Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

A Level Chemistry > Module 6 Section 2: Nitrogen Compounds, Polymers and Synthesis > Flashcards

Module 6 Section 2: Nitrogen Compounds, Polymers and Synthesis Flashcards

(105 cards)

Start Studying
1
Q

How can polymers be formed

A

Alkenes can form polymers by addition polymerisation or condensation polymerisation

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

What are two condensation polymers

A

Polyesters and polyamides

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

Where polyesters and polyamides originate from

A

Carboxylic acids and their derivatives are common starting materials

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

What is condensation polymerisation

A

The joining of monomers with loss of a small molecule
The small molecule usually includes water or hydrogen chloride
Two different functional groups are needed

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

How are monomers joined together in polyesters

A

Joined together by ester bonds (esterification) in a long chain to form a polymer

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

What do the monomers contain in polyesters

A

One monomer containing both a carboxylic acid and an alcohol group
Or from two monomers - one containing two carboxylic acid groups (dicarboxylic) and the other containing two alcohol groups (diol)

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

Example of a polyester formed from a monomer with two different functional groups

A

Glycolic acid contains both a hydroxyl group and a carboxyl group
It undergoes condensation polymerisation to form poly(glycolic acid) joined by ester linkages and water is released

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

Example of a polyester formed from two monomers each containing two functional groups

A

Terylene (polyethylene terephthalate or PET) is formed from the reaction between two monomers, benzene-1,4-carboxylic acid and ethane-1,2-diol
During the reaction a hydroxyl group on the diol reacts with a carboxyl group on the dicarboxylic acid forming an ester linkage and water

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

What are polyamides

A

Formed when monomers are joined by amide linkages in a long chain to form a polymer

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

What do the monomers contain in polyamides

A

Polyamides can be made from one monomer containing both a carboxylic acid (or acyl chloride) and an amine group
Or from two monomers, one containing two carboxylic acid groups (or acyl chlorides) (dicarboxylic acid) and the other containing two amine groups (diamine)

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

Example of a polyamide formed from one monomer with two functional groups

A

Amino acids contain both an amine group and a carboxylic acid group
Amino acids undergo condensation polymerisation to form polypeptides or proteins

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

What happens when an amide bond is formed

A

When an amide bond is formed the carboxyl group reacts with the amine group to form an amide linkage and water is lost (hydroxyl in COOH reacts with hydrogen in NH2)

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

Example of a polyamide formed from two monomers each with two functional groups

A

Nylon is formed from hexanedioic acid and 1,6-diaminohexane or hexanedioyl chloride and 1,6-diaminohexane
Different types of nylon can be made by varying the carbon chain length

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

How can polyesters and polyamides be hydrolysed

A

Can be hydrolysed using hot aqueous alkali such as sodium hydroxide
Or by hot aqueous acid such as hydrochloric acid

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

What do polyesters form when they are hydrolysed

A

They form a metal salt of the carboxylic acid (e.g. a dicarboxylic acid salt) and a diol

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

What do polyamides form when they are hydrolysed

A

They form a dicarboxylic acid and a diamine

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

How are polyesters and polyamides more easily hydrolysed

A

Polyamides are more easily hydrolysed with an acid than a base
Polyesters are more easily hydrolysed with a base than an acid

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

Characteristics of addition polymerisation

A

Monomer contains a C=C bond
Backbone of polymer is a continuous chain of carbon atoms

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

Characteristics of condensation polymerisation

A

Two monomers each with two functional groups
One monomer with two different functional groups
Polymer contains ester or amide linkages

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

Haloalkane to nitrile

A

NaCN or KCN Ethanol Reflux

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

Haloalkane to amine

A

Excess ethanolic NH3 (or amines)
Heat

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

Nitrile to amine

A

LiAlH4 then dilute acid
Or Na and ethanol, reflux
Or H2, Ni/Pt catalyst, high temp and pressure

