Selective electrophilic activation of alkanes

One major drawback for the direct use of alkanes as chemicals is their chemical inertness toward most of the usual reagents. For this reason, costly, large-scale refinery operations such as catalytic reforming and vapocracking are needed, which necessitate the use of noble metal catalysts and/or high temperature to activate the strong C-H and C-C bonds and yield the primary chemical building blocks such as ethylene, propylene, butadiene, benzene, toluene, and xylene. In response to the challenge to use more economically a larger share of alkanes, and increasing number of research groups are working on the activation functionalization processes of the saturated hydrocarbon C-H bond. The goal is to overcome smoothly and selectively the chemical inertness of the starting (paraffinic) material. A book and special issue have been published recently on this subject. Protonated alkanes are reaction intermediates in superacid-catalyzed protolysis. Protonation occurs on all C-C and C-H [sigma]-bonds independently of the further reactivity of the protonated alkane as confirmed by using [sup 2]H labeled superacids. Direct and selective C-H bond protolysis is limited to tertiary alkanes whereas linear alkanes undergo less selective C-C bond cleavage. 31 refs., 3 figs.