Environment Friendly Synthesis of Acetic Acid Based Compounds and Their Biological Characterzation

Abstract

The present study complies with different principles of environment friendly synthesis utilizing efficient instrumental techniques i.e.; microwaves and replacement of hazardous solvents with eco-friendly ones. The overall progress of chemical reactions achieved through application of environmental chemistry, was compared with the traditional methods. In the first part of this research work, synthesis of substituted ethyl 2-(4-nitrobenzylidene) hydrazinyl acetate was carried out for which, substituted benzoic acids were esterified to corresponding ethyl esters under the influence of microwaves followed by its hydrazinolysis. Substituted benzohydrazides thus obtained, were then reacted in a microwave oven with different benzaldehydes to get a series of substituted 4-nitrophenyl methylidene benzohydrazides. They were then changed into targeted products after reaction of substituted 4-nitrophenyl methylidene benzohydrazides with ethyl chloroacetate in the presence of dry acetone in anhydrous conditions by using microwaves. In the second series, naphthyl acetic acid was converted to ethyl naphthalen-1ylacetate followed by its hydrazinolysis. The compound 2-(naphthalen-1-yl) acetohydrazide thus, formed was reacted with different benzaldehydes under conventional and green technologies to get a series of substituted methylidene-2(naphthalen-1-yl) acetohydrazide. The targeted compounds were synthesized after their reaction of substituted methylidene-2-(naphthalen-1-yl) acetohydrazides with ethyl chloroacetate under anhydrous conditions. In the third series, substituted ethyl methylidene-1-[(2,4-dichlorophenoxy) acetyl] hydrazinyl acetate were synthesized by using 2,4-dichloro phenoxyacetic acid. After esterification of 2,4-dichlorophenoxy acetic acid ethyl (2,4-dichlorophenoxy) acetate was synthesized which underwent hydrazinolysis. The compound 2-(2,4dichlorophenoxy) acetohydrazide thus formed, was reacted with aromatic aldehydes and ketones to give methylidene-2-(2,4-dichlorophenoxy) acetohydrazide derivatives. Methylidene-2-(2,4-dichlorophenoxy) acetohydrazide on esterification under anhydrous conditions yielded ethyl methylidene-1-[(2,4-dichlorophenoxy) acetyl] hydrazinyl acetate. Similarly, in the fourth series derivatives of ethyl -1-[(4-chloro-2-methylphenoxy), acetyl]-2- hydrazinyl} acetate was synthesized after four steps of synthesis. Methyl xx

chloro -phenoxyacetic acid was esterified in the first step to synthesize ethyl (4chloro-2-methylphenoxy) acetate which underwent hydrazinolysis to give 2-(4chloro-2-methylphenoxy) acetohydrazide. The compound 2-(4-chloro-2methylphenoxy) methylidene acetohydrazide was prepared after reaction of aromatic aldehydes and ketones with 2-(4-chloro-2-methylphenoxy) acetohydrazide. These Schiff bases were changed into targeted compounds after reaction with ethyl chloro acetate under anhydrous conditions. Comparison of both the conventional and microwave assisted reactions indicates a significant reduction in reaction times and improvement in reaction yields. Besides chemical characterization, some of the synthesized compounds (series-1 and 2) were evaluated for their phytohormonal ability on tissue culture raised Bougainvillea glabra explants and hydroponically grown sunflower seedlings. Series-2 compounds were also evaluated for anti-fungal activity. Some of them were found to possess the potential as plant growth promoter. Series-3 and 4 compounds were evaluated for cytotoxicity assay protocol against 3T3 cell line and anti-cancer activity on Hela cell line. Few of them were found to possess potential as lead compounds for drug discovery.