Brainscape's Knowledge GenomeTM

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


See full index

A level Chemistry > Unit 4.6 - Amines > Flashcards

Unit 4.6 - Amines Flashcards

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

Where are free amines found?

A

They do not occur widely in nature but are found in decomposing protein material

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

Give an example of a free amine found in decomposing protein material

A

Dimethylamine is found in rotting fish

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

What can amines be regarded as?

A

Organic derivatives as ammonia

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

General primary amines formula

A

RNH2

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

Explain the primary amines general formula

A

RNH2
Hydrogen substituted for an R group

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

Why is ammonia defined as a weak base?

A

It’s a Proton acceptor

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

Is ammonia an acid or a base?

A

A weak base

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

Why is ammonia a weak base?

A

Because the lone pair of electrons on N can form a coordinate bond with a proton

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

What is a primary amine?

A

An amine where the nitrogen atom has one alkyl or aromatic group bonded to it. They contain the functional group -NH2

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

functional group of primary amines

A

-NH2

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

What are the 2 ways of naming primary amines?

A

Add the suffix -amine to the alkyl radicle
Add the prefix amino- to the parent alkane

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

CH3NH2

A

Methyl amine

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

CH3CH2NH2

A

Ethylamine

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

CH3CH2CH2CH2NH2

A

1-propylamine

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

CH3CH(NH2)CH3

A

2-propylamine

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

2-propylamine

A

CH3CH(NH2)CH3

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

Hexane-1,6 diamine structural formula and other name

A

H2N-CH2(CH2)4CH2-NH2
1,6 -diamino hexane

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

What is hexane - 1,6 diamine used for?

A

Making nylon

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

How do we prepare primary aliphatic amines?

A

Prepared by reacting a halogenoalkane with ammonia

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

How do we prepare aliphatic amines by reacting a halogenoalkane with ammonia?

A

The halogenoalkane is heated with a concentrated aqueous solution of ammonia

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

How do we prevent further reaction in the preparation of primary aliphatic amines by reacting a halogenoalkane with ammonia?

A

By using equimolar amounts of the two reagents

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

Equation for the production of a primary amine from bromoethane and ammonia

A

CH3CH2Br + NH3 —> CH3CH2NH2 + HBr

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

What does the primary aliphatic amine produced in a reaction go on to do and why?

A

Reacts with the HBr to form a salt
As he reaction is carried out in a sealed vessel

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

Why does a primary amine react with the HBr also formed in its production?

A

Since the reaction is carried out in a sealed vessel

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

How is the free amine obtained when a primary amine reacts with the side product to form a salt?

A

By adding sodium hydroxide solution (base)

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

How do we obtain a pure amine after obtaining a free amine from a salt by adding NaOH solution?

A

By distillation

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

Equation for ethylamine forming a salt and then the free amine being regenerated

A

CH3CH2NH2 ——> CH3CH2NH3+Br- ——> CH3CH2NH2
HBr. NaOH

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

CH3CH2NH3+Br-

A

Ethyl ammonium bromide (salt)

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

Ethyl ammonium bromide

A

CH3CH2NH3+Br-

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

Explain how ethyl amine reacts with HBr

A

The HBr is in the form H+ and Br-. The H+ will bond with the lone pair of electrons in the nitrogen atom, becoming the NH3+ cation which attracts the Br-

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

How are primary aromatic amines formed?

A

Prepared by reducing a nitro compound

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

What is formed by reacting a halogenoalkane with ammonia?

A

Primary aliphatic amines

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

What is formed by reducing a nitro compound?

A

Primary aromatic amines

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

How is phenylamine made?

A

By reducing nitrobenzene

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

What is made by reducing nitrobenzene?

A

Phenylamine

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

Reducing agent for reducing a nitro compound to a primary aromatic amine

A

A mixture of tin metal and concentrated HCl

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

Conditions when preparing a primary aromatic amine from a nitro compound

A

Reflux

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

What is formed when reducing nitrobenzene by refluxing it with a mixture of tin metal and concentrated HCl?

