Question

Following equation illustrates
\[{C_6}{H_5}Cl + 2NaOH \xrightarrow[200atm]{200-250^{\circ } C}
{C_6}{H_5}OH + NaCl + {H_2}O\]
A. Dow’s process
B. Kolbe’s process
C. Carbylamine test
D. Haloform reaction

Answer 1

Hint: The chemical name of a compound with formula \[{C_6}{H_5}OH\] is phenol. The reaction mechanism in this reaction involves the formation of intermediate sodium phenolate.

Complete Step by Step Solution:
The given reaction is shown below.
\[{C_6}{H_5}Cl + 2NaOH \xrightarrow[200atm]{200-250^{\circ } C}
{C_6}{H_5}OH + NaCl + {H_2}O\]
In the given reaction, one mole of chloro benzene on heating with two moles of sodium hydroxide at \[200 - 250^\circ \] and 200 atm to form phenol as the main product and sodium chloride with the elimination of water.
The process used for the formation of phenol from haloarenes is Dow’s process.
Firstly sodium phenoxide intermediate is formed by reacting chlorobenzene with sodium hydrogen which further acidification gives phenol. The reaction follows the elimination-addition mechanism.

 In the first step, the hydroxide ion removes the proton from the carbon present adjacent to the carbon bonded to the chlorine forming an intermediate of benzyne by removing the water molecule, the hydroxide ion further attacks the intermediate to form sodium phenoxide which further acidification forms phenol.
The reaction is shown below.

Image: Preparation of phenol
Therefore, the correct option is A.

Note: The main use of the Dow process is the extraction of bromine from brine. It is an electrolytic method. The Dow process was given by Herbert Henry Dow. The bromine extraction was his second revolutionary process. Before, this method bromine was extracted by evaporating brine by heating it with wood scrap. After that, the crystallised sodium chloride was removed. Due to the addition of an oxidising agent, bromine was generated which was then distilled and purified. This method was very costly.