Question

(b) Write short notes on the following:

(i) Preparation of ethanol from fermentation of sugar

(ii) Reimer-Tiemann Reaction

(iii) Williamson’s Synthesis

OR

(b) (i) Write chemical equations for the preparation of primary, secondary, and tertiary alcohols from Grignard’s reagent.

Primary Alcohol:

Secondary Alcohol:

Tertiary Alcohol:

Hint:

Gabriel synthesis selectively forms primary amines, Hoffmann’s reaction removes carbonyls, and Carbylamine reaction identifies primary amines.

Answer 1

Solution:

(i) Preparation of ethanol from fermentation of sugar

C₆H₁₂O₆ ⟶ (Yeast) 2C₂H₅OH + 2CO₂

(ii) Reimer-Tiemann Reaction

C₆H₅OH + CHCl₃ + NaOH ⟶ o-Hydroxybenzaldehyde + p-Hydroxybenzaldehyde

(iii) Williamson’s Synthesis

R-O⁻ + R'-X ⟶ R-O-R' + X⁻

OR

(i) Preparation of alcohols from Grignard’s reagent:

Primary Alcohol:

R-MgX + HCHO ⟶ (H₂O) R-CH₂OH + Mg(OH)X

Secondary Alcohol:

R-MgX + CH₃CHO ⟶ (H₂O) R-CHOH-CH₃ + Mg(OH)X

Tertiary Alcohol:

R-MgX + R'CO-R'' ⟶ (H₂O) R-C(OH)-R'R'' + Mg(OH)X