What is the Difference Between MPV Reduction and Oppenauer Oxidation

The key difference between MPV reduction and Oppenauer oxidation is that MPV reduction involves the conversion of a ketone or aldehyde into its corresponding alcohol, whereas Oppenauer oxidation involves the conversion of secondary alcohols to ketones.

MPV reduction refers to Meerwein-Ponndorf-Verley reduction. Oppenauer oxidation refers to a type of oxidation reaction named after Rupert Viktor Oppenauer. These are two opposing reactions.

CONTENTS

1. Overview and Key Difference
2. What is MPV Reduction  
3. What is Oppenauer Oxidation
4. MPV Reduction vs Oppenauer Oxidation in Tabular Form
5. Summary – MPV Reduction vs  Oppenauer Oxidation 

What is MPV Reduction?

MPV reduction refers to Meerwein-Ponndorf-Verley reduction. It is a type of reduction reaction that involves the reduction of ketones and aldehydes to form their corresponding alcohols utilizing aluminum alkoxide catalysis in the presence of a sacrificial alcohol. This reduction mechanism is advantageous because of its high chemoselectivity. We can use a cheap, environmentally friendly metal catalyst for this reduction technique.

The reduction reaction was named after Hans Meerwein, Wolfgang Ponndorf, and Albert Verley. We can categorize it as an organic redox reaction. Its founders found that a mixture of aluminum ethoxide and ethanol can reduce aldehydes or ketones to the corresponding alcohol.

The mechanism of this reaction has several steps:

1. Coordination of a carbonyl oxygen atom to the aluminum alkoxide to give the tetra coordinated aluminum intermediate.
2. Formation of intermediates, transferring the hydride to the carbonyl from the alkoxy ligand via a pericyclic mechanism.
3. Formation of an alcohol from solution by displacing the newly reduced carbonyl via regenerating the catalyst

What is Oppenauer Oxidation?

Oppenauer oxidation is a type of oxidation reaction that involves the conversion of secondary alcohols to ketones by selective oxidation. This oxidation reaction was named after Rupert Viktor Oppenauer. It is a gentle technique that involves selective oxidation. We can also describe it as a type of organic redox reaction.

This is the opposite reaction to the MPV reduction. In this reaction, the alcohol undergoes oxidation with aluminum isopropoxide in the presence of excess acetone, which causes the shifting of the equilibrium towards the product side.

Oppenauer oxidation reaction is highly selective of the secondary alcohols, and it does not oxidize other sensitive functional groups, including amines and sulfides. However, we can oxidize primary alcohols under this oxidation process. But it is done rarely because of the competing aldol condensation of aldehyde products. The Oppenauer oxidation reaction is still in use for the oxidation of acid-labile substrates. Furthermore, this technique was largely displaced by oxidation methods depending on the chromates or dimethyl sulfoxide because of its use of relatively mid and nontoxic reagents.

What is the Difference Between MPV Reduction and Oppenauer Oxidation?

MPV reduction and Oppenauer oxidation are important organic chemical reaction mechanisms. The key difference between MPV reduction and Oppenauer oxidation is that MPV reduction involves the conversion of a ketone or aldehyde into its corresponding alcohol, whereas Oppenauer oxidation involves the conversion of secondary alcohols to ketones.

The below infographic presents the differences between MPV reduction and Oppenauer oxidation in tabular form for side by side comparison.

Summary – MPV Reduction vs Oppenauer Oxidation

MPV reduction and Oppenauer oxidation are two opposing reactions. The key difference between MPV reduction and Oppenauer oxidation is that MPV reduction involves the conversion of a ketone or aldehyde into its corresponding alcohol, whereas Oppenauer oxidation involves the conversion of secondary alcohols to ketones.

Reference:

1. “Practical Oppenauer (OPP) Oxidation of Alcohols with a Modified Aluminum Catalyst.” ACS Publications.

Image Courtesy:

1. “MeerweinPonndorfVerleycycle” By Jkolev – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Oppenauer oxidation reaction scheme” By Lankaluf – Own work (Public Domain) via Commons Wikimedia