In the lecture notes, it says, “Reactivity with nucleophiles is decreased by the stabilizing conjugation, which depends on the electron donating ability of X.” This confuses me because I thought that weak bases were good leaving groups and, therefore, more reactive to nucleophilic substitution? That is correct. (Weak bases usually hold an electron pair better, so stabilization of the carbonyl group decreases, and, therefore, reactivity increases. It is another part of the explanation of the basicity trend. - GS). So does that mean that strong acids are bad leaving groups and are more reactive to nucleophilic substitution because they want to donate their electrons?