Synthesis of furan derivatives via cascade-type reactions catalyzed by solid acids

Abstract

The 2-methylfuran (2-MF), easily obtained from furfural as a lignocellulosic biomass derivative, can beconverted in good yields (70%) into 5,5-bis(5-methyl-2-furyl)pentan-2-one by condensation in the pres-ence of mineral acids. This molecule is an important precursor for various interesting industrial products,such as benzofuranics with physiological activity and hydrocarbon mixtures useful as fuel components. Inthis work, the synthesis of 5,5-bis(5-methyl-2-furyl)pentan-2-one was successfully achieved (yield = 80%)via hydrolysis/condensation of 2-methylfuran, by using ethanol/water as solvent and Amberlyst®15 as asolid catalyst under moderate reaction conditions. Different polymeric ionic exchange resins were tested,conversion of 2-MF and product performances during reaction showed a proportional dependence tothe capacity of proton exchange of resins. Amberlyst®15 presented the best results, and the resin canbe regenerated and reused several times arriving to a constant product yield after the 3rd 4th reuse.Results attained for different zeolites tested indicate that 2-MF conversion appears to be function of poresize and channels structure of zeolite. These catalysts produced low yields of desired product mainly dueto deactivation by the retention of intermediate reactions and products on the surface and inside pores.The use of H-Beta (F−) catalyst presenting a more hydrophobic surface could partially minimize catalyticdeactivation.