PERCHLORO-2-METHYLNAPHTHALENE, A NOVEL CHLOROCARBON WITH A HIGHLY STRAINED STRUCTURE

Perchloro-2-methylnaphthalene (1) is prepared in a two-step reaction: treatment of 2H-heptachloronaphthalene (3) with CCl3F in the presence of AlCl3 yields heptachloro-7-(trifluoromethyl)naphthalene (4), which in CS2 and with an excess of AlCl3 affords 1. The spectra and X-ray cr ystal structure of chlorocarbon 1 are reported, as well as that of the much less strained heptachloro-7-(dichloromethyl)naphthalene (10). Th e unusual UV spectrum, due to the distortion of the aromatic rings, is also discussed. The reduction of 1 with copper wire to give perchloro (2-naphthyl)methyl radical (11) has been studied by means of electron spin resonance. Steric inhibition to resonance of the free electron wi thin the aromatic ring in 11 has been estimated by a semiempirical AM1 method.