Volumetric and viscometric studies on L-ascorbic acid, nicotinic acid, thiamine hydrochloride and pyridoxine hydrochloride in water at temperatures (288.15-318.15) K and at atmospheric pressure

Apparent molar volumes V-2,V-phi,V- apparent molar isentropic compressibilities K-s,K-2,K-phi and viscosity B-coefficients have been determined for L-ascorbic acid, nicotinic acid, thiamine hydrochloride and pyridoxine hydrochloride in water at temperatures (288.15-318.15) K from density, speed of sound and viscosity measurements, respectively. Partial molar volumes V-2(o) and partial molar isentropic compressibilities K-S,2(o) at infinite dilution, and viscosity B-coefficients have been calculated from the corresponding data. The partial molar expansibilities V-E(o) (V-E(o) = (partial derivative V-2(o)/partial derivative T)(p)), second order derivative (partial derivative V-2(o)/partial derivative T)(p) and solvation number (S-n) have been calculated. Both volumetric and viscometric studies indicate that nicotinic acid acts as structure promoter where as other vitamins act as structure destroyer. The transition state theory has been used to calculate the activation free energy for viscous flow. (c) 2012 Elsevier B.V. All rights reserved.