.0520
0.0584
−1.5509
0.1268
1.0747
1.0429
0.0433
0.0554
0.0653
0.0808
0.0883
0.0987
0.1153
0.1229
AH-4
0.0561
0.0669
0.0783
0.0899
0.1013
0.1121
0.1221
−1.1905
−2.4502
3.0461
−1.8120
−2.6551
2.7754
0.0580
0.0668
0.0765
0.0873
0.0992
0.1122
0.1265
−4.7979
−2.4502
5.1511
1.0193
−0.6283
2.5152
0.3153
−0.3894
−0.7767
0.6029
−0.9709
−0.6029
0.6348
−3.1087
298.15
303.15
308.15
313.15
318.15
323.15
328.15
AH-5
0.0406
0.0510
0.0674
0.0790
0.0936
0.1050
0.1167
0.0429
0.0557
0.0696
0.0840
0.0979
0.0111
0.1214
−5.6650
−9.2157
−3.2947
6.3291
−4.5493
−5.7140
−4.0185
0.0461
0.0553
0.0659
0.0781
0.0921
0.1080
0.1260
0.7322
1.5929
0.0304
0.0360
0.0406
0.0447
0.0502
0.0550
0.0653
AH-6
0.0307
0.0355
0.0406
0.0459
0.0515
0.0572
0.0631
−0.9536
1.4163
0.0984
−2.7305
−2.6305
−4.0000
3.3394
0.0312
0.0355
0.0403
0.0455
0.0512
0.0574
0.0574
−2.5978
1.4162
1.0827
−1.6115
−1.8334
−4.0000
2.1140
−1.7839
−0.9056
1.5841
−2.5161
−0.0696
298.15
303.15
308.15
313.15
318.15
323.15
328.15
AH-7
0.5601
0.5690
0.5779
0.5880
0.5964
0.6060
0.6189
0.5595
0.5698
0.5799
0.5898
0.5995
0.6091
0.6185
0.1125
0.5596
0.5698
0.5798
0.5897
0.5995
0.6091
0.6186
0.1125
0.0904
0.1160
0.1332
0.1490
0.1679
0.1870
0.2092
AH-8
0.0929
0.1118
0.1315
0.1514
0.1709
0.1894
0.2061
−2.7768
3.6207
1.2392
−1.6107
−1.8049
−1.2834
1.4865
0.0967
0.1116
0.1283
0.1467
0.1672
0.1897
0.2144
−6.9808
3.7931
3.6425
1.4765
0.3991
−0.1406
−0.3548
−0.3061
−0.5198
−0.5115
0.0662
−0.1406
−0.3375
−0.2891
−0.5030
−0.4950
0.0662
−1.4438
−2.4807
298.15
303.15
308.15
313.15
318.15
323.15
328.15
0.1454
0.1488
0.1547
0.1600
0.1665
0.1700
0.1767
0.1449
0.1503
0.1556
0.1609
0.1663
0.1717
0.1771
0.3576
0.1449
0.1503
0.1556
0.1610
0.1663
0.1717
0.1771
0.3576
0.0404
0.0485
0.0550
0.0590
0.0659
0.0740
0.0821
0.0409
0.0475
0.0544
0.0613
0.0682
0.0749
0.0812
−1.3129
2.0619
1.1269
−3.8983
−3.4901
−1.2162
1.0962
0.0419
0.0475
0.0535
0.0601
0.0673
0.0750
0.0833
−3.7899
2.0619
2.7626
−1.8644
−2.1244
−1.3514
−1.5834
−1.0081
−0.6078
−0.5625
0.1261
−1.0000
−0.2037
−1.0081
−0.6078
−0.5625
0.1261
−1.0000
−0.1471
Ethanol
AH-1
AH-2
298.15
303.15
308.15
313.15
318.15
323.15
328.15
AH-3
0.0724
0.0850
0.1056
0.1213
0.1361
0.1482
0.1651
0.0728
0.0886
0.1050
0.1214
0.1371
0.1515
0.1640
−0.7131
−4.2753
0.5097
−0.0726
−0.7296
−2.2141
0.6174
0.0763
0.0883
0.1017
0.1167
0.1333
0.1516
0.1717
−5.4450
−3.8824
3.6476
3.7923
2.0645
0.0848
0.0940
0.1064
0.1230
0.1348
0.1460
0.1601
AH-4
0.0842
0.0958
0.1081
0.1208
0.1339
0.1472
0.1606
−1.1905
−2.4502
3.0461
−1.8120
−2.6551
2.7754
0.0763
0.0883
0.1018
0.1167
0.1333
0.1516
0.1718
−4.7980
−2.4502
5.1511
1.0193
−0.6283
2.5152
−2.2735
−4.0291
0.6348
−3.1087
298.15
303.15
308.15
313.15
318.15
323.15
328.15
AH-5
0.1017
0.1130
0.1199
0.1325
0.1484
0.1550
0.1725
0.1011
0.1113
0.1223
0.1339
0.1461
0.1591
0.1728
0.6339
1.5044
0.1011
0.1113
0.1223
0.1339
0.1461
0.1591
0.1728
0.7322
1.5929
0.0391
0.0500
0.0588
0.0716
0.0846
0.1000
0.1111
AH-6
0.0389
0.0487
0.0596
0.7160
0.0844
0.0977
0.1112
0.6958
0.0402
0.0486
0.0584
0.0697
0.0828
0.0978
0.1149
10.0130
6.0638
4.3952
5.1220
1.1714
−1.9149
−1.5214
1.7886
0.7266
−0.8219
−0.2935
−1.9506
−1.0566
1.5167
−2.6451
−0.1855
−1.7839
−0.9057
1.5841
−2.5161
−0.0696
−3.8356
−7.2254
298.15
303.15
308.15
313.15
318.15
323.15
328.15
AH-7
0.8143
0.8280
0.8393
0.8550
0.8689
0.8790
0.8930
0.8146
0.2820
0.8416
0.8547
0.8675
0.8801
0.8925
−0.0343
0.3623
−0.2717
0.0350
0.1588
−0.1251
0.0593
0.8151
0.8284
0.8414
0.8542
0.8667
0.8791
0.8912
−0.1081
−0.0483
−0.2478
0.0936
0.2509
−0.0114
0.1937
0.1051
0.1253
0.1451
0.1567
0.1786
0.1950
0.2172
AH-8
0.1353
0.1562
0.1774
0.1983
0.2183
0.2372
0.2542
−28.7350
−24.6610
−22.2940
−26.5480
−22.2010
−21.6410
−17.0240
0.1094
0.1242
0.1404
0.1580
0.1773
0.1982
0.2208
−3.9961
0.9577
3.2814
−0.7658
0.8061
−1.5897
−1.6481
298.15
303.15
308.15
313.15
318.15
323.15
328.15
0.3519
0.3720
0.3855
0.3986
0.4195
0.4300
0.4518
0.3539
0.3697
0.3858
0.4019
0.4182
0.4346
0.4512
−0.5626
0.6183
−0.0752
−0.8254
0.3051
0.3539
0.3697
0.3857
0.4019
0.4182
0.4346
0.4512
−0.5626
0.6183
−0.0493
−0.8254
0.3051
0.0553
0.0620
0.0701
0.0842
0.0946
0.1032
0.1194
0.0553
0.0629
0.0716
0.0816
0.0929
0.1058
0.1205
0.0000
0.0547
0.0630
0.0721
0.0823
0.0935
0.1058
0.1193
1.0850
−1.4516
−2.2127
3.0879
1.8074
−2.5194
−0.8875
−1.4516
−2.9265
2.2565
1.1732
−2.5194
0.2009
−1.0674
0.1416
−1.0674
0.1416
1-propanol
AH-1
AH-2
298.15
303.15
308.15
313.15
318.15
323.15
0.1256
0.1453
0.1657
0.1865
0.2063
0.2310
0.1257
0.1453
0.1655
0.1858
0.2058
0.2250
−0.0876
0.0138
0.0906
0.3753
0.2569
2.5974
0.1291
0.1454
0.1632
0.1824
0.2032
0.2256
−2.7948
−0.0551
1.4790
2.1984
1.5169
0.1352
0.1523
0.1785
0.1890
0.2154
0.2260
0.1353
0.1562
0.1774
0.1983
0.2184
0.2372
−0.1110
−2.5607
0.6385
−4.9206
−1.4116
−4.9558
0.1392
0.1560
0.1742
0.1938
0.2149
0.2375
−2.9967
−2.4294
2.4308
−2.5397
0.2600
2.3377
−5.0443

S. Baluja, A. Hirapara / Journal of Molecular Liquids 277 (2019) 692–704
695
Table 2 (continued)
xi·103
T(K)
xcia·103
100·RDa
xcib·103
100·RDb
−1.9808
xi·103
xcia·103
100·RDa
xcib·103
100·RDb
328.15
0.2449
0.2432
0.6739
0.2497
0.2551
AH-4
0.2541
0.3842
0.2617
−2.5561
AH-3
298.15
0.0835
0.1030
0.1213
0.1322
0.1501
0.1580
0.1673
0.0840
0.1023
0.1202
0.1364
0.1499
0.1599
0.1657
−0.5627
0.6796
0.9232
−3.1770
0.1599
−1.2025
0.9623
0.0972
0.1080
0.1195
0.1318
0.1449
0.1589
0.1738
−2.7948
−0.0551
1.4790
2.1984
1.5170
0.1251
0.1400
0.1503
0.1670
0.1854
0.2000
0.2200
AH-6
0.1255
0.1386
0.1527
0.1676
0.1836
0.2004
0.2182
−0.2877
1.0000
−1.5901
−0.3593
0.9922
0.1254
0.1386
0.1526
0.1676
0.1835
0.2003
0.2181
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
303.15
308.15
313.15
318.15
323.15
328.15
2.3377
−1.9808
−0.2000
0.8272
AH-5
298.15
303.15
308.15
313.15
318.15
323.15
328.15
1.0377
1.0560
1.0733
1.0930
1.1153
1.1450
1.1679
1.0340
1.0562
1.0782
1.0782
1.1212
1.1422
1.1630
0.3585
1.0341
1.0562
1.0781
1.0997
1.1211
1.1422
1.1630
0.1754
0.1568
0.1670
0.1769
0.1890
0.2053
0.2200
0.2440
AH-8
0.1566
0.1675
0.1796
0.1931
0.2080
0.2245
0.2428
13.6890
6.4671
0.1548
0.1676
0.1809
0.1948
0.2093
0.2244
0.2401
1.2503
−0.0189
−0.4528
1.3541
−0.5317
0.2445
−0.0852
−0.4062
−0.4666
−0.2717
0.5852
−0.2994
−2.2335
−3.0688
−1.8798
−1.9546
1.6964
−0.3110
−4.9206
−6.3602
−7.8182
−4.1633
0.4204
0.8571
AH-7
298.15
303.15
308.15
313.15
318.15
323.15
328.15
0.4901
0.5200
0.5407
0.5650
0.5856
0.6150
0.6278
0.4934
0.5160
0.5388
0.5619
0.5853
0.6088
0.6325
−0.6651
0.7692
0.3588
0.5487
0.0512
1.0081
−0.7567
0.4939
0.5165
0.5394
0.5625
0.5858
0.6093
0.6331
−0.7671
0.6731
0.2478
0.4425
−0.0512
0.9106
0.1145
0.1350
0.1641
0.1753
0.2057
0.2256
0.2505
0.1152
0.1376
0.1609
0.1843
0.2071
0.2287
0.2483
−0.5762
