Synthesis and microbial activity of pyrazolines and their derivatives
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Date
2014
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Publisher
Punjab Agricultural University, Ludhiana
Abstract
Claisen Schmidt reaction of different aromatic aldehydes with acetone gave α,β-unsaturated
ketones which on further reaction with hydrazine hydrate in the presence of glacial acetic acid
afforded pyrazolines. Acids viz. acetic acid and propanoic acid were treated with thionyl
chloride to give respective acid chlorides which were then reacted with synthesized
pyrazolines using triethylamine as catalyst in dry dichloromethane to give respective Nacetylated
pyrazolines and N-propanoylated pyrazolines. Pyrazolines and N-substituted
pyrazolines were characterized by their IR, 1H NMR and 13C NMR spectra. All the
synthesized pyrazolines and N-substituted pyrazolines were screened for their microbial
activity against Bacillus sp., Pseudomonas sp., Acinetobactor sp. and Klebsiella sp.
Pyrazolines having substitution on benzene ring exhibited lower MIC values than pyrazolines
having no substitution on benzene ring for all tested bacteria. All pyrazolines and Nsubstituted
pyrazolines exhibited less activity than standard ampicillin at all the tested
concentrations. None of the compounds exhibited activity at 100 µg/ml and all the
compounds showed significant differences among themselves at all the concentrations. All Nacetylated
and N-propanoylated pyrazolines having substitution of methoxy group at meta
position and hydroxy group at para position of benzene ring were found effective against
Bacillus sp., Acinetobactor sp. and Pseudomonas sp. but not against Klebsiella sp. Some of
the synthesized compounds showed promising to moderate activity against all the microbes.