Parker, Winstein,
and their coworkers have previously established that in the E2C elimination of
trans-2-phenylcyclopentyl p-bromobenzenesulfonate induced by Bu4NCl in
acetone some 9% of the olefinic product is produced
by a syn-elimination.
In view of the current idea that syn-eliminations in solution are assisted by association of
the base with its counterion, the stereochemistry of
the reaction induced by lithium chloride in acetone has been studied. There is
no increase in the amount of syn-elimination, and kinetic analysis reveals that lithium
chloride ion pairs are completely unreactive.
1-Phenylcyclopentene is not produced by rate-limiting attack of chloride ion on
a preformed symmetrical phenonium ion pair. These
results do not serve to distinguish between two alternative models of the E2C transition state.
Kinetic Analysis of Cellobiohydrolase: Quantification of Enzymatic Reaction at a Solid/Liquid Interface Applying the Concept of Surface Density