A Concise and Safe Synthesis of 1,2,3-Propanetriamine (PTA)

1,2,3-Propanetriamine (PTA) is the simplest aliphatic vicinal triamine, a key compound in coordination chemistry and for the preparation of polymers and for many other important applications. Despite its simple structure and its sesquicentennial history, the preparations of PTA have always been elaborate, hazardous, and low yielding. In this article a concise, safe and inexpensive synthesis of PTA is presented. PTA is prepared by a nitro-Mannich reaction between dibenzylamine, nitromethane and paraformaldehyde, followed by a catalytic reduction-debenzylation with Pearlman's catalyst leading to the desired triamine in 73 % yield over two steps. The procedure is amenable for larger-scale preparations.