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A-LEVEL CHEMISTRY > B6 Organic Chemistry II > Flashcards

B6 Organic Chemistry II Flashcards

1
Q

Which model of benzene is this

A

Kekulé’s model

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2
Q

Which model of benzene is this

A

Delocalised model

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3
Q

Describe the structure and bonding in Kekulé’s model of benzene

A
  • P-orbitals overlap to form pi-bonds
  • Pi-electrons are localised between carbon atoms
  • Alternating pi-bonds
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4
Q

What is the similarity between Kekulé’s benzene model and the delocalised benzene model

A

Both have overlap of p-orbitals

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5
Q

Describe the delocalised model of benzene

A

P-orbitals overlap to form pi-bonds, with pi-electrons delocalised into delocalised ring pi-system

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6
Q

What is the evidence to suggest that Kekulé’s model of benzene isn’t correct

A
  • Carbon-carbon bond lengths are all the same size in benzene, but not in Kekule’s model
  • Enthalpy of hydrogenation of benzene is less exothermic than Kekule’s model
  • Benzene is less reactive than alkenes - bromination requires a catalyst for benzene but not for alkenes
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7
Q

Name this molecule

A

Phenylamine

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8
Q

Name this molecule

A

Benzonic acid

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9
Q

Catalyst for benzene electrophillic substitution - nitration

A

Concentrated Sulfuric Acid

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10
Q

Conditions for benzene electrophillic substitution - nitration, and why

A

Less than 50c to prevent further substitutions occuring

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11
Q

Inorganic product for benzene electrophillic substitution - nitration

A

Water

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12
Q

Electrohphile generator step for benzene electrophillic substitution - nitration

A
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13
Q

Mechanism step for benzene electrophillic substitution - nitration

A
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14
Q

Catalyst regeneration step for benzene electrophillic substitution - nitration

A
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15
Q

Catalyst for benzene electrophillic substitution - halogenation

A

Halogen carrier - AlCl3 or FeCl3

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16
Q

Inorganic product for benzene electrophillic substitution - halogenation

A

Hydrogen halide

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17
Q

Catalyst generation for benzene electrophillic substitution - halogenation

A
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18
Q

Mechanism for benzene electrophillic substitution - halogenation

A
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19
Q

Catalyst regeneration for benzene electrophillic substitution - halogenation

A
20
Q

Reactant for Friedel-Crafts alkylation

A

Haloalkane

21
Q

Catalyst for Friedel-Crafts alkylation

A

Halogen carrier - AlCl3 or FeCl3

22
Q

Inorganic product of Friedel-Crafts alkylation

A

Hydrogen halide

23
Q

Reactant of Friedel-Crafts acetylation

A

Acyl chloride

24
Q

Catalyst for Friedel-Crafts aceytlation

A

Halogen carrier - AlCl3 or FeCl3

25
Q

Inorganic product of Friedel-Crafts acetylation

A

Hydrogen halide

26
Q

Structure of acyl chloride

A
27
Q

Describe and explain why benzene is more resistant to bromination than alkenes

A
  • In alkenes, electrons in the pi-bond are localised between carbon atoms
  • In benzene, electrons in the pi-bond delocalise into the delocalised ring pi-system
  • Alkenes therefore have a higher electron density
  • So can polarise electrophiles more
  • So are more suseptible to electrophillic attack
28
Q

Structure of phenol

A
29
Q

How to determine whether a molecule is a phenol or an alcohol

A
  • -OH must be directly bonded to the benzene ring to be a phenol
  • Otherwise, properties will be that of an alcohol
30
Q

Evidence to proove that phenols are weak acids

A
  • Will react with NaOH (Strong base)
  • Will not react with carbonates (weak base)
31
Q

How to test for the presence of a phenol in a compound

A
  • No reaction with carbonates, but reaction with strong bases (NaOH)
  • Decolourises bromine water, and forms a white precipitate
32
Q

Observations of bromination of phenol

A
  • Bromine water is decolourised
  • White precipitate forms
33
Q

Catalyst for phenol’s electrophillic substitution with bromine

A

None

34
Q

Equation for bromination of phenol

A
35
Q

Products of phenol’s bromination

A
  • 2,4,6-tribromophenol
  • 3HBr
36
Q

Catalyst for phenol’s nitration

A

No catalyst required

37
Q

What shows that phenol is more reactive than bromine with it’s nitration reaction

A
  • Dilute nitric acid not concentrated
  • No catalyst requried
38
Q

What must all acids be in benzene’s electrophillic substitutions

A

Concentrated

38
Q

Reactant of benzene’s electrophillic substitution - nitration

A

Concentrated nitric acid

39
Q

Products of phenol’s nitration

A

Mix of 2-nitrophenol and 4-nitrophenol

40
Q

Equation of phenol’s nitration

A
41
Q

Describe and explain why phenol is more suseptible to electrophillic substitution than benzene

A
  • Lone pair of electrons from oxygen in phenol partially delocalises into the delocalised ring pi-system
  • Therefore, electron density is higher than benzene
  • Electrophile is more polarised by phenol
  • Phenol is more suseptible to electrophillic attack
42
Q

What are the 2- and 4- directing groups

A

-OH and -NH3

43
Q

What are the -3 directing groups

A

-NO2

44
Q

What directing group is -NO2

A

3-

45
Q

What directing group is -NH2

A

2- and 4-

46
Q

What directing group of -OH

A

2- and 4-

A-LEVEL CHEMISTRY (13 decks)

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