Hydrolysis of Imines. 4. Micellar Effects upon the Spontaneous Acid, Base, and Copper(II) Ion Induced Hydrolysis of N-Salicylidene-2-aminothiazole and N-Salicylidene-2-aminopyridine

Article abstract of DOI:10.1021/jo00216a019

The rate of hydrolysis of the title imines in alkaline medium was strongly retarded by the cationic surfactant cetyltrimethylammonium bromide (CTAB) even though both reactants (i.e., the phenoxide forms of the imines and OH^-) might be bound to the micellar pseudophase.Anionic surfactant sodium dodecyl sulfate (SDS) did not affect the hydrolysis rate at pH>12.In mild alkaline medium (pH 9.2) both surfactants retarded the hydrolysis reaction of the imines, the effect being much stronger in the case of CTAB.Inhibition was attributed to selective partitioning of the phenol form of the imines into the micellar pseudophase of SDS, while both the phenol and phenoxide forms of the imines were found to be adsorbed in the micellar pseudophase of CTAB, where these undergo hydrolysis much slower than in the aqueous pseudophase.In the range pH 5.08-7.06, small acceleration in the rate of hydrolysis of the thiazole imine by SDS was observed.There was virtually no kinetic effect of SDS on the copper(II)-induced hydrolysis of the thiazole imine.Strikingly the copper(II)-N-salicylidene-2-aminopyridine chelate (CuL⁺) was found to undergo faster acid-catalyzed hydrolysis of the aldimine linkage in the micellar pseudophase of SDS than in the aqueous phase.