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Organic conversion

Propene to 1-bromopropane

1 step: peroxide effect (Kharasch)

Class 11, Chapter 9 Hydrocarbons

  1. PropeneCH₃CH=CH₂Alkene
  2. Step 1

    HBr, peroxide

    Peroxide effect (Kharasch)
    i

    Peroxide effect: only HBr gives anti-Markovnikov addition (free radical mechanism); HCl and HI do not.

    Br
    1-BromopropaneCH₃CH₂CH₂BrHaloalkane

Exam answer

  1. Step 1: Propene to 1-bromopropane: HBr, peroxide.
Alternative routes (1)
  • Propene → Propan-1-ol → 1-Bromopropane
    1. Propene to propan-1-ol: (i) B₂H₆ (ii) H₂O₂, OH⁻.
    2. Propan-1-ol to 1-bromopropane: red P + Br₂ (PBr₃).
Why these reagents

Reagent and reason, step by step

  • Step 1: Propene to 1-bromopropane: HBr, peroxide Peroxide effect: only HBr gives anti-Markovnikov addition (free radical mechanism); HCl and HI do not.
Good to know

Points to note

  • Step 1Peroxide effect: only HBr gives anti-Markovnikov addition (free radical mechanism); HCl and HI do not.
Questions

Propene to 1-bromopropane: quick answers

How many steps does it take to convert propene to 1-bromopropane?

1 step: Propene, then 1-bromopropane.

Which named reaction is used to convert propene to 1-bromopropane?

Peroxide effect (Kharasch). In the presence of peroxides, HBr adds to an unsymmetrical alkene against Markovnikov's rule.

What is the reagent for step 1 of propene to 1-bromopropane?

Propene to 1-bromopropane: HBr, peroxide. Peroxide effect: only HBr gives anti-Markovnikov addition (free radical mechanism); HCl and HI do not.

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