−1.9259
1.9261
−5.1341
−0.6953
−1.3741
0.8901
0.1196
0.1374
0.1571
0.1789
0.2028
0.2291
0.2578
−4.4177
−1.7037
4.2424
−1.9966
1.4441
−1.4628
−2.8619
−0.8523
1-butanol
AH-1
AH-2
298.15
303.15
308.15
313.15
318.15
323.15
328.15
AH-3
0.1701
0.1854
0.2115
0.2299
0.2584
0.2853
0.3115
0.1684
0.1882
0.2096
0.2326
0.2573
0.2838
0.3121
0.9819
−1.4993
0.9171
−1.1744
0.4257
0.5258
0.1687
0.1885
0.2099
0.2330
0.2577
0.2842
0.3125
0.8056
−1.6611
0.7753
−1.3484
0.2709
0.3856
0.2477
0.2750
0.2988
0.335
0.3742
0.4250
0.4653
AH-4
0.2465
0.2717
0.3008
0.3345
0.3735
0.4186
0.4708
0.4764
1.2000
−0.6727
0.1493
0.1924
1.5059
−1.1886
0.2535
0.2750
0.3040
0.3540
0.3875
0.4235
0.4618
2.3740
1.2000
−1.8106
−1.3134
−0.8231
1.6235
−0.1830
−0.3114
0.7458
298.15
303.15
308.15
313.15
318.15
323.15
328.15
AH-5
0.1502
0.1750
0.2013
0.2156
0.2398
0.2580
0.2952
0.1507
0.1754
0.2005
0.2255
0.2797
0.2724
0.2931
−0.3529
−0.2286
0.4073
−4.5918
−16.649
−5.5814
0.7181
0.1553
0.1752
0.1967
0.2201
0.2455
0.2728
0.3022
−3.4161
−0.0571
2.2949
−2.0872
−2.3438
−5.7364
−2.3643
0.1596
0.2090
0.2445
0.2800
0.3206
0.3500
0.3899
AH-6
0.1633
0.2025
0.2433
0.2839
0.3222
0.3564
0.3846
−2.3119
3.1100
0.4745
−1.3929
−0.5022
−1.8286
1.3770
0.1730
0.2020
0.2345
0.2711
0.3119
0.3573
0.4076
−8.3892
3.3971
4.1152
3.2500
2.7418
−2.0571
−4.4696
298.15
303.15
308.15
313.15
318.15
323.15
328.15
AH-7
1.5823
1.6000
1.6161
1.6480
1.6484
1.6530
1.6743
1.5846
1.6008
1.6167
1.6321
1.6471
1.6618
1.6760
−0.1460
−0.0500
−0.0396
0.9648
0.0758
−0.5324
−0.1033
1.5848
1.6009
1.6166
1.6320
1.6471
1.6618
1.6762
−0.1650
−0.0563
−0.0396
0.9648
0.0758
−0.5384
−0.1213
0.2942
0.3300
0.3543
0.4000
0.4446
0.5000
0.5333
AH-8
0.2960
0.3296
0.3657
0.4045
0.4459
0.4901
0.5371
−0.6221
0.1212
−3.2264
−1.1250
−0.2879
1.9800
0.2960
0.3296
0.3657
0.4044
0.4459
0.4900
0.5371
−0.6221
0.1212
−3.2546
−1.1250
−0.2879
2.0000
−0.7125
−0.7125
298.15
303.15
308.15
313.15
318.15
323.15
328.15
1.3336
1.3580
1.3834
1.4210
1.4541
1.4912
1.5125
1.3296
1.3613
1.3925
1.4235
1.4540
1.4843
1.5114
0.3022
1.3298
1.3613
1.3925
1.4234
1.4540
1.4843
1.5142
0.2872
0.2025
0.2356
0.2788
0.3240
0.3593
0.4023
0.4454
0.2017
0.2391
0.2788
0.3201
0.3622
0.4041
0.4452
0.4147
−1.4856
0.0215
0.2070
0.2388
0.2742
0.3135
0.3569
0.4046
0.4570
−2.1527
−1.3158
1.6711
3.2716
0.7069
−0.2430
−0.6585
−0.1759
0.0096
0.4647
0.0707
−0.2430
−0.6585
−0.1689
0.0096
0.4647
0.0707
1.2037
−0.7959
−0.4474
0.0427
−0.5469
−2.5843
1-pentanol
AH-1
AH-2
298.15
303.15
308.15
313.15
318.15
323.15
328.15
AH-3
0.2265
0.2740
0.3123
0.3810
0.4268
0.4570
0.4987
0.2251
0.2733
0.3232
0.3727
0.4198
0.4626
0.4991
0.6181
0.2555
−3.5002
2.1785
1.6355
0.2366
0.2731
0.3139
0.3591
0.4091
0.4642
0.5247
4.4592
0.2920
−0.5220
5.7218
4.1192
0.2566
0.3320
0.4065
0.4750
0.5352
0.5920
0.6391
AH-4
0.2589
0.3298
0.4037
0.4759
0.5414
0.5957
0.6354
−0.8924
0.6627
0.6839
−0.1895
−1.1622
−0.6250
16.2312
0.2796
0.3287
0.3845
0.4476
0.5184
0.5978
0.6864
−8.9981
0.9639
5.3582
5.7474
3.0980
−1.2254
−0.0722
−1.6193
−5.2452
−1.0135
−7.4256
298.15
303.15
308.15
313.15
318.15
323.15
0.2535
0.2750
0.3039
0.3540
0.3875
0.4235
0.2534
0.2865
0.3199
0.3530
0.3853
0.4161
0.0513
0.2579
0.2855
0.3150
0.3464
0.3799
0.4154
−1.7237
−3.8182
−3.6287
2.1186
1.9512
1.8890
0.3104
0.3300
0.3542
0.3749
0.3951
0.4120
0.3099
0.3324
0.3542
0.3750
0.3947
0.4133
0.1579
−0.7273
0.0028
−0.0267
0.0962
−0.3155
0.3153
0.3340
0.3531
0.3727
0.3927
0.4130
−0.8731
−0.6970
0.6522
0.8002
0.6530
−4.1818
−5.2407
0.2825
0.5575
1.7473
−0.3398
(continued on next page)

696
S. Baluja, A. Hirapara / Journal of Molecular Liquids 277 (2019) 692–704
Table 2 (continued)
T(K)
328.15
AH-5
298.15
303.15
308.15
313.15
318.15
323.15
328.15
xi·103
xcia·103
100·RDa
−0.6945
xcib·103
100·RDb
−2.5044
xi·103
xcia·103
100·RDa
−0.1349
xcib·103
100·RDb
−1.1819
0.4420
0.4451
0.4530
0.4298
AH-6
0.4304
0.4338
1.7575
1.7830
1.8109
1.839
1.8662
1.8900
1.9204
1.7577
1.7860
1.8138
1.8412
1.8680
1.8943
1.9201
−0.0131
−0.1683
−0.1585
−0.1196
−0.0965
−0.2275
0.0156
1.7579
1.7861
1.8139
1.8412
1.8680
1.8944
1.9203
−0.0131
−0.1683
−0.1585
−0.1142
−0.0911
−0.2222
0.0104
0.3542
0.4000
0.4483
0.5100
0.6000
0.6900
0.7400
AH-8
0.3531
0.4003
0.4539
0.5147
0.5835
0.6614
0.7495
0.3077
0.3497
0.4006
0.4568
0.5188
0.5868
0.6612
0.7423
1.2394
−0.0750
−1.2605
−0.9216
2.7500
4.1449
−1.2838
−0.1500
−1.9520
−1.7451
2.1667
4.1449
−0.3378
AH-7
298.15
303.15
308.15
313.15
318.15
323.15
328.15
1.5587
1.6220
1.6834
1.7400
1.7903
1.8500
1.9095
1.5650
1.6225
1.6802
1.7381
1.7959
1.8539
1.9118
0.3022
1.5722
1.5832
1.6395
1.6959
1.7524
1.8089
1.8655
0.2872
0.2806
0.3256
0.3679
0.4236
0.4551
0.5130
0.5572
0.2816
0.3260
0.3704
0.4171
0.4642
0.5112
0.5573
−0.3411
0.1689
−0.6983
1.5361
−2.0235
0.3448
−0.0072
0.2871
0.3248
0.3659
0.4106
0.4591
0.5117
0.5683
−2.3336
0.2479
0.5347
3.0564
−0.9111
0.2483
−0.2430
−0.6585
−0.1759
0.0096
0.4647
0.0707
−0.2430
−0.6585
−0.1689
0.0096
0.4647
0.0707
−2.0056
Ethyl acetate
AH-1
AH-2
298.15
303.15
308.15
313.15
318.15
323.15
328.15
AH-3
0.2412
0.2564
0.2739
0.2923
0.3166
0.3359
0.3650
0.2415
0.2570
0.2743
0.2935
0.3149
0.3386
0.3649
−0.1202
−0.2340
−0.1168
−0.4105
0.5495
0.2387
0.2571
0.2763
0.2963
0.3170
0.3384
0.3606
1.9112
0.1590
0.1952
0.2435
0.3120
0.3621
0.4030
0.4625
AH-4
0.1572
0.2020
0.2518
0.3051
0.3599
0.4142
0.4656
1.1507
0.1656
0.2015
0.2435
0.2926
0.3495
0.4152
0.4907
−4.1942
−3.2275
−0.0246
6.1859
3.4521
−3.0521
−6.1258
−6.5523
−14.5700
−22.8870
−29.2320
−38.2260
−43.7770
−3.4836
−3.3916
2.2115
0.6076
−2.7792
−0.6768
−0.8038
0.0301
298.15
303.15
308.15
313.15
318.15
323.15
328.15
AH-5
0.2567
0.2900
0.3282
0.3850
0.4323
0.4820
0.5265
0.2543
0.2934
0.3356
0.3808
0.4288
0.4794
0.5325
0.9620
0.2566
0.2932
0.3335
0.3779
0.4265
0.4795
0.5373
0.0662
0.3554
0.4250
0.4713
0.5200
0.5545
0.5900
0.6291
AH-6
0.3588
0.4081
0.4571
0.5046
0.5497
0.5912
0.6284
−0.9453
3.9765
3.0047
2.9615
0.8710
−0.2034
0.1033
0.3684
0.4076
0.4495
0.4941
0.5416
0.5920
0.6452
−3.6462
4.1176
4.6386
5.0000
2.3497
−1.1724
−2.2641
1.0909
0.8188
0.5394
−1.1035
−1.6242
1.8442
1.3508
0.5187
−0.3051
−2.5515
−1.1492
−2.0610
298.15
303.15
308.15
313.15
318.15
323.15
328.15
AH-7
1.4902
1.5220
1.5618
1.6000
1.6407
1.6809
1.7150
1.4878
1.5269
1.5656
1.6041
1.6422
1.6799
1.7173
0.1604
1.4879
1.5269
1.5656
1.6040
1.6421
1.6799
1.7174
0.1604
0.7700
0.9500
1.0670
1.2000
1.3470
1.4500
1.5720
AH-8
0.7820
0.9263
1.0719
1.2134
1.3456
1.4635
1.5629
−1.5584
2.4947
−0.4592
−1.1167
0.1039
0.8160
0.9246
1.0434
1.1730
1.3138
1.4663
1.6311
−5.9610
2.6842
2.2212
2.2583
2.4722
−0.3219
−0.2459
−0.2563
−0.0939
0.0595
−0.3154
−0.2395
−0.2438
−0.0817
0.0714
−0.9310
0.5789
−1.1172
−3.7532
