Solid acid catalysed acylation of 2-methoxy-naphthalene : role of intraparticle diffusion limitation

Abstract

Synthesis of fine chemicals and intermediates by using Friedel-Crafts acylations is important in organic chemical technology. In most of the cases very good yields and selectivity can be obtained with aluminium chloride as a catalyst in conjunction with nitrobenzene as a solvent. However, with the current environmental restrictions, replacement of aluminium chloride-nitrobenzene pair with solid acid catalysts has great industrial relevance. Acylation of 2-methoxynaphthalene with acetic anhydride was carried out using different solid acid catalysts such as zeolites, acid activated clays, ion exchange resins and sulphated zirconia. The products of the reaction are precursors of many organic and pharmaceutical intermediates. For example, the para isomer of the reaction product, 6- methoxy-2-naphthalene-a-methyl ketone is useful as a raw material for the manufacture of well-known anti-inflammatory drug called naproxen. The reaction products were isolated and confirmed by their melting points, ¹H-NMR, gas chromatography, etc.