What is the major product formed by HI on reaction with
?
(A)(see structure)
(B)(see structure)
(C)(see structure)✓ Correct
(D)(see structure)
Answer: (C)
Solution
The reaction involves the addition of HI to an alkene. According to Markovnikov's rule, the hydrogen adds to the carbon with more hydrogens, and the iodine adds to the more substituted carbon.
The alkene shown is 2,3,3-trimethylbut-1-ene. When HI adds:
A carbocation intermediate forms
The initial secondary carbocation rearranges to a more stable tertiary carbocation through a methyl shift
The iodide ion attacks the tertiary carbocation
The final product is 2-iodo-2,3,3-trimethylbutane, where the iodine is attached to the tertiary carbon, as shown in option (3). This is the thermodynamically most stable product due to carbocation rearrangement.
JEE Main · 2021 · 24 Feb 2021 · Shift 1 · Single correct option
