Solubility and Solution Thermodynamics of Diphenoxylate in Different Pure Solvents

Abstract

The solubility data of diphenoxylate in pure solvents of water, methanol, ethanol, acetone, acetonitrile, 2-propanol were measured within the temperature range of 293.15−318.15 K by a static analytical method under atmospheric pressure. Several commonly used thermodynamic models, including the ideal solution model, the modified Apelblat equation and the Buchowski-Ksiazaczak λh equation, were applied to correlate the experimental solubility data. The experimental results show that the solubility increases with the increasing temperature, and the highest solubility is in methanol, the lowest in pure water. Results of these measurements were well-correlated with the three equations above, but the modified Apelblat equation is more suitable in regressing the solubility data of diphenoxylate. Through the Van't Hoff equation, the enthalpy and the entropy in different solvents can be calculated.

Solubility and Thermodynamic Modeling of Sulfanilamide in 12 Mono Solvents and 4 Binary Solvent Mixtures from 278.15 to 318.15 K

“…The mole fraction solubility ( x ) with the dependence of absolute temperature T with high accuracy can be described by a frequently used semi empirical equation modified Apelblat model, − which was obtained from the Clausius–Clapeyron equation. The equation is expressed as below (eq ).…”

“…Based on the condition of a dilute solution which is approximately considered as an ideal solution, the van’t Hoff model was derived. Then, the nonrandom two liquid equation becomes as a function of temperature shown in eq when the activity coefficient equals to 1; eq was the simplified form of eq . − , where x represents the mole fraction solubility of sulfanilamide in solvents; T refers to absolute temperature; and a and b are the van’t Hoff parameters determined by solubility fittings.…”

Predicting the Solubility of Sulfur: A COSMO‐RS‐Based Approach to Investigate Electrolytes for Li–S Batteries

“…For a better understanding of the dissolution process and its driving forces, a more detailed thermodynamic analysis was carried out. By plotting the computed solubilities as ln ( x S ) against 1/T, the dissolution enthalpy (Δ sol H ) and entropy (Δ sol S ) could be obtained from the slope and intercept, respectively, using the van't Hoff equation [Eq. ], in which R is the universal gas constant. …”

“…Accordingly, the Gibbs free energy of dissolution (Δ sol G ) could be obtained using the mean temperature ( T mean ) of the investigated temperature range (303.15 K) [Eq. ]: …”

“…To compare the relative contributions of enthalpy (% ξ H ) and entropy (% ξ TS ) to the Gibbs free energy of dissolution for the process, the following equations [Eqs. ] were used: …”