Kinetic studies of the reactions of substituted phenacyl bromides (YC6H4COCH2Br) with pyridines (XC5H4N) are carried out in acetonitrile at 45.0° C. A biphasic Brønsted plot is obtained with a change in slope from a large (βX≌ 0.65-0.80) to a small (βX≌ 0.36-0.40) value at p K a°= 3.2-3.6, which can be attributed to a change in the rate-determining step from breakdown to formation of a tetrahedral intermediate in the reaction path as the ...
