Benzene

Question 1

Describe Kekules model

Answer 1

Proposed it was flat with alternating double bonds

Suggested there were 2 isomers

Question 2

What are the problems with kekules model

Answer 2

Lack of reactivity of benzene: bromine water isn’t colourless
Thermodynamic stability: more stable than expected due to ring of delocalised electrons as experimental value is less exothermic
Bond length - all bond lengths are the same

Question 3

Reagents and conditions of nitration

Answer 3

Conc HNO3 and conc H2SO4

50-55 degrees, reflux

Question 4

Reagents of halogenarenes

Answer 4

Benzene, halogen, halogen carrier

AlCl3 +cl2

Question 5

Describe alkylation of benzene

Answer 5

Halogenoalkane, anhydrous AlCl3, RTP, electrophile is carbon cation

Question 6

Acylation

Answer 6

Acyl chloride, anhydrous alcl3

50 degrees, reflux

Question 7

Describe electron releasing and withdrawing

Answer 7

releasing - CH3, OH, electron density increases, 2,4,6

Withdrawing - NO2 decreases electron density, 3,5

Question 8

Explain why its substitution of phenol

Answer 8

OH groups electron releasing as it has lone pair of electrons on oxygen which delocalise into the ring increasing density

Question 9

Why is there multiple substitution on phenol?

Answer 9

More reactive so no halogen carrier needed so multiple subsitutions
2,4,6

Question 10

Phenol and dilute HNO3

Answer 10

2nitrophenol and 4nitrophenol

Question 11

Phenol and con HNO3

Answer 11

2,4,6-trinitrophenol

Question 12

Why are aromatic compounds so unreactive?

Answer 12

electrophiles are less attracted to pie electron clouds
Ethene- 2pie electron per single bond forming a region of localisted high electron density attracting electrophiles
Benzene - 6 electron delocalisted overall, lower density