Numford
Name reaction

Hydroboration-oxidation

An alkene adds diborane to give a trialkylborane, which is oxidised by hydrogen peroxide in alkali to give an alcohol with anti-Markovnikov orientation.

Class 12, Chapter 7 Alcohols, Phenols and Ethers

  1. PropeneCH₃CH=CH₂Alkene
  2. Step 1

    (i) B₂H₆ (ii) H₂O₂, OH⁻

    Hydroboration-oxidation
    i

    Hydroboration-oxidation gives the anti-Markovnikov (primary) alcohol.

    OH
    Propan-1-olCH₃CH₂CH₂OHAlcohol

Reagents: (i) B₂H₆ (ii) H₂O₂, OH⁻

Mechanism

How it works

  1. Diborane adds across the C=C with boron on the less substituted carbon.
  2. Hydrogen peroxide with NaOH replaces boron by OH.
  3. The primary alcohol forms.
Used to prepare

What it makes

Primary alcohols from terminal alkenes.

Limitations

Where it fails

Gives the opposite orientation to acid-catalysed hydration.

Which chapter

Class 12, Chapter 7 Alcohols, Phenols and Ethers

Questions

Hydroboration-oxidation: quick answers

Why is this called anti-Markovnikov?

The OH ends up on the less substituted carbon.

What does propene give?

Propan-1-ol.

How does it differ from acid hydration?

Acid hydration of propene gives propan-2-ol.

Plan an organic conversion