Hydrogen atom transfer from toluene

Oxidations of arylalkanes by "Bu4NMn04 in toluene solvent led to the conclusion that rate-limiting hydrogen atom transfer from the substrate to a permanganate oxo group is consistent with all of the experimental evidence [69a] ... 

Srivastava et al. showed that the parent nitrenium ion is capable of adding to simple aromatics such as benzene, toluene and anisole (91) to give aniline derivatives (92a-c, Fig. 13.47). Unfortunately, these reactions give a distribution of regio-isomers as well as products derived from competing hydride and/or hydrogen atom transfer. 

Essentially no incorporation of deuterium label was observed when the same reaction was carried out in toluene-dg. Since the formation of more than one equivalent of CO(n) hydroxide requires the transfer of hydrogen atoms, we hypothesized that the mechanism of this transformation involved the formation of a dinuclear p-peroxo complex, followed by rapid cleavage of the 0-0 bond and hydrogen atom abstraction from the Tp-ligand. The inferred activation of the primary C-H bonds of the rm-butyl groups of the ligand requires a highly reactive species thus the "activation" of O2 seems to have been accomplished. 

Addition of 0- to double bonds and to aromatic systems was found to be quite slow. Simic et al. (1973) found that O- reacts with unsaturated aliphatic alcohols, especially by H-atom abstraction. As compared to O, HO reacts more rapidly (by two to three times) with the same compounds. In the case of 1,4-benzoquinone, the reaction with O consists of the hydrogen double abstraction and leads to the 2,3-dehydrobenzoquinone anion-radical (Davico et al. 1999, references therein). Christensen et al. (1973) found that 0- reacts with toluene in aqueous solution to form benzyl radical through an H-atom transfer process from the methyl group. Generally, the O anion-radical is a very strong H-atom abstractor, which can withdraw a proton even from organic dianions (Vieira et al. 1997). 

Christensen and co-authors (1973) found that O reacts with toluene in aqueous solution to form benzyl radical through an H-atom-transfer process from the methyl group. In general, the O- anion radical is a very strong hydrogen atom abstractor, which can withdraw a proton even from organic dianions (Vieira et al. 1997). 

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