Uma série de Bases de Schiff foi sintetizada através da reação de condensação do piperonal (3,4-metilenodioxibenzaldeido) com as correspondentes aminas primárias aromáticas. Seus espectros de RMN de 1 H e 13 C foram obtidos e estudou-se as correlações de Hammett envolvendo os deslocamentos químicos e as constantes dos substituíntes (σp, σR e σI). Observou-se correlações lineares e bilineares significativas para o carbono imínico (C-α) e C-1', indicando maior contribuição do efeito de ressonância do substituinte sobre os deslocamentos químicos. Os assinalamentos dos C-4' apresentaram-se bem alterados pelos efeitos dos substituíntes, especialmente pelos halogênios, na direção esperada. A série de Bases de Schiff foi ensaiada contra microorganismos, sendo que apresentou atividade significativa frente a fungos filamentosos, especialmente o Epidermophyton floccosum. Não foram observadas correlações significativas entre a atividade biológica e os efeitos eletrônicos.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 1 H and 13 C-NMR spectra have been obtained and the Hammett correlations including chemical shifts and the subsitutent constants (σp, σR e σI) were studied. Linear and bilinear significant correlations were observed for iminic carbon (C-α) 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.

p-Nitrobenzyl amylose xanthate (AmXNB) was synthesized and characterized by 13 C NMR spectroscopy in solution and the solid state. The degree of substitution (DS), calculated from the sulfur content, was 7.0, and this value was similar to that obtained from solid-state 13 C NMR using the signal of C-1 as internal standard. The hydrolysis of AmXNB was studied in 10% (v/v) DMSO with m = 0.5 (KCl) at 25°C. The basic hydrolysis was pseudo-first order, but the water-catalyzed hydrolysis in the pH range 7-9 showed a biphasic plot of ln (DAbsorbance) vs time, as has been observed for cellulose xanthate esters, occurring through two parallel reactions with rate constants k' H 2 O (fast) = 5.3 Â 10 À5 s À1 and k@ H 2 O (slow) = 3.3 Â 10 À6 s À1 . The fast hydrolysis was more than three orders of magnitude faster than that of the O-ethyl analog. The activation parameters were DH ≠ = 20.5 kcal mol À1 and DS ≠ = 10 cal K À1 mol À1 . They showed that the acceleration of the fast hydrolysis of AmXNB and cellulose analogs is due to an entropy of activation effect. There is a linear increase of logk' H 2O (fast) with increase in the concentration of the small Li ion that produces an increase of the 3-D hydrogen-bond network of water while the large singly charged iodide ion has a considerable inverse effect. These results are strongly consistent with the theory that the supramolecular catalysis induced by modified polysaccharide esters is due to the 3-D hydrogen-bond network of the water in the solvation shell.