Full N, N-Methylation of 4,4′-Methylenedianiline with Dimethyl Carbonate: A Feasible Access to 4,4′-Methylene bis(N, N-Dimethylaniline)

The full N, N-methylation of 4,4'-methylenedianiline (MDA) with dimethyl carbonate (DMC) was investigated. The yield of the major product 4,4'-methylene bis(N, N-dimethylaniline) (MBDMA) reached as high as 97% over NaY catalyst at 190 degrees C for 6h. The catalyst could be used for two more times with acceptable MBDMA yields higher than 90%. The main by-products were identified as three N-methylated derivatives. Surprisingly, the formation of the N-methoxycarbonylation product was extremely restrained, which could be produced in high yields of 98% on zinc acetate catalyst. Furthermore, the reaction pathway to the major product MBDMA was proposed. Finally, a feasible synthetic route of 4,4'-methylene bis(N, N-dimethylaniline) (MBDMA) was established, featuring a high yield, mild reaction conditions, and simple operations.