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

Hint: 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 \[PC{{l}_{3}}\].