−0.1318
−0.1318
298.15
303.15
308.15
313.15
318.15
323.15
328.15
0.8095
0.8260
0.8463
0.8680
0.8862
0.9100
0.9352
0.8077
0.8286
0.8492
0.8696
0.8899
0.9100
0.9299
0.2236
0.8077
0.8285
0.8491
0.8696
0.8899
0.9100
0.9299
0.2112
1.3007
1.4875
1.6977
1.9423
2.1658
2.4368
2.7694
1.3030
1.4912
1.6993
1.9287
2.1807
2.4566
2.7578
−0.1745
−0.2487
−0.0954
0.7002
−0.6889
−0.8125
0.4196
1.3025
1.4911
1.6996
1.9292
2.1811
2.4565
2.7567
−0.1361
−0.2420
−0.1131
0.6745
−0.7074
−0.8084
0.4593
−0.3148
−0.3486
−0.1843
−0.4221
0.0000
−0.3027
−0.3486
−0.1959
−0.4221
0.0000
0.5646
0.5646
Acetonitrile
AH-1
AH-2
298.15
303.15
308.15
313.15
318.15
323.15
328.15
AH-3
0.0291
0.0416
0.0587
0.0762
0.0921
0.1109
0.1218
0.0290
0.0423
0.0581
0.0754
0.0927
0.1083
0.1209
0.2751
−1.8252
0.9193
0.9576
−0.8686
2.0739
0.6568
0.0325
0.0421
0.0540
0.0687
0.0868
0.1089
0.1357
−11.761
−0.8646
8.0695
9.8780
5.7546
0.0571
0.0650
0.0761
0.0930
0.1017
0.1200
0.1325
AH-4
0.0568
0.0661
0.0766
0.0882
0.1013
0.1157
0.1317
0.5428
−1.6923
−0.7232
5.1613
0.3835
3.5833
0.6263
0.0568
0.0661
0.0766
0.0883
0.1013
0.1157
0.1317
0.5428
−1.8462
−0.7232
5.0538
0.3835
3.5000
0.6263
1.8034
−11.494
298.15
303.15
308.15
313.15
318.15
323.15
328.15
AH-5
0.1162
0.1350
0.1535
0.1712
0.1824
0.1930
0.2112
0.1172
0.1347
0.1521
0.1688
0.1842
0.1980
0.2097
−0.8432
0.2222
0.9379
0.1211
0.1345
0.1489
0.1643
0.1807
0.1982
0.2168
−4.1129
0.4444
3.0871
4.1056
0.9429
0.1131
0.1350
0.1519
0.1700
0.1889
0.2100
0.2304
AH-6
0.1146
0.1327
0.1517
0.1712
0.1909
0.2105
0.2296
−1.3711
1.7037
0.1054
−0.7059
−1.0267
−0.2381
0.3645
0.1170
0.1326
0.1497
0.1684
0.1887
0.2107
0.2344
−3.4056
1.8519
1.4882
1.0000
0.1905
1.4191
−0.9758
−2.5907
0.7008
−2.6943
−2.6139
−0.2857
−1.6751
298.15
303.15
308.15
313.15
318.15
323.15
328.15
0.7521
0.8020
0.8574
0.8900
0.9431
0.9700
1.0107
0.7624
0.8043
0.8471
0.8906
0.9350
0.9800
1.0258
−1.3735
−0.2868
1.2071
−0.0674
0.8589
0.7614
0.8033
0.8460
0.8895
0.9338
0.9788
1.0245
−1.2406
−0.1496
1.3354
0.0562
0.9861
0.0178
0.0600
0.1010
0.1400
0.1870
0.2100
0.2410
0.0206
0.0488
0.0943
0.1507
0.2012
0.2272
0.2190
−15.7300
18.6667
6.6337
−7.6429
−7.5936
−8.1905
9.1286
0.0526
0.0709
0.0947
0.1252
0.1642
0.2134
0.2752
−75.8430
20.1667
28.3168
22.8571
14.9198
−1.0309
−1.4960
−0.9072
89.8583
−10.2860
−38.0910

S. Baluja, A. Hirapara / Journal of Molecular Liquids 277 (2019) 692–704
697
Table 2 (continued)
T(K)
xi·103
xcia·103
100·RDa
xcib·103
100·RDb
xi·103
xcia·103
100·RDa
xcib·103
100·RDb
AH-7
AH-8
298.15
0.1647
0.2001
0.2274
0.2500
0.2823
0.3010
0.3291
0.1660
0.1948
0.2244
0.2536
0.2816
0.3077
0.3309
−0.7648
2.6487
1.3323
−1.4400
0.2586
−2.2259
−0.5592
0.1717
0.1945
0.2195
0.2466
0.2761
0.3081
0.3426
−4.2248
2.7986
3.5308
1.3600
2.2066
0.1026
0.1230
0.1476
0.1633
0.1897
0.2156
0.2323
0.1031
0.1235
0.1450
0.1672
0.1896
0.2113
0.2320
−0.4873
−0.4065
1.7615
−2.4330
0.0659
0.1063
0.1231
0.1418
0.1627
0.1858
0.2113
0.2394
−3.5838
−0.0342
3.9451
0.4127
2.0880
303.15
308.15
313.15
318.15
323.15
328.15
−2.3588
−4.1148
1.9694
0.2494
2.0102
−2.9067
(xi) = Experimental mole fraction solubility with an uncertainty of 0.00001.
a
Values obtained by Apelblat equation (Eq. (2)).
Values obtained by Buchowski-Ksiazczak equation (Eq. (3)).
b
Overall, eight compounds are synthesized and the IUPAC names of
these compounds are:
decrease in weight it suggests that solvent is not completely evaporated.
So, more evaporation time should be given. This should continue until
the weight was constant. The total evaporation of solvent was further
confirmed by comparing TG of residue with that of original compound.
At each temperature experiment was conducted three times in parallel
and the average value was used as experimental result to calculate the
mole solubility of compound. An analytical balance (Mettler Toledo
AB204-S, Switzerland) was employed to determine the mass of solute,
solvent, and saturated solution with the accuracy of 0.0001 g. The
mole fraction solubility of the solute i.e., compound (xexp) in different
pure solvents can be calculated by the following relation:
AH-1:(E)‑1‑(1H‑benzo[d]
imidazole‑2‑yl)‑3‑(3‑methxyphenyl‑1H‑pyrazol‑4‑yl)prop‑2‑en1one
AH-2:(E)‑1‑(1H‑benzo[d]imidazole‑2‑yl)‑3‑(1,
3‑diphenyl‑1H‑pyrazol‑4‑yl) prop‑2‑en‑1one
AH-3:(E)‑1‑(1H‑benzo[d]
imidazole‑2‑yl)‑3‑(3‑(4‑chlorophenyl)‑phenyl‑1H‑pyrazol‑4‑yl)
prop‑2‑en‑1one
AH-4:(E)‑1‑(1H‑benzo[d]
imidazole‑2‑yl)‑3‑(3‑(3,4‑dimethoxyphenyl)‑1‑phenyl‑1H‑pyrazol‑4‑yl)
prop‑2‑en‑1one
ðm2−m0Þ
AH-5:(E)‑1‑(1H‑benzo[d]
imidazole‑2‑yl)‑3‑(3‑(4‑fluorophenyl)‑1H‑pyrazol‑4‑yl)pop‑2‑en‑1one
AH-6:(E)‑1‑(1H‑benzo[d]imidazole‑2-
yl)‑3‑(3‑(2‑chlorophenyl)‑1‑phenyl‑1H‑pyrazol‑4‑yl) prop‑2‑en‑1one
AH-7:(E)‑1‑(1H‑benzo[d]
M2
ꢀ
ꢁ
ꢀ
ꢁ
xi ¼
ð1Þ
m2−mo
m1−m2
þ
M2
M1
imidazole‑2‑yl)‑3‑(3‑(4‑methxyphenyl)‑1‑phenyl‑1H‑pyrazol‑4‑yl)
prop‑2‑en‑1one
where M1 and M2 is the molecular weight of solvent and compound re-
spectively. m1 and m2 are weights of solvent and compound in the solu-
tion respectively. At each temperature, the measurement was repeated
three times and an average value is given in Table 2. The uncertainty of
experimental values is established to be less than 1.03%.
AH-8:
(E)‑1‑(1H‑benzo[d]
imidazole‑2‑yl)‑3‑(3‑(3‑nitrophenyl)‑1‑phenyl‑1H‑pyrazol‑4‑yl)
prop‑2‑en‑1one
Table 1 shows the physical parameters and different substitutions of
synthesized compounds.
3.1. Results and discussion
2.2. Spectroscopy studies
The experimental mole fraction solubilities (xi) of the studied com-
pounds in the selected solvents are listed in Table 2 at different temper-
atures. It is observed that for alcoholic solvent, solubility increases from
methanol to 1-pentanol. Thus, in alcohols, as -CH2- group increases, sol-
ubility increases. For each compound, in non-alcoholic solvents, solubil-
ity is higher in ethyl acetate than that in acetonitrile.
The structure confirmation was done by different spectroscopic
techniques such as IR, 1H NMR, 13CNMR and mass.
3. Solubility measurement
Table 3 shows dielectric constant, dipole moment and hydrogen
bonding capacity of studied solvents. It is observed that in alcohols,
there is a regular decrease in dielectric constant and δH (Hydrogen
bonding capacity) from methanol to 1-pentanol i.e., with increases in
-CH2- group. However, dipole moment is not in a systematic order.
Thus, solubility in alcohols is reverse of dielectric constant and hydrogen
bonding capacity.
For non-alcoholic solvents, all these three parameters are higher in
acetonitrile than those for ethyl acetate. So, solubility in alcohols is re-
verse of these parameters i.e., dielectric constant, dipole moment and
hydrogen bonding capacity.
