Microwave-assisted synthesis, characterization, and antimicrobial activity of some odorant Schiff bases derived from naturally occurring carbonyl compounds and anthranilic acid

ABSTRACT

Nine odorant Schiff bases, namely 2-(4-methoxybenzylideneamino) benzoic acid, 2-(benzylideneamino) benzoic acid, 2-(3-phenylallylidene amino) benzoic acid, 2-(3,7-dimethyloct-2,6-enylideneamino) benzoic acid, 2-(3,7-dimethyloct-6-enylideneamino) benzoic acid, 2-(4-isopropylbenzylideneamino)benzoic acid, 2-(3,4-dimethoxybenzylideneamino) benzoic acid, 2-(1-phenylethylideneamino) benzoic acid, and 2-[(4-(2,6,6-trimethylcyclohex-2-enyl)-but-2-enylideneamino)benzoic acid, were prepared by condensation of anthranilic acid with corresponding naturally occurring carbonyl compounds (anisaldehyde, benzaldehyde, cinnamaldehyde, citral, citronellal, cuminaldehyde, veratraldehyde, acetophenone, and α-ionone) employing conventional and microwave irradiation methods. These compounds were characterized with the aid of elemental and spectral (FT-IR, ¹H NMR, and ¹³C NMR) analysis. Microwave irradiation method was efficient in terms of reduced reaction time, solvent use, and increased yields of these compounds without affecting their olfactory characteristics. These Schiff bases also exhibited olfactory characteristics for various fragrance compositions and varied antimicrobial activity against Aspergillus niger, Penicillium chrysogenum, Staphylococcus aureus, and Escherichia coli.

GRAPHICAL ABSTRACT

KEYWORDS:

• Anthranilic acid
• antimicrobial activity
• microwave irradiation
• olfactory property
• Schiff bases

Acknowledgments

Authors are thankful to the Director, Forest Research Institute, Dehra Dun, India, and Dr. Suman L. Jain, Scientist, Chemical Sciences Division, CSIR–Indian Institute of Petroleum, Dehra Dun, for providing necessary facilities to carry out this work.