Reversible formation of bromonium ions. Preferential reaction of Br- on the Br+ of the bromonium ion produced from the solvolysis of trans-2-bromocyclohexyl triflate in methanol or acetic acid containing added bromide

The trans-2-bromotriflate of cycloherane (4) has been solvolyzed at ambient temperatures in HOAc and MeOH containing varying [Br - ] and in the presence of 0.5 M of a scavenger olefin, cyclopentene. The kinetics of solvolysis of 4 have been determined by observing the rate of change in color of an acid/base indicator that instantly responds to the production of HOTf or HBr. The kinetics show that the rate of solvolysis of 4 at constant ionic strength is independent of [Br - ]. The products of solvolysis of 4 under the various conditions have been determined by quantitative GLPC analysis. In the presence of Br - , the products consisted of the trans 1,2-dibromides and bromosolvates of cyclohexane and cyclopentane