It is also observed that different compounds have different solubility
in a particular solvent. This is due to different types of interactions tak-
ing place in solution due to different substitution groups present in
compounds. As shown in Table 1, all the studied compounds have
same central moiety but different side chain substitutions which are of
different nature. The solubility of AH-5 is maximum in all selected sol-
vents. AH-1 has minimum solubility in methanol, ethyl acetate and ace-
tonitrile. In 1‑propanol, 1‑butanol and 1‑pentanol, AH-3 had minimum
solubility whereas AH-4 was minimum soluble in ethanol.
The isothermal saturation method [20] was used to determine the
solubility of compounds. For each measurement, an excess amount of
compound was added to known volume of selected solvent at a definite
temperature. The desired temperature was controlled by the thermo-
static water bath (Model No. 140285, Nova, India) and had a standard
uncertainty of 0.05 K. A magnetic stirrer was used to mix the solution.
The solutions were stirred for few hours to reach solid-liquid equilib-
rium. The stirring was then stopped and the mixture was allowed to set-
tle so that undissolved compound should be completely settled at the
bottom. From this saturated solution, 5 ml of clear saturated solution
was quickly withdrawn from the pre-heated or pre-cooled syringe
from the solution and taken in a vial which had been weighed before
(m0). The vial with the saturated solution was then immediately
weighted (m1) to determine the weight of sample solution (m1-m0).
The solvent of the solution in the vial was then allowed to evaporate
at room temperature (about 35 °C) for at least 48 h. For some solvents,
it may take longer. When all the solvent is evaporated, the weight of vial
was again taken (m2) to determine the weight of dry residue compound
(m2-m0). This weight should be again taken after 24 h. If there is

698
S. Baluja, A. Hirapara / Journal of Molecular Liquids 277 (2019) 692–704
Table 3
role in solubility. Table 1 also shows the electronegativity of different
substitutions. The highest electronegativity is for flouro group present
in AH-5. It is observed that AH-5 exhibited maximum solubility in all
the solvents except ethyl acetate. However, for the other compounds,
the electronegativity order of order of substitution is not always ob-
served. This may be due to the fact that different substitutions interact
differently with different solvents thus, affecting solubility of com-
pounds in different solvents.
As temperature increases solubility increases and the trend of solu-
bility of compounds in different solvents changed. The temperature de-
pendence of solubility of compounds is described by the modified
Apelblat model [21].
Dielectric constant, dipole moment and hydrogen bond capacity of studied solvents at
293.15 K.
Solvent
Dielectric constant
Dipole moment
δH Hydrogen bonding
Methanol
Ethanol
33.00
25.30
20.80
17.84
15.30
6.08
1.70
1.69
1.55
1.66
1.70
1.78
3.93
29.60
26.30
24.30
23.30
22.30
18.60
24.30
1‑propanol
1‑butanol
1‑pentanol
Ethyl acetate
Acetonitrile
37.50
It is also observed that different compounds have different solubility
in a particular solvent. The solubility of AH-5 is maximum in all selected
solvents. AH-1 has minimum solubility in methanol, ethyl acetate and
acetonitrile. The different solubility of compounds in different solvents
may be due to different types of interactions taking place in solution
due to different substitution groups present in compounds. As shown
in Table 1, all the studied compounds have same central moiety but dif-
ferent side chain substitutions which are of different nature. Thus, dif-
ferent side substitution and orientation of compounds play important
B
T
lnxaci ¼ A þ þ C lnT
ð2Þ
where T is the experimental temperature and A, B and C are parameters
determined by least square method. The values of these parameters are
listed in Table 4 for all the compounds. Using these parameters, mole
fraction solubility (xaci) was evaluated and is given in Table 2.
To describe solid-liquid equilibrium, Buchowski et al. [22] intro-
duced a new model known as Buchowski-Ksiazczak (λh) model by
Table 4
Parameters of modified Apelblat equation, RMSD and ARD in the studied solvents.
Parameters
AH-1
AH-2
AH-3
AH-4
AH-5
AH-6
AH-7
AH-8
Methanol
A
B
C
114.88
377.28
746.80
135.15
−5.11
−385.98
−0.1892
2.1551
415.30
−5.33
261.34
−7886.10
−17.3658
0.2529
−284.60
−56.1135
2.2106
−37,947.20
−110.5077
38.5458
−8721.70
−20.4103
1.4814
−21,871.30
−61.6457
3.0832
−714.14
−0.1942
1.1013
−14,471.80
−39.1236
1.5201
103RMSD
100 ARD
−0.0058
−0.2359
8.0509
−0.7801
−0.2363
−0.1614
−0.4140
−0.8047
Ethanol
A
B
C
261.58
−25,849.80
−74.2105
2.1042
129.48
−8213.83
−19.5383
1.5096
−4.21
−1708.24
0.1299
23.3510
−0.4024
352.81
−19,714.90
−52.1000
1.5096
−4.97
−350.88
−0.1696
1.7205
286.98
−15,660.19
−42.7569
39.5064
−4.71
−819.05
−0.0853
2.6843
−116.65
2804.80
17.1016
1.8610
103RMSD
100 ARD
−0.8806
−0.2909
−0.2909
0.0316
−19.1956
−0.1289
−0.3108
1-propanol
A
B
C
261.58
−14,356.80
−39.0361
2.5667
302.75
−16,182.10
−45.1755
6.3069
757.20
−37,401.00
−112.5295
20.7630
−3.77
−1766.16
0.1247
1.5822
0.0957
−4.88
−415.92
−0.1046
7.3445
−121.90
4035.40
17.4818
14.3387
−2.4437
−4.36
−834.58
−0.0788
4.1047
394.42
−20,814.80
−58.5647
4.3743
103RMSD
100 ARD
0.5725
−1.8323
−0.2364
0.1451
0.2828
−0.9019
1-butanol
A
B
C
−3.69
−1930.54
0.2592
2.0557
−0.1412
−199.10
7060.42
29.3312
3.8434
318.98
−17,024.30
−47.5087
17.8166
613.78
−31,211.00
−90.8846
4.9127
−4.77
−232.00
−0.1570
7.5409
91.84
−4.63
−450.04
−0.0843
5.2529
−277.55
−15,439.50
−41.1189
2.5569
−6274.82
−13.8547
6.6894
103RMSD
100 ARD
0.1695
−3.7036
0.1768
0.0450
−0.4644
−0.0761
−0.2087
1-pentanol
A
B
C
512.22
−26,323.08
−75.8809
6.7208
814.12
−40,587.73
−120.4449
42.4911
211.88
−11,755.40
−31.7217
8.7167
104.46
−6120.57
−16.1489
1.1677
−4.63
−323.03
−0.1108
2.7065
−102.49
2308.34
15.2351
14.3513
0.4792
−4.19
−656.99
−0.0127
4.2038
206.73
−11,840.90
−30.7487
4.7972
103RMSD
100 ARD
−0.1040
2.2287
−1.0756
−0.1579
−0.1078
−0.0538
−0.0970
Ethyl acetate
A
B
C
−2.23
−2270.08
18.3379
1.4327
556.45
−29,186.30
−82.0195
7.1356
97.63
277.20
−14,758.80
−41.3572
11.2528
−4.51
−487.93
−0.0642
3.4097
450.18
0.01
−66.6687
14.0017
0.0958
−4.81
−495.25
−0.1141
3.2446
−2.23
−2270.07
0.5613
12.6234
−0.1037
−6944.29
−14.4995
4.9396
103RMSD
100 ARD
−0.1408
−1.0732
−0.3052
1.5305
−0.1415
−0.1007
Acetonitrile
A
B
C
1228.64
−61,362.30
−181.3525
1.1531
−3.18
−2620.72
0.3849
2.7074
1.0484
349.16
−18,220.10
−52.1972
2.5622
1.53
−12,436.60
−32.5214
1.5208
−3.97
−966.54
0.0047
10.1135
−0.1164
4430.49
−212,352.00
−654.4960
14.5724
365.05
−19,223.90
−54.2817
4.0953
347.42
−18,763.00
−51.5424
2.6276
103RMSD
100 ARD
0.2734
−0.0409
0.0289
1.5717
0.0021
0.1724

S. Baluja, A. Hirapara / Journal of Molecular Liquids 277 (2019) 692–704
699
Table 5
Parameters of Buchowski-Ksiazczak λh equation, RMSD and ARD in the studied solvents.
Parameters
AH-1
AH-2
AH-3
AH-4
AH-5
AH-6
AH-7
AH-8
Methanol
λ·102
0.0759
323.59
0.3846
0.2707
93.86
2.9194
0.6404
51.19
4.3981
0.0935
0.2353
1.2374
0.0928
35.19
2.0776
−0.2266
0.4978
52.17
4.5131
−0.2277
0.0382
170.88
1.0966
0.1057
211.72
1.3851
h·104
103RMSD
100 ARD
−0.1195
−0.3285
−1.0174
−0.7756
−0.4059
−0.8413
Ethanol
λ·102
0.2727
97.04
4.5802
−0.0972
0.2505
89.51
7.4597
0.8131
0.1403
124.61
2.2568
−0.2997
0.5686
0.3425
7.4597
0.8131
0.1279
22.75
1.5086
0.0329
0.3541
64.71
3.3585
0.1488
0.1148
69.02
2.6828
−0.1252
0.2134
70,361.77
1.6848
h·104
103RMSD
100 ARD
−0.4667
1-propanol
λ·102
0.2360
91.17
4.0335
0.7852
0.3126
65.81
6.3868
−1.4112
0.1681
112.68
6.6333
0.5462
0.0044
34,369.14
0.0000
0.1873
20.46
5.8225
0.0304
0.1356
105.49
4.1606
−1.1057
0.1645
49.24
3.9687
0.1958
0.4420
56.66
5.2074
−0.3340
h·104
103RMSD
100 ARD
0.0000
1-butanol
λ·102
0.2551
78.84
2.0938
−0.2698
0.5878
35.89
5.2158
−0.0539
533,474
0.4068
7.8237
0.9837
0.2103
8.69
7.5909
0.0407
0.5644
34.42
6.7426
−0.4655
0.2494
16.99
5.2201
−0.0750
0.8573
30.13
7.1468
0.1718
h·104
32,059.67
11.8787
0.9968
103RMSD
100 ARD
−1.4706
1-pentanol
λ·102
0.7908
32.86
16.4757
0.3924
2.3484
12.47
26.8527
0.9612
0.4092
44.90
9.5826
−0.57033
0.1418
1076.40
3.1988
0.2748
10.49
2.6542
−0.1062
1.4508
16.92
13.9559
0.3038
0.4028
15.73
11.1608
−0.0554
0.7114
31.30
7.7321
0.1672
h·104
103RMSD
100 ARD
−0.0162
Ethyl acetate
λ·102
0.1468
91.65
97.4333
−22.1778
3.5151
0.9653
24.98
6.4183
−0.1536
0.5173
35.34
18.5233
1.8928
0.3074
15.22
3.3239
−0.1344
2.5194
8.98
38.5259
0.6808
0.1597
28.76
3.2309
−0.1006
4.4241
5.53
12.7539
−0.1053
h·104
94,201.48
16.1596
−0.3989
103 RMSD
100 ARD
Acetonitrile
λ·102
1.7668
26.38
7.2925
1.8781
0.3588
90,289.29
2.6586
0.2111
89.99
5.0919
0.4674
0.3104
7.31
2.7221
0.3671
0.3426
25.26
0.3708
13.0256
18.9835
2.84
44.4275
5.4119
0.4887
145,648.57
8.4498
0.4839
54.71
4.6200
0.7879
h·104
103RMSD
100 ARD
0.9991
0.4889
which solubility data can be correlated with temperature by the rela-
tion:
This is further observed by relative deviation (RD), root-mean-
square deviations (RMSD) and relative average deviations (RAD)
which are calculated using following equations:
!
