Influence de la structure sur l'hydrolyse des N-pyrrolylmethylene-2 anilines |
| |
Authors: | A
cha Ali-Bey,Hasna Fatiha Loukil,Gilles Gosselin,Andr Mathieu,Abderrezzak Mesli |
| |
Affiliation: | Aǐcha Ali-Bey,Hasna Fatiha Loukil,Gilles Gosselin,André Mathieu,Abderrezzak Mesli |
| |
Abstract: | Hydrolysis of the imine function of a series of Schiff bases derived from pyrrole-2-carboxaldehyde and substituted anilines (X = H, p-OCH3, p-OC2H5, p-CH3, p-Cl, p-Br, m-CN, m-NO2, p-NO2) was studied in all of the pH ranges. The hydrolysis curves log kabs (mn?1) = f(pH) were established in buffered aqueous methanol by polarography or amperometry. The shapes of the curves obtained for pH > 5 indicates that N-pyrrolylmethylene-2 anilines hydrolyse according to the same mechanism as N-benzylidene anilines. The particular stability of these products for pH < 5 permits one to obtain complete hydrolysis curves in acid media. A very good Hammett correlation (kobs = + 1,73) has been established from the maxima which appear for strong acidity. This stability is interpreted as due to the specific electron-donating effect of the pyrrole nucleus. The influence of the structural parameter X on the morphology of the curves log kabs = f(pH) and on the hydrolysis mechanism of the imine function is discussed in all of the pH ranges. |
| |
Keywords: | |
|
|