REAL CARBENIUM-ION MECHANISM OF OLEFIN AND ALCOHOL TRANSFORMATIONS INSULFURIC-ACID

The conjugated polymerization of pentene-1 in 95% sulfuric acid was st udied in situ by C-13 NMR spectroscopy. The results of the study point to the carbenium-ion reaction mechanism, which involves the formation of sulfuric acid esters and their further heterolytic dissociation to yield aliphatic carbenium ions. The steady-state concentration of the se ions was low, which made their analysis by C-13 NMR spectroscopy ha rdly possible. On the contrary, the cationic olefin polymerization in 60-70% sulfuric acid was found to occur via the formation of oxonium i ons rather than carbenium ions.