ꢂ
ꢃ
ꢄ
ꢅ
λ 1−xbci
1
T
1
Tm
ꢆ
ꢇ
ln 1 þ
¼ λh
−
ð3Þ
xexp−xa=b
xbci
ci
RD ¼
ð4Þ
ð5Þ
xi
where T and Tm are the experimental and melting temperature of com-
pound. λ and h are two adjustable parameters. The values of λ and h are
evaluated using experimental solubility data and are reported in
Table 5. Using these values of adjustable parameters, solubility (xbci) is
calculated using Eq. (3) and obtained values are listed in Table 2.
The calculated solubility values by Apelblat and Buchowski-
Ksiazczak (λh) models are also plotted against temperature in Figs. 2
to 5. It is observed that for all the compounds, there is good agreement
between experimental solubility values with those evaluated (xbci) by
Apelblat model. However, when experimental solubility is compared
with calculated values (xbci) by Buchowski-Ksiazczak (λh) model, for
some of the compounds, discrepancies are observed in some solvents.
This indicates that for some solvents, Buchowski-Ksiazczak model is
not suitable.
Comparison of solubility variation with temperature among differ-
ent compounds suggest that when solubility various linearly with tem-
perature, (xbci) values evaluated by Buchowski-Ksiazczak (λh) model
are in good agreement with experimental data but when variation of
solubility with temperature is non-linear, (xbci) deviates from experi-
mental values.
1
2
3
ꢆ
ꢇ
=
2
2
xaci=b−xexp
N
i¼1
6
4
7
5
RMSD ¼
∑
N−1
ꢆ
ꢇ
xexp−xa=b
N
X
1
N
ci
RAD ¼
ð6Þ
xexp
i
where xexp is experimental solubility and xa/bci is calculated solubility.
xa and xb are calculated solubility values from Apelblat and
ci
ci
Buchowski–Ksiazczak models. N is the number of experimental points.
The evaluated relative deviation (RD) values for both models are given
in Table 2 where sroot-mean-square deviations (RMSD) and relative av-
erage deviations (RAD) values are listed in Tables 5 and 6 for both
models.
It is evident from Table 2 that for some compounds, for some sol-
vents, RD values for Buchowski-Ksiazczak model are higher than that
evaluated for Apelblat model.

700
S. Baluja, A. Hirapara / Journal of Molecular Liquids 277 (2019) 692–704
Table 6
Some thermodynamic parameters, ΔGsol, ΔHsol and ΔSsol of dissolution of chalcone derivatives in the studied solvents.
Parameters
AH-1
AH-2
AH-3
AH-4
AH-5
AH-6
AH-7
AH-8
Methanol
ΔGsol
26.3 0.2
20.4 0.2
24.3 0.3
24.7 0.04
28.2 0.4
11.2 0.8
26.0 0.3
19.4 0.6
19.3 0.5
2.7 0.2
44.5 0.8
22.7 0.3
25.3 0.02
18.6 0.2
kJ·mol−1
ΔHsol
21.1 0.2
21.0 0.1
5.4 0.6
kJ·mol−1
ΔSsol
−18.8 0.2
−10.2 0.7
−21.0 0.2
−53.1 0.6
−73.4 0.7
−55.2 0.03
−21.3 0.6
J·mol−1
Ethanol
ΔGsol
23.5 0.8
22.0 0.1
−5.0 0.1
23.5 0.1
17.5 0.01
−19.2 0.1
23.2 0.2
14.5 0.4
−27.7 0.3
24.9 0.3
28.47 0.8
11.3 0.6
18.3 0.8
2.4 0.8
22.7 0.8
19.0 0.5
20.3 0.5
6.5 0.9
24.4 0.9
21.1 0.3
kJ·mol−1
ΔHsol
kJ·mol−1
ΔSsol
−50.8 0.4
−11.9 0.3
−43.9 0.8
−10.7 0.2
J·mol−1
1-propanol
ΔGsol
22.4 0.1
17.8 0.9
22.2 0.6
17.1 0.1
23.3 0.1
18.4 0.4
−15.5 0.8
22.6 0.2
15.0 0.1
17.7 0.3
3.1 0.9
22.1 0.5
11.8 0.9
19.7 0.7
6.7 0.3
22.4 0.7
20.8 0.2
−5.2 0.7
kJ·mol−1
ΔHsol
kJ·mol−1
ΔSsol
−14.4 0.6
−16.4 0.6
−24.3 0.6
−46.4 0.8
−32.8 0.001
−40.7 0.2
J·mol−1
1-butanol
ΔGsol
21.7 0.7
16.7 0.2
20.7 0.9
17.5 0.4
21.9 0.3
18.0 0.4
21.3 0.09
23.2 0.4
5.9 0.2
16.6 0.9
1.5 0.2
20.4 0.6
16.1 0.5
17.0 0.5
3.5 0.2
21.0 0.1
21.4 0.8
1.4 0.9
kJ·mol−1
ΔHsol
kJ·mol−1
ΔSsol
−16.1 0.5
−10.4 0.02
−12.4 0.04
−48.5 0.1
−13.7 0.7
−43.2 0.6
J·mol−1
1-pentanol
ΔGsol
20.6 0.6
21.6 0.02
3.0 0.3
20.0 0.8
24.3 0.6
13.6 0.6
20.7 0.4
15.2 0.8
−17.4 0.7
20.5 0.6
8.9 0.1
16.3 0.8
2.3 0.9
19.6 0.9
20.4 0.1
2.2 0.8
16.5 0.4
5.4 0.3
20.3 0.04
18.5 0.2
−5.7 0.2
kJ·mol−1
ΔHsol
kJ·mol−1
ΔSsol
−37.2 0.2
−44.7 0.1
−35.5 0.1
J·mol−1
Ethyl acetate
ΔGsol
21.1 0.5
11.1 0.9
21.1 0.9
29.4 0.5
26.3 0.8
20.5 0.2
20.0 0.4
−1.5 0.2
19.8 0.2
15.2 0.01
−14.7 0.7
16.7 0.4
3.8 0.9
17.7 0.04
18.7 0.8
3.4 0.5
18.3 0. 4
3.8 0.2
16.2 0.8
20.3 0.3
12.9 0.5
kJ·mol−1
ΔHsol
kJ·mol−1
ΔSsol
−31.8 0.3
−41.0 0.9
−46.4 0.02
J·mol−1
Acetonitrile
ΔGsol
24.9 0.7
38.7 0.5
44.0 0.6
24.3 0.01
22.7 0.8
−4.8 0.5
22.6 0.8
15.7 0.9
−22.0 0.1
22.6 0.2
18.8 0.6
18.2 0.8
8.0 0.5
23.8 0.2
64.2 0.3
129.1 0.9
21.6292
18.7256
−9.2814
22.6 0.8
20.7 0.7
kJ·mol−1
ΔHsol
kJ·mol−1
ΔSsol
−12.0 0.3
−32.6 0.9
−6.1 0.06
J·mol−1
Comparison of root-mean-square deviations (RMSD) and relative
average deviations (ARD) values for both models in Tables 4 and 5
again confirms that Apelblat model is better for all the compounds in
all the studied solvents whereas Buchowski-Ksiazczak model exhibited
discrepancies in some solvents for few compounds, the reason of which
is not clear.
entropy (ΔSsol) have been evaluated. The following modified Van't
Hoff equation [24] was used to calculate enthalpy of dissolution (ΔHsol):
0
1
∂ ln xexp
ΔHsol
R
@
A
ꢆ
ꢇ
¼ −
ð7Þ
1
1
Thm
∂
−
T
p
3.2. Thermodynamic parameters
where T is the experimental temperature, R is universal gas constant (=
8.314 J/mol K). Thm is mean harmonic temperature [25] which is calcu-
lated by the following equation:
The dissolution process in solid and liquid is a pseudo chemical reac-
tion [23]. From the energy point of view, the thermodynamic properties
of dissolution process are of great significance in the study of solution
structures. Thus, using experimental solubility data of compounds in
different solvents, some thermodynamics parameters such as dissolu-
tion enthalpy (ΔHsol), Gibb's free energy of dissolution (ΔGsol) and
n
ꢀ ꢁ
Thm
¼
ð8Þ
P
1
n
i¼1
T

S. Baluja, A. Hirapara / Journal of Molecular Liquids 277 (2019) 692–704
701
where n is the number of experimental temperatures studied. In the
present study, the value of Thm is 312.83 K.
solvents for all the compounds. This suggests that there is no obvious as-
sociation formed during dissolution process.
Using Eq. (7), dissolution enthalpy was evaluated from the slope of
the plot of ln xexp versus (1/T-1/Thm) for all the compounds in different
solvents. The Gibb's free energy of dissolution was calculated by the in-
tercept of these plots by the relation:
The contribution of enthalpy and entropy to standard Gibb's energy
of dissolution is also evaluated using the following equations [27]:
jΔHsol
j
%ξH
¼
:100
ð11Þ
jΔHsolj þ jT:ΔSsol
j
ΔGsol ¼ −R:Thm:Intercept
ð9Þ
The entropy of dissolution (ΔSsol) was evaluated by the following
equation [26]:
jT:ΔSsol
j
%ξS ¼
:100
ð12Þ
jΔHsolj þ jT:ΔSsol
j
ðΔHsol−ΔGsol
Þ
The ξH and ξTS represent the comparison of relative contribution to
the standard Gibbs energy by enthalpy and entropy towards the solu-
tion process, respectively. These values are listed in Table 7. The com-
parison of these evaluated contributions of enthalpy and entropy to
solubility does not give systematic order.
ΔSsol
¼
ð10Þ
Thm
All these thermodynamic parameters are given in Table 6. It is ob-
served that for all the compounds, enthalpy (ΔHsol) and Gibb's free en-
ergy of dissolution (ΔGsol) are positive. The entropy values are both
positive and negative for different compounds in different solvents.
