MONTE-CARLO STUDIES ON AQUEOUS-SOLUTIONS OF METHYLAMINE AND ACETONITRILE - HYDRATION OF SP3 AND SP NITROGEN

Monte Carlo simulations have been carried out on dilute aqueous solutions of methylamine and acetonitrile to model the hydration of the sp3 and sp nitrogens. In general, the calculated enthalpy of solvation, relative free energy, and partial molar volume compared favorably with experimental data. Solution structures were considered as relevant to analysis of the hydrogen bonding around the nitrogen atom. There are approximately three water molecules in the first hydration shell around the amino group of methylamine forming two hydrogen bonds to the solute. Acetonitrile has 1.3-1.4 water molecules around the nitrogen atom in the first shell with all of them hydrogen bonding. No hydrogen bonds were found in the methyl regions that are hydrated by 19 water molecules in the first shell for both solutes. © 1990 American Chemical Society.