arenes

Question 1

conditions for nitration of benzene

Answer 1

conc HNO3, conc H2SO4, 55°C

generation of electrophile:
HNO3 + H2SO4 → H3O+ + 2HSO4- + NO2+

Question 2

conditions for halogenation of benzene

Answer 2

X2, AlX3/FeX3

generation of electrophile
Br2 + FeBr3 → [FeBr4]- + Br+

Question 3

conditions for alkylation of benzene

Answer 3

R-Cl, AlCl3/FeCl3

generation of electrophile:
CH3Br + AlBr3 → [AlBr4]- + CH3+

Question 4

conditions for acylation of benzene

Answer 4

R-COCl, AlCl3/FeCl3

Question 5

how does a substituent on the benzene ring affect the reactivity of the benzene ring?

Answer 5

if X is an activating group, the benzene ring is made more reactive. reaction conditions would be milder

if X is a deactivating group, benzene ring is made less reactive. reaction conditions would be harsher

Question 6

conditions for nitration of methylbenzene

Answer 6

conc HNO3, conc H2SO4, 30°C
methyl group is EDG (activating)

Question 7

conditions for nitration of phenol

Answer 7

HNO3 (aq), room temp
-OH group is a stronger activating group

Question 8

conditions for nitration of nitrobenzene

Answer 8

conc HNO3, conc H2SO4, >55°C

Question 9

what must be present for the side chain oxidation of methylbenzene to take place?

Answer 9

benzylic H

Question 10

why do arenes not undergo addition reactions?

Answer 10

due to resonance stabilisation, benzene rings prefer to undergo substitution rather than addition, where the electron cloud is less electrophilic compared to that in a C=C