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Acid Induced Mesoporous Si-Mcm-41 as Solid Acid Catalyst for Friedel-Crafts Alkylation and Acylation

Tarun F. Parangi, Rajesh M. Patel and Uma V. Chudasama

Mesoporous MCM-41 has been synthesized by sol-gel method at room temperature possessing good thermal stability, high surface area as well as retention of surface area at high temperature. The MCM-41 neutral framework has been modified and put to practical use. Al3+ has been incorporated in the siliceous MCM-41 framework and 12TPA (12-Tungstophosphoric acid) anchored onto MCM-41 by process of anchoring and calcination to induce Brønsted acidity in MCM-41 to yield Al-MCM-41 and 12TPA-MCM-41, respectively. The synthesized materials have been characterized for elemental analysis, ICP-AES, XRD, SEM, TEM, EDX, FTIR and TGA. Surface area has been determined by BET method and pore size and pore size distribution determined by BJH method. Surface acidity has been evaluated by NH3-TPD method. The potential use of Al-MCM-41 and 12TPA-MCM-41 as solid acid catalysts has been explored and compared by studying Friedel-Crafts alkylation and acylation as model reactions. Friedel-Crafts acylation of anisole and veratrole with acetic anhydride and alkylation of toluene with benzyl chloride have been performed to obtain 4-methoxy acetophenone (4-MA), 3,4-dimethoxy acetophenone (3,4-DMA) and parabenzyltoluene (PBT), respectively under solvent free condition, and several parameters such as catalyst amount, reaction time, reaction temperature, mole ratio of reagents, etc.