The percentages of migration of the substituted rings in the alkaline rearrangements of 2-, 3- and 7-chlorophenanthraq~ inone-9-C~~ were found to be 83.1, 66.8 and 79.8, respectively. A mechanism for the benzilic acid rearrangement is advanced based on the proposal that the migratory preferences are determined by the initial point of attack by hydroxide ion and not by the intrinsic migratory aptitudes of the aryl groups. Isotope effects of 1.09 and 1.12 ...
