PHOTOCHEMICAL NITRATION BY TETRANITROMETHANE .23. ADDUCT FORMATION INTHE PHOTOCHEMICAL-REACTION OF 1,3-DIMETHYLNAPHTHALENE - STERIC EFFECTS AND THE REGIOCHEMISTRY OF TRINITROMETHANIDE ION ATTACK ON THE RADICAL-CATION OF 1,3-DIMETHYLNAPHTHALENE

The photolysis of 1,3-dimethylnaphthalene with tetranitromethane in di chloromethane at 20 degrees C gives adducts (total 50%) including 5,7- dimethyl-r-2-nitro-t-1-trinitromethyl-1, 2-dihydronaphthalene 7, -1-ni tro-t-4-trinitromethyl-1,4-dihydronaphthalene 8 and its epimer 10, nit ro cycloadduct 9, yl-t-2-trinitromethyl-1,2-dihydronaphthalen-r-1-ol 1 1, hydroxy cycloadduct 12, and -2-nitro-t-1-trinitromethyl-1,2-dihydro naphthalene 13, and aromatic substitution products (total 50%) includi ng 6,8-dimethyl-2-trinitromethylnaphthalene 14, 5,7-dimethyl-1-trinitr omethylnaphthalene 15 and 2,4-dimethyl-1-nitronaphthalene. The nitro-t rinitromethyl adduct 7 undergoes slow nitro-alkene cycloaddition to gi ve the second nitro cycloadduct 17. The mode of formation of these pro ducts is discussed with particular reference to the regiochemistry of attack of trinitromethanide ion on the radical cation of 1,3-dimethyln aphthalene. Photolysis of 1,3-dimethylnaphthalene-tetranitromethane in dichloromethane containing trifluoroacetic acid gives 2,4-dimethyl-1- nitronaphthalene 16 and the dehydrodimer, 2,2',4,4'-tetramethylbinapht halene 22. X-Ray crystal structures are reported for adducts 8-10 and 17.