Heteropolyacids due to their unique physicochemical properties are widely used as homogeneous and heterogeneous acid and oxidation catalysts. In many cases HPA-based catalysts have higher activity than known traditional catalysts. Heteropolyacids (HPAs) are strong Bronsted acids composed of heteropolyanions and protons as the countercations and are used to replace environmentally harmful liquid acid catalysts. In view of green chemistry, the substitution of harmful liquid acids by solid reusable HPAs as catalyst in organic synthesis is the most promising application of these acids. In comparison with liquid mineral acids, solid acids could be easily separated from the reaction mixture by simple filtration with high recovery. This advantage directly leads to a decrease in equipment cauterization and environment pollution. In the present investigation, we have applied a green and recyclable solid acid catalyst, nanosilica-supported preyssler (H14[NaP5W30O110]) for highly selective and rapid liquid-phase O-acetylation of salicylic acid in order to synthesize aspirin at room temperature. The usual catalysts in aspirin synthesis are toxic liquid acids such as HNO3 and H2SO4, which would cause serious corrosive and other environmental problems. The application of clean catalytic technologies, especially those with the use of heterogeneous catalysts, is becoming increasingly important for the development of environmentally benign chemical processes. To our knowledge, no attempt has been made to use nanosilica-supported preyssler catalysts for the mentioned reaction. The reaction was carried out by using H14P5/nanoSiO2 with different loadings. Catalyst loading was varied from 10 to 50wt%. The performance of nanosilica-supported preyssler in various loadings was compared with those of H2SO4. The yield of aspirin was increased from 27% to 85% with an increase in catalyst loading from 10 to 50wt%. The yield is 53% in sulfuric acid method.

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