Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A level Chemistry > Unit 4.3 - Alcohols and Phenol > Flashcards

Unit 4.3 - Alcohols and Phenol Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Chemistry flashcards Periodic Table flashcards Chemistry 101 flashcards Organic Chemistry 101 flashcards
1
Q

Alcohols

A

Compounds with one or more hydroxy (-OH) groups attached to the aliphatic chain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Phenols

A

Compounds where the hydroxy groups are directly attached to the benzene ring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why are phenol and alcohols chemically different and react differently?

A

Because of the interaction between the oxygen atom and the benzene ring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How do we name alcohols?

A

Alcohols with one hydroxy group form a homologous series - the suffix -ol is added to the alkane stem

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are propan-1-ol and propan-2-ol to each other?

A

Structural isomers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Primary alcohols

A

The carbon which carries the OH- group is only attached to 1 alkyl group (1 other Carbon atom_

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Secondary alcohols

A

The carbon which carrier the OH- group is attached to 2 alkyl groups (which may be the same or different)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Tertiary alcohols

A

The carbon which carries the OH- group is attached to 3 alkyl group s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What does Butan-2-ol form and why?

A

Optical isomers
Has a chiral centre

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Explain in detail the solubility of alcohols

A

The lower alcohols (shorter chain) are completely soluble in water (are able to form hydorgen bonds with water)
As the alkyl (hydrocarbon) chain increases in length, the contribution of the hydrogen bond to the overall intermolecular forces decreases = the higher alcohols from butanol onwards are not very soluble in water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Why are lower alcohols completely soluble in water whereas longer ones aren’t?

A

Shorter = are able to form hydrogen bonds with water
Longer = the contribution of the hydrogen bond to the overall intermolecular forces decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How come hydrogen bonds between alcohols and water form?

A

Highly polarising + hydrogen atom attracts a lone pair of electrons from a small, highly electronegative atom in another molecule (N, O, F)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Compare the boiling point of alcohols to the boiling points of alkanes of similar molar mass

A

Higher

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Which bonds do not break when a covalent compound boils?

A

Covalent bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Why do alcohols have higher boiling points than alkanes of similar molar mass?

A

Alkanes only have induced dipole-induced dipole forces
Alcohols have additional hydrogen bonding that elevate the boiling temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Which has the highest boiling point - ethanol or propane? Why?

A

Ethanal
It has hydrogen bonds which require more energy to break than the intermolecular forces in ethanol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How will ethanol dissolve in water?

A

As hydrogen bonds form between ethanol and water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What will ethanol dissolve in as well as water and why?

A

Non-polar solvents
Due to the presence of the hydrocarbon chain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Why is ethanol an important solvent?

A

Will dissolve in both water and non-polar solvents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What else do we need to consider on top of the intermolecular forces when working out boiling points? Explain

A

Chain lengths
Longer chain lengths = increased boiling points due to increased van der wall atracctions
Therefore, the higher the Mr or a molecule, the higher the boiling point

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Why do longer chain lengths lead to higher boiling points?

A

Increased Van der Waal attractions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Explain and give the conditions and equation for the preparation of alcohols from alkenes. What type of reaction is this?

A

Ethanol is produced industrially by the steam hydrolysis of ethene

Phosphoric acid catalyst/concentratd sulfuric acid
300C
60 atm pressure

CH2=CH2 + H2O (g) —> CH3CH2OH

Electrophillic addition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the more natural way to produce ethanol that doesn’t involve steam hydrolysis of ethene?

A

By fermentation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How can ethanol be made by fermentation?

A

Fermentation followed by distillation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What happens during fermentation?

A

Sugars (glucose) from plants are converted into Hanoi by the action from enzymes in yeast (zymase)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Enzymes in yeast and what they do

A

Zymase
Convert sugars (glucose) form plants into ethanol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Why is fermentation a good way to produce ethanol?

A

Carbon neutral
More sustainable
Temperature required much lower than the industrial process

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Equation for the fermentation of glucose to produce ethanol

A

C6H12O6 (aq) —> 2C2H5OH (aq) + 2CO2 (g)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What temperature is used during fermentation of glucose for ethanol? Explain why

A

35C
It’s a compromise since the reaction is slow at low temperatures and enzymes which bring down the enegry required are denatured at high temperatures
The temperature is much over than the industrial process

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Why is air kept out of the reaction vessel during fermentation?

