SiO2-H3PO4 catalyzed condensation of amines and aldehydes: Solvent-free synthesis of some E-imines, spectral correlations of (E)-N-(substituted benzylidene)-1-benzylpiperidin-4-amines and XRD structure of (E)-N-(4-nitrobenzylidene)-1-benzylpiperidin-4-amine

摘要

A series of Schiff bases (aryl E-imines) including (E)-N-(substituted benzylidene)1-benzylpiperidin-4-amines have been derived from the SiO2-H3PO4 catalyzed solvent-free condensation of aryl amines including 1-benzylpiperidin amines and substituted benzaldehydes under microwave irradiation. The yields of the imines are more than 85%. The synthesized imines are characterized by their physical constants, analytical and spectroscopic data earlier reported in literature. The group frequencies of imines such as infrared (v, cm(-1)), NMR both H-1 and C-13 chemical shifts (delta, ppm) have been correlated with Hammett substituent constants, F and R parameters. The XRD structure of the (E)-N-(4-nitrobenzylidene)-1-benzylpiperidin-4-amine have been established.