Selective carbomethoxylation of aromatic diamines . with mixed carbonic acid diesters in the presence of phosphorous acids

Abstract

The reactivity of industrially relevant amines, 4,4′-methylenedianiline (MDA) and 2,4-diaminotoluene (TDA), towards methylphenylcarbonate (MPC), in the presence of Ph₂P(O)OH, has been investigated. Both MDA and TDA are catalytically and selectively converted into mono- and di-methylcarbamate esters. Under the relatively mild working conditions used, the formation of ureas and/or N-methyl derivatives is totally repressed. The full spectroscopic characterization of the compounds formed upon interaction of amines with Ph₂P(O)OH is also reported. The methodology here described also holds for other mono- and di-amines, both aliphatic and aromatic.