for a recent elaboration of this scheme.(14) This value is close to that observed for near Lim solvolyses (e.g., for ferf-BuCl in water the value is 1.37 per CDs). See E. R. Thornton, "Solvolysis Mechanisms," Ronald Press, New York, N. Y., 1964, for a discussion.(15) As a corollary it should be noted that the elimination reactions which accompany these ion-pair Sn2 reactions no doubt occur by ionpair E2 mechanisms. In our opinion, ion-pair E2 mechanisms, rather than concerted E2 mechanisms, are responsible for the second-order components which commonly appear in the rate expressions when high concentrations of lyate ion are introduced into solvolysis reactions of tertiary halide (or like) substrates.

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