Ionic liquids have attracted extensive research interest in recent years as green solvents due to their favorable properties like negligible vapor pressure, recyclability and thermal stability. They have been used in various organic reactions as solvent, reagent or Br?nsted acid. Their high polarity and ability to solubilize both organic and inorganic compounds have been resulted in enhanced rates of chemical process and higher selectivity in compare to conventional solvents. The aliphatic quaternary ammonium cation is a useful cationic component of room temperature ionic liquids. The excellent dielectric properties of these salts offer advantages like enhanced reaction rates, easier workup and facilitated purification, when made them eligible as solvents in microwave assisted organic synthesis. The dipole characteristics of ionic liquid translate into rapid excitation by microwave and consequently faster reactions. According to mentioned properties of ionic liquids the following projects have been performed: - Oxidation of benzylic alcohols to their corresponding carbonyl compounds using potassium periodate in the presence of catalytic amount of tetraethyl ammonium bromide as ionic liquid. - Synthesis of aromatic aldoximes under microwave irradiation using tribenzylamine or 1, 4-diazabicyclo[2.2.2]octane or 1-benzyl-4-aza-1azoniabicyclo[2.2.2]octane bromide serve as useful bases and precursors of ionic liquids. Ionic liquids have been known to as designer solvents since their physical and chemical properties could be adjusted by a careful choice of cation and anion. Apart from this they exhibit acidic properties. In this work br?nsted acidic ionic liquid 3-methylimidazolinium hydrogensulfate ([Hmim] + HSO 4 - ) has been synthesized and has been used as a catalysts and reaction medium for the follow reactions. - Efficient and selective iodination of benzylic alcohols with sodium iodide in the presence of br?nsted acidic ionic liquid 3-methylimidazolinium hydrogensulfate. - Oxidation of benzylic alcohols to their corresponding carbonyl compounds with sodium nitrate in the presence of catalytic amount of br?nsted acidic ionic liquid 3-methylimidazolinium hydrogensulfate. - Protection of alcohols with 3,4-dihydro-2H-pyran and catalytic amount of br?nsted acidic ionic liquid 3-methyl imidazolinium hydrogensulfate.