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

Nitrile to Carboxylic acid

A

Dilute HCI Reflux

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

Hydroxynitrile to carboxylic acid

A

Dilute HCI Reflux

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Ketone to 2° alcohol
NaBH4 then water
26
Aldehyde to hydroxynitrile
HCN or NaCN
27
Ketone to hydroxynitrile
NaCN or HCN
28
Hydroxynitrile to amine
LiAlH4 then dilute acid Or Na and ethanol, reflux Or H2, Na/Pt catalyst, high temp and pressure
29
Aldehyde to 1° alcohol
NaBH4 then water
30
Alcohol to carboxylic acid
K2Cr2O7 H2SO4 Reflux
31
Alcohol to ester
Carboxylic acid, H2SO4 catalyst, heat Or acyl chloride Or acid anhydride
32
Carboxylic acid to ester
Alcohol, H+ (acid) catalyst
33
Ester to carboxylic acid
Dilute acid or alkali
34
Ester to carboxylate
OH- Heat
35
Acyl chloride to ester
Alcohol 20°C
36
Acyl chloride to carboxylic acid
Cold H2O
37
Carboxylic acid to acyl chloride
SOCI2
38
Acyl chloride to 1° amide
NH3 20°
39
Acyl chloride to 2° amide
Primary amine 20°
40
Benzene to nitrobenzene
Conc HNO3 Conc H2SO4 Warm
41
Benzene to halobenzene
X2 AlCl3 catalyst Warm
42
Benzene to alkyl benzene
Haloalkane AlCl3 catalyst Reflux
43
Benzene to phenylketone
Acyl chloride AlCl3 catalyst Reflux
44
Nitrobenzene to phenylamine
Tin Conc HCl Reflux then add NaOH
45
Phenol to sodium phenoxide
NaOH 20°
46
Phenol to phenyl ester
Acyl chloride 20°
47
Phenol to 2-nitrophenol or 4 nitrophenol
Dilute HNO3 20°
48
Phenol to 2,4,6 tribromophenol
Bromine water (Br2) 20°
49
How do you get an amine from ammonia
If one or more hydrogen is replaced by an organic group
50
What determines if an amine is primary, secondary, tertiary or quaternary
This is determined by how many alkyl groups the nitrogen atom is bonded to
51
What do you get if the nitrogen atom is bonded to 4 alkyl groups
You get a positively charged quaternary ammonium ion
52
Difference between an aliphatic and aromatic amine
Aliphatic: when the amine doesn’t contain any benzene structures Aromatic: amine contains a benzene ring
53
Are amines basic or acidic
Amines are bases There's a lone pair of electrons on the nitrogen atom of an amine that's able to accept protons (H+ ions)
54
How do amines react with acids
Amines are neutralised by acids to make ammonium salts. E.g. ethylamine reacts with HCl to form ethylammonium chloride
55
How to get an amine from haloalkane
Heat the haloalkane with an excess of ethanolic ammonia
56
Possible products of preparing an amine from a haloalkane
Get a mixture of primary, secondary and tertiary amines, and quaternary ammonium salts More than one hydrogen is likely to be substituted. Can separate the products using fractional distillation.
57
How can multiple different products be formed in stages from bromoethane reacting with ammonia
Reacts to form ethylamine This is nucleophilic substitution Ethylamine can then react with ammonia and bromoethane again to form diethylamine Can continue until quaternary amine formed
58
How can multiple different products be formed in stages from bromoethane reacting with ammonia
Reacts to form ethylamine This is nucleophilic substitution Ethylamine can then react with ammonia and bromoethane again to form diethylamine Can continue until quaternary amine formed
59
How to form an aromatic amine
Must reduce a nitro compound Nitro compounds must be reduced using 2 steps Heat mixture of nitro compound, tin and conc HCl under reflux to make a salt Then add NaOH to get aromatic amine
60
What are amides
Derivatives of carboxylic acids Contain functional group -CONH2
61
Why do amides behave differently from amines
The carbonyl group pulls electrons away from the rest of the -CONH2 group
62
What types of amides can you get
Can be either primary, secondary or tertiary amides This depends on how many carbon atoms the nitrogen is bonded to
63
What functional groups do amino acids have
Amino acids have a basic amino (NH2) group and acidic carboxylic group (COOH)
64
Structure of an α (alpha) amino acid
This is where both groups are attached to the same carbon atom (the α (alpha) carbon) The general formula of an alpha amino acid is RCH(NH2)COOH
65
How do amino acids react with alkalis
The carboxylic acid group in the amino acid can react with an alkali to form a conjugate base: RCH(NH2)COO- This can combine with a positive ion to form a salt:
66
How do amino acids react with acid
The amino group can react with an acid to form a salt of the conjugate acid E.g:
67
How do amino acids react with alcohols
Carboxylic acid group in an amino acid can react with an alcohol to form an ester Requires strong acid catalyst (normally H2SO4)
68
What is a chiral carbon
A chiral (or asymmetric) carbon atom is one which has four different groups attached to it.
69
What does a chiral carbon atom mean for the possible structures of the molecule
It's possible to arrange the groups in two different ways around the carbon atom so that two different molecules are made These molecules are called enantiomers or optical isomers
70
What are enantiomers
Enantiomers are mirror images of eachother No matter which way you turn them, they can't be superimposed
71
What does being optically active mean for a molecule
Optical isomers are optically active They can rotate plane-polarised light One enantiomer rotates it in a clockwise direction The other rotates it the same amount but in an anticlockwise direction
72
Difference between normal light and plane polarised light
Normal light vibrates in all directions Plane-polarised light only vibrates in one direction
73
How to identify the different enantiomers
Can be identified as D and L isomer (don’t need to know which is which)