A

Otherwise the ethanol will react (oxidise) to form ethanoic acid —> vinegar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

When does fractional distillation occur during the production of ethanol via fermentation?

A

Once the solution contains 15% ethanol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Why is a fractioning column needed during the fermentation of glucose to produce ethanol?

A

As we have small differences in boiling temperatures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Boiling point of ethanol

A

78C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

How is the ethanol distilled off during fermentation?

A

Using frictional distillation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Process that has to be stopped and restarted?

A

Batch process

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What type of process is fermentation known as and why?

A

Batch process
Has to be stopped and restarted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

How are alcohols produced from halogenoalkanes?

A

The halogenoalkane is refluxed with aqueous sodium hydroxide
This is the alkaline hydrolysis of a halogenoalkane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

If the sodium hydroxide used to reflux with the halogenoalkane to produce alcohol was ethanolic as opposed to aqueous, what kind of reaction would it be?

A

Elimination reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Method for preparing a pure sample of butan-1-oil from 1-bromobutane

A
  1. Measure 25cm^3 of CH3CH2CH2CH2Br using a measuring cylinder and decant to a 100cm^3 round bottomed flask. This step should be performed in a fume cupboard (toxic)
  2. Add 25cm^3 of 0.1moldm^3 NaOH (irritant) solution and a few anti-bumping granules in to the round bottom flask. This should also be performed in the fume cupboard.
  3. Swirl the flask gently to mix the reagents and set up the reflux condenser apparatus for refluxing
  4. Turn on the water to run through the condenser
  5. Turn on the heating mantle (or hot plate, or Bunsen burner) and heat the solution to reflux for 15 minutes
  6. Rearrange the apparatus for distillation
  7. Distilled off the CH3CH2CH2CH2OH produced and collect in a clean, dry 100cm^3 conical last
  8. Record the temperature at which eh liquid product is collected
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Why do we need anti-bumping granules when preparing alcohol from a halogenoalkane?

A

Since 2 unmissable liquids will bump, especially under heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What’s another way of avoiding bumping (except for using anti-bumping granules)?

A

Using a larger container

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

How do anti-bumping granules prevent bumping?

A

By preventing large bubbles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Why is reflux used?

A

To avoid loss of reagents/products

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Why should the escape of vapour be prevented when refluxing?

A

Since complete oxidation could not occur
Since vapour is flammable
Since the yield would be reduced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Why do we use a heating mantle when preparing an alcohol from a halogenoalkane?

A

Alcohol is flammable and could ignite with a naked flame

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

How long do we reflux for?

A

Long enough to enough to establish equilibrium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Where should a thermometer be during distillation and why?

A

Opposite the opening of the condenser since were measuring the temperature of thee vapour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

Why do we use a fractionating column?

A

Since we have small differences in boiling temperatures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

How does a thermometer help to determine purity?

A

By measuring the boiling point

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Why is water put at the bottom of a reflux condenser?

A

Allows better cooling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What type of reaction is the reaction between a halogenoalkane and NaOH to make an alcohol and why?

A

Nuelcophilic substitution
OH- ion is the nucleophile

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Reflux

A

The constant flow of evaporation and condensation and is a reaction technique
Heat volatile (easily evaporated at normal temperatures) reactants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Volatile

A

Easily evaporated at normal temperatures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

What type of reactants are heated when refluxing?

A

Volatile ones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

volatile

A

Easily evaporated at normal temperatures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

Fractional distillation

A

A separation technique that separation molecules based on their boiling temperatures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

What are primary alcohols formed from the reduction of?

A

Aldehydes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

What are secondary alcohols formed form the reduction of?

A

Ketones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

What is formed from the reduction of aldehydes?

A

Primary alcohols

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

What is formed form the reduction of ketones?

A

Secondary alcohols

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

Reducing agent when reducing aldehydes and ketones to form alcohols

A

Sodium borohydride, NaBH4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

Sodium borohydride purpose when forming primary and secondary alcohols from aldehydes and ketones

A

Reducing agent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

Stronger reducing agent to use than NABH4 during the reduction of carbonyl compounds

A

LiAlH4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

How is the reaction carried out when reducing carbonyl compounds?

A

By refluxing the reagents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

Shorthand for oxidation and reduction

A

[O] [R]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

What kind of reactions are those for going from aldehydes and ketones to alcohols?

A

Reversible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

Are carboxylic acids easily reduced? How do you know?

A

No
They’re not reduced by NaBH4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

What are carboxylic acids reduced by and to what?

