Simple and practical halogenation of arenes, alkenes and alkynes with hydrohalic acid/H2O2 (or TBHP)

A simple protocol for the halogenation of arenes utilizing a combination of aqueous hydrogen peroxide (34 %) or terl-butylhydroperoxide (70 %) and hyd rohalic acid is presented. A similar procedure of oxyhalogenation involving the in situ generation of positive halogen reagents is applied for the pre paration of vicinal trans-dibromoalkanes and dichloroalkanes from alkenes. The reaction of alkenes with a combination of hydrochloric acid and hydrobr omic acid with hydrogen peroxide gave a mixture of 1-bromo 2-chloro alkanes and 1,2-dibromoalkanes. Oxidative bromination of alkynes is also reported under similar conditions. (C) 1999 Published by Elsevier Science Ltd. All r ights reserved.