Excess volumes and excess enthalpies of N-methyl-2-pyrrolidone with branched alcohols

Excess molar volumes (VE) at 303.15 K and excess enthalpies (HE) at 298.15 K and ambient pressure have been measured as a function of composition for the binary liquid mixtures of N-methyl-2-pyrrolidone (NMP) with branched alcohols. The branched alcohols include 2-propanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol and 3-methyl-1-butanol. The VE values were measured using a dilatometer and are negative over the entire mole fraction range for all the systems. The HE values for the above mixtures have been measured by a Paar 1451 solution calorimeter and are positive over the whole range of compassion. The experimental results have been correlated using Redilich–Kister polynomials and the results are interpreted on the basis of possible hydrogen bonding between unlike molecules and changes in molecular association equilibria as well as structural effects for these systems.