A

Lithium aluminium hydride (LiAlH4) to primary alcohols

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

How are primary alcohols formed form carboxylic acids?

A

The acid is reacted with LiAlH4 dissolved in ether at room temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

Conditions for reducing carboxylic acids to form primary alcohols

A

Dry conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

Why must the reduction of carboxylic acids to primary alcohols be done under dry conditions?

A

As LiAlH4 reacts violently with water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

Test for alcohols + results

A

Acidified dichromate solution
Primary —> carboxylic acid
Secondary —> ketone
Tertiary —> no reaction

Colour change from orange to green

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

What is happening to cause the colour change from orange to green when adding acidified dichromate solution to alcohols?

A

The dichromate (VI) ion is reduced to the chromium (III) ion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

Why do alcohols form hydrogen bonds?

A

The OH bond in alcohols is highly polar. It’s able to form hydorgen bonds as hydrogen is bonded with. Highly electronegative atom

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

What does NaBH4 not reduce?

A

Carboxylic acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

What happens to the =O bond when reduced to form alcohols?

A

Replaced with OH and H

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

Carbonyl groups

A

C=O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

How do we work out how many C=O groups are present after a reaction of a ketone to form an alcohol?

A

For every carboxyl, the number of hydrogen toms will increase by 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

Conditions and oxidising agent when oxidising alcohols

A

Potassium dichromate (VI) acidified with concentrated sulfuric acid
Heated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

Acidified potassium dichromate symbol

A

H+/Cr2O7^2- or H+/K2Cr2O7

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

What happens to ethanol when distilled and what happens when refluxed?

A

Distilled = ethanal
Refluxed = ethanoic acid

82
Q

What is a primary alcohol immediately converted into when heated with acidified potassium dichromate (vI) and why?

A

Aldehyde is immediately formed since the reaction is exothermic enough

83
Q

Why does a primary alcohol need to be refluxed to form a carboxylic acid?

A

Not exothermic enough

84
Q

What are aldehydes formed from the oxidation of?

A

Primary alcohols

85
Q

What are ketones formed from the oxidation of?

A

Secondary alcohols

86
Q

What does a secondary alcohol form when it undergoes oxidation with acidified potassium dichromate (VI)?

A

A ketone

87
Q

When does a carboxylic acid not form when oxidising an alcohol?

A

When it’s a secondary alcohol that’s formed a ketone

88
Q

Why are ketones resistant to further oxidation?

A

As they do not possess an oxidisable hydrogen
There’s no hydrogen attached to the carbonyl group

89
Q

Oxidisable hydrogen

A

Hydrogen attached to the carbonyl group

90
Q

What happens to the dichromate (VI) ion during the oxidation of alcohols reactions and what does this do?

A

Cr2O7^2- is reduce to Cr^3+
Colour change from orange to green

91
Q

How does Cr3+ behave with NaOH?

A

Amphoterically

92
Q

Dichromate (VI) ion

A

Cr2O7^2-

93
Q

Conditions for the dehydration of primary alcohols

A

Reacted with concentrated sulfuric acid (in excess)
170C

94
Q

Main Product of the dehydration of a primary alcohol

A

Alkene

95
Q

Why is sulfuric acid used during the dehydration of primary alcohols?

A

It removes the elements of water from the alcohol

96
Q

What type of reaction is the dehydration of primary alcohols?

A

Elimination reaction

97
Q

Conditions for the chlorination of alcohols

A

Hydrogen chloride gas is passed into the alcohol in the presence of anhydrous zinc chloride, which acts as a catalyst

98
Q

Type of reaction during the chlorination of alcohols

A

Nucleophilic substitution

99
Q

Conditions for the bromination of an alcohol

A

Carry out an “in situ” reaction
A mixture of alcohol, potassium bromide and 50% sulfuric acid is heated

100
Q

How does sulfuric acid aid the formation of the halogenoalkane during the bromination of an alcohol?