The positive enthalpy (ΔHsol) indicates that dissolution of studied
compounds in selected solvents is endothermic process. As men-
tioned above, presence of different groups interact differently with
solvent molecules. However, these interactions are stronger than in-
tramolecular interactions of compounds. Thus, these powerful inter-
action between compounds and solvent molecules results in positive
enthalpy. The positive Gibb's free energy of dissolution (ΔGsol) sug-
gests spontaneous dissolution of compounds. The negative entropy
is due to more order in solutions whereas positive entropy suggests
more randomness in solution. Further, comparison of enthalpy of
different compounds shows that in all the studied solvents, AH-5 ex-
hibited minimum enthalpy whereas its solubility is maximum in all
the studied solvents. However, there is no systematic correlation be-
tween solubility and Gibb's free energy and entropy. Again, due to
different type and magnitude of interactions, thermodynamic pa-
rameters vary for different compounds due to different nature of
substitution groups.
Among alcohols, only for compounds AH-5, AH-7 and AH-6, solu-
bility is reverse of ξH. For other compounds, in both alcoholic and
non-alcoholic solvents, no regular trend is observed. However, in al-
most all the cases, the main contributor to standard Gibbs energy of
solution is enthalpy during the dissolution because the values of %ξH
are greater than 50%. The ξH and ξTS values are different for different
compounds in different solvents. It is observed that in alcohols, for all
the solvents, highest enthalpy of contribution is for AH-3 in metha-
nol, AH-1 in ethanol, AH-1 in 1‑propanol, AH-8 in 1‑butanol, AH-6
in 1‑pentanol, AH-3 in ethyl acetate and AH-2 in acetonitrile. How-
ever, entropy of contribution is higher for AH-5 in all the alcohols.
Further, comparison of these evaluated contributions of enthalpy
and entropy to electro negativity of substitutions (Table 1) does
not give any systematic order.
The net variation in enthalpy results from the contribution of several
kinds of interactions such as ion-dipole, vander Waals, Lewis acid-base
interactions etc. [28]. The synthesized compounds could act as Lewis
base in solutions due to the presence of free electron pairs on carbonyl
and secondary amine groups (Fig. 1). These compounds may form hy-
drogen bonding with proton acceptor groups present in the solvents.
Otherwise, these compounds could also act as Lewis acid because the
proton on its secondary group present on benzo [d] imidazole ring
may interact with the free electron pair of oxygen present in most of
the studied solvents [29]. Thus, more deep research is required to un-
derstand the possible mechanism involved in the dissolution of studied
compounds.
In Buchowski-Ksiazczak (λh) model, the parameter λ denotes the
average value of the associative amount of solute molecules in a solute
i.e., compound. Table 5 shows that values of λ are very small in studied
Table 7
The relative contribution by enthalpy and entropy derived from thermodynamic data.
Parameters
AH-1
AH-2
AH-3
AH-4
AH-5
AH-6
AH-7
AH-8
The apparent dissolution enthalpy ΔHsol can be derived from the
Gibbs-Helmholtz equation [30] and the modified Apelblat equation,
and then expressed as following equation
Methanol
%ξTS
%ξH
22.3
77.6
13.2
86.8
11.1
88.9
25.3
74.7
86.0
14.0
51.6
48.4
76.0
24.0
26.4
73.6
Ethanol
%ξTS
%ξH
ΔHsol ¼ Rð−B þ CTÞ
ð13Þ
6.6
93.4
25.6
74.4
37.4
62.6
11.1
88.91
86.5
13.5
16.4
83.6
67.6
32.4
13.7
86.3
1-propanol
%ξTS
%ξH
where B and C are parameters of modified Apelblat equation repre-
sented in Table 4, R is the universal gas constant (8.314 J·K−1·mol−1),
and T is the absolute temperature.
20.2
79.8
23.1
76.9
20.9
79.1
33.7
66.3
82.0
18.0
46.3
53.7
65.4
34.6
7.3
92.7
1-butanol
%ξTS
%ξH
The evaluated values are listed in Table 8. Comparison of enthalpy
values reported in Tables 6 and 8 shows that either of two equations
(Eqs. (7) and (13)) can be used for the evaluation of enthalpy. By
Eq. (7), only one value of enthalpy was evaluated from the slope of
the plot whereas by Eq. (13), at each temperature, enthalpy can be
calculated.
23.2
76.8
15.6
84.4
17.7
82.3
7.4
92.6
90. 9
9.1
21.1
78.9
79.3
20.7
2.1
97.9
1-pentanol
%ξTS
%ξH
4.2
95.2
14.9
85.1
26.4
73.6
56.7
43.3
85.4
14.6
3.4
96.6
67.2
32.8
8.8
91.2
Ethyl acetate
%ξTS
%ξH
The enthalpy of mixing is the enthalpy liberated or absorbed from a
substance upon mixing [31]. When a substance or compound is com-
bined with any other substance or compound the enthalpy of mixing
is the consequence of the new interactions between the two substances
or compounds. This enthalpy if released exothermically can in an ex-
treme case cause an explosion.
47.1
52.9
21.9
78.1
2.3
97.7
23.3
76.7
76.8
23.2
5.4
94.6
79.2
20.8
16.6
83.4
Acetonitrile
%ξTS
%ξH
26.2
73.8
6.2
93.8
30.4
69.6
16.6
83.3
56.0
44.0
38.6
61.4
13.4
86.6
8.4
91.6

702
S. Baluja, A. Hirapara / Journal of Molecular Liquids 277 (2019) 692–704
Table 8
The apparent molar dissolution derived from thermodynamics data using Eq. (13).
Temp (K)
Methanol
Ethanol
1‑propanol
1‑butanol
1‑pentanol
Ethyl acetate
Acetonitrile
ΔHsol / (kJ·mol−1
)
AH-1
298.15
303.15
308.15
313.15
318.15
323.15
328.15
22.5 0.2
21.7 0.2
21.0 0.7
20.3 0.5
19.6 0.3
18.9 0.1
18.1 0.9
30.9 0.6
27.8 0.2
24.7 0.9
21.7 0.1
18.6 0.2
15.5 0.3
12.4 0.5
22.5 0.9
20.9 0.8
19.3 0.5
17.7 0.3
16.1 0.1
14.4 0.9
12.8 0.7
16.6 0.9
16.7 0.04
16.7 0.1
16.7 0.3
16.7 0.4
16.7 0.5
16.7 0.6
30.7 0.5
27.6 0.06
24.4 0.5
21.2 0.9
18.1 0.3
14.9 0.8
11.8 0.3
8.9 0.8
9.7 0.4
60.6 0.3
53.0 0.8
45.5 0.5
38.0 0.1
30.4 0.7
22.9 0.3
15.3 0.9
10.5 0.002
11.2 0.6
12.0 0.2
12.7 0.9
13.5 0.5
AH-2
298.15
303.15
308.15
313.15
318.15
323.15
328.15
27.8 0.9
25.5 0.6
23.2 0.2
20.8 0.9
18.5 0.6
16.2 0.3
13.8 0.9
19.8 0.6
19.0 0.5
18.2 0.3
17.4 0.2
16.6 0.1
15.7 0.9
14.9 0.8
22.5 0.6
20.6 0.8
18.7 0.9
16.9 0.2
15.0 0.4
13.1 0.7
11.2 0.9
15.8 0.1
15.9 0.5
16.0 0.9
16.2 0.5
16.3 0.9
16.5 0.4
16.6 0.9
38.8 0.9
33.8 0.8
28.8 0.7
23.8 0.7
18.8 0.6
13.8 0.5
8.8 0.4
39.3 0.4
35.9 0.3
32.5 0.2
29.1 0.1
25.7 0.1
22.2 0.9
18.8 0.9
22.7 0.4
22.7 0.6
22.7 0.7
22.7 0.9
22.8 0.1
22.8 0.2
22.8 0.3
AH-3
298.15
303.15
308.15
313.15
318.15
323.15
328.15
41.5 0.6
36.9 0.7
32.3 0.7
27.7 0.8
23.1 0.9
18.5 0.9
14.0 0.01
14.5 0.2
14.5 0.3
14.5 0.3
14.5 0.4
14.5 0.5
14.5 0.5
14.5 0.6
32.0 0.1
27.3 0.3
22.6 0.6
17.9 0.8
13.3 0.01
8.6 0.2
23.7 0.7
21.7 0.9
19.8 0.2
17.8 0.5
15.8 0.7
13.9 0.0
11.9 0.3
19.1 0.02
17.7 0.8
16.4 0.6
15.1 0.5
13.8 0.3
12.5 0.1
11.1 0.9
21.7 0.9
21.1 0.9
20.5 0.8
19.9 0.8
19.3 0.8
18.7 0.8
18.1 0.7
22.0 0.9
19.9 0.3
17.7 0.6
15.5 0.9
13.4 0.2
11.2 0.5
9.0 0.8
3.9 0.4
AH-4
298.15
303.15
308.15
313.15
318.15
323.15
328.15
21.9 0.2
21.0 0.1
20.2 0.2
19.3 0.7
18.5 0.2
17.6 0.8
16.8 0.3
34.7 0.6
32.5 0.9
30.4 0.3
28.2 0.7
26.1 0.001
23.9 0.3
21.7 0.6
14.9 0.9
14.9 0.9
15.0 0.03
15.0 0.1
15.0 0.1
15.0 0.1
15.0 0.2
34.2 0.01
30.4 0.2
26.6 0.5
22.8 0.7
19.0 0.9
15.3 0.1
11.5 0.3
10.8 0.6
10.1 0.8
9.5 0.1
8.8 0.4
8.1 0.7
7.4 0.9
6.8 0.3
20.1 0.8
18.4 0.7
16.7 0.5
15.0 0.2
13.3 0.1
11.5 0.9
9.8 0.7
22.7 0.8
21.4 0.3
20.0 0.8
18.7 0.3
17.3 0.7
16.0 0.2
14.6 0.7
AH-5
298.15
303.15
308.15
313.15
318.15
323.15
328.15
2.7 0.4
2.7 0.3
2.7 0.2
2.7 0.2
2.7 0.1
2.7 0.01
2.6 0.9
2.4 0.9
2.4 0.9
2.4 0.8
2.4 0.8
2.4 0.7
2.4 0.6
2.4 0.5
3.1 0.9
3.1 0.9
3.1 0.8
3.1 0.8
3.1 0.8
3.1 0.7
3.1 0.7
1.5 0.4
1.5 0.3
1.5 0.3
1.5 0.2
1.5 0.1
1.5 0.1
1.5 0.04
2.4 0.1
2.4 0.1
2.4 0.1
2.3 0.9
2.3 0.9
2.3 0.9
2.3 0.8
3.8 0.9
3.8 0.9
3.8 0.9
3.8 0.9
3.8 0.9
3.8 0.8
3.8 0.8
8.0 0.4
8.0 0.5
8.0 0.5
8.0 0.5
8.0 0.5
8.0 0.5
8.0 0.5
AH-6
298.15
303.15
308.15
313.15
318.15
323.15
328.15
29.0 0.3
26.4 0.7
23.9 0.1
21.3 0.4
18.7 0.8
16.2 0.2
13.6 0.6
24.2 0.04
22.4 0.3
20.6 0.5
18.8 0.7
17.0 0.9
15.3 0.2
13.5 0.4
9.7 0.8
10.5 0.1
11.2 0.3
11.9 0.6
12.6 0.9
13.4 0.2
14.1 0.4
17.8 0.3
17.2 0.5
16.6 0.7
16.0 0.9
15.5 0.2
14.9 0.5
14.3 0.7
18.5 0.7
19.2 0.1
19.8 0.4
20.4 0.7
21.1 0.1
21.7 0.4
22.3 0.7
26.8 0.3
24.0 0.5
21.2 0.8
18.5 0.1
15.7 0.4
12.9 0.9
10.1 0.9
143.1 0.2
115.9 0.1
88.7 0.02
61.4 0.9
34.2 0.8
7.0 0.8
−20.1 0.2
AH-7
298.15
303.15
308.15
313.15
318.15
323.15
328.15
5.4 0.5
5.4 0.5
5.4 0.4
5.4 0.3
5.4 0.4
5.4 0.2
5.4 0.1
6.5 0.9
6.5 0.9
6.5 0.9
6.5 0.8
6.5 0.8
6.5 0.8
6.5 0.7
6.7 0.4
6.7 0.4
6.7 0.4
6.7 0.3
6.7 0.3
6.7 0.3
6.7 0.2
3.5 0.3
3.5 0.3
3.5 0.3
3.5 0.2
3.5 0.2
3.5 0.2
3.5 0.1
5.4 0.3
5.4 0.3
5.4 0.3
5.4 0.3
5.4 0.3
5.4 0.3
5.4 0.3
3.8 0.3
3.8 0.3
3.8 0.3
3.8 0.2
3.8 0.2
3.8 0.1
3.8 0.1
25.2 0.7
23.0 0.1
20.7 0.6
18.5 0.03
16.2 0.05
13.9 0.9
11.7 0.3
AH-8
298.15
303.15
308.15
313.15
318.15
323.15
328.15
23.3 0.3
21.7 0.1
20.0 0.8
18.4 0.5
16.8 0.3
15.2 0.06
13.5 0.8
19.0 0.7
19.7 0.8
20.4 0.9
21.2 0.05
21.9 0.2
22.6 0.3
23.3 0.2
27.8 0.8
25.4 0.5
23.0 0.1
20.5 0.8
18.1 0.4
15.7 0.1
13.2 0.8
26.4 0.4
24.7 0.3
23.0 0.2
21.3 0.1
19.6 0.01
17.8 0.9
16.1 0.8
22.2 0.2
20.9 0.5
19.6 0.7
18.3 0.9
17.1 0.1
15.8 0.3
14.5 0.6
25.2 0.7
23.0 0.1
20.7 0.6
18.5 0.03
16.2 0.5
13.9 0.9
11.7 0.3
28.2 0.3
26.0 0.8
23.9 0.4
21.8 0.03
19.6 0.6
17.5 0.2
15.3 0.7

S. Baluja, A. Hirapara / Journal of Molecular Liquids 277 (2019) 692–704
703
Table 9
The excess of enthalpy derived from thermodynamics data using Eq. (14).
