Cross-interaction Constants in the Nucleophilic Reactions of Carbonyl Compounds Involving a Tetrahedral Intermediate

摘要

Cross-interaction constants, ヱeXY, ヱYZ and ヱXZ are defined using observed rate constant, kN=(k1/k-1)k2=Kk2, for the stepwise carbonyl addition reactions involving the rate-limiting breakdown of a tetrahedral intermediate (T【). Abundant experimental evidence in the literature enables us to determine signs for the three constants for such mechanism, ヱeXY>0, ヱYZ<0 and ヱXZ>0. These are in contrast to those for the concerted SN2 mechanism, ヱXY<0, ヱYZ>0 and ヱ XZ, and provide useful mechanistic criteria. In the light of these criteria, mechanisms of some nucleophilic reactions of carbonyl compounds are re-examined.