A

It removes the water formed in the reaction and aids the bromination process since it prevents the reverse reaction taking place since the reaction is reversible

101
Q

Equation for the chlorination of butan-1-oil

A

CH3CH2CH2CH2OH —> CH3CH2CH2CH2Cl + H2O

102
Q

Equation for the dehydration of ethanol

A

CH3CH2OH —><— CH2=CH2 + H2O

103
Q

Equation for the bromination of butan-1-ol’

A

CH3CH2CH2CH2OH + KBr + H2SO4 —> CH3Ch2CH2CH2Br + KHSO4 + H2O

104
Q

Conditions for the iodination of alcohols

A

Warm damp red phosphorus and iodine together to form phosphorus (III) iodide, PI3, which then reacts with the alcohol present

105
Q

2 equations for the 2-step process of the iodination of alcohols

A

2P + 3I2 —> 2PI3
3CH3CH2CH2CH2OH + PI3 —> 3CH3CH2CH2CH2I + H3PO3

106
Q

How does the iodination of alcohols work?

A

One of the iodines replaces the OH

107
Q

Why do we need to be careful with white phosphorus?

A

It spontaneously combusts

108
Q

What is ethanol chloride?

A

An acid chloride

109
Q

Ethanoyl chloride formula

A

CH3COCl

110
Q

Describe ethanoyl chloride as a compound

A

Very reactive

111
Q

Conditions for the reaction of alcohol with ethanoyl chloride

A

Room temperature
Anhydrous (dry) conditions
Fume cupboard (harmful HCl gas)

112
Q

Why should the reaction between alcohol and ethanoyl chloride be carried out in a fume cupboard?

A

Due to the release of harmful hydrogen chloride gas

113
Q

Equation for the reaction between ethanoyl chloride and ethanol

A

CH3COCl + CH3CH2OH —> CH3COOCH2 + HCl

114
Q

Ethyl ethanoate

A

CH3COOCH2CH3

115
Q

What is formed during the reaction between propan-2-ol and ethyl ethnote?

A

The ester CH3COOCH(CH3)2 is formed
(1-methylethyl ethanoate)

116
Q

What can the reaction between alcohols and ethanoyl chloride be used for?

A

To produce an ester form phenol

117
Q

Why can’t we react phenol and carboxylic acids to form an ester?

A

Phenol doesn’t behave as an alcohol

118
Q

Reaction between alcohols and carboxylic acid

A

Forms an ester and water

119
Q

How is an ester formed from a reaction between alcohols and carboxylic acids?

A

The reaction mixture is refluxed with concentrated sulfuric acid

120
Q

Reaction between an alcohol and carboxylic acid

A

Ester + water

121
Q

What type of reaction is that between an alcohol and a carboxylic acid

A

Reversible

122
Q

Describe the reaction between alcohol and carboxylic acid

A

Very slow

123
Q

What is needed for the reaction between an alcohol and a carboxylic acid to go to completion?

A

Concentrated sulfuric acid

124
Q

Explain how the concentrated sulfuric acid works when reacting an alcohol and carboxylic acid

A

It speeds up the reaction by acting as a catalyst and as a dehydrating agent by removing water form the reaction mixture. In doing so, the position of equilbirium is pushed to the right and the reaction can go to completion

125
Q

Which reaction is preferred for making esters - the reaction of alcohols with ethanoyl chloride or with carboxylic acids?

A

Reaction with ethanoyl chloride

126
Q

Why is the reaction of alcohols with ethanoyl chloride preferred for making esters over the reaction with carboxylic acids?

A

The reaction of alcohols with ethanoyl chloride is not an equilbirium reaction - it’s one directional, whereas the reaction with carboxylic acids is an equilbirium reaction
It’s easier to separate the co-products with the reaction with ethanoyl chloride since HCl naturally evaporates

127
Q

Describe the hydroxy (OH) group in phenols

A

Is bonded to the benzene ring

128
Q

Why are some of the properties of phenol different to those of alcohols?

A

Since the OH group is directly bonded to the benzene ring in phenols

129
Q

Molecular formula of phenol

A

C6H5OH

130
Q

Melting point of phenol

A

40-43C

131
Q

Solubility of phenol in water + explanation

A

Moderately soluble (can form hydorgen bonds with water)

132
Q

What happens if you try to dissolve too much phenol in water?

A

You get 2 layers of liquid
Top layer = phenol in water
Bottom layer = water in phenol

133
Q

Toxicity of phenol

A

Quite toxic via oral exposure

134
Q

Explain why the reactivity of phenol is different to that of alcohols

A

One of the lone pairs of the oxygen atom can overlap with the delocalised pi system to form a more extended delocalised system in phenol
Therefore, the C-O bond in phenols is shorter and stronger than in alcohols

135
Q

Why is the C-O bond shorter and stronger in phenols than in alcohols?

