Supported CuII Single-Ion Catalyst for Total Carbon Utilization of C2 and C3 Biomass-Based Platform Molecules in the N-Formylation of Amines

Abstract

The shift from fossil carbon sources to renewable ones is vital for developing sustainable chemical processes to produce valuable chemicals. In this work, value-added formamides were synthesized in good yields by the reaction of amines with C₂ and C₃ biomass-based platform molecules such as glycolic acid, 1,3-dihydroxyacetone and glyceraldehyde. These feedstocks were selectively converted by catalysts based on Cu-containing zeolite 5A through the in situ formation of carbonyl-containing intermediates. To the best of our knowledge, this is the first example in which all the carbon atoms in biomass-based feedstocks could be amidated to produce formamide. Combined catalyst characterization results revealed preferably single Cu^II sites on the surface of Cu/5A, some of which form small clusters, but without direct linking via oxygen bridges. By combining the results of electron paramagnetic resonance (EPR) spin-trapping, operando attenuated total reflection (ATR) IR spectroscopy and control experiments, it was found that the formation of formamides might involve a HCOOH-like intermediate and ^. NHPh radicals, in which the selective formation of ^. OOH radicals might play a key role.

Keywords: C−C bond cleavage; amines; biomass-based feedstocks; electron paramagnetic resonance spectroscopy; formylation; selective oxidation.