One-step synthesis of 2,5-dihydroxyterephthalic acid by the oxidation of p-xylene over M-MCM-41 (M = Fe, Fe/Cu, Cu) catalysts

One-step hydroxylation of C-H (sp(2)) of aromatic ring synchronized with the oxidation of C-H (sp(3)) of side chain of p-xylene to 2,5-dihydroxyterephathalic acid was performed using M-MCM-41 (M = Fe, Fe/Cu, Cu) as the catalysts. Cu-MCM-41 (Cu:Si = 1:100) catalyst exhibited good selectivity (73.0%) of 2,5-dihydroxyterephathalic acid and conversion (21.7%) of p-xylene using acetic acid and acetonitrile (V: V = 3:7) as the solvents at 80 degrees C for 5 h. The possible mechanism of the oxidation of p-xylene to 2,5-dihydroxyterephathalic acid was proposed and would guide us to design high performance catalyst for sp(2) and sp(3) C-H oxidation. This procedure is also expected to be an alternative method to Kolbe-Schmitt Process for the synthesis of o-hydrobenzoic acids and their derivatives. (C) 2016 Elsevier B.V. All rights reserved.