Question

Product B is :

(a)-

(b)-

(c)-

(d)-

Answer 1

Hint: The reactant in the reaction is 4-Ethyl toluene or p-Ethyl toluene. NBS means the compound is N-Bromosuccinimide and 2 moles of NBS is used means two bromine atoms will be attached in the reactant compound. In the next step, the KCN is in which the cyanide group is the nucleophile and it will replace the bromine atom which is attached to the carbon atom having more number of hydrogen atoms.

Complete step by step answer:
- The reactant molecule in the given reaction is 4-Ethyl toluene or p-Ethyl toluene means the ethyl group is present at the 4th position of the benzene ring and at the 1st position methyl group is present.
- Now, in the first reaction, the reactant molecule is treated with NBS, which means N-Bromosuccinimide, and this NBS is reacted for the addition of bromine atoms. As there are 2 moles used in this reaction, two bromine atoms will be substituted in the compound. One bromine atom will be attached to the carbon atom attached to the benzene ring at the 1st position and the second bromine will be attached to the carbon atom which is attached to the 4th atom of the benzene ring.
- Now, this compound is treated with KCN, in which the cyanide ($C{{N}^{-}}$) is a nucleophile that replaces the bromine atom which is attached to the carbon atom having a higher number of hydrogen atoms. The series of reaction is given below:

The correct answer is option “B” .

Note: The structure of N- Bromosuccinimide, is given below:

This reagent is used in many types of Electrophilic addition and substitution reaction as well as Nucleophilic addition and substitution reaction, and it is an excellent source of bromine atoms in the reaction.