OPTIMIZATION OF MICROWAVE ASSISTED SOLVENT-FREE SYNTHESIS OF SOME SCHIFF BASES

Objective: To optimize microwave assisted solvent free synthesis of Schiff bases of aromatic aldehydes and aromatic amines (ethyl 4-aminobenzoate) by using wetting reagent ð›½-ethoxyethanol. The goal of this study was to investigate the % yields and time required for the completion of reaction for Schiff bases by microwave and conventional conditions.Methods: Schiff bases have been synthesized by condensation of substituted various aromatic aldehyde (.001 mol) with Ethyl 4-aminobenzoate (.001 mol) by two different methods as by conventional method (Heating) & Microwave accelerated synthesis by using wetting reagent ð›½-ethoxyethanol. The reaction time for conventional method and microwave method is in the range of 60-240 min and 10-180s respectively. All the synthesized compounds recrystallized & characterized by IR, NMR, and Mass and element analysis.Results: The simple microwave assisted solvent-free method for the synthesis of Schiff bases using a wetting reagent (ð›½-ethoxyethanol) led to improvement in the yield of all the target compounds with reduction in their reaction byproducts & substantially reduced the overall process time as expected as compare to traditional method. Excellent isolated yields (up to 96%) were attained within short reaction times (typically, 60s) when the reaction was performed under microwaves irradiation.Conclusion: The advantages of this environmentally benign and safe protocol include a simple reaction set-up, high product yields, short reaction times as well as the elimination of side products.Â