IR Spectroscopy Method for Determining The Reactivity of Isocyanate Groups in Isophorone Diisocyanate Reactions

We have developed a fast IR spectroscopy method for determining the concentrations of cycloaliphatic and aliphatic isocyanate groups in isophorone diisocyanate that react to form urethanes. It is based on the experimentally established fact that there is a difference between the frequencies of the stretching vibrations for the N–H bond in urethanes formed by cycloaliphatic and aliphatic isocyanate groups in isophorone diisocyanate, when the IR spectra are recorded for dilute solutions of the reaction mixture in carbon tetrachloride. The method can be used to determine the reactivity of isocyanate groups in different reactions involving isophorone diisocyanate.