The aminolysis of aryl chlorothionoformates (7, YC6H4OC (S) Cl) with anilines (XC6H4NH2) in acetonitrile at 5.0° C has been investigated. The rates are slower than those for the corresponding reactions of aryl chloroformates (6, YC6H4OC (O) Cl). This rate sequence is a reverse of that for alkyl chloroformates (1-4) in water, for which rate-limiting formation of a tetrahedral intermediate, T±, is predicted. On the basis of the large negative cross- ...
