Question

HBr can be added to alkenes in either the absence or presence of peroxides (producing either the Markovnikov or the anti-Markovnikov addition product). What intermediates leading to the formation of the major product are observed when 1-butene is treated with 1) HBr or 2) HBr/peroxides?

Answer 1

1) 2-bromobutane

2) 1-bromobutane

Step-by-step explanation:

In the HBr reaction, we will have a markovniknov reaction due to the carbocation formation. The Br- then would be added in the most substituted carbon of the double bond.

In the HBr/peroxide reaction we have the opposite case: an anti-markovnikov reaction. Therefore the Br- would be added in the least substitued carbon of the double bond.