6751 constant. The plots remained linear until 2.5-3.0 of the four protons were exchanged, after which the rate gradually dropped off, presumably due to isotope effects. The rate constants were reproducible within 5 %. (Y
Acknowledgment. This investigation was supported by Public Health Service Research Grant No. CA-0735 1 from the National Cancer Institute.
Favorskii Reactions. 11. Evidence Concerning the Nature of Halide Release F. G. Bordwell and Richard G. Scamehorn' Contribution f r o m the Chemistry Department, Northwestern University, Evanston, Illinois 60201. Received M a y 4 , 1968 Abstract: The rates and products of the reaction of various meta- and para-substituted a-chlorobenzyl methyl ketones (ArCHC1COCH3)with sodium methoxide in methanol have been studied. For the parent compound, PhCaHC1COCa'H3,7 9 x of deuterium exchange at C-a' occurred prior to reaction. The yield of Favorskii ester increased from 9% at 0" with
