Which of the following statement are true about aryl halides ?

Options

A. Formation of phenol from chlorobenzene through Dow's process involves `S_(N)2` mechanism
B. Presence of electron withdrawing groups at o and p - position in aryl halide leads to the greater reactivity towards a nucleophile
C. When chlorobenzene is treated with `KNH_(2)` benzyne intermediate is formed
D. At NTP chlorobenzene reacts with NaOMe to give phenylmethyl ether

Answer

To determine which statements about aryl halides are true, we will analyze each statement one by one.

### Step 1: Analyze Statement A
**Statement A:** "Formation of phenol from chlorobenzene through the DOS process involves SN2 mechanism."

**Analysis:**
The formation of phenol from chlorobenzene typically involves the treatment of chlorobenzene with a strong base, such as potassium amide (KNH2), which leads to the formation of a benzyne intermediate. The reaction does not proceed through an SN2 mechanism because aryl halides are less reactive towards nucleophilic substitution due to the stability of the aromatic ring. Instead, the reaction is more of an acid-base reaction followed by the formation of benzyne.

**Conclusion:** This statement is **incorrect**.

### Step 2: Analyze Statement B
**Statement B:** "Presence of electron-withdrawing groups at ortho and para positions in aryl halide leads to greater reactivity towards the nucleophile."

**Analysis:**
Electron-withdrawing groups (EWGs) at the ortho and para positions increase the reactivity of aryl halides towards nucleophilic substitution. This is because EWGs stabilize the negative charge that develops during the nucleophilic attack, making it easier for the nucleophile to attack the aromatic ring.

**Conclusion:** This statement is **correct**.

### Step 3: Analyze Statement C
**Statement C:** "When chlorobenzene is treated with KNH2, a benzyne intermediate is formed."

**Analysis:**
When chlorobenzene is treated with potassium amide (KNH2), the strong base abstracts a proton, leading to the formation of a benzyne intermediate. This intermediate is characterized by a triple bond between two carbon atoms in the aromatic ring, which is a key feature of the reaction.

**Conclusion:** This statement is **correct**.

### Step 4: Analyze Statement D
**Statement D:** "At NTP, chlorobenzene reacts with sodium methoxide to give phenyl methyl ether."

**Analysis:**
When chlorobenzene reacts with sodium methoxide (NaOMe), a similar mechanism occurs as with KNH2. The methoxide ion acts as a base, forming a benzyne intermediate, which can then react with the methoxide ion to form phenyl methyl ether (C6H5-O-CH3).

**Conclusion:** This statement is **correct**.

### Final Conclusion
The correct statements about aryl halides are:
- Statement B: Correct
- Statement C: Correct
- Statement D: Correct
- Statement A: Incorrect

Thus, the correct answers are B, C, and D.

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