Lederer-Manasse Reaction
In Lederer-Manasse reaction, -CH2OH group is introduced at ortho- or para- position in phenol. Phenol condenses with aliphatic and aromatic aldehydes in either acidic or basic medium at low temperature.
Example, condensation of phenol with formaldehyde in basic medium at low temperature produce hydroxybenzyl alcohols. Para hydroxybenzyl alcohol is major Product while Ortho hydroxybenzyl alcohol is minor Product. The products of the reaction are known as shellac substitutes because they are soluble in alcohol, alkaline hydroxide, and acetone. They also melt when heated and solidify again when cooled.
Mechanism of Lederer-Manasse Reaction
In Acidic Medium
In Basic Medium
Test Your Understanding: Lederer-Manasse Reaction and Mechanism
1. which of the following products is formed in Lederer-Manasse reaction ?
- (A) o-Crosol
- (B) o-Hydroxybenzyl alcohol
- (C) Benzyl alcohol
- (D) Resorcinol
View Answer
Explanation: The Lederer-Manasse reaction involves the condensation of phenol with formaldehyde in the presence of a dilute acid or base. Because the hydroxyl group (-OH) on phenol is strongly ortho- and para-directing, electrophilic aromatic substitution yields a mixture of o-hydroxybenzyl alcohol and p-hydroxybenzyl alcohol. Since the ortho isomer is given here, option B is the correct product.
2. Which of the following acts as the active electrophile during the acid-catalyzed Lederer-Manasse reaction?
- (A) Phenoxide ion
- (B) +CH2OH
- (C) CHO-
- (D) CH3+
View Answer
Explanation: Under acidic conditions, the carbonyl oxygen of formaldehyde accepts a proton, which creates a strong carbon-centered electrophile capable of attacking the aromatic ring.
3. The Lederer-Manasse reaction serves as the critical first step in the industrial production of which plastic?
- (A) Nylon-6,6
- (B) Polyvinyl Chloride (PVC)
- (C) Bakelite
- (D) Polystyrene
View Answer
Explanation: If the reaction continues beyond the initial hydroxybenzyl alcohol step, these intermediates undergo further cross-linking and condensation to form a thermosetting phenol-formaldehyde resin known commercially as Bakelite.