Question

Ethyl benzoate reacts with $PC{{l}_{5}}$ to give:
A.)${{C}_{2}}{{H}_{5}}Cl+{{C}_{6}}{{H}_{5}}COCl+POC{{l}_{3}}+HCl$
B.)${{C}_{2}}{{H}_{5}}Cl+{{C}_{6}}{{H}_{5}}COCl+POC{{l}_{3}}$
C.)$C{{H}_{3}}COCl+{{C}_{6}}{{H}_{5}}COCl+POC{{l}_{3}}$
D.)${{C}_{2}}{{H}_{5}}Cl+{{C}_{6}}{{H}_{5}}COOH+POC{{l}_{3}}$

Answer 1

Alkyl halides are prepared by the reaction of alkyl benzoates with $PC{{l}_{5}}$. This reaction is called a halogenation reaction. $PC{{l}_{5}}$ is called phosphorus pentachloride. This reaction is the best example to prepare alkyl halides from esters in a simple way.

Complete answer:
The molecular formula of ethyl benzoate is ${{C}_{6}}{{H}_{5}}COOC{{H}_{2}}C{{H}_{3}}$ contains one benzene ring and ester functional group and one ethyl (alkyl) group.
The reaction of ethyl benzoate with phosphorus pentachloride is as follows.

$\underset{Ethyl\text{ }benzoate}{\mathop{{{C}_{6}}{{H}_{5}}COOC{{H}_{2}}C{{H}_{3}}}}\,\xrightarrow{PC{{l}_{5}}}\underset{Ehtyl\text{ }chloride}{\mathop{{{C}_{2}}{{H}_{5}}Cl}}\,+\underset{Benzoylchloride}{\mathop{{{C}_{6}}{{H}_{5}}COCl}}\,+\underset{phosphorous\text{ }oxy\text{ }chloride}{\mathop{POC{{l}_{3}}}}\,$
Ethyl benzoate reacts with $PC{{l}_{5}}$and forms ethyl chloride, benzoyl chloride and phosphorous oxy Chloride.

Coming to the given options, option A, ${{C}_{2}}{{H}_{5}}Cl+{{C}_{6}}{{H}_{5}}COCl+POC{{l}_{3}}+HCl$ it is wrong because HCl is not going to form as by-product when ethyl benzoate reacts with phosphorus pentachloride.

Coming to the given option C, $C{{H}_{3}}COCl+{{C}_{6}}{{H}_{5}}COCl+POC{{l}_{3}}$ . It is also wrong because acetyl chloride ($C{{H}_{3}}COCl$) is not going to form during the reaction

Coming to option D, ${{C}_{2}}{{H}_{5}}Cl+{{C}_{6}}{{H}_{5}}COOH+POC{{l}_{3}}$. It is also wrong because benzoic acid (${{C}_{6}}{{H}_{5}}COOH$) is not going to form during the reaction.

Coming to option B, ${{C}_{2}}{{H}_{5}}Cl+{{C}_{6}}{{H}_{5}}COCl+POC{{l}_{3}}$. The products in option B are exactly matching with the products formed during the reaction.

So, the correct answer is “Option B”.

Note:
The structure of ethyl benzoate is $\underset{{}}{\mathop{{{C}_{6}}{{H}_{5}}COOC{{H}_{2}}C{{H}_{3}}}}\,$ not $\underset{{}}{\mathop{{{C}_{2}}{{H}_{5}}COO{{C}_{6}}{{H}_{5}}}}\,$. Don’t be confused with the structures. The ethyl benzoate ethyl group is attached to the oxygen part of the ester functional group.
The molecular formula of phosphorus pentachloride is $PC{{l}_{5}}$ and the molecular formula of phosphorus trichloride is $PC{{l}_{3}}$.