ADDITION OF ORGANOLITHIUM REAGENTS OF 1,1-DIPHENYLETHYLENE IN TETRAHYDROFURAN . KINETICS AND STRUCTURE-REACTIVITY RELATIONSHIP

Kinetic studies of the addition of six organolithium reagents to 1,1-diphenylethylene in tetrahydrofuran solution show the reaction to be first order in DPE but of variable order in organolithium reagent. Benzyllithium and allyllithium follow approximate first-order dependence, methyllithium and vinyllithium show approximate 0.25-order dependence, and phenyllithium shows 0.66-order dependence. Reaction rates of these species were obtained by monitoring the increase in the visible spectrum of the respective adduct. A competitive technique was required to evaluate the rate of adduct formation with n-butyllithium. These latter data are not extensive, but a fractional reaction order, i.e., 0.25, is indicated. The result of the differences in effective reaction order is that the relative reactivity of these species is strongly concentration dependent. Comparative reactivities in this series differ by approximately four powers of ten. The reactivity order of these organolithium species is seen to depend on factors other than the foreseeable basicities, e.g., differences in aggregation behaviors and ion-pair interactions. © 1969, American Chemical Society. All rights reserved.