Some cyclic compounds derived from 6,6'-dichlorodipheric acid

Abstract

6,6'-Dichlorodihenic Acid was prepared by an easier route than that of Christie, James and Kenner. The acid was optically resolved, and the diol and bisbromomethyl compound prepared from the dextrorotatory enantiomer. The diol was converted into the oxepin and the bisbronoraethyl used to prepare the azepinium bromide; the circular dichroism spectra of these products were measured. Measurements of racemisation rates were made, and the oxepin and azepinium bromide were found to have activation energies of 34.8 and 38.3 Kcal/mole respectively. Racemic azepinium bromide was subjected to Hofmann degradation conditions and the products investigated. The neutral fraction gave a small yield of 4,5-dichlorophenanthrene, and the basic part gave four products; of these the main product was the expected dichloro'9-dimethylamino-dihydrophenanthrene; a second product proved to be an unbridged amine. Traces of other amines were found in different experiments and the nature and ratio of the products would appear to be very sensitive to the conditions. 4,5-Dichloro-9,10-dihyilrophenanthrene was prepared in small yield from dichlorobisbromomethylbiphenyl. The ultraviolet spectra of the bridged biphenyls and the infrared spectra of most compounds are recorded and discussed.