Cleavage products, molecular yields

The a-cleavage in molecular ions of ketones, amines, ethers and similar functionalized compounds yields specific cleavage products of high importance for structure elucidation. Analogous behavior is observed in the mass spectra of phenylal-kanes. [49]... 

Figure 16 Molecular structures of a thymine dimer (TT) model compound and of its oxidative cleavage products. Here bimolecular oxidation of the cis-syn 1,3-dimethyl-thymine dimer (DMTADMT) yields two 1,3-dimethylthymine monomers (DMT).

This reaction has often reached explosive proportions in the laboratory. Several methods were devised for controlling it between 1940 and 1965. For fluorination of hydrocarbons of low (1—6 carbon atoms) molecular weight at room temperature or below by these methods, yields as high as 80% of perfluorinated products were reported together with partially fluorinated species (9—11). However, fluorination reactions in that eta involving elemental fluorine with complex hydrocarbons at elevated temperatures led to appreciable cleavage of the carbon—carbon bonds and the yields invariably were only a few percent. 

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