Question

p-Methyl benzene nitrile can be prepared from which of the following?

• A.

  

• B.

  

• C.

  

• D.

  

Hint:

The Sandmeyer reaction is a useful method for introducing cyanide groups into aromatic rings.

Answer 1

The Correct Option is C

p-Methyl benzene nitrile can be prepared from p-toluidine (p-methyl aniline) by the Sandmeyer reaction. In the Sandmeyer reaction, an aromatic primary amine is converted to a diazonium salt by treatment with sodium nitrite and hydrochloric acid at low temperature (273-278 K). The diazonium salt is then reacted with copper(I) cyanide (CuCN) or potassium cyanide (KCN) to replace the diazonium group with a cyanide group (CN). 
(1) and (2) are not possible because aryl halides do not undergo nucleophilic substitution with cyanide ions easily. 
(4) is not possible because the reaction of aniline with chloroform and potassium hydroxide is the Reimer
-Tiemann reaction, which introduces an aldehyde group (-CHO) at the ortho position. 
Thus, the correct option is (3).