Question

What is the major organic product that results when 1-heptyne is treated with 2 equivalents of HBr? Question 10 options: 2,2-dibromoheptane 1,1-dibromoheptane 1,2-dibromoheptane 2,3-dibromo-1-heptene 2,3-dibromo-2-heptene

Answer 1

The major organic product is 2,2-dibromoheptane

Step-by-step explanation:

At first, 1-heptyne is protonated by 1-equivalent HBr and produces a stable
`2^(o)` carbocation followed by nucleophilic attack by bromide ion.

Then another equivalent of HBr adds on double bond to produce another
`2^(o)` carbocation which is highly stable due to electron donating resonating effect of Br atom (+R effect). Thus a consequent nucleophilic attack onto that carbocation leads to formation of 2,2-dibromoheptane as a major product.

Detailed mechanism has been attached below.