Which of the following reactions will yield phenol ?

Options

A.
B.
C.
D.

Explanation

To determine which of the given reactions will yield phenol, we will analyze each reaction step by step.

### Step 1: Analyze Reaction 1 - Chlorobenzene with NaOH
- **Reaction:** Chlorobenzene + NaOH (at 380 atm and 623 K) → Sodium phenoxide
- **Process:** Chlorobenzene (C6H5Cl) reacts with sodium hydroxide (NaOH) under high pressure and temperature. The chlorine atom is replaced by a sodium phenoxide group (C6H5O-Na+).
- **Next Step:** Sodium phenoxide reacts with water in the presence of an acid (H+).
- **Final Product:** The sodium ion (Na+) is replaced by a hydrogen ion (H+), yielding phenol (C6H5OH).
- **Conclusion:** This reaction yields phenol.

### Step 2: Analyze Reaction 2 - Aniline with NaNO2 and HCl
- **Reaction:** Aniline + NaNO2 + HCl → Benzene diazonium chloride
- **Process:** Aniline (C6H5NH2) reacts with sodium nitrite (NaNO2) and hydrochloric acid (HCl) to form benzene diazonium chloride (C6H5N2+Cl-).
- **Next Step:** The diazonium salt is treated with warm water.
- **Final Product:** This leads to the formation of phenol (C6H5OH).
- **Conclusion:** This reaction also yields phenol.

### Step 3: Analyze Reaction 3 - Benzene with Oleum and NaOH
- **Reaction:** Benzene + Oleum + NaOH → Phenol
- **Process:** Benzene (C6H6) reacts with oleum (H2S2O7) to form benzene sulfonic acid (C6H5SO3H).
- **Next Step:** The sulfonic acid is treated with NaOH and acid (H+).
- **Final Product:** The sulfonic group (SO3H) is replaced by a hydroxyl group (OH), yielding phenol (C6H5OH).
- **Conclusion:** This reaction yields phenol as well.

### Step 4: Analyze Reaction 4 - Chlorobenzene at Room Temperature
- **Reaction:** Chlorobenzene + NaOH (at room temperature)
- **Process:** Chlorobenzene does not react with NaOH at room temperature due to its low reactivity towards nucleophilic substitution.
- **Final Product:** No reaction occurs, and thus phenol is not produced.
- **Conclusion:** This reaction does not yield phenol.

### Summary of Results
- **Reactions that yield phenol:**
- Reaction 1 (Chlorobenzene with NaOH at high pressure and temperature)
- Reaction 2 (Aniline with NaNO2 and HCl)
- Reaction 3 (Benzene with oleum and NaOH)
- **Reaction that does not yield phenol:**
- Reaction 4 (Chlorobenzene at room temperature)

### Final Answer
The reactions that will yield phenol are the first, second, and third reactions.

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