Olefins nitroxyl radical reactions

Phosphinyl radicals, obtained by hydrogen abstraction from dialkyl phosphites, have been trapped with t-nitrosobutane and the resultant nitroxyl radicals examined by e.s.r, The reaction of phosphinyl radicals, e.g. (5) and (6), with olefins has been shown to occur with retention of configuration at phosphorus. " These radicals have also been postulated as intermediates in the reactions of dialkyl disulphides and diaryl disulphides with phosphinates. " From the reaction of diphenyl disulphide... 

Under thermal conditions, hydroxylamine ethers can reversibly decompose (Reaction 15). The radicals formed disproportionate to eliminate olefins and yield hydroxylamine (Reaction 16). In the presence of sufficiently effective acceptors of alkyl radicals (e.g., oxygen), the reaction rate of peroxy radical formation is much higher than that of hydroxylamine formation. Thus, in the process of polymer photooxidation, nitroxyl radicals regenerate and can break multiple oxidative chains. 

M (por)(olefin)] Intermediates in Reactions of [M (por)(alkyls)J With Nitroxyl Radicals... 

The phenomenon of selective inhibition of chain reactions was for the first time explained by N.M. Emanuel, E.A. Bliunberg, L.A. Tavadyan and S.A. Maslov [11]. It was experimentally observed in a mnnber of liquid-phase oxidation reactions. Thus, introducing small amoimts of an additive stable nitroxyl radical (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, TEMPOL) and a heterogeneous inhibitor (WSc2) makes it possible to increase the selectivity of formation of imsaturated acids and epoxides in chain oxidation reactions of a-methylacrolein, 2-ethylhexenal, as well as co-oxidation of aldehydes and olefins (Table 5.1). 

---