REACTIONS OF NITRIC-OXIDE AND NITROGEN-DIOXIDE WITH FUNCTIONALIZED ALKENES AND DIENES

Pure nitric oxide does not add to alkenes containing acceptor or donor substituents, or to conjugated dienes, to afford beta-nitrosoalkyl ra dicals. EPR spectra show that reactions are initiated by NO2 addition to carbon-carbon double bonds to produce beta-nitroalkyl radicals whic h combine with nitric oxide to yield beta-nitro-nitroso-compounds. The latter trap other radicals to afford mixtures of aminoxyl radicals an d, where possible, the nitroso-compounds tautomerise to oximes which o xidise to iminoxyl radicals. EPR spectra obtained on reaction of NO-NO 2 mixtures with 2,5-dimethylhexa-2,4-diene have shown the presence of a di-tert-alkylaminoxyl plus a tert,sec-dialkylaminoxyl, providing goo d support for this mechanism. Product analyses have established that 2 -oxo-4-methylpent-3-ene and 1-acetylcyclohexene undergo extensive oxid ative degradation. For enol ethers, reaction with NO-NO2 leads to hydr olysis giving the corresponding carbonyl compound and alcohol, followe d by ketal and ester formation.