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Topic Question Set

Q 1 :    

Number of compounds from the following which cannot undergo Friedel-Crafts reaction is ______.
toluene, nitrobenzene, xylene, cumene, aniline, chlorobenzene, m-nitroaniline, m-dinitrobenzene.                [2024]


(4)

     C6H5-G→no Friedel Craft acylation or alkylation.

     G=(i) all -M groups such as -CHO,-NO2,-COCl,-CN etc

     (ii) Very strong +M groups such as -CH2-,-NH-,-O-,-OH,-NH2,-NHR, and -NR2

      (iii) Very strong -I groups such as -CX3,-NH3+ and  NH3+

       Thus, nitrobenzene, aniline, m-nitroaniline and m-dinitrobenzene cannot undergo Friedel Crafts reaction.

 

Q 2 :    

Which of the following molecule/species is most stable?                      [2024]

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(1)

Cyclic, planar compounds having completely delocalized (4n+2)π electrons (n = 1,2,3...)are aromatic. Aromatic compounds are highly stable. Cyclic, planar compounds having completely delocalized 4nπ electrons (n = 1,2,3...) are anti-aromatic. Anti-aromatic compounds are highly unstable.

 

Q 3 :    

Identify major product ‘P’ formed in the following reaction.                    [2024]

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(2)

 

Q 4 :    

The correct order of reactivity in electrophilic substitution reaction of the following compounds is:               [2024]

  • D > C > B > A

     

  • B > C > A > D

     

  • A > B > C > D

     

  • B > A > C > D

     

(4)

Reactivity of the benzene ring towards an electrophile is directly proportional to electron density on the ring.

–CH3 supplies electrons to benzene by its hyperconjugation and +I effect.

–Cl Has +M effect and –I effect. The –I effect of –Cl is more than its +M effect. Hence, –Cl decreases electron density on benzene and reduces its reactivity towards electrophilic substitution reactions.

–NO2 Has –M and –I effect.

Q 5 :    

Which of the following compound will most easily be attacked by an electrophile?                    [2024]

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(4)

Reactivity of benzene ring towards an electrophile is directly proportional to electron density on the ring.
–OH exerts more electron density on the ring than the given groups –CH3 and Cl and therefore make more appropriate to electrophilic attack.

 

Q 6 :    

Given below are two statements:

Statement I: Nitration of benzene involves the following step –

Statement II: Use of Lewis base promotes the electrophilic substitution of benzene.

In the light of the above statements, choose the most appropriate answer from the options given below:                [2024]

  • Statement I is correct but Statement II is incorrect

     

  • Both Statement I and Statement II are correct

     

  • Statement I is incorrect but Statement II is correct

     

  • Both Statement I and Statement II are incorrect

     

(1)

In nitration of benzene, commonly used reagent is conc. (H2SO4+HNO3). This generates electrophile as follows:

In electrophilic substitution of benzene, Lewis acid helps in generation of electrophile, not Lewis base.

 

Q 7 :    

Identify major product ‘X’ formed in the following reaction:                      [2024]

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(2)

This is Gatterman Koch reaction.

 

Q 8 :    

Which of the following are aromatic?                     [2024]

  • C and D only

     

  • B and D only

     

  • A and C only

     

  • A and B only

     

(2)

B and D are aromatic.

 

Q 9 :    

Among the given organic compounds, the total number of aromatic compounds is :             [2024]


(3)

 

Q 10 :    

The product (C) in the following sequence of reactions has ______ π bonds.                    [2024]


(4)

Number of π bonds in C = 4