In the addition reaction of Cl2 to buta-1,3-diene at low temperatures, it produces 60 % of product A and 40 % of product B. However, when the same reaction is carried out at a higher temperature, the product ratio changes to 10 % of A and 90% of B.
(a) Propose a mechanism for this reaction and show the structures of products A and B.
(b) Explain why product A is predominant at low temperatures, while product B is favored at high temperatures.
