Solubilities of Phosphoramidic Acid, N-(phenylmethyl)-, Diphenyl Ester in Selected Solvents

Abstract

Phosphoramidic acid, N-(phenylmethyl)-, diphenyl ester (PANDE) was synthesized, and its thermostability was measured by thermogravimetric analysis. The melting temperature and the fusion enthalpy of PANDE were evaluated by a differential scanning calorimeter. The solubilities of PANDE in chloroform, tertrahydrofuran, dichloromethane, acetone, methyl acetate, ethyl acetate, acetonitrile, methanol, and toluene were measured by a gravimetric method at different temperatures. The solubilities of PANDE in different solvents at low temperatures are in the order of chloroform > tetrahydrofuran > dichloromethane > acetone > methyl acetate > ethyl acetate > acetonitrile > methanol > toluene. At higher temperatures the order is the same except that acetonitrile now becomes the least soluble. The solubility data of PANDE in nine selected solvents were well fitted by the Wilson, nonrandom two-liquid (NRTL), and universal quasichemical equations. The Wilson model and the NRTL model show better agreement in general. Finally, the solubility parameters of PANDE were evaluated by the Scatchard–Hildebrand model, and meanwhile, the standard dissolution enthalpy, the standard dissolution entropy, and the standard molar Gibbs energy of PANDE in the selected solvents were also calculated by the van’t Hoff model and the Gibbs–Helmholtz equation. The results show that the dissolution process is endothermic and entropy-driven.