Question

Which of the following does NOT give yellow precipitate when reacted with (NaOH + I\(_2\)) mixture?

• A. Acetophenone
• B. Benzaldehyde
• C. Acetone
• D. Acetaldehyde

Hint:

The iodoform test is used to detect compounds with the CH\(_3\)CO- group. Benzaldehyde does not have this group and thus does not react with iodine and NaOH to form a yellow precipitate.

Answer 1

The Correct Option is B

Step 1: Understanding the reaction.
The reaction with iodine and sodium hydroxide (NaOH + I\(_2\)) is known as the iodoform test, which forms a yellow precipitate of CHI\(_3\) in the presence of methyl ketones or compounds with the group CH\(_3\)CO-.

Step 2: Analyzing the options.
(A) Acetophenone: Acetophenone reacts with iodine and NaOH to form a yellow precipitate of iodoform.
(B) Benzaldehyde: Benzaldehyde does not have the CH\(_3\)CO- group, so it does not give the yellow precipitate.
(C) Acetone: Acetone reacts with iodine and NaOH to give the yellow precipitate of iodoform.
(D) Acetaldehyde: Acetaldehyde reacts with iodine and NaOH to give the yellow precipitate of iodoform.

Step 3: Conclusion.
The correct answer is (B) Benzaldehyde.