Answer
The intermediate is on the left of the image below:
Work Step by Step
1. Analyze the arrows.
First arrow (Top):
- Tail: It is breaking a bond...
- Head: to give the electrons pair to the top "Br".
Second arrow (Middle):
- Tail: It is taking 2 electrons from the bottom "Br"...
- Head: to form a bond between this "Br" and a carbon.
Third arrow (Bottom):
- Tail: It is breaking a pi bond...
- Head: to form other bond between the bottom "Br" and another carbon.
2. Now, let's find the formal charges:
The top "Br" had neutral charge, then it lost a bond (+1), and gained 2 electrons (-2) = -1 formal charge.
The bottom "Br" had neutral charge, then it lost 2 electrons (+2); it lost a bond (Br-Br) (+1), and formed 2 bonds (-2) = (+1) formal charge.
