Nucleophilic Substitution Reactions of 1-Halogeno-4-COR-2-nitrobenzenes and 1-Halogeno-6-COR-2-nitrobenzenes with Sodium Benzenethiolate and Piperidine. Can an "Inverted Built-In Solvation" Be Responsible for the Peculiar Activation by an o-Carboxamido Group in S(N)Ar Reactions with an Anionic Nucleophile?

A kinetic study of the title reactions has allowed an interpretation of the higher efficiency of an o-carboxamido group with respect to an o-carbomethoxy group in activating the benzenethiolate-dehalogenation reactions in methanol (k(CONH)()2/k(CO)()2(Me) 2.2-3.0) as due to an interaction between the anionic nucleophile and the hydrogen atoms of the carboxamido group.