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MPV Reduction: Meerwein-Ponndorf-Verley

By Chemca Editorial Team • Last Updated: January 2026 • 8 min read

The Meerwein-Ponndorf-Verley (MPV) Reduction is a specific method for reducing aldehydes and ketones to their corresponding primary and secondary alcohols. It uses Aluminium Isopropoxide in Isopropyl Alcohol. It is the direct reverse reaction of the Oppenauer Oxidation.

1. General Reaction

A ketone (or aldehyde) is treated with Aluminium Isopropoxide in excess Isopropyl Alcohol. The ketone is reduced to a secondary alcohol, while the Isopropyl Alcohol acts as the hydride donor and is oxidized to Acetone.

$$ \underbrace{R_2C=O}_{\text{Ketone}} + \underbrace{(CH_3)_2CH-OH}_{\text{Isopropyl Alcohol}} \xrightarrow{Al[OCH(CH_3)_2]_3} \underbrace{R_2CH-OH}_{2^\circ \text{ Alcohol}} + \underbrace{(CH_3)_2C=O}_{\text{Acetone}} $$

Conditions:

• Reagent/Catalyst: Aluminium Isopropoxide ($Al(O-iPr)_3$).
• Reductant/Solvent: Isopropyl Alcohol (IPA) in excess.
• Driving Force: Continuous removal of Acetone by distillation shifts the equilibrium to the right (Le Chatelier's principle).

2. Detailed Mechanism

The reaction proceeds via a concerted hydride transfer through a six-membered cyclic transition state.

Step 1: Coordination

The carbonyl oxygen of the ketone coordinates to the aluminium atom of the catalyst, activating the carbonyl carbon.

Step 2: Hydride Transfer (The Key Step)

A hydride ion ($H^-$) is transferred from the $\alpha$-carbon of an isopropoxide ligand (attached to Al) to the carbonyl carbon of the ketone via a six-membered transition state.

The Transition State involves Al, O(ketone), C(ketone), H(hydride), C(isopropoxide), and O(isopropoxide).

Step 3: Product Release

After hydride transfer, the ketone becomes an alkoxide attached to aluminium, and the isopropoxide becomes acetone (which leaves). Ligand exchange with the solvent (IPA) releases the product alcohol.

3. Chemoselectivity (Why use MPV?)

Highly Selective for C=O

The MPV reduction is extremely chemoselective. It specifically reduces aldehydes and ketones to alcohols.

It does NOT reduce:

• Carbon-Carbon double bonds ($C=C$).
• Nitro groups ($-NO_2$).
• Acetals.
• Halides.

This makes it superior to catalytic hydrogenation for unsaturated ketones.

Example: Reduction of Crotonaldehyde

Crotonaldehyde ($CH_3CH=CHCHO$) contains both an alkene and an aldehyde. MPV reduction yields Crotyl Alcohol ($CH_3CH=CHCH_2OH$) without touching the double bond.

4. Reversibility

The reaction is reversible.

• Forward Direction (Reduction): MPV Reduction (Use excess IPA, remove Acetone).
• Reverse Direction (Oxidation): Oppenauer Oxidation (Use excess Acetone).

5. Comparison Table

Feature	MPV Reduction	Oppenauer Oxidation
Substrate	Ketone/Aldehyde	Secondary Alcohol
Product	Alcohol	Ketone
Excess Reagent	Isopropyl Alcohol	Acetone

MPV Reduction Quiz

Test your concepts on Selective Reduction. 10 MCQs with explanations.

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