Which of the following compounds not shows positive Tollen's Test

Options

A.
B.
C.
D.

Answer

To determine which of the given compounds does not show a positive Tollen's Test, we need to understand the nature of the Tollen's Test and the structure of the compounds involved.

### Step-by-Step Solution:

1. **Understanding Tollen's Test**:
- Tollen's Test is used to identify the presence of aldehydes (RCHO) in a compound. When an aldehyde reacts with Tollen's reagent (Ag(NH3)2+), it gets oxidized to a carboxylic acid (RCOOH), and silver ions are reduced to metallic silver, which deposits as a silver mirror.

2. **Analyzing the Compounds**:
- We need to analyze each compound provided in the question to check for the presence of the aldehyde functional group (CHO).

3. **Compound 1**:
- Structure: RCHO (where R is any alkyl or aryl group)
- This compound has a CHO group, so it will give a positive Tollen's Test.

4. **Compound 2**:
- Structure: PhCHO (where Ph represents a phenyl group)
- This compound also contains a CHO group, hence it will also give a positive Tollen's Test.

5. **Compound 3**:
- Structure: Ph-C(=O)-OH (a carboxylic acid)
- This compound does not have a CHO group; instead, it has a carboxylic acid functional group (COOH). Therefore, it will give a negative Tollen's Test.

6. **Compound 4**:
- Structure: Ph-C(=O)-Ph (a ketone)
- Similar to Compound 3, this compound lacks a CHO group and has a carbonyl group (C=O) bonded to two phenyl groups. Thus, it will also give a negative Tollen's Test.

7. **Conclusion**:
- The compounds that do not show a positive Tollen's Test are Compound 3 and Compound 4.

### Final Answer:
The compounds that do not show a positive Tollen's Test are **Compound 3 and Compound 4**.