A

One of the lone pairs of the oxygen atom can overlap with the delocalised pi system to form a more extended delocalised system in phenol

136
Q

Is C-O bond fission in a phenol easier or harder than C-O bond fission in an alcohol? Why?

A

Harder
The C-O bond in phenols is shorter and stronger than in an alcohol

137
Q

What are more susceptible to attack by electrophiles - phenol or alcohol? Why?

A

Phenol
Due to the extended delocalisation (caused by the lone pairs on the oxygen atom overlapping with the delocalised pi system to make a more extended delocalised system) creating a higher electron density in the ring

138
Q

What are the most acidic - phenols or alcohols?

A

Phenols are much more acidic than alcohols

139
Q

What are the strongest acids out of these - phenol, ethanol, ethanoic acid?

A

Phenol is a stronger acid than ethanol but a considerably weaker acid than ethanoic acid

140
Q

What does the ionisation of phenol give?

A

The phenoxide ion, C6H5O-

141
Q

Phenoxide ion

A

C6H5O-

142
Q

Where does the position of equilibrium lie in the equation for the ionisation of phenol?

A

To the left

143
Q

What gives added stability to the phenoxide ion?

A

Delocalisation of the negative charge

144
Q

Why is phenol not very soluble in water?

A

Since the Oh- group is only a small part of a largely hydrophobic molecule

145
Q

What does phenol dissolve in readily and what does this giv?

A

Aqueous NaOH
To give a solution of sodium phenoxide

146
Q

What is an example of phenol reacting as an acid? Explain

A

When it dissolves readily in aqueous NaOH
Phenol loses a proton to the aqueous OH- ion present from NaOH

147
Q

What affects the acidity of phenol?

A

The presence of substituents on the benzene ring

148
Q

What is phenol not strong enough to react with since it’s only a weak acid?

A

Sodium carbonate or sodium hydrogencarbonate to produce CO2

149
Q

Test to distinguish between a simple aliphatic acid (e.g - ethanoic acid) and phenol

A

Add sodium carbonate solution
Ethanoic acid —> bubbles of CO2
Phenol —> no results

150
Q

What activates the ring of phenol to attack by electrophiles?

A

The presence of an OH- group bonded directly to the benzene ring

151
Q

What does the presence of an OH- group on phenol activates it to?

A

Attack by electrophiles

152
Q

Which positions are activated towards attack by electrophiles in phenol?

A

All of them, but the 2-, 4- and 6- positions are activated to a greater extent

153
Q

What does it mean since the 2-, 4- and 6- positions on phenol are activated to a greater extent for attack from electrophiles?

A

An incoming substituent is likely to replace a hydrogen atom at one or more of these positions

154
Q

What is formed when phenol is treated with dilute nitric acid?

A

Both 2- and 4- nitrophenol

155
Q

What polarises bromine when phenol reacts with bromine?

A

The increased electron density in the ring

156
Q

What is used when phenol reacts with bromine?

A

Aqueous bromine (bromine water)

157
Q

What is produced when bromine water reacts with phenol?

A

A white precipitate of 2, 4, 6 - tribromophenol

158
Q

Conditions for the reaction of phenol with bromine

A

Cold
No catalyst

159
Q

Why is bromine described to be “decolorised” during its reaction with phenol?

A

Since aqueous bromine is an orange solution and the products of the reaction are a colourless solution and a white precipitate

160
Q

What reaction can be used as a test for phenol?

A

The reaction between phenol and bromine

161
Q

Explain why bromine is used as a test for phenol

A

When adding bromine, the result is different from the reaction of bromine with an alkene as the reaction with phenol results in the decolorisation of bromine with the additional formation of a white precipitate

162
Q

Mechanism for the reaction between phenol and bromine

A

Electrophilic substitution

163
Q

What happens during the reaction between phenol and bromine if the 2-, 4- and 6- positions of a phenol are already blocked by a substituent?

A

Bromine generally substitutes in the remaining 2-, 4- and 6- positions

164
Q

What does the reaction between 2-methyl phenol and bromine give?

A

4-6-dibromo-2-methyl phenol

165
Q

What does the reaction between 3-methyl phenol and bromine give?

A

2-4-6-tribromo-3-methyl phenol

166
Q

What happens in the reaction between 2-4-dinitrophenol and bromine? Why?

A

6-bro o-2,4-dinitrophenol
Only the 6-position is free for substitution

167
Q

How can alcohols and phenols react as nucleophiles?

