Reaction of aromatic diamines with diphenylcarbonate catalyzed by phosphorous acids: a new clean synthetic route to mono- and di-carbamates

In the presence of organophosphorus acids [Ph2P(O)OH, (PhO)2P(O)OH, (BuO)2P(O)OH, (BuO)P(O)(OH)2], aromatic diamines, such as 4,4′-methylendianiline (MDA) or 2,4-diaminotoluene (TDA), react with diphenylcarbonate (DPC) to afford in a very selective way mono- and dicarbamate phenyl esters. The carbamation process is strongly influenced by the temperature and solvent. The influence of both these factors on carbamate yield and selectivity has been investigated and we present in this study the kinetics of formation of both mono- and dicarbamate esters