Dimethylamino radical, from photolysis

Although neutral dialkyl ami no radicals generally do not add to simple alkenes it was possible to observe some addition of dimethylamino radicals to styrene and a-methylstyrene (48). Photolysis of tetramethy1-2-tetrazene (TMT) in cyclohexane, at room temperature, in the presence of a-methylstyrene resulted in the formation of small but reproducible yields of addition products. The bulk of the amino radicals were consumed in the formation of tetramethylhydrazine and dimethyl amine. The relative rate of formation of the adducts from substituted a-methylstyrenes were correlated by the Hammett equation yielding a p = +0.69 + 0.03 (corr. coeff.. 99). This result indicates that the dimethylamino radical behaves like a nucleophile in addition reactions i.e. the styrenes substituted by electron attracting substituents reacted more rapidly than the electron rich styrenes. This result is in marked contrast to that obtained for dimethylamino radicals coordinated by zinc chloride (48). These... 

A method was devised to determine extinction coefficients of radicals. A flash photolysis unit with filters to confine irradiation to a spectral region where only biimidazoles absorbed was utilized to generate radicals whose initial absorbance was recorded photographically from an oscilloscope. In the same cell another solution was then photolyzed as above. This second solution contained an identical concentration of biimidazole to the first plus leuco Crystal Violet dye, tris-(4-dimethylamino-phenyl) methane, and toluenesulfonic acid. The absorbance of dye produced by oxidation of leuco dye by was observed at an unobstructed wavelength. The extinction of the dye at this wavelength in this medium was determined experimentally. The stoichiometry of radical attack on dye was and the quantum yield of this reaction under... 

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