Acylation of 2-methoxynaphthalene and isobutylbenzene over zeolite beta

The acylation of 2-methoxynaphthalene (2MN) with acetic anhydride is carrie d out in the liquid phase in the presence of zeolite beta, Two main product s, 1-acetyl-2-methoxynaphthalene (1,2-AMN) and the desired 2-acetyl-6-metho xynaphthalene (2,6-AMN) are obtained. Variations of reaction temperature, t he concentration of the acylating agent, and the weight of the catalyst are investigated to find reaction conditions sufficient to provide for good co nversion of 2MN and limited deactivation. Surface-poisoning experiments sho w that the formation of 1,2-AMN occurs on the external surface of the zeoli te. When the external surface of zeolite beta is passivated by coating with amorphous silica, a significant increase in the selectivity of 2,6-AMN is observed and this result is a clear example of shape-selective acylation wi th zeolite catalysts. The acylation of isobutylbenzene with acetic anhydrid e is investigated also. At conversions of around 10%, the selectivity to 4- isobutylacetophenone is excellent (>97%). For the acylation of isobutylbenz ene, the external surface of the zeolite contributes significantly to the f ormation of 4-isobutylacetophenone, so the shape-selective properties of th e zeolite are not utilized. (C) 2000 Academic Press.