Thermal and photochemical decomposition pathways of trinitromethylarenes .2. The effects of ethanol on the photolysis reactions of some alkoxy- and dialkoxyarenes in the presence of tetranitromethane. Enhancement of adduct and trinitromethyl substitution product formation

The photolysis of the charge transfer (CT) complex of tetranitromethane 1-methoxynaphthalene, 1,4-dimethoxybenzene, 1,2-dimethoxybenzene 1,2-methylenedioxybenzene or 2-methylanisole is reported for dichloromethane acetonitrile, dichloromethane-ethanol and acetonitrile-ethanol solvent systems, The effects of adding ethanol (8% v/v similar to 1.4 mol dm(-3)) to dichloromethane or acetonitrile as reaction solvents include: (i) the stabilization of alkoxytrinitromethylarenes, thus reducing their normal tendency for decomposition according ArC(NO2)(3) -->ArCOOH -->ArNO2, (ii) a reduction in the nucleophilicity of trinitromethanide ion, and (iii) changes in the regioselectivity of trinitromethanide ion attack on the radical cations of alkoxy-aromatic compounds away from attack ipso to the alkoxy substituent. Adducts are also stabilized, as shown by the photolysis of the CT complex of 1,4-dimethoxybenzene-tetranitromethane in dichloromethane-ethanol (8% v/v) gives the epimeric 1,4-dimethoxy-3-nitro-6-trinitromethylcyclohexa-1,4-dienes and 1,4-dimethoxy-2-trinitromethylbenzene, in addition to 1,4- dimethoxy-2-nitrobenzene. The adducts are detected also among the products of photolysis reactions in neat dichloromethane or acetonitrile.