ION-RADICAL MECHANISMS OF THE ISOMERIZATION OF ALKANES ON ACID CATALYSTS

In the conversion of C-13-labelled pentanes in the presence of alumini um halides and superacids, the distribution of the label in the isomer ization products fails to comply with any of the existing schemes of t his reaction within the framework of classic ionic mechanisms. Further more, when the process was carried out in a deuterium atmosphere, by m ass-spectral analysis it was established that molecular hydrogen is no t included in the general scheme of the isomerization process. An alte rnative mechanism of catalytic isomerization of alkanes in the presenc e of acids is examined, assuming that the activation of a substrate mo lecule occurs not as a result of detachment of a hydride ion, but by i ts single-electron oxidation with the formation of cation-radicals as primary intermediates. (C) 1997 Elsevier Science Ltd. All rights reser ved.