Thermodynamic Solubility and Mixing Properties of Phenformin in 14 Pure Solvents at Temperatures Ranging from 278.15 to 323.15 K

The equilibrium solubility of phenformin in 14 solvents of N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidinone (NMP), dimethyl sulfoxide (DMSO), methanol, isopropanol, ethanol, n-propanol, 1,4-dioxane, n-butanol, isobutanol, acetonitrile, ethyl acetate, ethylene glycol (EG), and water was gained using the saturation shake-flask method over a temperature range of 278.15 to 323.15 K under pressure p = 101.2 kPa. The mole fraction solubility of phenformin in the above neat solvents increased as the temperature increased and had a variation trend in the different solvents: DMF > DMSO > NMP > EG > methanol > ethanol > ethyl acetate > n-propanol > isopropanol > n-butanol > isobutanol > water > acetonitrile > 1,4-dioxane. It was correlated using the nonrandom two-liquid model, modified Apelblat equation, λh equation, and the Wilson model. The obtained values of maximum root-mean-square deviation and relative average deviation gained via the four models were, respectively, 29.14 × 10^–4 and 4.46 × 10^–2. Also, the reduced excess enthalpy, activity coefficient under infinitesimal concentration, and mixing properties were derived based on the determined solubility data.