The reaction between 2-methylpropene also known as isobutene and hydrobromic acid HBr in the presence of peroxide follows a free radical mechanism, specifically, the anti-Markovnikov addition of HBr to the alkene. This reaction is also known as the peroxide effect or the Kharasch effect. The overall reaction can be represented as:2-methylpropene + HBr 1-bromo-2-methylpropaneThe mechanism involves the following steps:1. Initiation: The peroxide usually a weak O-O bond undergoes homolytic cleavage by heat or light, generating two alkoxy radicals RO .R-O-O-R 2 RO2. Propagation Step 1: The alkoxy radical reacts with HBr, abstracting a hydrogen atom and forming a bromine radical Br and an alcohol ROH .RO + HBr ROH + Br3. Propagation Step 2: The bromine radical reacts with 2-methylpropene, forming a secondary free radical at the less substituted carbon anti-Markovnikov due to the greater stability of the secondary radical compared to the primary radical.Br + CH2=C CH3 2 CH3C CH3 24. Propagation Step 3: The secondary radical reacts with another molecule of HBr, abstracting a hydrogen atom and forming the final product, 1-bromo-2-methylpropane.CH3C CH3 2 + HBr CH3CBr CH3 25. Termination: Two free radicals combine to form a stable molecule, ending the chain reaction. This can occur in various combinations, such as two bromine radicals, two alkoxy radicals, or a bromine radical and an alkoxy radical.Br + Br Br2RO + RO R-O-O-RBr + RO R-O-BrThe intermediates formed during the reaction are the alkoxy radicals, bromine radicals, and the secondary carbon radical. These intermediates contribute to the overall reaction mechanism by propagating the chain reaction and leading to the formation of the final product, 1-bromo-2-methylpropane.