Alcohol to Aldehyde/Ketone using Manganese Dioxide

General Info

Reaction & Reagents info

  • MnO2 (Manganese dioxide) (DMSO, Oxalyl chloride) is generally useful to oxidize activated alcohols (such as allylic and benzylic alcohols) to their corresponding aldehydes.
  • It is not a suitable reagent for unactivated alcohols
  • The reaction is heterogeneous and requires large excess of MnO2
  • Freshly prepared MnO2 is usually preferred, as its quality would go down over a period of time.

Advantages

  • Inexpensive oxidation method on manufacturing scale
  • Compared to other oxidising agents, it is a safer alternative

Disadvantages

  • A large excess of MnO2 (about 10 X) is usually required
  • Freshly prepared MnO2 is usually preferred, as its quality would go down over a period of time.

Useful Links on Reagent & Reaction:

Mechanism

Additional details

Scheme & Procedure

General Procedure:

To a solution of Substrate (alcohol, 1 eq.) in dry CH2Cl2 (20 ml) is added MnO2 (20 eq.) and stirred at RT overnight. The reaction is monitored by TLC. The RM was filtered through celite pad  and the filtrate was concentrated to give rise to the product.

Note:

  • The reaction is heterogeneous and requires large excess of MnO2
  • Activated alcohols such as Allylic and Benzylic alcohols are easily oxidized to corresponding aldehydes. However, MnO2 is not suitable for unactivated alcohols.
  • Freshly prepared MnO2 is usually preferred, as its quality would go down over a period of time.

Typical Procedure:

WO2010045258, page no. 221

WO2010038081, page no. 819

Process perspective

MnO2 oxidation could be carried out on large-scale. However, the reaction requires large excess of MnO2.

  • MnO2 Oxidation is one of the inexpensive methods to manufacture aldehydes or ketones from Alcohols, though it oxidises only activated alcohols

Scale-Up Typical Procedure:

Green Chemistry Aspects:

Reaction Tree

References

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