Thermolysis, Photolysis, and Acid Catalysis of an α-(Dimethylamino)azoalkane. Amino Stabilization of a Carbon Radical Center

Article abstract of DOI:10.1021/jo00296a032

The unsymmetrical azoalkane 2-(tert-butylazo)-2-(dimethylamino)propane (7) has been synthesized cleanly by nucleophilic displacement of chloride from the corresponding α-chloroazoalkane 5 with dimethylamine.Thermolysis of 7 in hydrocarbon solvents affords typical radical-derived products and exhibits activation parameters ΔH(excit.) = 26.6 +/- 0.4 kcal/mol and ΔS(excit.) = -6.6 +/- 1.1 eu.Since the thermolysis rate of 7 is 10⁴ faster than that of 1,2-di-tert-butyldiazene, the large stabilization of α-amino radicals is supported.Unusual products were obtained in acetonitrile, suggesting reduction of the azo linkage by 2-(dimethylamino)-2-propyl radicals and cleavage of the resulting hydrazyl radicals.In protic solvents, 7 undergoes acid catalyzed decomposition via tert-butyldiazene as a postulated intermediate.