Toluene ions, decomposition

The intramolecular isotope effect, IH //D, on metastable ion decomposition of benzene to lose a hydrogen atom has been reported as 1.9 [59]. A tandem magnetic deflection/ion cyclotron resonance (ICR) instrument has been used to study isotope effects on metastable ion decompositions of benzene, toluene and anisole in some detail [779]. 

The information on the characteristic ion decomposition times t < 10 s is rather limited. Experiments using ionization of complex molecules by electron impact in a relatively strong electric field [214] show that most ions in the mass spectra of ethylene, ethane, and hexane are formed in less than 10 s. However, fragment ions formed in a time > 10 s are observed in the mass spectra of hexane and toluene in considerable amounts. The characteristic decomposition times of and other ions [214, 461] include ... 

Howe, I. McLafferty, F.W. Unimolecular Decomposition of Toluene and Cyclohep-tatriene Molecular Ions. Variation of the Degree of Scrambling and Isotope Effect with Internal Energy. J. Am. Chem. Soc. 1971,93,99-105. 

A major problem associated with such autoxidations is that they are largely indiscriminate, i.e. they exhibit poor chemo- and regio- selectivities. They are synthetically useful only with relatively simple substrates containing one reactive position, e.g. the oxidation of toluene to benzoic acid or p-xylene to terephthalic acid. Any catalytic oxidation has to complete with this non-catalytic pathway. Moreover, the situation is further complicated by the fact that transition metal ions also catalyze autoxidations by mediating the decomposition of trace amounts of hydroperoxides into chain-initiating radicals, via the so-called Haber-Weiss mechanism ... 

McLafferty, F. W., and Howe, I. (1971). Metastable ion characteristics. XVII. Unimolecular decomposition of toluene and cycloheptatriene molecular ions. Variation of the degree of scrambling and isotope effect with internal energy. J. Am. Chem. Soc. 93, 99-105. 

The apparent symmetry of subsequent decomposition (loss of C2H2) of the C7H7 ion from toluene was best accommodated by a tropylium... 

Chloroformates are sufficiently reactive to undergo decomposition in solution. A four-centered S yl mechanism was originally suggested however, subsequent kinetic studies favor an initial decomposition to ions. The first-order decomposition of substituted a-phenethyl chloroformates was studied in dioxane and toluene by carbon dioxide evolution , viz. 

---