Electrophilic reactions at single bonds. XII. Hydrogen-deuterium exchange, protolysis (deuterolysis), and oligocondensation of alkanes with superacids

Superacid catalysis of light hydrocarbon conversion. Eleventh quarterly report, April 1, 1996--June 30, 1996

“…This carbocation chemistry accounts for the ethane reactivity with FMSZ, being consistent with Olah's results (Olah et al, 1973), except that Olah did not observe autocatalysis, presumably because products were analyzed only following the batch reactor experiment. The behavior suggestive of autocatalysis in ethane conversion was not observed for propane (Cheung et al, 1995A) or n-butane (Cheung et al, 1995ABC).…”

“…At 723 K and 20 kPa alkane partial pressure, the rate of ethane conversion in the presence of FMSZ [4x10-8 mol/(s g)] is lower than that of propane conversion [determined by extrapolating published data (Cheung et al, 1996), 4x10-6 moV(s -g)]. The products formed from ethane [or propane (Cheung et al, 1995A)l at 473 K are nearly the same as those reported (Olah et al, 1973) for reaction in superacid solution.…”

“…Light alkanes in liquid superacids react at temperatures e 7 3 K, giving heavier hydrocarbons via carbenium ion and carbonium ion intermediates (Olah et al, 1973). In the presence of Fe-and Mn-promoted sulfated (FMSZ), propane reacts similarly, being converted largely into butane at 473 K (Cheung et al, 1995A), and nbutane is catalyhcally isomerized and disproportionated even at 298 K Cheung et al, 1995B).…”

“…In the presence of Fe-and Mn-promoted sulfated (FMSZ), propane reacts similarly, being converted largely into butane at 473 K (Cheung et al, 1995A), and nbutane is catalyhcally isomerized and disproportionated even at 298 K Cheung et al, 1995B). The propane product distribution and the high catalytic activity for n-butane conversion suggest superacid chemistry (Olah et al, 1973). Although FMSZ was called a superacid (Lin and Hsu, 1992), the acid strength is still debated (Adeeva et al, 1995;Tabora and Davis, 1995).…”

“…Activation of low-molecular-weight alkanes by superacids at subambient temperatures in solution was investigated by Olah et al (1968Olah et al ( , 1969Olah et al ( , 1973, who demonstrated the involvement of penta-coordinated carbocations (carbonium ions).…”