New catalysts for urea formation reactions. II. Catalytic activity of carboxylic acids

Carboxylic acids with weak acidities showed large catalytic activity. For instance, for chlorine‐substituted acetic acid the activity increased with decreasing chlorine content. For benzoic acid derivatives, electron acceptor substituents, such as NO2, CI, and OH, lowered the catalytic activity, while electron donor substituents such as alkyl and alkoxy groups increased it. Detailed study on the cure rate of polyureaurethane, with 2‐methyl benzoic acid as a catalyst, showed that pot life (PL) and the minimum demolding time (DT) had a correlation with the catalyst amount [X] represented by the following equation: \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm PL}^{ - 1} \left( {or{\rm DT}^{ - 1} } \right) = A + B\left[ {\rm X} \right] $$\end{document} where A and B are constants. Further, use of appropriate amounts of the catalyst enhanced tensile strength at break for polyureaurethane.