Abstract
BACKGROUND5-(Aminomethyl)-2-furanmethanol (AMF), used widely in medicinal chemistry, is usually synthesized by the reductive amination of furfural or 5-hydroxymethylfurfural (HMF) with ammonia. However, a challenging task when synthesizing this furyl primary amine is to enhance the selectivity of the product due to its high nucleophilicity. Conventional measures have used excessive liquid ammonia and precious metal catalysts. Usually, the molar ratio of ammonia to substrate is up to 30:1. This study employed aqueous ammonia to synthesize AMF by the direct reductive amination of HMF using the non-noble metal Ni/SBA-15 catalyst.
RESULTSThe Ni/SBA-15 catalyst displayed higher catalytic selectivity in the reductive amination of HMF to AMF compared to other precious metal catalysts, such as Ru/C, Pd/C and Pt/C. The AMF yield of 89.8% was obtained at the relatively mild reaction temperature of 100 degrees C for 4h. After the fifth cycle, an acceptable decrease in catalytic activity with 74.2% yield of AMF was observed.
CONCLUSIONAn improved process was developed for preparing AMF by the reductive amination of HMF with aqueous ammonia using the non-noble Ni/SBA-15 catalyst. The high selectivity of nickel catalyst is attributed mainly to the moderate catalytic activity. Moreover, a small amount of water enhanced the yield of AMF by promoting the formation of ammonium ions to prevent the further side reaction of AMF with HMF. Results of recycling experiments and analyses showed that agglomeration, loss and oxidization of nickel species together with carbon deposition were responsible for the slight deactivation of the catalyst. (c) 2018 Society of Chemical Industry