Measurement and Correlation of the Solubility,Dissolution Enthalpy,and Entropy of R-2[4-(6-Chloro-2-benzoxazolyloxy)phenoxy]propanoic Acid in Different Pure Solvents

Russian Journal of Physical Chemistry A - The solubility of R-2[4-(6-chloro-2-benzoxazolyloxy)phenoxy]propanoic acid (abbreviated as Fenoxaprop-P) in acetone, methyl ethyl ketone (MEK),...     

Solubility and Dissolution Properties of Zaltoprofen in Alcohol,Acid, and Ester Solvents at Atmospheric Pressure and Different Temperatures

Russian Journal of Physical Chemistry A - In this paper, by the polythermal method, the solubility values of zaltoprofen in alcohols, carboxylic acid, and esters were evaluated from 278.15 to...     

Enthalpy of Solution of Terfenadine in Different Solvents

Enthalpies of solution of various terfenadine samples in methanol and in ethanol were measured. Samples were prepared by crystallization in different solvents. The calorimetric results give important information on crystal structure of the terfenadine forms and on the solute/solvent interactions of this compound with the solvents.This revised version was published online in November 2005 with corrections to the Cover Date.     

Formation Enthalpy and Entropy of Exciplexes with Variable Extent of Charge Transfer in Solvents of Different Polarity

Temperature dependence was studied for relative quantum yields of emission from some exciplexes of pyrene, 1,12-benzoperylene, and 9-cyanoanthracene with methoxybenzenes or methylnaphthalenes in solvents of different polarity (ranging from toluene to acetonitrile). The enthalpy H _Ex ^*, the entropy S _Ex ^*, and the Gibbs free energy G _Ex ^*of formation of the exciplexes were determined. Depending of the Gibbs free energy of excited-state electron transfer (G _et ^*) and solvent polarity, the values of H _Ex ^*, S _Ex ^*, and G _Ex ^*vary over the ranges from –5 to –40 kJ mol^–1, from +3 to –90 J mol^–1K^–1, and from +3 to –21 kJ mol^–1, respectively. The possibility is discussed that the effect of solvent polarity G _et ^*on the exciplex formation enthalpies can be rationalized in terms of the model of correlated polarization of an exciplex and the medium.     

Enthalpy and Entropy Changes by Formation of Different Types of Complexes

The different types of bonding in complexes formed in aqueous solution are clearly reflected in the values of ΔH⁰ and ΔS⁰ for the complex formation reaction.     

Thermodynamic Solubility Profile of Temozolomide in Different Commonly Used Pharmaceutical Solvents

The solubility parameters, and solution thermodynamics of temozolomide (TMZ) in 10 frequently used solvents were examined at five different temperatures. The maximum mole fraction solubility of TMZ was ascertained in dimethyl sulfoxide (1.35 × 10⁻²), followed by that in polyethylene glycol-400 (3.32 × 10⁻³) > Transcutol^® (2.89 × 10⁻³) > ethylene glycol (1.64 × 10⁻³) > propylene glycol (1.47 × 10⁻³) > H₂O (7.70 × 10⁻⁴) > ethyl acetate (5.44 × 10⁻⁴) > ethanol (1.80 × 10⁻⁴) > isopropyl alcohol (1.32 × 10⁻⁴) > 1-butanol (1.07 × 10⁻⁴) at 323.2 K. An analogous pattern was also observed for the other investigated temperatures. The quantitated TMZ solubility values were regressed using Apelblat and Van’t Hoff models and showed overall deviances of 0.96% and 1.33%, respectively. Apparent thermodynamic analysis indicated endothermic, spontaneous, and entropy-driven dissolution of TMZ in all solvents. TMZ solubility data may help to formulate dosage forms, recrystallize, purify, and extract/separate TMZ.     

