Sapling Homework Chapter 6 Number 5

In the reaction between the alkene shown and HBr, draw the structures of the: more stable carbocation intermediate, less stable carbocation intermediate, and the major product.
















The first step in this problem is to break the double bond between carbon 2 and 3 to form a carbocation  intermediate. The double bond in the alkene attacks the H-Br bond and the positive charge from the Hydrogen forms the carbocation. The carbocation can attach to either carbon 2 or 3 as shown below.















In path A, the carbocation is at carbon 2, which is a secondary carbon because it is one sigma bond away from 2 carbons.















In path B, the carbocation is at carbon 3, which is tertiary because it is one sigma bond away from 3 carbons. This intermediate drawing is the more stable one because tertiary carbons are more stable and will lead to the major product.

To form the major product, the negative charge from the Br atom attacks the carbocation...













... and attaches to carbon 3.