A

By the use of their oxygen lone pairs

168
Q

Why is it more difficult for phenol to react as a nucleophile than alcohol?

A

The delocalisation of an electron pair from the oxygen atom in phenol means that it is more difficult for a phenol to react s a nucleophile

169
Q

Why are carboxylic acids not suitable reagents to make an ester with phenol?

A

Because in the reaction with a carboxylic acid to give an ester, the phenol needs to act as an electrophile
However, the delocalisation of an electron pair from the oxygen atom in phenol means that it is more difficult for a phenol to react as a nucleophile

170
Q

Describe the reaction between phenol and ethanoyl chloride

A

Slow at room temperature

171
Q

What is used to speed up the reaction between phenol and ethanoyl chloride?

A

A base such as pyridine, C5H5N

172
Q

Pyridine

A

C5H5N

173
Q

C5H5N

A

Pyridine

174
Q

What pyridine do during the reaction between phenol and ethanoyl chloride?

A

Reacts with the hydrogen chloride co-product to give pyridinium chloride, C5H5NH+Cl-

175
Q

What is often used instead of ethanoyl chloride for its reaction with phenol and why?

A

Ethanoic anhydride
Ethanoyl chloride is an expensive reagent

176
Q

What can be used if phenol is reacted with a less reactive acyl chloride? Why?

A

Aqueous conditions
As the acyl chloride in only slowly hydrolysed by water

177
Q

Less reactive acyl chloride than ethanoyl chloride

A

Benzoyl chloride

178
Q

Benzoyl chloride

A

C6H5COCl

179
Q

What is done during the reaction between phenol and benzoyl chloride (less reactive than ethanoyl chloride)?

A

Phenol is added to aqueous NaOH
The mixture is shaken

180
Q

What is the main test for phenols?

A

Test with neutral aqueous iron (III) chloride

181
Q

What is the result of the test for phenols with neutral aqueous iron (III) chloride?

A

A purple colour in aqueous solution is produced

182
Q

How is the purple colour produced in the reaction between phenol and neutral aqueous iron (III) chloride?

A

A complex is formed between the two reagents

183
Q

What will happen when any compound that contains an -OH group bonded directly to a benzene ring is reacted with iron (III) chloride?

A

It will give a brightly coloured complex
Generally these are purple, blue or green in colour

184
Q

What can the reaction between phenol and aqueous iron (III) chloride be used for?

A

As a test to differentiate between an aliphatic alcohol and a phenol

185
Q

What are the 2 common drug obtained from phenol

A

Aspirin
Paracetamol

186
Q

Formula for aspirin

A

C9H8O4

187
Q

Systematic names for aspirin

A

2-acetoxybenzoic acid
Or
Acetylsalicylic acid

188
Q

Uses for aspirin

A

Anaesthetic

189
Q

Disadvantages of aspirin

A

Bleeding risks, aspirin poisoning from overdosing

190
Q

Conditions for the production of aspirin from phenol?

A

Heat
Pressure

191
Q

Explain the test to test that no salicylic acid remains as an impurity after the reaction to produce aspirin

A

Add neutral iron (III) chloride
Would give a purple solution of phenol was present (and notice that salicylic acid is both an acid and a phenol since it was an OH group bonded to the benzene ring)

192
Q

Why is salicylic acid also a phenol?

A

Has an OH group bonded to the benzene ring

193
Q

% yield equation

A

Actual/theoretical x100

194
Q

If we have an OH group directly bonded to a benzene ring, what do we need to remember to do when naming functional groups?

A

One of the functional groups is NOT alcohol, it’s phenol

195
Q

What would happen when aqueous sodium hydroxide is added to phenol and why?

A

Na will substitute with the H in OH too since phenol is acidic

196
Q

How do we separate the products of nitration?

A

By fractional distillation

197
Q

How do we convert an alcohol into an alkene? Explain

A

Use sulfuric acid since it’s a dehydrating agent

198
Q

How many products would form when we have a symmetrical alcohol compared to an asymmetrical alcohol when reacting an alcohol with sulfuric acid to form an alkene?

A

One product forms when we have a symmetrical alcohol
More than one product forms when we have an asymmetrical alcohol

199
Q

What do we get when adding sulfuric acid to an alcohol and why?

A

Alkene
Sulfuric acid is a dehydrating agent

200
Q

What does sulfuric acid act as?

A

A dehydrating agent

201
Q

Asymmetrical alcohol

A

OH in the middle of

A level Chemistry (39 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions