Cyclic Azo Dioxides. Synthesis and Properties of Bis(o-nitrosobenzyl) Derivatives

Article abstract of DOI:10.1021/jo01311a009

Several cyclic azo dioxides have been prepared by oxidation of the corresponding diamines with sodium tungstate-hydrogen peroxide in ethanol-water: 4 (related to o,o'-dinitrosobibenzyl), 8 (related to bis(o-nitrosobenzyl)ether), 14 (related to bis(o-nitrosobenzyl)amine), 13 (the trifluoroacetate salt of 14), 12a and 12b (the N-carbomethoxy and N-carbo-tert-butoxy derivatives of 14).In solution the azo dioxides are in equilibrium (K_e) with the corresponding dinitroso forms: K_e increases with decreasing polarity of solvent and with increasing temperature.For azo dioxide 4 in dioxane at 25 deg C K_e = 0.18, Δ H⁰ = 7.09 +/- 0.47 kcal mol^-1, and Δ S⁰ = 20.4 cal mol^-1 deg^-1.The azo dioxides decompose at elevated temperatures (>100 deg C); azo dioxide 14 is converted to 2-(o-nitrosobenzyl)indazole (15) in refluxing methylene chloride.