Spectrophotometric Determination of Phenylenediamines in Different Solvents

Absorption spectra of isomeric phenylenediamines (1,2-phenylenediamine, 1,3-phenylenediamine, and 1,4-phenylenediamine) in ten organic solvents were studied. A hypsochromic shift (toward shorter wavelengths) was observed in the spectra when the polarity of the solvent increased. Procedures for determining phenylenediamines in some solvents were developed and compared to procedures based on the formation of azo compounds.     

Determination and Correlation of the Solubility of Acetylpyrazine in Pure Solvents and Binary Solvent Mixtures

The solubilities of acetylpyrazine in seven pure solvents and one binary solvent mixture were determined by a dynamic analytic method at temperatures ranging from 268.15 to 308.15 K under atmospheric pressure. For pure solvents, the solubility of acetylpyrazine increases with increasing temperature and solvent polarity. For the binary solvent mixture of ethyl acetate and isopropanol, the solubility increases with increasing temperature and mole fraction of ethyl acetate. The solubility data were correlated with some thermodynamic models, including the modified Apelblat model, λh model, CNIBS/R-K model, and NRTL model. In addition, the relationship between solubility and solvent polarity was investigated by using the Arrhenius equation. All the models or equations gave satisfactory correlation results. The results showed that the solubility of acetylpyrazine generally rises with the increase of solvent polarity at the same temperature. Moreover, the dissolution thermodynamic properties of acetylpyrazine in different solvents were calculated and are discussed based on the NRTL model.     

Solubility and Thermodynamic Data of Febuxostat in Various Mono Solvents at Different Temperatures

This study examines the solubility and thermodynamics of febuxostat (FBX) in a variety of mono solvents, including “water, methanol (MeOH), ethanol (EtOH), isopropanol (IPA), 1-butanol (1-BuOH), 2-butanol (2-BuOH), ethylene glycol (EG), propylene glycol (PG), polyethylene glycol-400 (PEG-400), ethyl acetate (EA), Transcutol-HP (THP), and dimethyl sulfoxide (DMSO)” at 298.2–318.2 K and 101.1 kPa. The solubility of FBX was determined using a shake flask method and correlated with “van’t Hoff, Buchowski-Ksiazczak λh, and Apelblat models”. The overall error values for van’t Hoff, Buchowski-Ksiazczak λh, and Apelblat models was recorded to be 1.60, 2.86, and 1.14%, respectively. The maximum mole fraction solubility of FBX was 3.06 × 10⁻² in PEG-400 at 318.2 K, however the least one was 1.97 × 10⁻⁷ in water at 298.2 K. The FBX solubility increased with temperature and the order followed in different mono solvents was PEG-400 (3.06 × 10⁻²) > THP (1.70 × 10⁻²) > 2-BuOH (1.38 × 10⁻²) > 1-BuOH (1.37 × 10⁻²) > IPA (1.10 × 10⁻²) > EtOH (8.37 × 10⁻³) > EA (8.31 × 10⁻³) > DMSO (7.35 × 10⁻³) > MeOH (3.26 × 10⁻³) > PG (1.88 × 10⁻³) > EG (1.31 × 10⁻³) > water (1.14 × 10⁻⁶) at 318.2 K. Compared to the other combinations of FBX and mono solvents, FBX-PEG-400 had the strongest solute-solvent interactions. The apparent thermodynamic analysis revealed that FBX dissolution was “endothermic and entropy-driven” in all mono solvents investigated. Based on these findings, PEG-400 appears to be the optimal co-solvent for FBX solubility.     

