Q36E
Question
Addition of HBr to 1-phenylpropene yields only (1-bromopropyl) benzene. Propose a mechanism for the reaction, and explain why none of the other regioisomer is produced.
Step-by-Step Solution
Verified Answer
Proposed mechanism for the reaction is shown below.
1Step 1: Markovnikov rule
Halogens are added to alkene as per Markovnikov rule. According to this rule, the electron-rich component is added to carbon with few hydrogens like halogen and hydrogen is added to carbon with more hydrogen.
2Step2: Formation of carbocation
As the double bond breaks, two carbocations are formed and the carbocation formed near the phenyl ring is more stable than the carbocation formed away from the phenyl ring due to the inductive resonance effect which overpowers the hyperconjugation effect as shown below.
Breaking of Double bond
3Step 3: Mechanism
- Formation of carbocation.
- Addition of the Br ion to the carbocation.
- Formation of the 1bromo propyl benzene product.
Addition of HBr
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