Rates of Deuterium Exchange from Deuterated M-Dichlorobenzene in Methanolic Sodium Methoxide Solutions

Rate constants were determined for deuterium exchange fro.m m-diohlorobenzene-2-d in 0.5 to 5 molar methanolic sodium methoxide solutions at 80.3° C. Since this is a base catalyzed reaction, an attempt was made to correlate the rates with the appropriate basicity parameter. The methoxide ion concentration was an entirely inadequate parameter since a plot of log k1 against log [OCH3] showed a linear variation with a slope of 2.40. Significant correlation would demand a slope of unity. The D0 function provided correlation for all kinetic runs except those of sodium methoxide concentrations higher than 4.05 M. The H_ function failed to provide adequate correlation for those kinetic runs made at base concentrations higher than 3.6M. The lack of correlation with either of these functions at high base concentrations is attributed to inaccuracies in the determination of D0 at these concentrations