Study of the Reaction between Ethylene Glycol or 1,2-Propylene Glycol with Diphenylmethane. 4,4′-diisocyanate

A 13C-NMR study of the reaction between ethylene glycol or 1,2-propylene glycol with diphenylmethane-4,4′-diisocyanate is reported. Assignation of -CH2-, -NHCOO-, and -CH3 groups was made and their concentration dependence on reaction time established. On the basis of these data, the rate constants for different reactions were calculated. It was found that the primary groups of 1,2-propylene glycol are more reactive than the secondary -OH group, and that ethylene glycol is more reactive than 1,2-propylene glycol. Side reactions at low temperature and without catalyst do not take place.