Question

An organic halide is shaken with aqueous NaOH followed by the addition of dil. \[HN{O_3}\] and silver nitrate solution and gives white ppt. The substance can be
A. \[{C_6}{H_4}(C{H_3})Br\]
B. \[{C_6}{H_5}C{H_2}Cl\]
C. \[{C_6}{H_5}Cl\]
D. None of these

Answer 1

Hint: When two compounds in their aqueous state react with each other to form a solid product, the reaction is known as a precipitation reaction. The solid form is known as a precipitate. The precipitation reaction is also known as a double displacement reaction or ionic reaction.

Complete Step by Step Solution:
It is given that an organic halide is shaken with aqueous NaOH followed by the addition of dilute nitric acid and silver nitrate solution which gives a white precipitate.
The organic halide in the given reaction is \[{C_6}{H_5}C{H_2}Cl\].

The chemical name of \[{C_6}{H_5}C{H_2}Cl\] is benzyl chloride.
When benzyl chloride reacts with sodium hydroxide, benzyl alcohol is formed.
Benzyl alcohol on reaction with nitric acid and silver nitrate forms benzaldehyde.
The reaction is shown below.
\[{C_6}{H_5}C{H_2}Cl \overset{NaOH}{\rightarrow} {C_6}{H_5}C{H_2}OH \overset{AgNO_{3}+dil.HNO_{3}}{\rightarrow}
{C_6}{H_5}CHO\]

When benzyl chloride is reacted with sodium hydroxide, the chloride ion is removed and benzyl carbocation is formed as the lone pair of oxygen atom attacks the benzyl carbocation to form benzyl alcohol. After that benzyl alcohol in reaction with dilute nitric acid and silver nitrate form benzaldehyde and a precipitate of silver chloride.
Therefore, the correct option is B.

Note: Silver mirror test is used to differentiate between aldehyde and ketone. Aldehyde shows a positive silver mirror test whereas ketone shows a negative test. In the silver mirror test, Tollen’s reagent is used which is a solution of ammoniacal silver nitrate.