The Mechanism and Stereochemistry of Chlorination of Some 2,4-Dichloro-6-methylphenols; X-Ray Crystal Structures of Some Polyhalo Ketones

The additions of chlorine to the 2,4,6-trichloro-5,6-dimethyl- (7a) and 2,4,6-trichloro-6-methyl- (7b) cyclohexa-2,4-dienones to give pentachlorocyclohexenones (8)-(11) are described. The stereochemistry of some of these additions has been determined from structural studies of the chlorination products of the 2,4-dibromophenols (12). X-Ray crystal structure determinations are reported for compounds (11b), (18), (20) and (23).