Classical carbonium ions. Part 14. The lifetime of secondary carbocations in acetic acid

Abstract

Oct-1-ene and cis- and trans-oct-4-enes were treated with p-nitrobenzenesulphonic acid in acetic acid (0.1M) at 25°, when addition of the sulphonic acid and of acetic acid and the direct formation of isomeric octenes were all observed. At a greater rate, the covalent ester underwent acetolysis. The kinetically controlled mixture of products from the olefins was deduced from analyses at varying small degrees of reaction, extrapolating to zero conversion, and correcting for the products known to have been formed via covalent arenesulphonate. The results for cis-oct-4-ene proved that the lifetime of the 4-octyl cation in acetic acid is short compared with the time for rotation around a C₃H₇CH–CH₂C₃H₇ bond.