Question

Write the chemical reactions of ${C_2}{H_5}OH$ with $PC{l_3}$ and $PC{l_5}$ separately.

Answer 1

Hint: Both $PC{l_3}$ and $PC{l_5}$ can react with ethanol to form the same product in which alcohol is replaced by halide ion. The other side products formed are different in both the cases.
There is a requirement of heat for both the reactions to proceed.

Complete step by step answer:
In the question, we are asked about the chemical reactions of ethanol with phosphorus trichloride and phosphorus pentachloride.
The reactions are:-
1.) When ethanol reacts with phosphorus trichloride in the presence of heat ethyl chloride and phosphorus acid is produced.
${C_{_2}}{H_5}OH + PC{l_3}\xrightarrow{\Delta }{C_2}{H_5} - Cl + {H_3}P{O_3}$

We can balance the equation as-
$3{C_{_2}}{H_5}OH + PC{l_3}\xrightarrow{\Delta }3{C_2}{H_5} - Cl + {H_3}P{O_3}$

2.) When ethanol reacts with phosphorus pentachloride in the presence of heat ethyl chloride hydrochloric acid and phosphoryl chloride is produced.
${C_{_2}}{H_5}OH + PC{l_5}\xrightarrow{\Delta }{C_2}{H_5} - Cl + H - Cl + POC{l_3}$
This equation is already balanced so no need for any change.

Additional Information:
The ethanol is colourless and volatile in nature. It shows some odour. The hydroxyl group in ethanol is capable of hydrogen bonding. This provides it with some viscous nature.

Note: The solid phosphorus pentachloride reacts vigorously with the alcohol at room temperature. As a result of reaction, HCl is produced in the form of clouds.
Usually phosphorus pentachloride is not used to form ethyl chloride because the reaction is violent.
The best way to make ethyl chloride is to react ethanol with thionyl chloride.
The thionyl chloride reacts with ethanol to give ethyl chloride, HCl and sulphur dioxide at room temperature. The reaction is as -

${C_{_2}}{H_5}OH + SOC{l_2} \to {C_2}{H_5} - Cl + H - Cl + S{O_2}$

The advantage of this method is that the other two products formed i.e. the HCl and sulphur dioxide are gases and thus they can easily escape giving the pure product.