KINETICS OF PROTON TRANSFER FROM ALPHA CARBON OF ETHYL THIOACETATE AND ITS DIMETHYLIMINIUM DERIVATIVE

Rate constants at 250 for the hydrolysis of and enamine formation from ethyl N,N-dimethylthioacetimi-date, CH3C(=N+(CH3)2)SC2H5, have been determined. Both reactions are catalyzed by general bases; enamine formation occuss moee rapidly than hydrolysis. The rate constant for abstraction of a proton by hydroxide ion from the a carbon of ethyl thioacetate at 25° has also been determined. Comparison of this rate constant with that for the analogous reaction of ethyl N,N-dimethylthioacetimidate shows that C(=N+(CH3)2)SR activates an α-hydrogen atom for proton transfer to hydroxide ion about 2 X 104 times better than C(=O)SR. © 1968, American Chemical Society. All rights reserved.