The Synthesis, Infra-Red Analysis and Antimicrobial Studies of the Schiff Base, Oxime, Hydrazone and Azine of Vanillin

Abstract

Schiff bases, oximes, hydrazones, and azines are organic compounds that contain the imino functional group (C = N). They are obtained by reacting an amine or amino compound and a carbonyl compound in the presence of an acid. This research was focused on synthesizing these four compounds using the primary reactant, Vanillin (4-hydroxy-3-methoxybenzaldehyde), to achieve vanillin derivatives. The Schiff base, Oxime, and hydrazone were synthesized by reacting an equimolar amount of vanillin with aniline, hydroxylamine hydrochloride, and hydrazine hydrate, respectively, in ethanol by stirring under reflux for about 2 hours. However, the azine was obtained by reacting vanillin and hydrazine hydrate in a 2:1 ratio. At the end of the reaction, solid products were obtained and weighed, giving a percentage yield of 52.4%, 88.1%, 85.7%, and 54.9% for the Schiff base, oxime, hydrazone, and azine, respectively. Furthermore, to verify the formation of the imino group, an IR analysis was carried out on the product and the presence of an IR band at 1659 cm − 1 for Schiff base (C = N) imino, 1689 cm − 1 for oxime (-C = N-) imino, 1626 cm − 1 for hydrazone (-C = N--) and 1652 cm − 1 for azine (-C = N-) alkene, proved that the expected functional formed. In addition, this research showed that these compounds have antimicrobial properties. The Vanillin-Schiff Base was the most effective and broad-spectrum (best against Pseudomonas sp. , Staphylococcus sp. , and Bacillus sp. ), Vanillin-Oxime was moderately effective, showing some inhibition against E. coli and Candida sp. , Vanillin-azine was only strongly effective against Staphylococcus sp. , but weak against others, while the Vanillin-Hydrazone was the weakest, with almost no inhibition at lower concentrations. This research simply recommends that scientists should concentrate on developing more eco-friendly methods and solvents for the synthesis of those compounds which will give very high yields.