Temp(K)
E / (kJ·mol−1
Methanol
Ethanol
1‑propanol
1‑butanol
1‑pentanol
Ethyl acetate
Acetonitrile
H
)
AH-1
298.15
303.15
308.15
313.15
318.15
323.15
328.15
1.1 0.3
1.2 0.5
1.3 0.7
1.5 0.1
1.6 0.4
1.7 0.8
1.9 0.6
0.9 0.8
1.0 0.8
1.2 0.5
1.3 0.7
1.4 0.9
1.5 0.9
1.7 0.3
1.3 0.5
1.4 0.9
1.6 0.5
1.81 0.2
1.9 0.6
2.1 0.5
2.2 0.5
9.6 0.7
10.5 0.03
11.9 0.3
12.9 0.3
14.4 0.8
15.9 0.5
17.3 0.7
1.0 0.2
1.1 0.5
1.2 0.5
1.4 0.4
1.5 0.6
1.6 0.5
1.7 0.6
1.0 0.6
1.0 0.9
1.1 0.5
1. 0.9
1.2 0.6
1.3 0.2
1.3 0.9
0.6 0.2
0.7 0.2
0.8 0.5
0.9 0.8
1.1 0.001
1.2 0.4
1.3 0.3
AH-2
298.15
303.15
308.15
313.15
318.15
323.15
328.15
0.5 0.01
0.5 0.8
0.7 0.07
0.7 0.7
0.8 0.5
0.9 0.8
1.0 0.4
0.7 0.9
0.8 0.8
0.9 0.8
1.1 0.2
1.2 0.2
1.3 0.2
1.4 0.3
0.8 0.2
0.9 0.1
1.0 0.5
1.1 0.1
1.2 0.6
1.3 0.1
1.4 0.7
6.2 0.2
6.8 0.9
7.4 0.9
8.3 0.9
9.3 0.6
10.6 0.2
11.6 0.2
0.3 0.4
0.4 0.2
0.4 0.9
0.5 0.7
0.6 0.3
0.6 0.9
0.7 0.3
0.2 0.1
0.2 0.4
0.2 0.8
0.3 0.4
0.3 0.8
0.4 0.1
0.4 0.6
0.5 0.3
0.5 0.9
0.6 0.9
0.8 0.2
0.8 0.9
1.0 0.3
1.1 0.3
AH-3
298.15
303.15
308.15
313.15
318.15
323.15
328.15
0.1 0.8
0.2 0.3
0.3 0.008
0.3 0.5
0.4 0.1
0.4 0.6
0.5 0.1
1.0 0.6
1.1 0.8
1.2 0.6
1.3 0.9
1.5 0.5
1.6 0.2
1.8 0.01
0.7 0.9
0.9 0.8
1.1 0.5
1.2 0.5
1.4 0.2
1.4 0.9
1.5 0.8
5.5 0.5
6.4 0.5
7.4 0.4
7.9 0.6
8.8 0.6
9.5 0.3
10.9 0.001
0.9 0.6
1.0 0.4
1.1 0.4
1.3 0.4
1.4 0.6
1.5 0.9
1.6 0.6
0.5 0.5
0.6 0.2
0.6 0.9
0.8 0.1
0.9 0.1
1.0 0.1
1.1 0.07
0.8 0.8
1.0 0.2
1.1 0.6
1.2 0.9
1.3 0.8
1.4 0.6
1.5 0.9
AH-4
298.15
303.15
308.15
313.15
318.15
323.15
328.15
0.8 0.5
0.9 0.7
1.0 0.6
1.1 0.5
1.2 0.6
1.3 0.6
1.5 0.8
0.4 0.1
0.4 0.6
0.5 0.1
0.5 0.7
0.6 0.4
0.7 0.2
0.7 0.7
1.3 0.2
1.4 0.5
1.5 0.4
1.6 0.9
1.8 0.5
1.9 0.8
2.1 0.5
3.3 0.5
4.3 0.2
5.0 0.2
5.7 0.1
6.5 0.1
7.0 0.8
7.8 0.7
1.3 0.1
1.3 0.8
1.4 0.7
1.5 0.5
1.6 0.2
1.6 0.8
1.7 0.4
1.2 0.6
1.4 0.6
1.5 0.9
1.7 0.4
1.8 0.4
1.9 0.5
2.0 0.6
0.9 0.01
1.0 0.3
1.1 0.3
1.2 0.4
1.3 0.6
1.4 0.9
1.6 0.1
AH-5
298.15
303.15
308.15
313.15
318.15
323.15
328.15
1.7 0.4
1.7 0.6
1.7 0.9
1.8 0.3
1.8 0.5
1.8 0.8
1.9 0.2
1.6 0.5
1.6 0.7
1.6 0.9
1.7 0.2
1.7 0.5
1.7 0.7
1.7 0.9
1.8 0.7
1.9 0.005
1.9 0.3
1.9 0.6
2.0 0.01
2.0 0.5
2.0 0.9
9.6 0.1
9.7 0.2
9.8 0.2
10.0 0.1
10.0 0.1
10.0 0.4
10.1 0.7
1.6 0.4
1.6 0.6
1.6 0.8
1.7 0.1
1.7 0.3
1.7 0.5
1.7 0.8
1.9 0.9
2.0 0.3
2.0 0.8
2.1 0.3
2.1 0.8
2.2 0.3
2.2 0.7
1.8 0.7
1.9 0.9
2.1 0.2
2.1 0.9
2.3 0.2
2.3 0.8
2.4 0.8
AH-6
298.15
303.15
308.15
313.15
318.15
323.15
328.15
0.4 0.6
0.5 0.7
0.6 0.4
0.7 0.1
0.7 0.9
0.8 0.8
0.9 0.7
0.6 0.3
0.7 0.4
0.8 0.4
0.9 0.2
1.0 0.2
1.1 0.2
1.2 0.3
1.4 0.4
1.5 0.3
1.6 0.3
1.7 0.6
1.8 0.9
2.0 0.3
2.1 0.9
7.0 0.6
7.8 0.5
8.7 0.3
9.9 0.4
10.6 0.5
11.6 0.3
12.7 0.6
0.5 0.6
0.6 0.3
0.6 0.9
0.7 0.8
0.8 0.9
1.0 0.08
1.1 0.08
0.6 0.4
0.7 0.8
0.8 0.7
0.9 0.6
1.0 0.7
1.1 0.5
1.2 0.4
0.0 0.7
0.0 0.7
0.0 0.7
0.0 0.7
0.0 0.7
0.0 0.7
0.0 0.7
AH-7
298.15
303.15
308.15
313.15
318.15
323.15
328.15
2.0 0.9
2.1 0.4
2.2 0.3
2.3 0.0
2.3 0.9
2.4 0.4
2.5 0.4
1.9 0.9
2.1 0.07
2.1 0.8
2.2 0.9
2.3 0.8
2.4 0.4
2.5 0.7
5.4 0.3
5.5 0.3
5.6 0.4
5.7 0.9
5.9 0.3
6.0 0.8
6.1 0.6
15.6 0.3
15.9 0.2
16.2 0.2
16.6 0.6
17.0 0.5
17.4 0.8
17.7 0.3
2.0 0.7
2.1 0.5
2.2 0.3
2.3 0.02
2.3 0.7
2.4 0.5
2.5 0.2
1.9 0.6
2.0 0.02
2.0 0.5
2.1 0.03
2.1 0.5
2.2 0.03
2.2 0.6
0.6 0.6
0.7 0.9
0.8 0.9
0.9 0.9
1.1 0.09
1.1 0.8
1.2 0.9
AH-8
298.15
303.15
308.15
313.15
318.15
323.15
328.15
0.8 0.3
0.9 0.8
1.0 0.9
1.1 0.6
1.2 0.8
1.4 0.3
1.5 0.7
0.6 0.7
0.7 0.4
0.8 0.2
0.9 0.6
1.0 0.6
1.1 0.4
1.3 0.1
0.6 0.6
0.7 0.6
0.8 0.9
0.9 0.5
1.0 0.9
1.1 0.9
1.3 0.02
4.3 0.4
5.0 0.3
5.9 0.3
6.8 0.8
7.6 0.07
8.5 0.8
9.3 0.9
0.8 0.5
0.9 0.7
1.0 0.8
1.2 0.3
1.3 0.1
1.4 0.6
1.5 0.7
0.7 0.2
0.8 0.06
0.9 0.03
1.0 0.1
1.1 0.1
1.2 0.4
1.3 0.9
0.5 0.9
0.6 0.8
0.7 0.9
0.8 0.6
0.9 0.8
1.1 0.03
1.1 0.8

704
S. Baluja, A. Hirapara / Journal of Molecular Liquids 277 (2019) 692–704
[6] C. McGuigan, T.J. O'Oonnor, R. Nicholls, C. Nickson, D. Klnchlnqton, Synthesis and
3.3. Excess enthalpy of solutions
anti-HIV activity of some novel substituted dialkyl phosphate derivatives of AZT
and dd Cyd, Antivir. Chem. Chemother. 6 (1990) 355–360.
