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Topic Question Set

Q 1 :    

The set of meta directing functional groups from the following sets is:                 [2024]

  • —CN,—NH2,—NHR,—OCH3

     

  • —CN,—CHO,—NHCOCH3,—COOR

     

  • —NO2,—NH2,—COOH,—COOR

     

  • —NO2,—CHO,—SO3H,—COR

     

(D)

–M groups decrease electron density at ortho and para position of benzene, thereby directing the incoming electrophile to meta position. Hence –M groups are meta directing groups for electrophilic aromatic substitution reactions.

Groups of the type –X = Y or –X ≡ Y act as –M groups. Among given species, —NO2,—C≡N,—COR,—COOH,—COOR and —SO3H are –M groups, hence are meta directing groups.

 

Q 2 :    

Among the following, total number of meta directing functional groups is ________ . (Integer based) 

—OCH3,—NO2,—CN,—CH3,—NHCOCH3,—COR,—OH,—COOH,—Cl             [2024]             


(4)

        Among given species, —NO2,—C≡N,—COR and —COOH are -M groups, hence are meta directing groups.

 

Q 3 :    

The arenium ion which is not involved in the bromination of Aniline is ____.                        [2024]

  • [IMAGE 211]

     

  • [IMAGE 212]

     

  • [IMAGE 213]

     

  • [IMAGE 214]

     

(3)

-NH2 due to its +M effect is ortho and para directing group for electrophilic substitution reactions such as bromination. Hence, bromine would not attack the meta position (low electron density position).

[IMAGE 215]

 

 

Q 4 :    

[IMAGE 216]

The correct arrangement for decreasing order of electrophilic substitution for above compounds is:                  [2024]

  • (III) > (I) > (II) > (IV)

     

  • (IV) > (I) > (II) > (III)

     

  • (III) > (IV) > (II) > (I)

     

  • (II) > (IV) > (III) > (I)

     

(1)

More is electron density on the ring, more is the rate of electrophilic substitution reaction.

[IMAGE 217]

Q 5 :    

Total number of deactivating groups in aromatic electrophilic substitution reaction among the following is ______.            [2024]

[IMAGE 218]


(2)

-M groups decrease electron density on aromatic ring hence act as deactivating groups in electrophilic aromatic substitution reactions. Groups of the type –X=Y and –X≡Y act as –M groups. Among given options –COOCH3 and –C≡N are –M groups, thus acts as deactivating groups.

–NHCOCH3, –NHCH3 and –OCH3 are +M groups hence act as activating groups for electrophilic aromatic substitution reactions. +M groups have a lone pair of electrons on first atom.