Protium–deuterium exchange of cyclic and acyclic alkenes in dilute acid medium at elevated temperatures

A modification of the high temperature – dilute acid (HTDA) method for deuterium labelling of aromatic compounds has been applied to the H–D exchange of a number of cyclic and acyclic alkenes. Cyclopentene, cyclohexene, cyclododecene, and tetramethylethylene have been completely exchanged in excellent yield. 1-Methylcyclopentene and 1-methylcyclohexene have also been perdeuterated and cycloheptene and cyclooctene partially labelled but require spinning band distillation or preparative glpc for separation from rearrangement products. A variety of C5–C8 acyclic alkenes have also been treated under HTDA conditions.