Liquid-phase permethylation of diethylenetriamine using methanol over robust composite copper catalysts

Abstract

Pentamethyldiethylenetriamine is a permethylated polyamine that is widely used to prepare foam polyurethane. The current technology for its synthesis relies on diethylenetriamine methylation with formaldehyde under H₂. This route is selective, but the use of formaldehyde raises safety and environmental concerns. Herein we present an alternative non-toxic route using methanol as greener and cheaper methylating reagent. The reaction proceeds fast and selectively over composite copper catalysts with a pentamethyldiethylenetriamine yield of 75% and resistance to sintering.