顶空-气相色谱法测定盐酸贝尼地平中4种溶剂残留量

盐酸贝尼地平化学名为(4RS)-2,6-二甲基-4-(3-硝基苯基)-1,4-二氢-3,5-吡啶二甲酸-3-[(3RS)-1-苯甲基-3-哌啶基]酯-5-甲酯盐酸盐。盐酸贝尼地平是日本协和发酵工业公司在70年代后期为改善硝苯地平副作用而合成、筛选得到的一种新型持续性钙拮抗剂[1-2]。     

三聚氰胺的生成焓、热容和熵

通过多种热化学方法研究了三聚氰胺的热力学性质. 首先用氧弹式燃烧热量计测定了三聚氰胺在298.15 K 时的燃烧热, 根据燃烧热结果, 计算出三聚氰胺的标准摩尔燃烧焓和标准摩尔生成焓, 分别为: △cHΘm=(-2455.17±4.65) kJ·mol-1; △fHΘm =(-763.38±5.16) kJ·mol-1. 然后根据键焓与燃烧焓之间的关系, 估算出三聚氰胺中的C≈N(此键介于单键与双键之间)键能为458.30 kJ·mol-1, 此值介于碳氮单键键能和双键键能之间. 通过绝热热量计测定了三聚氰胺从80到385 K的低温热容. 根据热容值, 计算了此温度区间的标准摩尔生成焓, 其与温度呈线性关系. 另外, 三聚氰胺的热稳定性也用热重-差示扫描量热(TG-DSC)法进行了分析, 确定其分解的DSC曲线的峰顶温度为603.37 K.     

Solubility Measurements of Surfactants and Dissolution of Cytochrome c in 1,1,1,2‐Tetrafluoroethane Modified with Organic Solvents

The solubilities of four surfactants, sodium bis‐2‐ethylhexyl sulfosuccinate (AOT), cetyltrimethylammonium chloride, didodecyldimethylammonium bromide, and n‐dodecyltrimethylammonium chloride in liquid refrigerant 1,1,1,2‐tetrafluoroethane (R134a) modified with methanol, ethanol, and 2‐propanol were measured. The measurements were performed under 25 and 50 bar at 25 °C. The solubility of AOT was as high as 92 mM in R134a with addition of 2% ethanol. Cytochrome c molecules were then verified to be soluble in the AOT‐containing and ethanol‐modified R134a solution. Accordingly, liquid R134a is suggested as a potential extraction solvent for hydrophilic compounds.     

毛细管柱气相色谱法测定盐酸特比萘芬中残留溶剂

应用HP-5毛细管柱(25 m×0.32 mm,0.25 μm)气相色谱法测定了盐酸特比萘芬药物中乙醚、异丙醇、乙酸乙酯、三氯甲烷、四氢呋喃、甲苯、二甲基甲酰胺等6种残留溶剂.经烘干的试样溶于二甲替甲酰胺(DMF)中,试样溶液中的残留溶剂经毛细管柱分离后,以苯为内标物,内标法定量测定.6种残留溶剂具有良好的分离效果,整体回收率在92.7%～101.0%之间,相对标准偏差(n=6)在1.5%～2.8%之间,6种残留溶剂检出限(S/N=3)依次为1.5,2.8,2.5,12.0,1.7,1.6 mg·L-1.     

Solubility of Adipic Acid in Organic Solvents and Water

The solubility of adipic acid in methanol, ethanol, propanol, isopropanol, n-butanol, tert-butanol, acetone, 1,4-dioxane, acetic acid, and water was measured within the 0–60°C temperature range. A sampler for determination of the temperature dependence of the solubility of solids in liquids by the isothermal method was suggested. The thermodynamic parameters of solution of adipic acid in the above solvents were calculated. The dependence of the solubility on the solvent and temperature was considered.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 3, 2005, pp. 403–407.Original Russian Text Copyright © 2005 by Gaivoronskii, Granzhan.     

Solubility of Acetyl- and Diacetylferrocene in Mixed Aqueous-Alcoholic Solvents

Solubility of acetyl- and diacetylferrocene in aqueous-alcoholic solvents as a function of temperature was studied. At any composition of the mixed solvent, the solubility of both compounds increases with temperature. The enthalpies and entropies of solution of both compounds are positive.     

