Sulfonic acid functionalized MCM-41 as solid acid catalyst for tert-butylation of hydroquinone enhanced by microwave heating

Covalently linked sulfonic acid (SO3H) modified MCM-41 mesoporous catalysts was prepared, characterized and its catalytic activity under microwave irradiation was evaluated. The NH2-MCM-41 was first prepared by anchoring (3-aminopropyl)triethoxysilane (APTES) on Si-MCM-41 and further reacted with 1,4-butane-sultone to yield the desired acid catalyst. The mesophase and porosity of samples were determined by XRD, TEM and N2 sorption isotherm analyses. The presence of sulfonic acid moiety was confirmed by FT-IR, TG/DTA, sulfur elemental analysis and in situ IR study of pyridine and ammonia adsorptions. The catalyst showed high catalytic activity and high selectivity in tert-butylation of hydroquinone under microwave irradiation. No leaching problem was observed after several runs, while the catalyst can be recovered and reused without loss of reactivity under the described reaction conditions.

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► SO3H-MCM-41 was prepared via sultone ring opening approach.
► SO3H-MCM-41 exhibited ordered mesoporous straight channels with SBET of 475 m2 g−1.
► The catalyst gave 88% conversion in tert-butylation reaction within 8 min under microwave irradiation.
► The catalyst gave 93% product selectivity to 2-tert-butyl hydroquinone.