Postsynthesis-Treated Iron-Based Metal-Organic Frameworks as Selective Catalysts for the Sustainable Synthesis of Nitriles

Abstract

The dehydration of aldoximes to the corresponding nitriles can be performed with excellent activity and selectivity by using iron trimesate as a homogeneous catalyst. Iron trimesate has been heterogenized by synthesizing metal-organic frameworks (MOFs) from iron trimesate, that is, Fe(BTC), and MIL-100 (Fe). These materials were active and selective aldoxime dehydration catalysts, and postsynthesis-treated MIL-100 (Fe) produced the desired nitriles with 100 % conversion and selectivities >90 % under mild reaction conditions and in short reaction times. X-ray photoelectron spectroscopy showed the presence of different Fe species in the catalyst, and in situ IR spectroscopy combined with catalytic results indicates that the catalytic activity is associated with Fe framework species. The postsynthesis-treated MIL-100 (Fe)-NH4 F can be recycled several times and has an excellent reaction scope, which gives better catalytic results than other solid acid or base catalysts.

Keywords: heterogeneous catalysts; iron; lewis acids; metal-organic frameworks; zeolites.