Activation, isomerization and H/D exchange of small alkanes in triflic acid

In contrast with the HF/SbF5 superacid system and despite its strong acidit y (H-0 = -14.1), CF3SO3H is not able to protonate reversibly small alkanes. At room temperature propane and n-butane do not exchange their hydrons for deuteriums with deuterated triflic acid. The H/D exchange occurring betwee n isobutane and the CF3SO3D acid is regiospecific as observed in weaker aci ds such as D2SO4 or solid acids such as sulfated zirconia or zeolites. In t he same way, the formation of C-5 alkanes during C-4 isomerization is indic ative of a classical bimolecular process, in the presence of carbon monoxid e, isomerization as well as H/D exchange are suppressed due to chemical tra pping of the carbenium intermediates.