The Amount Effect of Catalyst on the Urethane Reaction of 1,2-Propanediol in Xylene

Abstract

The urethane reaction kinetics of 1,2-propanediol with phenyl isocyanate is monitored with in-situ FT-IR with xylene as solvent. Triethylamine is used as catalyst and its amount effect is investigated. Rate constants for the reaction with different concentrations of triethylamine are worked out. The urethane reaction has been found to be a second order reaction and the reaction is largely accelerated with the increase of catalyst concentration. Furthermore, when triethylamine is used as catalyst, the rate constants are different between initial stage and final stage, which belong to different hydroxyls in 1,2-propanediol. However, the rate constant is the same when there is no catalyst, which shows no reactivity difference for hydroxyls in 1,2-propanediol.