Solution:

The expansion of HBr to propene is an illustration of an electrophilic replacement response.

Being a corrosive, the hydrogen bromide gives an electrophile, H+. This electrophile assaults the propene twofold cling to frame carbocations of 1 ° and 2 °, as displayed underneath:

Optional carbocations are steady in examination with essential carbocations. The optional carbocations thusly prevail, as they structure at a quicker rate than essential carbocations. Accordingly, Br–assaults the essential carbocation to shape 2-bromopropane as the principle item in the following stage.

This response observes the guideline of Markovnikov, where the negative piece of the addendum is appended to the carbon molecule with less hydrogen particles than other carbon iotas present in the compound.

While, within the sight of benzoyl peroxide, an expansion response happens hostile to Markovnikov’s standard. The response follows a free extreme chain system as displayed underneath:

Auxiliary free revolutionaries are steady in correlation with essential extremists. The auxiliary revolutionary consequently prevails, for it structures at a quicker rate than the essential extremist. Accordingly 1 – bromopropane is acquired as the principle item.

Br goes about as an electrophile within the sight of peroxide, as a free revolutionary. Along these lines, in the presence and nonappearance of peroxide, two changed items are acquired on expansion of HBr to propene.