Question

Which of the following are the compound(s) that do not give Tollen's test?

• A. A, B
• B. C, D
• C. A, C
• D. B, D

Hint:

Acetals and ketals do not react with Tollen's reagent because they do not have an aldehyde functional group. Only aldehydes give a positive Tollen's test.

Answer 1

The Correct Option is A

To determine which compounds do not give Tollen's test, we must understand what Tollen's test detects. Tollen's test is used to identify aldehydes. It involves the oxidation of an aldehyde to a carboxylic acid, while the Tollen’s reagent, containing silver ions, gets reduced to metallic silver. Ketones, on the other hand, do not react in this way with Tollen's reagent.

Let's analyze each compound:

1. Compound A: This compound is a ketone because it has a -C=O group attached to two carbon atoms. Ketones do not give a positive Tollen's test.
2. Compound B: This compound is also a ketone. Like Compound A, it will not give a positive Tollen's test.
3. Compound C: This compound is an aldehyde. It contains a -CHO group, which will react with Tollen's reagent to give a positive test.
4. Compound D: This compound is an aldehyde. Similar to Compound C, it will give a positive Tollen's test.

Based on the above analysis, Compounds A and B do not give Tollen's test because they are ketones.

Therefore, the correct answer is: A, B.