PHOTOCHEMICAL NITRATION BY TETRANITROMETHANE .8. ISOLATION, X-RAY STRUCTURAL-ANALYSIS AND CHEMICAL-PROPERTIES OF A VICINAL NITRO TRINITROMETHYL ADDUCT FROM FLUORANTHENE

The photolysis of a dichloromethane solution of fluoranthene and tetranitromethane by light with cut-off at lambda < 435 nm gave a mixture of nitro/trinitromethyl adducts (almost-equal-to 10%) and nitrofluoranthenes (almost-equal-to 60%). One of the adducts could be isolated and proved to be a vicinal one, trans-2-nitro-3-trinitromethyl-2,3-dihydrofluoranthene (1), as demonstrated by an X-ray crystallographic analysis. Adducts were formed in acetonitrile too, but the adduct yield was smaller. Adduct 1 was stable for many days in dichloromethane but slowly (tau1/2 about 19 h) eliminated nitroform to give 2-nitrofluoranthene in acetonitrile, whereas added hindered or unhindered bases strongly accelerated the reaction in both dichloromethane and acetonitrile. Under GLC conditions 1 analyzed as 2-nitrofluoranthene. The spin adduct of trinitromethyl radical and alpha-phenyl-N-tert-butylnitrone (PBN) was formed and detected by EPR spectroscopy in low concentration and persisted for a long time when 1 and PBN were kept in dichloromethane solution.