The above reaction requires which of the following reaction conditions?

Chlorobenzene reacts with sodium hydroxide only under very harsh conditions because the $$\mathrm{C-Cl}$$ bond in aryl halides has partial double bond character due to resonance, making nucleophilic substitution difficult.

When chlorobenzene is fused with aqueous $$\mathrm{NaOH}$$ at high temperature and high pressure, it forms sodium phenoxide.

$$\mathrm{C_6H_5Cl + NaOH \xrightarrow[300\ atm]{623\ K} C_6H_5ONa + NaCl}$$

On subsequent acidification, sodium phenoxide is converted into phenol.

$$\mathrm{C_6H_5ONa + HCl \rightarrow C_6H_5OH + NaCl}$$

Therefore, the required reaction conditions for the conversion of chlorobenzene to sodium phenoxide are:

• Temperature = $$623\ \mathrm{K}$$
• Pressure = $$300\ \mathrm{atm}$$

Hence, the correct answer is Option (D): $$623\ \mathrm{K},\ 300\ \mathrm{atm}$$.