[7] K.V. Sashidhara, S.R. Avula, V. Mishra, G.R. Palnati, L.R. Singh, N. Singh, Y.S. Chhonker,
P. Swami, R.S. Bhatta, G. Palit, Identification of quinoline-chalcone hybrids as poten-
tial antiulcer agents, Eur. J. Med. Chem. 89 (2015) 638–653.
[8] A. Kamal, G. Ramakrishna, P. Raju, A. Viswanath, M.J. Ramaiah, G. Balakishan, M. Pal-
Bhadra, Synthesis and anti-cancer activity of chalcone linked imidazolones, Bioorg.
Med. Chem. Lett. 20 (2010) 4865–4869.
The excess enthalpy (HE) of solution can provide a more detail infor-
mation on understanding the behaviour of a solution. This excess en-
thalpy (HE) of solution can be evaluated by experimental solubility
data and λ parameter of Buchowski-Ksiazczak λh model using the fol-
lowing equation [32]:
[9] C.A. Lipinski, F. Lombardo, B.W. Dominy, P.J. Feeney, Experimental and computa-
tional approaches to estimate solubility and permeability in drug discovery and de-
velopment settings, Adv. Drug Deliv. Rev. 64 (2012) 4–17.
[10] A. Chaudhary, U. Nagaich, N. Gulati, V.K. Sharma, R.L. Khosa, Enhancement of solubi-
lization and bioavailability of poorly soluble drugs by physical and chemical modifi-
cations: a recent review, J. Adv. Pharm. Educ. Res. 2 (2012) 32–67.
[11] S.M. Honmane, Y.D. Dange, R. Ali, M. smani, D.R. Jadge, General considerations of de-
sign and development of dosage forms: pre-formulation review, Asian J. Pharm. 11
(2017) 479–488.
.
HE
hR ¼ ΔfusH þ
ð14Þ
xexp
where ΔfusH is the fusion of enthalpy of compounds, xexp is the solubility
data in mole fraction of in solvents and R is gas constant. h refers the pa-
rameter in the Buchowski-Ksiazczak λh model.
[12] Y.V. Yushkova, E.I. Chernyak, Y.V. Gatilov, V.G. Vasil'ev, S.V. Morozov, I.A. Grigor'ev,
Synthesis, structure, antioxidant activity, and water solubility of trolox ion conju-
gates, Saudi, Pharm. J. 26 (2018) 84–92.
[13] S. Akay, B. Kayan, Y. Yang, Solubility and chromatographic separation of 5-
fluorouracil under subcritical water conditions, J. Chem. Eng. Data 62 (2017)
1538–1543.
[14] A.R. Holguín, D.R. Delgado, F. Martínez, Thermodynamic study of the solubility of
triclocarban in ethanol + propylene glycol mixtures, Quim Nova 35 (2012)
280–285.
[15] F.L. Mota, A.P. Carneiro, A.J. Queimada, S.P. Pinho, E.A. Macedo, Temperature and sol-
vent effects in the solubility of some pharmaceutical compounds: measurements
and modeling, Eur. J. Pharm. Sci. 37 (2009) 499–507.
The calculated HE values for all the compounds are listed in Table 9
for the studied solvents in different temperatures. It is observed that
table that HE is positive which increases with increase in temperature.
This may be due to contribution of several interactions in the solution.
The cavity formation at compounds dissolution requires the absorption
of heat to overcome the interactions between the solvents. The intermo-
lecular interactions between compound and solvent molecules are
again proved by the positive enthalpy. Therefore, the dissolution of
studied compounds needs to absorb energy, so dissolution of com-
pounds is endothermic [33].
[16] A.V. Yadav, V.B. Yadav, Preparation and evaluation of polymeric carbama zepin
spherical crystals by emulsion solvent diffusion technique, Asian J. Pharm. 3
(2009) 18–25.
[17] R. Ferrer, G. Lobo, N. Gamboa, J. Rodrigues, C. Abramjuk, K. Jung, M. Lein, J.E. Charris,
Synthesis of [(7‑Chloroquinolin‑4‑yl)amino]chalcones: potential anti-malarial and
anticancer agents, Sci. Pharm. 77 (2009) 725–741.
[18] R. Abonia, D. Insuasty, J. Castillo, B. Insuasty, J. Quiroga, M. Nogueras, J. Cobo, Synthe-
sis of novel quinoline-2-one based chalcones of potential anti-tumor activity, Eur. J.
Med. Chem. 57 (2012) 29–40.
[19] J.A. Riddick, W.B. Bunger, T. Sakano, J. Wiley, Organic solvents: Physical Properties
and Methods of Purification, Fourth edition, 1986 109 (New York).
[20] J. Wang, A. Xu, R. Xu, Solubility of 2‑nitro‑p‑phenylenediamine in nine pure solvents
and mixture of (methanol + N‑methyl‑2‑pyrrolidone) from T = (283.15 to 318.15)
K: determination and modelling, J. Chem. Thermodyn. 108 (2017) 45–48.
[21] A. Apelblat, E. Manzurola, Solubility of oxalic, malonic, succinic, adipic, maleic, malic,
citric, and tartaric acids in water from 278.15 to 338.15 K, J. Chem. Thermodyn. 19
(1987) 317–320.
4. Conclusions
The solubility of studied compounds is found to increases with in-
crease in temperature. The agreement between experimental solubility
data with those evaluated by modified Apelblat and Buchowski–
Ksiazczak models is satisfactory. The positive enthalpy and Gibb's free
energy of dissolution suggest endothermic and spontaneous dissolution
of compounds in all the studied solvents respectively. In all the solvents
except 1-butanol, entropy values are found to be negative for the stud-
ied compounds, suggesting thereby more ordered structure in solutions.
[22] H. Buchowski, A. Ksiazczak, S. Pietrzyk, Solvent activity along a saturation line and
solubility of hydrogen-bonding solids, J. Phys. Chem. 84 (1980) 975–979.
[23] F. Wang, Y. Jang, Molecular Thermodynamics and Chromatography Reaction,
Metereology Press, Beijing, 2001.
[24] M. Gantiva, F. Martinez, Thermodynamic analysis of the solubility of ketoprofen in
some propylene glycol + water cosolvent mixtures, Fluid Phase Equilib. 293
(2010) 242–250.
Acknowledgments
Authors are thankful to Department of Chemistry, Saurashtra
University-Rajkot for providing research facilities also NFDD, Rajkot
for providing the spectra of compounds.
[25] R.R. Krug, W.G. Hunter, R.A. Grieger, Enthalpy-entropy compensation. Separation of
the chemical from the statistical effects, J. Phys. Chem. 80 (1976) 2341–2351.
[26] S.P. Bustamante, A.P. Romero, B. Escalera, A. Reillo, Nonlinear enthalpyentropy com-
pensation for the solubility of drugs in solvent mixtures:paracetamol, acetanilide
and nalidixic acid in dioxane-water, J. Pharm. Sci. 87 (1998) 1590–1596.
[27] A.R. Holguin, G.A. Rodriguez, D.M. Cristancho, D.R. Delgado, F. Martinez, Solution
thermodynamics of indomethacin in propylene glycol + water mixture, Fluid
Phase Equilib. 314 (2012) 134–139.
[28] D.R. Delgado, R.G. Sotomayor, D.R. Monterroza, C.P. Mora, E.F. Vargar, F. Martinez,
Thermodynamics of mixing of sodium naproxen and procaine hydrochloride in
ethanol + water co-solvent mixtures, Rev. Colomb. Cienc. Quim. Farm. 39 (2010)
132–148.
Appendix A. Supplementary data
Supplementary data to this article can be found online at https://doi.
org/10.1016/j.molliq.2018.12.081.
References
[1] P. Venkatesan, T. Maruthavanan, Piperidine-mediated synthesis of thiazolyl
chalcones and their derivatives as potent antimicrobial agents, J. Heterocyclic
Chem. 48 (2011) 1181–1186.
[2] M. Pandya, K. Kapdiya, C. Pandit, D. Purohit, Synthesis of halogenated chalcones,
pyrazolines and microbial evaluation of derived scaffolds, J. Sci. Ind. Res. 76
(2017) 173–178.
[29] M. Abbasi, F. Martinez, A. Jouybanm, Prediction of deferiprone solubility in aqueous
mixtures of ethylene glycol, propylene glycol and polyethylene glycol 400 at various
temperatures, J. Mol. Liq. 197 (2014) 171–175.
[30] D.A. McQuarrie, J.P. Chemistry, A Molecular Approch, University Science Book, USA,
[3] B.M. Sahoo, M. Rajeswari, P. Jnyanaranjan, S. Binayani, Green expedient synthesis of
pyrimidine derivatives via chalcones and evaluation of their anthelmintic activity,
Indian J. Pharm. Educ. Res. 51 (2017) S700–S706.
[4] H. Rücker, N. Al-Rifai, A. Rascle, E. Gottfried, L. Brodziak-Jarosz, C. Gerhäuser, T.P.
Dick, S. Amslinger, Enhancing the anti-inflammatory activity of chalcones by tuning
the Michael acceptor site, Org. Biomol. Chem. 14 (2015) 3040–3047.
[5] C. Díaz-tielas, E. Graña, M.J. Reigosa, A.M. Sánchez-Moreiras, Biological activities and
novel applications of chalcones, Planta Daninha 34 (2016) 607–616.
1997.
[31] Phillip Carlson, Hazardous Chemicals Handbook, 2nd edition Elsevier, 2002 52.
[32] Y. Xie, H. Shi, C. Du, Y. Cong, H. Zhao, Modeling of solubility of 1, 5-dinitro-
naphthaline in eight organic solvents from T = (272.15 to 313.15) K and dissolution
properties, J. Mol. Liq. 221 (2016) 1054–1062.
[33] K. Ray Sinnot, Chemical Engineering Design– SI Edition, 5th edition Elsevier, 2009
95.