Question Detail
Question
Which of the following compounds is the major product when 1-hexyne is treated with excess HBr?
Correct Answer
Option D is the correct answer.
Detailed Explanation
Addition of excess HBr (2 equivalents) to 1-hexyne (CH≡C-CH2-CH2-CH2-CH3) gives 2,2-dibromohexane. The first equivalent adds (Markovnikov) to give 2-bromo-1-hexene, and the second equivalent adds to give the geminal dibromide with both bromines on the same carbon.
Hint
What is the product of two equivalents of HBr addition to a terminal alkyne?