THERMAL AND PHOTOCHEMICAL DECOMPOSITION PATHWAYS OF TRINITROMETHYLARENES .2. THE EFFECTS OF ETHANOL ON THE PHOTOLYSIS REACTIONS OF SOME ALKOXYARENES AND DIALKOXYARENES IN THE PRESENCE OF TETRANITROMETHANE - ENHANCEMENT OF ADDUCT AND TRINITROMETHYL SUBSTITUTION PRODUCT FORMATION

The photolysis of the charge transfer (CT) complex of tetranitromethan e 1-methoxynaphthalene, 1,4-dimethoxybenzene, 1,2-dimethoxybenzene 1,2 -methylenedioxybenzene or 2-methylanisole is reported for dichlorometh ane acetonitrile, dichloromethane-ethanol and acetonitrile-ethanol sol vent systems, The effects of adding ethanol (8% v/v similar to 1.4 mol dm(-3)) to dichloromethane or acetonitrile as reaction solvents inclu de: (i) the stabilization of alkoxytrinitromethylarenes, thus reducing their normal tendency for decomposition according ArC(NO2)(3) -->ArCO OH -->ArNO2, (ii) a reduction in the nucleophilicity of trinitromethan ide ion, and (iii) changes in the regioselectivity of trinitromethanid e ion attack on the radical cations of alkoxy-aromatic compounds away from attack ipso to the alkoxy substituent. Adducts are also stabilize d, as shown by the photolysis of the CT complex of 1,4-dimethoxybenzen e-tetranitromethane in dichloromethane-ethanol (8% v/v) gives the epim eric thoxy-3-nitro-6-trinitromethylcyclohexa-1,4-dienes and 1,4-dimeth oxy-2-trinitromethylbenzene, in addition to 1,4- dimethoxy-2-nitrobenz ene. The adducts are detected also among the products of photolysis re actions in neat dichloromethane or acetonitrile.