Behaviour of C6Cl8 isomers upon pyrolysis and electron impact in a mass spectrometer

Abstract

Mass-spectral examination of five C₆Cl₈ isomers has clarified some aspects of their chemistry on pyrolysis and electron impact. Two isomers having the fulvene skeleton are thermally dechlorinated to hexachlorofulvene at 250° and about 5 × 10^–2 torr; two linear isomers and octachloro-1,2-dimethylenecyclobutane are thermally stable under these conditions. Under electron impact, the cyclic isomers give ionic product distributions closely resembling that obtained from hexachlorofulvene; those from the linear iosmers favour hexachlorobenzene. Prominent features in the spectra of the cyclic isomers can be accounted for by differences in stabilisation associated with conjugation of the olefinic bonds, and by a preference for cleaving allylic bonds.