Derivatization, characterization and antifungal potential of aza heterocyclic amines
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Date
2021
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Punjab Agricultural University, Ludhiana
Abstract
Heterocyclic compounds are one of the intriguing parts of synthetic organic chemistry that comprises heteroatoms (nitrogen, sulfur, oxygen, etc.) other than carbon atoms as a part of aromatic rings. Aza heterocyclic compounds are those that contain nitrogen atoms as a part of the ring. In the present work, firstly, 4-(thio-2'-ylmethyleneamino)benzoic acid was synthesized by carrying out a condensation reaction between 4-amino benzoic acid and thiophene-2-carboxaldehyde. Then, oxidation of 4-isopropyl benzaldehyde was done to yield 4-isopropyl benzoic acid. Both the acids have then undergone a reaction with aza heterocyclic amines (2-aminopyridine, 3-amino pyridine, 4-amino pyridine, 4-amino antipyrine, and 4amino-1,2,4-triazole) using two eco-friendly methods, silica gel and water extract of banana peel (WEB) to yield benzamides (II-XI). Further, aza heterocyclic amines were derivatized to form azomethines (XII-XXV) by carrying out their condensation reaction with veratraldehyde and isovanillin using glacial acetic acid/NaOH as the catalyst. Synthesized azomethines of 4amino-1,2,4-triazole and 4-amino antipyrine with veratraldehyde and iso vanillin were then cyclized using chloroacetyl chloride to yield β-lactams (XXVI-XXIX) in the presence of
trimethylamine as a base. In the next series, azo compounds (XXX-XXXIII) of 4-amino1,2,4-triazole was synthesized using different substituted benzaldehydes (4bromobenzaldehyde, 4-chlorobenzaldehyde, 4-nitrobenzaldehyde, and 3-nitrobenzaldehyde) followed by their derivatization using various aromatic amines (4-amino antipyrine, 2,4dinitrophenyl hydrazine, phenylhydrazine, and 2-amino-4-phenyl thiazole to yield azo Schiff bases (XXXIV-XLIX) using glacial acetic acid or concentrated sulfuric acid as catalyst in methanol as solvent. The synthesized compounds were characterized using various spectroscopic techniques viz. UV-Visible, IR, 1H NMR, and 13C NMR. All the compounds were evaluated for their antifungal potential against four different maize pathogenic fungi i.e. R. solani, F. verticillioides, D. maydis, and M. phaseolina using poisoned food technique. It was found that compound (XII) with ED50 (11.02 µg ml-1) which was azomethine derivative of 4-amino-1,2,4-triazole and veratraldehyde was at par with standard carbendazim 50 WP
against R. solani. None of the compounds was found more effective than standard carbendazim 50 WP.
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Verma, Diksha (2021). Derivatization, characterization and antifungal potential of aza heterocyclic amines (Unpublished Ph.D. Dissertation). Punjab Agricultural University, Ludhiana, Punjab, India.