Microwave assisted organocatalytic synthesis of 5-hydroxymethyl furfural in a monophasic green solvent system

Abstract

Monophasic microwave assisted dehydration of fructose to 5-hydroxymethyl furfural (HMF) catalyzed by p-toluene sulphonic acid (PTSA) was studied in non-aqueous organic solvents. Of the three monophasic systems studied (isopropyl alcohol, N,N-dimethyl formamide and dimethyl sulfoxide), isopropyl alcohol, a preferred green solvent gave the product in highest yield. Use of PTSA as proton source for microwave (2.45 GHz) assisted dehydration of fructose in isopropyl alcohol resulted in >98% fructose conversion with >90% HMF yield in 90 s of reaction time. The use of inexpensive and mild acid catalyst PTSA for HMF synthesis with an ecofriendly solvent IPA offers ease of catalyst handling and solvent recovery.