Dakin Reaction

Dakin Reaction converts ortho- and para-hydroxy aromatic aldehydes or ketones to dihydroxybenzenes using hydrogen peroxide.

Overview of Dakin Reaction:

• The Dakin reaction involves the oxidation of aryl aldehydes or aryl ketones, especially those with electron-donating groups (–OH or –OR) in the ortho or para position, to phenols using hydrogen peroxide in basic medium.

Reagents:

• Hydrogen peroxide (H2O2)
• Base (e.g., NaOH or KOH)
• Aqueous or alcoholic medium

General Reaction:

For aryl aldehyde:

Ar–CHO  +  H2O2/NaOH  →  Ar–OH  +  HCOO⁻

For aryl ketone:

Ar–CO–R  +  H2O2/NaOH  →  Ar–OH  +  R–COO⁻

Mechanism of Dakin Reaction:

Step 1: Nucleophilic addition

• Under basic conditions, H2O2 forms the hydroperoxide anion (⁻OOH).
• This anion attacks the electrophilic carbonyl carbon to form a tetrahedral intermediate.

Step 2: Aryl migration

• The aryl group migrates to the adjacent oxygen (from the hydroperoxide group).
• A rearrangement occurs, and the leaving group (formate or carboxylate) departs.

Step 3: Hydrolysis

• The aryl peroxide formed is hydrolyzed to produce a phenol.

Key Features:

• Requires electron-donating substituents for activation
• Selective for ortho- and para-substituted aryl aldehydes and ketones
• Environmentally friendly (H2O2 is a green oxidant)
• Useful in synthetic and pharmaceutical chemistry

Thank you for reading from Firsthope's notes, don't forget to check YouTube videos!