Question

Mechanism of preparation of urea formaldehyde resin

Answer 1

Abstract

The various initial reactions in the urea-formaldehyde reaction have been isolated and the course of the reaction investigated using a quantitative thin-layer chromatographic technique developed for the purpose. The rate constants for the formation of monomethylol urea pass through a minimum in the pH range 4.5–8, thereby proving catalysis by H+ and OH−. Whereas the reaction under alkaline conditions leads to methylol formation, acidic conditions favour formation of methylene bridges. It was found that the higher homologues were formed through the methylolation of methylene urea followed by its condensation with free urea and not by the reaction of methylene urea with methylol urea.