Question

For the following substitution reaction, which statement is FALSE? The use of a polar aprotic solvent will enhance the rate. The process is bimolecular. The reaction proceeds via a carbocation intermediate. Increasing the concentration of hydroxide will cause an increase in the rate of reaction.

Answer 1

Answer:

FALSE: The reaction proceeds via a carbocation intermediate.

Explanation:

There is a large increase in the speed of the reaction when changing from a protic solvent to an aprotic one. This difference arises from acid / base reactions between protic solvents, which do not occur with aprotic solvents, and strong nucleophiles.

It is a reaction with 2nd order kinetics, this means that the velocity determining step is bimolecular, that is, the hydroxide ion and methyl bromide are involved in the transition state.

It is a concerted reaction, that is, in a single step, where the hydroxide ion acts as a nucleophile using its electron pair and attacks the carbon on the side opposite the link with the leaving group. In the transition state the nucleophile and the leaving group are partially attached to the carbon undergoing the reaction.