Question

Identify which of the following two reactions you would expect to occur more rapidly: (1) addition of HBr to 2-methyl-2-pentene or (2) addition of HBr to 4-methyl-1-pentene. Explain your choice. Addition of HBr to should be more rapid because the reaction can proceed via a carbocation. In contrast, addition of HBr to proceeds via a less stable, carbocation.

Answer 1

Answer:

(1) addition of HBr to 2-methyl-2-pentene

Explanation:

In this case, we will have the formation of a carbocation for each molecule. For molecule 1 we will have a tertiary carbocation and for molecule 2 we will have a secondary carbocation.

Therefore the most stable carbocation is the one produced by the 2-methyl-2-pentene. So, this molecule would react faster than 4-methyl-1-pentene. (See figure)