Decarbamoylation rate constants were determined by following the recovery of the diluted inhibited enzyme at room temperature (Figures ) and are presented in Table . The rates translate to half-lives that span from 13 h for dimethyl carbamate 6 and to 13 days for diethyl analogue 11, and to Gibbs activation energies on the scale of 24-25 kcal/mol. Increasing, the size of one of the carbamate substituents to pent-4-yn-1-yl or benzyl prolonged the duration of the inhibition to approx. 2 and 4 days, respectively. The decreased steric demands and degrees of freedom in the case of dipropargyl 19 vs. diethyl carbamate shortened the half-lives by almost 30-fold, comparable to the dimethyl carbamate 6. These data agree with those obtained by progress curve analysis on a same-scaffold BChEI from a previous series and (with some extrapolation for different experimental conditions) the data on BChE