Electrophilic Aromatic Substitution

Question 1

General reaction of EAS

Answer 1

Ar-H + EA = Ar-E + H-A
; Ar-H arenes
EA -electrophile

Question 2

Benzene + X2,FeX3= ?

Halogenation reaction

Answer 2

Benzene + X2,FeX3= benzene-X + HX

Question 3

Benzene + HONO2/H2SO4 = ? ( Nitration Reaction )

Answer 3

Benzene + HONO2/H2SO4 = Benzene-NO2 + H20

Question 4

Benzene + SO3/H2SO4= ? ( Sulphonation Reaction )

Answer 4

Benzene + SO3/H2SO4= benzene-SO3H

Question 5

Benzene + RCl/AlCl3= ? (Friedel Craft Alkylation)

Answer 5

Benzene + RCl/AlCl3= benzene-R + HCl

Question 6

Benzene + RCOCl/AlCl3= ? ( Fridel craft acylation )

Answer 6

Benzene + RCOCl/AlCl3= benzene-RCO + HCl

Question 7

True intermediate in EAS reaction ?

Answer 7

Arenium ion

Question 8

Facts about Activating groups( op directors )

Answer 8

Fast reactions take place.
Direct incoming electrophile towards ortho or para position.
Occurrence mostly due to resonance effect.
Low Activation barrier and stabler Arenium ion.

Question 9

Facts about deactivating groups ( m directors )

Answer 9

Slow reactions take place.
Direct incoming electrophile towards meta position.
Have partial or full positive charge on atom directly attached to ring
Higher Activation barrier and less stabler Arenium ion.

Question 10

Electron Releasing group effect on transition state, Activation barrier and reaction rate.

Answer 10

Make transition state stabler.
Lower Activation barrier.
High reaction rate.

Question 11

Electron withdrawing group effect on transition state , Activation barrier and reaction rate.

Answer 11

Make transition state stabler.
Increases activation barrier.
Slower reaction rate.

Question 12

? Groups cause the group to be more stabler than benzene itself in EAS ?

Answer 12

Activating groups.

Question 13

Op directors list.

Answer 13

-NH2, -OH, O- , NHCOCH3 , OCH3, OR, CH3( R ) , C6H5 , -F/Cl/Br/I( weakly deactivating )

Question 14

Mera directors list.

Answer 14

-C=- N, SO3H, CO2H, CO2R, CHO, NO2 , CF3, CCl3