The rearrangement of polyhaloalkyl radicals in solution with 1,2-chlorine atom migration

Radicals XCCl₂CYCH₂Z (l; X=Cl,H,F,CH₃; Y=H,CH₃,Cl,Br; Z=Br,Cl,CCl₃,SR) were generated by homolytic addition of addition of various addenda to unsaturated compounds XCCl₂CY=CH₂. Radicals (I) were shown to rearrange in solution into radicals XCCl---CYCl---CH₂Z (II), the latter being more stable than the former. It was found that compounds XCCl₂CBr=CH₂ with X=Cl,CH₃,F could isomerize under the action of initiators of radical processes to compounds XCCl=CClCH₂Br. This isomerization was proved to be of a radical chain character and involves the 1,2-chlorine migration in the intermediate radical XCCl₂CBrCH₂Br (III). The dependence between the structure of starting radicals and their ability to undergo rearrangement in solution has been established and the effect of the nature of addendum on the reaction course investigated. The polyhaloalkyl radicals were arranged in a sequence according to their relative stability.