Alpha- alkyl radical

As the temperature approaches the NTC zone, the reversibility of reaction 2 comes into play and the steady-state concentration of alkyl radicals rises. There is a competing irreversible reaction of oxygen with radicals containing an alpha hydrogen which produces a conjugate olefin (eq. 23). 

Amatore C, Bayachou M, Boutejengout F, Verpeaux J-N (1993) Evidences for the generation of alpha-alkoxy and alpha-alkyl thioalkyl radicals upon reduction of alpha-functionalized... 

Figure 6 shows the uncorrected thermochemical excitation distributions corresponding to energetic substitution reactions at the fluorinated alpha carbon atom positions in CH3CHF2 and CH3CF3. From the left the respective fractional yield segments include the undecomposed primary species and the decomposition products from HF-eliminations, from secondary carbon-carbon scissions to alkyl radicals, and from tertiary radical dissociations. Following these alpha substitution processes product decomposition occurs principally via HF-elimination. 

The reaction described here is probably responsible for the slow decomposition of many oxaziranes at room temperature, 2-fert-Alkyl-oxaziranes are stable at room temperature for unlimited periods radical attack on the a-C-atom of the iV-alkyl group is not possible. By contrast, oxaziranes containing a C—H group which is alpha to the N-atom are unstable at room temperature on keeping they are largely decomposed within a few weeks. 

On heating, migration of a hydrogen atom, alpha to a polyene group, to an alkyl free radical site would also convert a polyene to a polyenyl free radical, a transformation similar to transformation of the allyl free radical described above ... 

N—H deprotonation to form a nitrogen radical is obviously more important than alpha-deprotonation of the pendant alkyl group. Such reactions are reminiscent of the photocatalyzed oxidation of ammonia reported by Pichat and coworkers... 

This process makes some of the alkylation reactions of cyclic ethers at elevated temperatures unsuitable for the preparation of alkylated alpha-cyclic ethers. Ring cleavage of cyclic ethers hardly takes place at room temperature, and thus cyclic ethers can be alkylated under these conditions without undergoing ring cleavage. Once these radicals are produced at room temperature they participate in reactions as cyclic radicals (8, 21,39). 

In the second route an alpha olefin derived from ethylene reacts with hydrogen bromide and a free radical initiator resulting in an alkyl bromide. The alkyl bromide is reacted with dimethylamine providing the desired product [11,12] ... 

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