A

A salt - phenyl ammonium chloride

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

Why is a salt formed when reducing nitrobenzene with tin metal and concentrated HCl?

A

As the reaction is occuring in a sealed vessel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

How is the free amine obtained from the phenyl ammonium chloride formed from the reduction of nitrobenzene?

A

By the addition of excess NaOH solution (base)

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

Equation for the regeneration of the free amine from phenyl ammonium salt

A

C6H5NH3+ + OH- —> C6H5NH2 + H2O

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

How is phenylamine obtained when regenerated from the salt using NaOH? Why?

A

Phenylamine is insoluble in water and is obtained from the mixture by steam distillation

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

Phenylamine in water

A

Insoluble

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

Is phenylammonium chloride soluble in water?

A

Yes

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

How is phenylamine separated from its water during steam distillation?

A

Using a separating funnel

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

How is pure phenylamine recovered during its steam distillation?

A

By re-distilling

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

What is steam distillation useful for?

A

With liquids which have high boiling points high do not decompose in water

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

Why are amines able to form hydrogen bonds?

A

Due to the presence of the N-H bond

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

Why are lower aliphatic amines readily soluble in water?

A

Since they form hydrogen bonds with water molecules

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

Why do lower aliphatic amines have higher boiling points compared to alkanes of similar molar mass?

A

Since they can form hydrogen bonds with themselves

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

Describe phenylamine at room temperature

A

Liquid

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

Describe phenylamine with water

A

Does not mix readily with water (is immiscible with water)

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

Odour of amines

A

Distinct, somewhat like rotting fish

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

Chemical properties of amines to remember

A

Basic properties
Reaction with ethanoyl chloride
Reaction with nitrous acid (nitric III acid)

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

What type of substances are amines - basic or acidic?

A

Basic

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

How do we know that amines are basic substances?

A

Since they react with acids to form salts

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

Where is the lone pair of electrons in primary amines?

A

On the nitrogen atom

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

Why are primary amines able to accept protons?

A

Due to the lone pair of electrons on the nitrogen atom

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

Explain why primary amines are basic substances

A

Primary amines, like ammonia, have a lone pair of electrons on the nitrogen atom which is available for bonding. Thus, they are able to accept a proton and can act as weak bases.

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

Are amines hydrolysed by water?

A

Only partially

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

Equation for the hydrolysis of methylamine in water

A

CH3NH2 + H2O —> CH3NH3+ + OH-

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

How do primary amines react with dilute acids and why?

A

Produce a salt
They are basic substances

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

Methylamine and HCl equation + name the product

A

CH3NH2 + HCl —> CH3NH3+Cl-
Methyl ammonium chloride

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

Phenylamine and HCl equation + name the product

A

C6H5NH2 + HCl ——> C6H5NH3+Cl-
Phenylammonium chloride

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

Methylamine and H2SO4 equation + name the product

A

CH3NH2 + H2SO4 —> (CH3NH3)2SO4^2-
Methyl ammonium sulphate

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

How can the salts formed from amines and dilute acids by isolated?

A

As white crystalline solids with fairly high melting temperatures

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

How do we regenerate the amine from the salt formed from reacting an amine with a dilute acid?

A

By the addition of sodium hydroxide solution

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

Equation for the addition of NaOH to the methyl ammonium chloride salt

A

CH3NH3+Cl- + NaOH —> CH3NH2 + H2O + HCl

69
Q

What can be seen when phenylammonium chloride is reacted with NaOH? Why?

A

Two layers are formed
Phenylamine is immiscible in water

70
Q

Phenylamine in water

A

Immiscible

71
Q

List the following in terms of basicity
Ammonia
phenylamine
Primary aliphaphatic amine

A

Most basic = primary aliphatic amine
Ammonia
Phenylamine

72
Q

What is R in R-NH2?

