Question

Given below are two statements: Statement (I): In the case of formaldehyde, \( K \) is about 2280, due to small substituents, hydration is faster.
\includegraphics[]{54 i.PNG} Statement (II): In the case of trichloroacetaldehyde, \( K \) is about 2000 due to the -I effect of Cl. \includegraphics[]{54 ii.PNG} In the light of the above statements, choose the correct answer from the options given below:

• A. Statement I true but Statement II is false
• B. Both Statement I and Statement II are true
• C. Statement I is false but Statement II is true
• D. Both Statement I and Statement II are false

Hint:

The rate of hydration and the equilibrium constant depend on the electron-withdrawing or electron-donating effects of substituents on the carbonyl group. Small substituents favor faster hydration.

Answer 1

The Correct Option is B

Statement (I): Formaldehyde (\( CH_2O \)) has small substituents, and the small size of the substituents leads to faster hydration due to less steric hindrance around the carbonyl group. The equilibrium constant \( K \) for the hydration of formaldehyde is about 2280, indicating that hydration is relatively fast. - Statement (II): Trichloroacetaldehyde (\( CCl_3CHO \)) has three chlorine atoms attached to the alpha-carbon. The chlorine atoms withdraw electron density from the carbonyl carbon through the -I effect, making the carbonyl carbon less electrophilic and slowing down hydration. The equilibrium constant \( K \) for trichloroacetaldehyde is around 2000, indicating slower hydration. Both statements are true.