Which of the following will not give positive test with neutral `FeCl_(3)` ?

Options

A. Nitrophenol
B. Phenol
C. Allyl alcohol
D. o-cresol

Answer

To determine which of the given compounds will not give a positive test with neutral FeCl3, we need to analyze the presence of phenolic hydroxyl groups in each compound. Neutral FeCl3 is used to test for these groups, which will produce a violet coloration if present.

### Step-by-Step Solution:

1. **Understanding Neutral FeCl3 Test**:
- Neutral FeCl3 is used to detect the presence of phenolic hydroxyl groups (-OH) in compounds. A positive test is indicated by a violet coloration.

2. **Analyzing Each Option**:
- **Option A: Nitro Phenol**:
- Nitro phenol (both ortho and para forms) contains a phenolic hydroxyl group (-OH). Therefore, it will give a positive test with neutral FeCl3.
- **Option B: Phenol**:
- Phenol itself has a phenolic hydroxyl group (-OH). Thus, it will also give a positive test with neutral FeCl3.
- **Option C: Aryl Alcohol (Allyl Alcohol)**:
- The structure of allyl alcohol is CH2=CH-CH2OH. The hydroxyl group here is attached to a carbon that is not part of a phenolic ring (not attached to a benzene ring). Therefore, it does not have a phenolic hydroxyl group and will not give a positive test with neutral FeCl3.
- **Option D: Ortho-Cresol**:
- Ortho-cresol has a phenolic hydroxyl group (-OH) attached to a benzene ring, thus it will give a positive test with neutral FeCl3.

3. **Conclusion**:
- Among the options, only allyl alcohol (Option C) does not contain a phenolic hydroxyl group and will not give a positive test with neutral FeCl3. Therefore, the correct answer is **C: Allyl Alcohol**.