Predict the major product(s) of the following reactions and explain their formation.
`H_(3)C-CH=CH_(2) underset("HBr")overset(Ph-CO-O_(2)H)to`
`H_(3)C-CH=CH_(2) overset("HBr")to`

Explanation

In presence of peroxides , addition of HBr to propene follows anti-Markovnikov's rule and hence give 1-bromopropane as the major product . The reaction occurs through a free radical mechanism via a more stable free radical intermediate as shown below :

However, in absence of peroxides , addition of HBr to propene follows Markovnikov's rule and hence give 2-bromopropane as the major product. The reaction occurs through ionic mechanism via a more stable carbocation intermediate as shown below :