Conversion of Phenanthrols to the Corresponding Chloro- and Bromophenanthrenes and Their Dipole Moment Measurements

Abstract

2-Phenanthrol (0.1 mol) was added to a slurry of dichlorotriphenylphosphorane in CCl4obtained from O.11 mol of triphenylphosphine and 0.11 mol of chlorine. After the mixture was stirred for 30 min at 70 °C, the solvent was removed, and the residue was further heated at 320-340°C until evolution of hydrogen chloride ceased. Extraction of the mass by hexane gave crude 2-chlorophenanthrene in a yield of 59%, mp 85-85.5 °C after recrystallization from ethanol. Bromination was carried out similarly. All five isomeric phenanthrols and some monochloro- and monobromophenanthrols were converted to the corresponding halophenanthrenes and the dipole moments of the latter were measured. The results are given in Table 1.1-Chloro- and 1, 3(?)-dichloro-2-phenanthrols also were newly prepared by chlorination of 2-phenanthrol as shown in Scheme (2).