Two facile synthetic methods for a Schiff base from 4-ethoxyaniline and 2-pyridinecarboxaldehyde

The Schiff base was acquired from the reaction between 4-ethoxyaniline and 2-pyridinecarboxaldehyde using three (3) synthetic methods: 2 hours reflux in ethanol, stirring in ethanol and in an ethanol-water (1:1 v/v) mixture at ambient temperature for an hour. The synthesis of 4-ethoxyaniline-2-pyridinecarboxaldehyde Schiff base afforded dark-brown crystals with a melting point of 118-120°C. The reflux reaction in ethanol gave the highest yield of 83.5% while the reaction in ethanol and in ethanol-water (1:1 v/v) mixture at ambient temperature gave 73.0% and 43.6% yield respectively. The confirmation for the formation of a new aliphatic C=N functional group was given by the IR spectrum that showed a band at 1625cm-1 for an aliphatic C=N group; the 13C NMR spectrum that showed the presence of the imino carbon (C=N) at chemical shift 158.48ppm while the 1H NMR spectral data δ(ppm) for the compound gave a one proton singlet (HC=N-) at 8.69. The spectral data were in correlation with the predicted structure of the Schiff base.