| abstract |
A process for the preparation of permethylated amines, particularly pentamethyldiethylenetriamine, by the reductive methylation of diethylenetriamine in the presence of hydrogen, a nickel-containing catalyst, aqueous formaldehyde and methanol, comprising feeding continuously the formalehyde to the reaction system in two phases. In the first phase, a sufficient amount of formaldehyde to mono-methylate the primary amine groups present, is fed to the reaction system at a high flow rate, and thereafter the flow rate of the formaldehyde is substantially reduced, for the reductive methylation of the secondary amine groups. By this method the production of by-products is substantially reduced and preparation times are significantly shorter in comparison to processes where the formaldehyde flow rate remains constantly high for the entirety of the reaction. |