Halogen Derivatives JEE Advanced Previous Year Questions With Solutions

Halogen Derivatives JEE Advanced Questions With Solutions is provided here to help students take their fundamental understanding of the concept to a higher level. Additionally, going through these questions and practising solving them will enable students to learn about the type of questions that can be asked from this chapter in the JEE Advanced exam. Halogen Derivative previous year questions and solutions will further allow students to revise the previous year questions and prepare effectively for the second stage of the engineering entrance exam. Students will also find accurate solutions that will further boost their problems solving skills.

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JEE Advanced Previous Year Questions on Halogen Derivative

Question 1. The total number of alkenes possible by dehydrobromination of 3-bromo-3-cyclopentylhexane using alcoholic KOH is.

A. 3

B. 4

C. 5

D. 6

Solution: (C)

The substrate has three different types of B—H, therefore, first, three structural isomers of alkenes are expected as

The last two alkenes (II) and (III) are also capable of showing geometrical isomerism hence, two geometrical isomers for each of them will be counted giving a total of five isomers.

Question 2. The reactivity of compound Z with different halogens under appropriate conditions is given below:

The observed pattern of electrophilic substitution can be explained by:

A. The steric effect of the halogen

B. The steric effect of the tert-butyl group

C. The electronic effect of the phenolic group

D. The electronic effect of the turt-butyl group

Solution: (A, B and C)

This problem includes the concept of the effect of steric and electronic effects on the reactivity of organic compounds. Steric effect of halogens is as follows

Cl₂<Br₂<I₂

The electronic effect of the phenolic group directs the approaching electrophile towards ortho and para positions.

The tertiary butyl group has a large size so it causes a steric effect around the aromatic nucleus.

Hence, orientation in electrophilic substitution reaction is decided by

(A) The steric effect of halogen

(B) The steric effect of the tertiary butyl group

(C) The electromeric effect of phenolic group

Question 3. The maximum number of isomers (including stereoisomers) that are possible on mono-chlorination of the following compounds, is/are;

A. 5

B. 8

C. 6

D. 10

Solution: (B)

If we add all of them together: 2 + 4 + 1 + 1= 8

Question 4. KI in acetone, undergoes SN2 reaction with each of P, Q, R and S. The rates of the reaction vary as _______________.

A. P > Q > R > S

B. S > P > R > Q

C. P > R > Q > S

D. R > P > S > Q

Solution: (B)

The correct order is S>P>R>Q.

It is a fact that methyl halides are more reactive than primary alkyl halides towards the SN2 substitution reaction. Likewise, in comparison to secondary halides, primary alkyl halides tend to be more reactive towards SN2 substitution reaction.

This is mainly a result of the steric hindrance and the electron donating effect of alkyl groups. These properties also cause an increase of electron destiny on the carbon attached to halogen further making it less electrophilic. This basically explains the order P>R>Q

If we look at compound S, we will find a phenyl group and a carbonyl group. Interestingly, both these groups are electron-withdrawing groups. Because of this characteristic, the electron density on the carbon attached to the chlorine atom decreases. It further results in the increment of electrophilicity of the carbon and the attack of nucleophilic becomes much easier. So the rate of SN2 reaction for compound S is highest. T

Thus, the order of rate of SN2 reaction is: S > P > R > Q.

Question 5. What are the products in the given reaction;

Solution: (D)

Due to the stronger aryl-oxygen bond, alkyl aryl ethers are usually cleaved at the alkyl-oxygen bond. The reaction will yield phenol and alkyl halide. Therefore,

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