Aromatic Compounds

Question 1

Why is the Kekule model for benzene inaccurate

Answer 1

Lack of reactivity of benzene
Lengths of carbon carbon bonds
Hydrogenation enthalpies

Question 2

Enthalpy change of hydrogenation of benzene

Answer 2

-208

Question 3

Nitration of benzene reagents and conditions

Answer 3

HNO2 and H2SO4
50 degree Celsius

Question 4

What happens if the temperature of nitration surpasses 50 degrees

Answer 4

Further substitution (dinitrobenzene)

Question 5

Equation for production of NO2+ and regeneration of catalyst during nitration

Answer 5

HNO3 + H2SO4 > NO2(positive)+ HSO4(negative) + H2O
H(positive) + HSO4(negative) > H2SO4

Question 6

Reactants required for halogenation of benzene

Answer 6

(E.g Br)
Al3Br (halogen carrier)
Br2

Question 7

Equation for formation of Br(positive) and regeneration of catalyst during bromination

Answer 7

Br2 + AlBr3 > AlBr4(negative) + Br(positive)

H(positive) + AlBr4(negative) > AlBr3 + HBr

Question 8

Acylation

Answer 8

Formation of an aromatic ketone from reaction of an acyl chloride with benzene in the presence of AlCl3 catalyst

Question 9

Alkylation

Answer 9

Substitution of a hydrogen in benzene with an alkyl chain

Question 10

Reagents for alkylation

Answer 10

Benzene, haloalkane
AlCl3(catalyst)

Question 11

Why is a halogen carrier needed to react benzene with a halogen

Answer 11

When a non-polar halogen molecule approaches the benzene, there is insufficient electron density to polarise the molecule