Screening,Preparation,Characterization and Solubility of Polymorphic Forms of Ethinyl Estradiol

Ethinyl estradiol(EE) as a contraceptive,(17α)-19-nopregna-1,3,5-(10)-trien-20-yne-3,17-diol(formula: C_(20)H_(24)O_2, molecular weight: 296.4, CAS number: 57-63-6), is known to have different pseudo-polymorphic forms. Some EE polymorphs have been synthesized by means of physical or chemical methods, characterized by X-ray powder diffraction(XRPD), thermogravimetric(TG), differential scanning calorimetry(DSC) and IR spectra. Dissolution profile was tested by high performance liquid chromatography(HPLC). Meanwhile, the crystal structure of the new EE solvate(formamide) was characterized by single-crystal X-ray structure analysis(SXRD). The results confirmed that EE existed polymorphism. Five crystal forms of EE were presented and two of them were reported firstly. Furthermore, five polymorphs' dissolution curves were drawn and they could be identified by several analysis methods. Our study on polymorphs of EE could provide a variety of crystal material composition, preparation methods and solubility.     

Solubility Behavior of Pimozide in Polar and Nonpolar Solvents: Partial Solubility Parameters Approach

The solubility behavior of pimozide in individual solvents ranging from nonpolar to highly polar was studied. For understanding the solute-solvent interactions, the partial solubility parameters concept was utilized. Solutions containing excess drug were shaken in a water bath for 72 hours at 25 °C. After the solutions attained equilibrium, they were filtered and analyzed for drug content. A multiple regression method, using extended Hansen’s partial solubility parameters, was applied to verify the solubilities of pimozide in pure polar and nonpolar solvents and to predict its solubility in untested solvents. The three-parameter approach and the Flory-Huggins size correction term ‘B’ give predictions of solubilities with correlations up to 97%. The four-parameter approach involving proton-donor and proton-acceptor parameters was also used in fitting the solubility data. The correlations are appreciable (94%). Further, the ‘B’ term coupled with four-parameter approach was examined in order to improve the data representation, and resulted in a 1% improvement (98%) in the correlation when compared to the Flory-Huggins size-correction method. The solubility parameter obtained by this method is 10.43 H which is closer to the values obtained by theoretical methods, such as Fedors’ and Hoy’s. The resulting partial solubility parameters are δ _2d =8.85 H, δ _2p =2.17 H, δ _2a =3.15 H, and δ _2b =4.08 H, which give insights into the interaction capability of pimozide and are consistent with its chemical structure. Pimozide is a Lewis base as its δ _2b >δ _2a . The total solubility parameter of pimozide is assigned at 10.43 H. This work demonstrates for the first time the validity of the four-parameter approach coupled with the Flory-Huggins size-correction term and therefore the result is interesting.     

顶空-毛细管柱气相色谱法测定盐酸艾司洛尔中有机溶剂的残留量

提出了顶空-气相色谱法测定盐酸艾司洛尔中甲醇、乙醇、丙酮、异丙醇、乙醚、吡啶和甲苯7种有机溶剂残留量的方法。选择顶空平衡温度和时间分别为70℃和30min,用DB-1 125-1032毛细管柱分离,火焰离子化检测器检测。7种芳香烃化合物在一定的质量浓度范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.5～3.8mg·L-1之间。在2个浓度水平上做回收试验,加标回收率在96.2%～102.7%之间,相对标准偏差(n=9)在0.69%～3.0%之间。     

Studies on Systems of Salts and Mixed Solvents. XXVI. Solubility and Solvation Behaviour of Aluminium(III) Chloride in Mixed Aqueous Organic Solvents

Using sections of 25°C solubility isotherms of 14 systems of the type AlCl₃? H₂O-organic solvent the investigations are intended to illustrate the possibility of qualitative interpretation of the solubility data on the basis of empirical solvent parameters. Within the group of solvents according to the Kolthoff classification a largely analogous influence on the solubility of aluminium chloride has been noticed. Similarities result from the typical influence on the solvation state of AlCl₃. The results obtained from the solubility investigations and parageneses of the solid phases correlate with the results of spectroscopic investigations. Solid phases so far not observed are reported.