Green Synthesis of Tertiary Aryl Dialkyl Amines and Theoretical Investigation of the Formate-Mediated Mechanism

Abstract

Amines and their derivatives are important functionalities. Therefore, developing efficient methods for the synthesis of amines has attracted tremendous attention. Among a number of synthetic methods, the direct reductive amination of carbonyl compounds is still the most common procedure. Dibutylbenzylamine and diethylbenzylamine were synthesized through the direct reductive amination of benzaldehyde with dibutylamine and diethylamine, respectively. This results in the 63% and 33% yield for the dibutylbenzylamine and diethylbenzylamine. The non-commercially available products were then used as the standards for the analysis of reaction products. Recently, green chemistry has become an important issue. The aim of green chemistry is to use non-toxic and environmentally friendly reagents. The green method used in this study uses subcritical water as the reaction medium. In representative comparisons, reactions in subcritical water occurred consistently faster and produced fewer by-products. Time, temperature, and the ratio of reagents were optimized for each reaction. The optimal conditions for dibutylbenzylamine were 1:6 (benzaldehyde to DBF), 340 °C, and 60 min with 88% yield, while for diethylbenzylamine were 1:6 (benzaldehyde to DEF), 340 °C, and 75 min with 54% yield.