A

CH3, CH3CH2…etc

73
Q

Explain exactly why primary aliphatic amine are stronger bases than ammonia

A

As the alkyl groups bonded to the nitrogen atoms are electron releasing. As a result, electrons are released towards the nitrogen atom. This makes the nitrogen atom more electronegative and increases the electron density around it. This makes the lone pairs of electrons on the nitrogen more available for bonding and is more able to accept a proton than the nitrogen in ammonia.

74
Q

Explain exactly why phenylamine is a weaker base than ammonia

A

Th lone pair of electrons on the nitrogen atom is partially delocalised into the ring which means that is it less available for bonding. This is because it’s less electron rich and so less likely to accept a proton than NH3.

75
Q

What is more stable - phenyl ammonium salt or ammonium salt?

A

Ammonium salts

76
Q

What is it that makes amines all basic?

A

The lone pair of electrons on the nitrogen atom that can accept a proton

77
Q

What can primary aliphatic amines react as?

A

Nucleophiles

78
Q

Why can primary aliphatic amines react as nucleophiles?

A

Because of the presence of the lone pair of electrons on the nitrogen atom

79
Q

Give 2 things that primary aliphatic amines can react with due to them being able to react as nucleophiles

A

React with transition metals to form a complex
React with acid chlorides to form amides

80
Q

What do amines react with to form amides?

A

Acid chlorides

81
Q

What forms when primary aliphatic amines react with acid chlorides?

A

Amides

82
Q

What is the reaction between a primary aliphatic amine and an acid chloride ac example of?

A

Acetylation in which a CH3CO group is added to the amine

83
Q

Acetylation

A

CH3CO group is added

84
Q

Additional of a CH3CO group

A

Acetylation

85
Q

Conditions for the addition of ethanoyl chloride to primary aliphatic amines

A

Room temperature
Dry

86
Q

Equation for the reaction between methyl amine and ethanoyl chloride

A

CH3COCl + CH3NH2 —> CH3CONHCH3 + HCl

87
Q

HCl appearance in the reaction between ethanoyl chloride and a primary aliphatic amine

A

White misty fumes

88
Q

N-methylethanamide

A

CH3CONHCH3

89
Q

CH3CONHCH3

A

N-methylethanamide

90
Q

What does “N” mean in, for example, N-methylethanamide?

A

That the methyl group is bonded to the nitrogen atom because of the lone pair of electrons and is known as an n substituted derivative of ethanamide

91
Q

Nitrous acid other name

A

Nitric III acid

92
Q

Nitric III acid

A

Nitrous acid

93
Q

Describe the nitric acids we normally use

A

Stable, H is in the +5 oxidation state

94
Q

Formula of nitrous acid

A

HNO2

95
Q

HNO2

A

Nitrous acid

96
Q

Describe nitrous acid

A

An unstable compound that is prepared in situ during the course of the reaction

97
Q

What is nitrous acid formed from?

A

Sodium nitrite NaNO2, conc. HCl

98
Q

Do primary aliphatic amines and primary aromatic amines react in eh same way with nitrous acid?

A

No

99
Q

1-butylamine other name

A

1-aminobutane

100
Q

In what condition should the nitrous acid be when reacting it with aliphatic or aromatic amines?

A

Cold (less than 10 degrees Celsius)

101
Q

What happens when 1-aminobutane is reacted with cold nitrous acid?

A

There is effervescence as nitrogen gas is released. A mixture of products is formed in the reaction including butan-1-ol.

102
Q

Equation for the reaction between 1-butylamine and nitrous acid

A

CH3Ch2CH2CH2NH2 + HNO2 ——> CH3CH2CH2CH2OH + N2 + H2O

103
Q

What is formed when phenylamine is reacted with cold nitrous acid?

A

A diazonium salt is formed

104
Q

When is a diazonium salt formed?

