Reactions of arylnitroso oxides with substituted styrenes: Kinetics and products

The kinetics of the reactions of phenylnitroso oxide and 4-CH₃O- and 4-Cl-phenylnitroso oxides with a series of substituted styrenes (4-X-C₆H₄-CH=CH₂; X = H, CH₃O, Cl, CN) in acetonitrile at 22 ± 2°C was studied using the flash photolysis technique. It was shown for 4-CH₃O-C₆H₄NOO as an example that only the trans isomers of the nitroso oxides are involved in the reaction. There is a linear correlation between the logarithm of the rate constant and the electronic properties of the substituent in the nitroso oxide aromatic ring on the Hammett scale: ρ = 2.3 ± 0.3 (r = 0.993) for 4-CH₃O-styrene ρ = 2.03 ± 0.07 (r = 0.995) for styrene, and ρ = 1.77 ± 0.05 (r = 0.9996) for 4-Cl-styrene. Both the electron-donating and electron-withdrawing substituents in the aromatic ring of styrene increase its reactivity toward a given nitroso oxide. An analysis of the products of phenyl azide photooxidation in the presence of styrene showed that the product of phenylnitroso oxide 3+2]cycloaddition to the double bond of the olefin decomposes into benzalaniline and carbonyl oxide.