The reaction of ketone arylhydrazone (1) with nitric oxide affords C1'-nitro azo-compounds (2) in good yields. Products were identified by NMR, IR, MS, and X-ray crystallography. The reaction is assumed to be most likely initiated by an electrophilic addition of NO2 to the carbon atom of the carbon-nitrogen double bond.

Free radicals generated from UV irradiation of simple aliphatic amides in anaerobic and nitric oxide (NO)-saturated liquid mixtures or solutions gave EPR spectra of nitroxides. The application of isotopic effects to EPR spectra and the generation of radicals by transient radical attack on substrate molecules or by photolysing amine or acetoin were used to help identify photochemically produced radicals from the amides. The aliphatic amides used were formamide, acetamide and their N-methyl-or deuteriumsubstituted derivatives. Transient radicals used to attack the amides via hydrogen-atom abstraction were generated from the initiator AIBN or AAPH. The observation of various nitroxides indicates the reactivity of NO for trapping acyl, carbamoyl and other carbon-centered radicals. Possibly mechanistic pathways diagnosed with this trap are proposed.

Stable aminoxyls and an iminoxyl were observed by spin trapping and EPR techniques during the nitrationof coumarins containing a hydroxy group by nitric oxide. The trapped free radicals are deduced to be the resonance stabilized phenoxy-like radicals. The mechanisms for the nitrations are suggested.

4-oxo-2, 2, 6, 6-tetramethylpiperidinyl-1-oxy radical (TEMPO), a nitroxide, oxidized 4-substituted Hantzsch 1,4-dihydropyridines (DHP) under UV irradiation in CH3CN to give aromatic products in good yields. A possible mechanism for the oxidation was suggested.

Epoxide rings of 2,3-epoxy phenyl ketones were cleaved by nitric oxide, affording regioselectively the C-3 ring-opened products, erythro-a-hydroxyl nitrates (2), in a highly syn-selective manner (isolated yield of the erythro products up to 91%). Products were identified by NMR, MS, and X-ray crystallography. The reaction is assumed to be initiated by NO2, unlike a nucleophilic attack.