A

When phenylamine is reacted with cold nitrous acid

105
Q

Does the diazonium salt form with aliphatic amines?

A

No

106
Q

What type of amine does the diazonium salt form with the reaction with nitrous acid?

A

Aromatic amines

107
Q

Why doesn’t the diazonium salt form when aliphatic amines react with nitrous acid?

A

As the aliphatic diazonium ion is too unstable to be isolated

108
Q

Diazonium ion

A

C6H5N2+

109
Q

C6H5N2+

A

Diazonium ion

110
Q

Why is the reaction between an aliphatic and an aromatic amine with nitrous acid completely different?

A

Because the diazonium salt only forms with aromatic amines

111
Q

Equation for the reaction between phenylamine and nitrous acid

A

C6H5NH2 + HNO2 + HCl ——> C6H5N2+Cl- + 2H2O

112
Q

Under which condition is the benzene diazonium ion stable?

A

When it’s cold (under 10 degrees Celsius)

113
Q

Under which condition can benzene diazonium salts be isolated?

A

At low temperatures

114
Q

What can be done to benzene diazonium ions at low temperatures?

A

Can be isolated

115
Q

Why do benzene diazonium ions have to be stored at ow temperatures?

A

They’re unstable above 10 degrees Celsius

116
Q

Above which temperature are benzene diazonium ions unstable?

A

10 degrees Celsius

117
Q

What are benzene diazonium salts important for?

A

They’re an important groups of reagents in organic synthesis - especially in the formation of azo dyes

118
Q

Which salts are important in the formation of azo dyes?

A

Benzene diazonium salts

119
Q

What happens to benzene diazonium ions above 10 degrees Celsius?

A

It decomposes

120
Q

What happens as the benzene diazonium ion decomposes above 10 degrees Celsius?

A

Phenol is formed and nitrogen gas is liberated

121
Q

Equation for the reaction between benzene diazonium chloride and water

A

C6H5N2+Cl- + 2H2O —> C6H5OH + N2 + HCl

122
Q

How are azo dyes formed?

A

When benzonium ions are kept below 10 degrees Celsius and phenol is added

123
Q

What forms when benzonium ions are kept below 10 degrees Celsius and phenol is added?

A

Synthetic dyes - azo dyes

124
Q

What are azo dyes?

A

Synthetic dyes

125
Q

What type of reactions are azo dyes made in?

A

Diazo-coupling reactions (diazotization reaction)

126
Q

What happens during a diazo-coupling reaction?

A

A benzene diazonium ion is reacted with a phenol

127
Q

What are retained during the reaction between a benzene diazonium ion and a phenol?

A

The nitrogen atoms

128
Q

What type of reaction does it involve to retain the nitrogen atoms during the reaction between the benzene diazonium ion and a phenol?

A

A coupling reaction

129
Q

What are the compounds formed during the reaction between diazonium ions and phenol known as and why?

A

Azo compounds
They contain the azo group, -N=N-

130
Q

Azo group

A

-N=N-

131
Q

-N=N- group

A

Azo group

132
Q

Typical phenol used for the production of azo dyes

A

Napthalene-2-ol

133
Q

How come napthalene-2-ol is still a phenol?

A

Since the OH group is directly bonded to the benzene ring

134
Q

Conditions for the reaction between benzene diazonium chloride and napthalene-2-ol

A

Below 10 degrees Celsius
In aqueous NaOH

135
Q

Product of the reaction between napthalene-2-ol in aqueous NaOH and benzene diazonium chloride

A

Red solid

136
Q

The reaction between benzene diazonium chloride and which phenol forms a red solid?

A

Napthalene-2-ol

137
Q

Describe azo compounds + their use

A

Highly coloured
Used widely in fabric dyes and food colouring e.g - E104

138
Q

What are the different colours in different azo dyes due to?

A

The different substituents

139
Q

Why does methyl red have a red colour?

