Kinetic Studies on the Urethane Reaction of Propanediol with Isocyanate in Nitrogenous Solvents

Abstract

The urethane reactions of 1,2-propanediol, 1,3-propanediol, and n-propanol with phenyl isocyanate were respectively carried out in nitrogenous solvents. In situ FT-IR was used to monitor the reactions, and rate constants were determined. It was shown that the reaction rate of 1,2-propanediol was fastest, followed by the reaction rates of 1,3-propanediol and n-propanol. After that, activation energy (Ea), activation enthalpy (ΔH), and activation entropy (ΔS) were calculated. It was found that these thermodynamic parameters for 1,2-propanediol and 1,3-propanediol are very similar, but they were very different from those of n-propanol, which is very useful to understand the urethane reaction mechanism.