Why does having a destabilized nucleophile in an SN2 reaction decrease the free energy of activation? (Because the transition state retains its energy, so the activation barrier is lower. - GS).

How does a polar, protic solvent reduce the free energy of activation and stabilize an intermediate in an SN1 reaction? (By solvation of the very polar transition state - GS). And, why does a stabilized intermediate reduce the energy barrier? (Because the less polar starting compound is not stabilized as efficiently as the transition state - GS).

Can you just briefly explain what a meso compound is? Is it just a compound that hasn't been distinguished between cis and trans?(No. It is an achiral compound with chiral centers. - GS).

Dr. Sereda, I was looking over some of the previous year’s quizzes and in the preparation of 5-methyl-2-hexyne from propyne, what would be the nucleophile? Would it be the same as the alkylating agent? Thanks. (The nucleophile is deprotonated alkyne, which attacks the alkylating agent and kicks out the leaving group from it. Overall, it results in the introduction of the alkyl group to the alkyne. - GS).