PHOTOCHEMICAL NITRATION BY TETRANITROMETHANE .39. THE PHOTOLYSIS OF TETRANITROMETHANE WITH 2,8-DIMETHYL-DIBENZOFURAN AND 1,3,7,9-TETRAMETHYL-DIBENZOFURAN

The photolysis of the charge transfer complex of 2,8-dimethyldibenzofu ran in dichloromethane gives 2,8-dimethyl-3-trinitromethyldibenzofuran (11) and 2,8-dimethyl-3-nitrodibenzofuran (12) as the major products, with minor amounts of 2,8-dimethyl-4-nitrodibenzofuran (13) and the 4 -hydroxy-3-trinitromethyl adduct 14. In 1,1,1,3,3,3-hexafluoropropan-2 -ol the yield of the 3-trinitromethyl compound 11 is much reduced, and the adduct 14 is not detected. Similar photolysis of 1,3,7,9-tetramet hyldibenzofuran gives predominantly 1,3,7,9-tetramethyl-2-nitrodibenzo furan (15) accompanied by the epimeric -1-nitro-4-trinitromethyl-1,4-d ihydrodibenzofurans 16 and 17. For reactions in dichloromethane contai ning trifluoroacetic acid (0.8 M), or in 1,1,1,3,3,3-hexafluoropropan- 2-ol, adducts 16 and 17 are not seen among the products and the 2-nitr oarene 15 is close to the exclusive reaction product.