This reaction involves the addition of HBr to an alkene in the presence of peroxide (ROOR), which follows anti-Markovnikov addition (Kharasch effect). The peroxide initiates a free radical mechanism, causing the bromine to add to the less substituted carbon of the double bond.

The given alkene is 1-methylcyclohexene. Under peroxide conditions, HBr adds anti-Markovnikov:

Step 1: Peroxide decomposes to form alkoxy radicals, which abstract hydrogen from HBr, generating bromine radical (Br•).

Step 2: Bromine radical adds to the less substituted carbon of the double bond (terminal carbon), forming a more stable secondary radical (since addition to the tertiary carbon would give a primary radical, which is less stable).

Step 3: The radical intermediate abstracts a hydrogen from HBr, yielding the anti-Markovnikov product: 1-bromo-1-methylcyclohexane.

The major product is $B r - {C H}_{2} - c y c l o h e x a n e$ (1-(bromomethyl)cyclohexane).

Related Topics:

Free Radical Addition: Mechanism where radicals add to alkenes, common with HBr and peroxides.
Markovnikov vs Anti-Markovnikov: Markovnikov addition puts the hydrogen on the less substituted carbon, while anti-Markovnikov (under peroxide) puts the bromine there.
Stability of Radicals: Tertiary > Secondary > Primary, influencing where the radical forms.

Formulae:

General reaction: Alkene + HBr (ROOR) → Anti-Markovnikov alkyl bromide.
Radical stability order: 3° > 2° > 1° > methyl.