| Abstract
| - The alkaline hydrolysis of the title esters, possessing three conjugated π units between the internalnucleophile (the hydroxyl group) and the reaction center, follows an E1cB mechanism involvingthe participation of an “extra extended” p-oxo azoketene type intermediate. For the hydrolysis ofthe 2,4-dinitrophenyl ester kinetic data, activation parameters and trapping of the intermediateare consistent with a dissociative pathway carrying the reaction flux. The effect of the leavinggroup variation on reactivity agrees with the proposed mechanism, and the existence of anintermediate is also supported by diode array stopped-flow experiments. The presence of sp2 nitrogenatoms in the conjugated backbone is beneficial to the dissociative mechanism.
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