Question

R R + H2O R OH OH R

Statement (I): In the case of formaldehyde

C (H H), K is about 2280, due to small substituents, hydration is faster.

Statement (II): In the case of trichloro acetaldehyde

C Cl acetaldehyde H K is about 2000 due to – I effect of – Cl. Cl Cl

In the light of the above statements, choose the correct answer from the options given below:

• A. Both Statement (I) and Statement (II) are correct
• B. Both Statement (I) and Statement (II) are incorrect
• C. Statement (I) is correct but Statement (II) is incorrect
• D. Statement (I) is incorrect but Statement (II) is correct

Answer 1

Answer: (C)

Statement (I) is correct but Statement (II) is incorrect

Answer 2

The hydration of carbonyl compounds is influenced by the size of substituents and the electron‐withdrawing (–I) effect. In formaldehyde, the small substituents allow rapid and favorable hydration (K ≈ 2280). In contrast, for trichloroacetaldehyde, the strong –I effect of the –Cl groups increases the electrophilicity of the carbonyl carbon so that hydration is extremely favored. Therefore, the reported value of K ≈ 2000 for trichloroacetaldehyde is too low.