A

Because it absorbs light at the blue end of the spectrum, leaving the red light to be transmitted
Thus, it is red because it allows red light to pass through it while absorbing all other light

140
Q

What happens to the electrons in a substance when light is absorbed by it?

A

The outer electrons are promoted form their normal energy level to a higher (excited) energy level

141
Q

Why do many organic molecules absorb visible light?

A

Because of the presence of a particular functional group

142
Q

What does the presence of a particular functional group cause many organic molecules to do?

A

Absorb visible light

143
Q

Chromophores

A

The functional group responsible or the absorption of visible light and the colour changes in an organic compound

144
Q

The functional group responsible or the absorption of visible light and the colour changes in an organic compound

A

Chromophores

145
Q

Chromophore in azo dyes

A

-N=N-

146
Q

What does the -N=N- group act as in azo dyes?

A

A chromophore

147
Q

What do the wavelengths of light absorbed by different molecules depend on?

A

The other groups present in the molecule

148
Q

What does the intensity of the colour observed in solution depend on?

A

The concentration of the compound present and is the basis of colorimetry

149
Q

How can we easily identify the colour absorbed and the coloured transmitted (not absorbed) by a compound when light is shone through it?

A

Using a colour hexagon

150
Q

Give an example of how we would use a colour hexagon

A

If magenta was absorbed, it would appear green (colour on the opposite side of the hexagon)

151
Q

What would happen if we mixed all of the colours in the colour hexagon?

A

It would appear white

152
Q

Energy equations when talking about light

A

E=hf

H = hc/lambda

153
Q

What would we input into E=hc/lambda with a graph?

A

The maximum wavelength (highest peak wavelength)

154
Q

Give a detailed explanation of the colour in organic molecules

A

Pi electrons belonging to the two nitrogen atoms interact with the delocalised pi electrons in the benzene rings
As they interact, there is a change in the energy gap, which corresponds to the frequencies in the visible part of the spectrum, between the energy levels of the nitrogen electrons
Visible light causes electrons to transfer between these levels and the compound is coloured because of the light frequencies which are transmitted

155
Q

Which light frequencies are the ones that actually cause the colour of an organic molecule?

A

The ones which are transmitted

156
Q

Which electrons interact with the delocalised pi electrons in benzene rings?

A

The pi electrons belonging to the two nitrogen atoms

157
Q

What happens when the pi electrons belonging to the two nitrogen atoms interact with the delocalised pi electrons in benzene rings?

A

There is a change in the energy gap, which corresponds to the frequencies in the visible part of the spectrum, between the energy levels of the nitrogen electrons

158
Q

What causes electrons to transfer between energy levels?

A

Visible light

159
Q

What type of bonding is the lone pair of electrons on the nitrogen atom of amines available for?

A

Covalent bonds

160
Q

How is a covalent bond formed form the lone pair of electrons on the nitrogen atom of amines?

A

The lone pair of electrons are donated

161
Q

Equation for the reaction between ethyl ammonium chloride and sodium hydroxide

A

CH2CH2NH3+Cl- + NaOH —> CH3CH2NH2 + H2O + NaCl

162
Q

Which part of NH2 always bonds to the phenol?

A

The N

163
Q

Describe and explain what used be seen in a test tube containing phenylamine and water

A

Top layer = water
Bottom layer = phenylamine

164
Q

Type of HCl used to as a reducing metal with tin metal to prepare aromatic amines

A

Concentrated

165
Q

% yield equation

A

Actual/theoretical x 100

166
Q

What do we need to remember to do when naming amines?

A

Specify the type e.g - primary or secondary

167
Q

What do we need to do with phenylamine after it’s formed and why?

A

Since it’s an immiscible aromatic amine, it needs to be separated, dried and redistilled to produce the pure amine

168
Q

What is there as a side product when NaOH is added to form a free amine from the salt? What do we do therefore?

A

Complex mixture of tin compounds
Steam distillation needed

A level Chemistry (39 decks)

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