Transmission of substituent effects in pyridines. Part III. A comparison of the pyridine nitrogen and aromatic nitro-groups by ester hydrolysis

Abstract

The rates of alkaline hydrolysis of three methyl methoxypyridinecarboxylates are compared with those of the analogous ethyl methoxynitrobenzoates. Methyl 6-methoxypicolinate and methyl 2-methoxyisonicotinate hydrolyse at ca. half the rate predicted from additive substituent effects, while methyl 4-methoxypicolinate reacts at the calculated rate. These results are interpreted in terms of electronic interactions between the methoxy-group and ring nitrogen. Differences from these results in the corresponding ethyl methoxynitrobenzoates are ascribed to effects associated with twisting of the nitro-group.