The addition of HCl to an unknown alkene of molecular formula C ₆ H ₁₂ yields 2 -chloro- 2,3 -dimethylbutane as the major product. The total number of structurally isomeric alkenes of formula C ₆ H ₁₂ that can produce this compound as the major product is.........

Step-by-step solution

The major product, 2 -chloro- 2,3 -dimethylbutane, is formed via the most stable carbocation intermediate, which is the tertiary 2,3 -dimethyl- 2 -butyl cation: CH ₃- C ^+( CH ₃)- CH ( CH ₃)- CH ₃ . We must identify all structurally isomeric alkenes of formula C ₆ H ₁₂ that form this specific carbocation (either directly or via rearrangement) as their most stable intermediate. Direct protonation yields this cation from two alkenes: 1 . 2,3 -dimethyl- 2 -butene ( CH ₃- C ( CH ₃)= C ( CH ₃)- CH ₃ ) 2 . 2,3 -dimethyl-