Question

Anti-Markovnikov addition of one mole $HBr$ is not observed in :

• A. ethyne
• B. butene
• C. propene
• D. propyne

Answer 1

The correct option is A ethyne

In case of symmetrical alkene (alkyne), it will make same product with $HBr$ and there is no use of Markovnikov's rule.

But in case of asymmetrical alkene (alkyne), it will make different product when it reacts with $HBr$ in presence of peroxide according to anti-Markovnikov's rule.

As among all given options, only ethyne is symmetrical so, it will make same product.

Hence the correct option is A.