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 crystal structure of chlorocarbon 1 are reported, as well as that of the much less strained heptachloro-7-(dichloromethyl)naphthalene (10). The 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 within the aromatic ring in 11 has been estimated by a semiempirical AM1 method.