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Anilinolysis of Picryl Benzoate Derivatives in Methanol: Reactivity, Regioselectivity, Kinetics, and Mechanism

Authors


Correspondence to: Mahmoud F. Ibrahim; E-mail: mfawzy59@yahoo.com.

ABSTRACT:

The reaction of picryl benzoate derivatives 1a–g with aniline in methanol proceeds through CO[BOND]O and Ar[BOND]O bond cleavage pathways. Furthermore, the reactivity of these esters toward anilinolysis is correlated to the energy gap between highest occupied molecular orbital aniline and lowest unoccupied molecular orbital of each ester. The regioselectivity of acyl[BOND]oxygen versus aryl[BOND]oxygen cleavage is also discussed. The overall rate constants ktot split into kCO[BOND]O (the rate constant of acyl-oxygen cleavage) and kAr[BOND]O (rate constant of aryl-oxygen cleavage). The CO[BOND]O bond cleavage advances through a stepwise mechanism in which the formation of the tetrahedral intermediate is the rate-determining step. The Ar[BOND]O bond cleavage continues through a SNAr mechanism in which the departure of the leaving group from the Meisenheimer complex occurs rapidly after its formation in the rate-determining step.

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