New Brønsted acidic ionic liquid, 3-methyl-1-sulfonic acid imidazolium chloride {[Msim]Cl} was used as an efficient, green and reusable catalyst and solvent for the synthesis of N-sulfonyl imines via the condensation of sulfonamides with aldehydes as well as isatin. The reactions proceeded at room temperature and the title compounds were obtained in high to excellent yields and in relatively short reaction times.

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Neat chlorosulfonic acid reacts with silica gel to give silica sulfuric acid in which sulfuric acid is immobilized on the surface of silica gel via covalent bonds. A combination of silica sulfuric acid and wet SiO2 was used as an effective deacetalizating agent for the conversion of acetals to their corresponding carbonyl derivatives under thermal conditions.

The synthesis of quinoline derivatives via Friedländer method from ortho-aminoaryl ketones in the presence of a catalytic amount of silica sulfuric acid (SSA) under solvent-free condition and microwave irradiation was described. A good range of simple ketones such as cyclohexanone and deoxybenzoin were used.

This paper is dedicated to Professor H. Firouzabadi for his great contribution to the development of organic chemistry in the country in the occasion of his 6S th birthday and also his retirement.A simple, rapid and efficient method for the preparation of benzoxazoles, benzimidazoles and oxazolo[4,S-b]pyridines from the reaction of orthoesters with o-aminophenols, a-phenylenediamine and 2-amino-3-hydroxypyridine in the presence of silica sulfuric acid under heterogeneous and solvent-free conditions is reported. The significant features of this method are short reaction times, high yields of the products, mild reaction conditions, solvent free reaction, cheapness, non-toxicity and reusability of the catalyst.