NOVEL CHANGE IN RATE-DETERMINING STEP WITHIN AN E1CB MECHANISM DURINGAMINOLYSIS OF A SULFAMATE ESTER IN ACETONITRILE

The observation of biphasic Bronsted plots (beta(1) Ca. 0.7 and beta 2 Ca. 0) in the aminolysis (alicyclic amines, pyridines) of 4-nitrophen yl N-benzylsulfamate 1a in MeCN is interpreted as being due to a mecha nistic change from (ElcB)(irrev) to (ElcB)(rev); the change in rate-de termining step occurs at approximately the pK(a) of 1a and other more basic substrates give straight line plots; an entropy study supports t he change from a bimolecular to a unimolecular mechanism.