Reaction of Benzene

Question 1

what are benzenes similar to

Answer 1

alkenes

Question 2

what type of reactions do alkenes undergo

Answer 2

electrophilic addition

Question 3

since benzenes are similar to alkenes, what type of reaction do we expect them to have

Answer 3

electrophilic addition

Question 4

what type of reaction do benzenes actually undergo

Answer 4

electrophilic substitution

Question 5

why do benzenes undergo electrophilic substitution

Answer 5

Because they have a delocalised ring of Π electrons so benzene react with
electrophiles and benzenes dont generally undergo addition reactions because these would involve breaking up
the delocalised system. Most of Benzene’s reactions involve substituting one H for another atom or group of atoms.

Question 6

what benefit is there of benzene undergoing electrophilic substitution

Answer 6

this maintains the delocalised ring and it’s stability

Question 7

what is a halogen carrier

Answer 7

a Lewis acid that can bind to a halogen molecule

Question 8

what is the role of a hydrogen carrier for the reaction

Answer 8

it catalyses the reaction

Question 9

what is a lewis acid

Answer 9

a substance to generate an electrophile for the benzene reactions

Question 10

examples of lewis acids are

Answer 10

AlCl3, FeBr3

Question 11

what are the 6 benzene reactions

Answer 11

bromination, chlorination, nitration, hydrogenation, Friedel-Crafts Alkylation and Friedel-Crafts Acylation

Question 12

what is the reagent for the bromination of benzene

Answer 12

bromine

Question 13

what are the conditions for the bromination of benzene

Answer 13

Warm under reflux with Fe/FeBr3 catalyst

Question 14

what is the electrophile needed for the bromination of benzene

Answer 14

Br+

Question 15

what is the electrophile formation for bromination

Answer 15

FeBr3 + Br2 → FeBr4− + Br+

Question 16

what is the reagent for the chlorination of benzene

Answer 16

chlorine

Question 17

what are the conditions for the chlorination of benzene

Answer 17

Warm under reflux with AlCl3/FeCl3 catalyst

Question 18

what is the electrophile needed for the chlorination of benzene

Answer 18

Cl+

Question 19

what is the electrophile formation for chlorination

Answer 19

AlCl3 + Cl2 → AlCl4− + Cl+

FeCl3 + Cl2 → FeCl4− + Cl+

Question 20

what is the observation for the chlorination of benzene

Answer 20

Steamy White Fumes of HCl

Question 21

what is the reagent for the nitration of benzene

Answer 21

nitric acid

Question 22

what are the conditions for the nitration of benzene

Answer 22

Warm below 55oC, In presence of Concentrated Sulfuric Acid

Question 23

what is the electrophile needed for the nitration of benzene

Answer 23

NO2 +

Question 24

what is the electrophile formation for nitration

Answer 24

HNO3 + 2H2SO4 → NO2+ + 2HSO4− + H3O+

Question 25

if temp for nitration is below 55oC how many NO2 groups are added

Answer 25

1

Question 26

if temp for nitration is above 55oC how many NO2 groups are added

Answer 26

multiple

Question 27

what is the reagent for the hydrogenation of benzene

Answer 27

hydrogen

Question 28

what are the conditions for the hydrogenation of benzene

Answer 28

Heated at 2000C and 30atm in presence of Ni Catalyst.

Question 29

what does the hydrogenation of benzene form

Answer 29

cyclohexane

Question 30

what is cyclohexane used for

Answer 30

production of nylon in industry

Question 31

what is a Friedel-craft reaction

Question 32

what is Friedel-Crafts Alkylation of Benzene

Answer 32

Benzene can have a hydrogen substituted for an alkyl chain

Question 33

what is the reagent used for alkylation of benzene

Answer 33

chloroalkane

Question 34

what is the conditions used for alkylation of benzene

Answer 34

Warmed under reflux in presence of anhydrous AlCl3 catalyst

Question 35

what is the electrophile needed for the alkylation of benzene

Answer 35

R+, the alkyl chain

Question 36

what is the electrophile formation for the alkylation of benzene

Answer 36

AlCl3 + R-Cl → AlCl4− + R+ (where R is the alkyl chain)

Question 37

what is Friedel-Crafts Acylation of Benzene

Answer 37

Benzene can have a hydrogen substituted for an acyl chain in the following reaction

Question 38

what is the reagent used for acylation of benzene

Answer 38

Acyl chloride

Question 39

what is the conditions used for acylation of benzene

Answer 39

Warmed under reflux in presence of anhydrous AlCl3 catalyst

Question 40

what is the electrophile needed for the acylation of benzene

Answer 40

RCO+, alkyl chain and carbonyl group

Question 41

what is the electrophile formation for the acylation of benzene

Answer 41

AlCl3 + R-COCl → AlCl4− + R-CO+ (where R is the alkyl chain)

Question 42

what is a phenol

Answer 42

a benzene ring which has an OH group attached to it

Question 43

is a phenol more or less recative than benzene

Answer 43

more

Question 44

why cna the benzene ring be described as 'activated' in a phenol

Answer 44

because it can polarise electrophiles more readily meaning reactions can occur in milder conditions and without catalysts.

Question 45

what 2 types of recations do phenols go through

Answer 45

bromination and nitration

Question 46

what is the reagent for the bromination of phenol

Answer 46

bromine

Question 47

what is the condition for the bromination of phenol

Answer 47

room temp

Question 48

what does the bromination of phenol produce

Answer 48

a white ppt of 2,4,6-tribromophenol

Question 49

what is the electrophile for the bromination of phenol

Answer 49

Br+

Question 50

how does the bromination of phenol differ from benzene

Answer 50

doesnt need a catalyst andit undergoes multiple substitutions

Question 51

what is the reagent for the nitration of phenol

Answer 51

dilute nitic acid

Question 52

what is the condition for the nitration of phenol

Answer 52

room temp

Question 53

what is the electrophile for the nitration of phenol

Answer 53

NO2+

Question 54

what does the nitration of phenol produce

Answer 54

mixture of 2-nitrophenol and 4-nitrophenol