74
How do you normally find chiral compounds in nature
Chiral compounds are common in nature Usually only 1 enantiomer can be found E.g. all naturally occurring amino acids are L-amino acids and most sugars are D-isomers
75
76
77
78
When is an amine most reactive
When it has the maximum amount of R groups attached to the Nitrogen They donate electron density towards the lone pair to make it more effective to act as a nucleophile
79
How to turn an ammonium salt back into an amine
React it with a base (NaOH) to reform the amine, a salt from the base (NaCl) and H2O
80
Name
81
What is a molecule that can be superimposed called
If a molecule can be superimposed on its mirror image, it's achiral and it doesn't have an optical isomer.
82
How does recrystallisation work
Solid is dissolved in minimum amount of warm solvent to make a saturated solution Let it cool and solubility of product falls It then forms crystals when it reaches a point when it can’t stay in solution
83
Process of recrystallisation
Very hot solvent is added to impure solid until it just dissolves Produces saturated solution of impure product Solution left to cool and crystals of product form Impurities stay in solution as they are in small amounts so take longer to crystallise Crystals then removed by reduced pressure filtration and washed in ice cold solvent Then leave to dry to give crystals of pure product
84
How do you make a carbon chain longer during organic synthesis
Need reactants and reagents that have a nucleophilic or electrophilic carbon atom Cyanide (CN-) has a negatively charged carbon atom which acts as a nucleophile It reacts with carbon centres that have a slight positive charge to create a new carbon bond This produces a nitrile
85
What specific reagents to use to increase the carbon chain
React a compound that contains a slightly positive carbon centre with a cyanide reagent: KCN, NaCN, HCN
86
Mechanism for the reaction between a haloalkane and cyanide ion
Nucleophilic substitution
87
How to increase carbon chain using nucleophilic substitution
Relfux haloalkane with NaCN or KCN in ethanol to make it undergo nucleophilic substitution to form the nitrile
88
How to increase carbon chain using nucleophilic addition
Aldehydes and ketones contain a polar C=O Mixing them with hydrogen cyanide (HCN) will allow the CN- with react with the positive carbon centre to form a hydroxynitrile
89
Mechanism for increase carbon chain length with nucleophilic addition
90
Why are nitrile groups useful in 2 step synthesis
Nitrile (or hydroxynitrile) are very reactive meaning they can be made into a new functional group
91
How to reduce a nitrile and hydroxynitrile to a primary amine
Can use LiAlH4 (strong reducing agent) then dilute acid Na and ethanol H2, Ni or Pt catalyst at high temperature and pressure (catalytic hydrogenation)
92
Equations for reducing nitrile to a primary amine using LiAlH4 or H2
93
Equation for reducing hydroxynitrile to a primary amine using LiAlH4
94
Why is catalytic hydrogenation used to reduce nitriles more than other methods
LiAlH4 and sodium are too expensive for industrial use
95
How to turn a nitrile or hydroxynitrile into a carboxylic acid
Refluxing with dilute HCl causes the nitrile group to be hydrolysed to form a carboxylic acid
96
Equation for hydrolysing nitrile to carboxylic acid
97
Equation for hydrolysing hydroxynitrile to carboxylic acid
98
99
Why is the solvent used in recrystallisation important
Recrystallisation will only work if the solid is very soluble in the hot solvent but nearly insoluble when the solvent is cold If product isn’t soluble enough in the hot solvent then it won’t be able to be dissolved at all If the product is too soluble in the cold solvent, most of it will stay in solution even after cooling Means that when you filter, most of the product will be lost giving a low yield
100
What is filtering under reduced pressure used for
Used to separate solid product from any liquid impurities This is because the reduced pressure caused suction through the funnel causing the liquid to pass quickly into the flask which leaves behind dry crystals of the product
101
How to carry out reduced pressure filtration
The reaction mixture is poured into a Büchner funnel with a piece of filter paper in it. The Büchner funnel is on top of a sealed sidearm flask which is connected to a vacuum line, causing it to be under reduced pressure.
102
How does melting and boiling points use to determine purity
Most pure substances have a specific melting and boiling point. If they're impure, the melting points lowered and the boiling point is raised. If they're very impure, melting and boiling will occur across a wide range of temperatures.
103
How to accurately measure melting point
Put a small amount of the solid in a capillary tube and gently tap the tube to get the solid to fall to the bottom. Place the tube in a beaker of oil with a very sensitive thermometer. Slowly heat, with constant stirring until the solid just melts and read the temperature on the thermometer.
104
How to check the purity of a product after melting point has been obtained
Can compare the experimental melting point to a known melting point of the substance to determine its purity If the melting points are similar then your sample is quite pure If the value is much lower than the standard value then your sample has impurities
105
What amine is the most basic
Least: aromatic Primary Secondary Most: tertiary Tertiary have the most alkyl groups which donate electrons by inductive effect so there are more electrons present to readily donate and act as a nucleophile

A Level Chemistry (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions