NMR Spectroscopy, Hammett Correlations and Biological Activity of Some Schiff Bases Derived from Piperonal

• Main Authors: Echevarria Aurea, Nascimento Maria da Graça, Gerônimo Vanilde, Miller Joseph, Giesbrecht Astréa
• Format: Article
• Language: English
• Published: Sociedade Brasileira de Química 1999-01-01
• Series: Journal of the Brazilian Chemical Society
• Subjects: Hammett NMR correlations; piperonal
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50531999000100010

A series of eleven Schiff Bases have been synthesized. They were obtained by condensation of piperonal (3,4-methylenedioxybenzaldehyde) with the corresponding aromatic primary amines. Their ¹H and 13C-NMR spectra have been obtained and the Hammett correlations including chemical shifts and the subsitutent constants (sigmap, sigmaR e sigmaI) were studied. Linear and bilinear significant correlations were observed for iminic carbon (C-alpha) and C-1?, showing a more significant ressonance effect on chemical shifts. The chemical shifts for C-4? were highly affected by substituent effects, especially for halogens in the expected direction. Their biological activity against microorganisms has also been measured and significant activity was showed against Epidermophyton floccosum. The biological activity did not give a reasonable relationship with electronic effects.