Synthesis of 3,3′-dimethyl-4,4′-diaminodiphenylmethane catalyzed by zeolites replacing mineral acids

Abstract

Synthesis of 3,3′-dimethyl-4,4′-diaminodiphenylmethane (MDT) from o-tolylamine and formaldehyde over zeolites was investigated. Among the three tested zeolites, Hβ showed higher catalytic activity than HY and HZSM-5 for MDT synthesis. In the case of Hβ as a catalyst, the effects of feed composition, reaction time and temperature on the yield and selectivity of product MDT were further examined to optimize process conditions. In an o-tolylamine:formaldehyde=8:1 molar ratio, the two-step reaction running at 413K for 0.5h and then 433K for 0.5h gave the MDT yield of 87.5%.