Liebermann's test is used for which class of compounds -

Options

A. Alcohols
B. Phenols
C. Aldehydes
D. Ketones

Answer

**Step-by-Step Solution:**

1. **Understanding Liebermann's Test**:
- Liebermann's test, also known as Liebermann's nitroso test, is a chemical test used to identify certain classes of organic compounds.

2. **Identifying the Class of Compounds**:
- The options provided are:
a) Alcohols
b) Phenols
c) Aldehydes
d) Ketones
- Among these, the test is specifically known for its application to phenols.

3. **Mechanism of the Test**:
- The test involves the reaction of phenols with nitrous acid (HNO2), which is generated in situ from sodium nitrite (NaNO2) and sulfuric acid (H2SO4).
- When phenol reacts with nitrous acid, it forms a nitroso derivative known as paranitrosophenol.

4. **Formation of Colored Compounds**:
- The paranitrosophenol can undergo further reactions, leading to the formation of a colored compound known as indophenol.
- The indophenol formed can exhibit a red color initially, and upon treatment with a base like NaOH, it can turn blue.

5. **Conclusion**:
- Since the Liebermann's test specifically gives a positive result with phenols, we conclude that the correct answer is **phenols**.

**Final Answer**: Liebermann's test is used for **phenols**.

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