Solubility Determination and Thermodynamic Mixing Properties of 5-Methyl-2-pyrazinecarboxylic Acid in Different Solvents

Abstract

The solubility of 5-methyl-2-pyrazinecarboxylic acid (MPCA) in 12 pure solvents within the temperature range from 273.15 to 313.15 K under 101.3 kPa was determined and correlated by some thermodynamic models including the modified Apelblat equation, λh equation, and Wilson model. The results increased with the rising temperature, and it decreased with the following sequence (at a certain temperature): 1,4-dioxane > ethanol > n-propanol > 1-butanol > methanol > isopropanol > acetone > 2-butanone > ethyl acetate > water > acetonitrile > toluene. Moreover, the solvent effect and solute−solvent intermolecular interaction were analyzed during the dissolution process of MPCA in pure organic solvents. The maximum values of the relative average deviation and root-mean-square deviation were no more than 1.67% and 3.43 × 10 −4 , respectively. Furthermore, the mixing Gibbs energy, mixing enthalpy, and mixing entropy were calculated by the Wilson model as well, and the values of Δ mix G and Δ mix H are all negative, while those of the Δ mix S are all positive. The calculated results of thermodynamic properties indicate that the mixing process is not only exothermic but also entropy-driven.

Solubility Measurement and Data Correlation of Isatoic Anhydride in 12 Pure Solvents at Temperatures from 288.15 to 328.15 K

“…According to the Lewis–Randall rule, where the actual state of a pure substance is considered as the standard state, the mixing properties of the solution can be derived from the experimental solubility data on the basis of thermodynamic models. For an ideal binary solution, the mixing properties including the mixing Gibbs energy, mixing enthalpy, and mixing entropy could be described as eqs –. , where x i represents the mole fraction of component i .…”

“…For an ideal binary solution, the mixing properties including the mixing Gibbs energy, mixing enthalpy, and mixing entropy could be described as eqs 15−17. 31,32 (17) where x i represents the mole fraction of component i.…”

Solubility and Thermodynamic Properties of Clotrimazole in 16 Organic Solvents at Temperature of 283.15 to 323.15 K

“…The Wilson model is an activity coefficient model proposed by Wilson. According to the model, the activity coefficient of a binary dissolution system can be expressed by eqs −. , ln nobreak0em.25em⁡ γ 1 = prefix− ln ( x 1 + x 2 Λ 12 ) + x 2 [ Λ 12 x 1 + x 2 Λ 12 − Λ 21 x 2 + x 1 Λ 21 ] normalΛ 12 = V 2 V 1 exp ( − λ 12 − λ 11 R T ) = V 2 V 1 exp [ − true( a…”

“…The Wilson model is an activity coefficient model proposed by Wilson. According to the model, the activity coefficient of a binary dissolution system can be expressed by eqs −. , where R is the ideal gas constant; V 1 and V 2 are the molar volumes of the solute and solvent, respectively; Λ ij is the model parameter; λ ij represents the interaction energy between molecules; (λ ij – λ ij ) is the energy parameter; and a ij and b ij are constants determined by fitting the experimental data.…”

“…According to the model, the activity coefficient of a binary dissolution system can be expressed by eqs 4−6. 18,22 (5)…”