3. electrophilic substitution

Question 1

definition of electrophilic substitution

Answer 1

substitution reaction
electrophile + attracted to electron rich part of molecule
new covalent bond formed
electrophile accepting electron pair

Question 2

4 general steps of electrophilic substitution in benzene

Answer 2

1. delocalised ring attracts electrophile (x+)
2. electrophile accepts pair of pi electrons from delocalised ring. covalent bond formed
3. reactive intermediate- delocalised electrons disrupted
4. unstable intermediate releases H+ ion

Question 3

Reagent for nitration of benzene

Answer 3

concentrated nitric acid HNO3

Question 4

Catalyst for nitration of benzene

Answer 4

concentrated sulfuric acid H2SO4

Question 5

electrophile for nitration of benzene

Answer 5

NO2+

Question 6

how catalyst generates the electrophile (nitration of benzene)

Answer 6

HNO3 + H2SO4 -> NO2+ + HSO4- + H20

Question 7

how the catalyst is regenerated (nitration of benzene)

Answer 7

H+ + HSO4- -> H2SO4

Question 8

summary equation of nitration of benzene

Answer 8

C6H6 + HNO3 -> C6H5NO2 + H2O

Question 9

why cant benzene react directly with halogens

Answer 9

delocalised ring is too stable

Question 10

catalyst for the bromination of benzene

Answer 10

AlBr3 FeBr3 (halogen carriers)

Question 11

catalyst for chlorination of benzene

Answer 11

AlCl3 FeCl3 (halogen carriers)

Question 12

e.g of Br + electrophile generated (halogenation of benzene )

Answer 12

Br2 + FeBr3 -> Br+ + FeBr4-

Question 13

how the catalyst is regenerated (halogenation of benzene)

Answer 13

FeBr4- + H+ -> FeBr3 + HBr