5.4.2 Organic Nitrogen Compounds: Amines, Amides, Amino Acids and Proteins Flashcards

1
Q

What is an amine?

A

Ammonia with at least one of the hydrogens substituted with an organic group.

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2
Q

Give an example of a tertiary amine.

A

Trimethlyamine

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3
Q

Give an example of an aromatic amine.

A

Phenylamine.

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4
Q

How do the smells of amines compare to that of ammonia.

A

More fishy.

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5
Q

What happens when you add small amines to water?

A

They dissolve to form alkaline solutions.

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6
Q

What makes small amines very soluble in water?

A

They hydrogen bonds that it forms with water.

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7
Q

What happens to solubility of an amine as you increase the length of the carbon chain? Why?

A

It decreases because the london forces between amines increase.

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8
Q

Give the equation to show ethylamine dissolving in water.

A

CH3CH2NH2(aq) + H2O(l) ⇌ CH3CH2NH3+(aq) + OH-(aq)

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9
Q

What happens when you react an acid with an amine?

A

They form salts. The lone pair on the nitrogen atom forms a dative covalent bond with the H+ ion.

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10
Q

Give the equation for the reaction between ethyl amine and hydrochloric acid.

A

CH3CH2NH2 + HCl → CH3CH2NH3+Cl-

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11
Q

What do amines form with copper(II) ions?

A

Complex ions.

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12
Q

What happens when you add a small amount of methyl amine solution to copper(II) sulfate solution?

A

Insoluble copper hydroxide forms.

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13
Q

What happens when you add a large amount of methyl amine solution to copper(II) sulfate solution?

A

A deep blue solution forms.

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14
Q

Why might copper complex with large amine ligands be different form small ones?

A

They can’t fit six around the copper ion.

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15
Q

What happens when amines are reacted with acyl chlorides?

A

An H atom on the amine is swapper for the acyl group to produce an N-substituded amide and HCl which then goes on to react again to produce a salt.

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16
Q

Give the overall equation for the reaction between ethanoyl chloride and butylamine.

A

CH3COCl + 2C4H9NH2 → CH3CONHC4H9 + [C4H9NH]+Cl-

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17
Q

What are the conditions required for creating N-substidued amides?

A

Add ethanoyl chloride to a concentrated aqueous solution of amine.

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18
Q

Describe the reaction and product of the acylation of amines.

A

The reaction is violent and a mixture of white solid products is formed.

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19
Q

What happens when you add a primary amine to a halogenoalkane?

A

The lone pair of electrons attack the δ+ carbon on the haloalkane, displacing the chlorine and making salt. The Chlorine then removes an H to make Hal and a secondary amine. This could repeat to make a tertiary amine.

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20
Q

Why might products from the acylation of phenylamine be stained brown?

A

Unreacted phenylamine.

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21
Q

What functional group do amides have?

A

-CONH2

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22
Q

Why do amides behave differently from amines?

A

Because the carbonyl group draws electrons away from the rest of the group.

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23
Q

What is the difference between an amide and an N-substituted amide?

A

On an N-sub amide one of the hydrogens on the nitrogen is replaced with an alkyl group.

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24
Q

What is the name of H2NCONH2?

A

Urea.

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25
Q

What is the product of the reaciotn between ethanoyl chloride and ammonia?

A

Ethanamide (and HCl which goes on to make a salt).

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26
Q

How can you make aromatic amines?

A

Reducing nitro commands.

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27
Q

What is the first step of the reduction of a nitro compound?

A

Heat it with tin and concentrated HCl under reflux to make an ammonium salt.

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28
Q

What is the second set of the reduction of a nitro compound?

A

Add sodium hydroxide to remove an H+ form the salt, giving an aromatic amine.

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29
Q

Name the catalyst used when reducing nitrobenzene.

A

Tin, Sn.

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30
Q

What name the products of reducing nitrobenzene.

A

Phenylamine and H2O.

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31
Q

What is the azo group?

A

-N=N-

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32
Q

Where is the azo group commonly found?

A

Manmade azo dyes.

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33
Q

What does the azo group link in most azo dyes?

A

Two aromatic groups.

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34
Q

Why are two aromatic groups linked by the azo group very stable?

A

The azo group forms part of the delocalised electron system.

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35
Q

How are different colours of azo dyes created?

A

Combining different phenols and amines.

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36
Q

What causes the colours of azo dyes?

A

The light absorption by the delocalised system.

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37
Q

What do diazonium compounds contain?

A

-N+≡N

38
Q

How are ago dyes made?

A

By coupling a diazonium salt with an aromatic compound that is susceptible to electrophilic attack, such as phenol.

39
Q

How can you make phenylamine into a diazonium salt?

A

React it with nitrous acid, HNO2.

40
Q

Why does nitrous acid, HNO2, have to be made in situ?

A

Because it is unstable.

41
Q

Give the equation for the reaction producing nitrous acid.

A

NANO2 + HCL → HNO2 + NaCl.

42
Q

Give the reagents and conditions needed to create benzenediazonium chloride.

A

Nitrous acid, phenylamine and hydrochloric acid at mourned 5ºC.

43
Q

Why must the temperature be kept below 5ºC when creating azo dyes?

A

To prevent phenol forming.

44
Q

What does the skeletal formula of benzenediazonium chloride look like?

A

⬡-N+≡N Cl-

45
Q

Why must the diazonium salts be used as soon as they’re made.

A

Because they’re very unstable and decompose quickly.

46
Q

How do you make sodium phenoxide solution?

A

Dissolve phenol in sodium hydroxide solution.

47
Q

How do you make a yellow-orange azo compound from phenol and benzenediazonium chloride?

A

Dissolve the phenol in sodium hydroxide, stand it in ice and add chilled benzenediazonium chloride.

48
Q

What makes phenol a coupling agent?

A

The lone pairs on its oxygen increase the electron density of the benzene ring, giving the diazonium something to attack.

49
Q

What makes azo dyes fit for purpose.

A

The molecules don’t fall apart so the colours don’t fade.

50
Q

What is an amino acid?

A

A chemical that contains a basic amino group (NH2) and an acidic carboxyl group (COOH).

51
Q

Why are amino acids amphoetic?

A

Because ethyl have both acidic and basic properties.

52
Q

What is an α-amino acid?

A

One where both the amino group and carboxyl group are attached to the same carbon, the α-carbon.

53
Q

What is the general formula of an α-amino acid?

A

RCH(NH2)COOH

54
Q

What is significant about glycine?

A

It is the simplest possible α-amino acid and is not chiral.

55
Q

What is a zwitterion?

A

A dipolar ion with both positive and negative charges in different parts of the molecule.

56
Q

When do zwitterions exist?

A

Near to the amino acid’s isoelectric point.

57
Q

What is an amino acid’s isoelectric point?

A

The pH where the overall charge on the amino acid is zero.

58
Q

Outline the process of paper chromatography of an unknown amino acid.

A

Draw a pencil line on chromatography paper then put of spot of the sample on the line. Dip the bottom of the paper in solvent and let it move up the paper. Spray the paper with ninhydrin to reveal purple spot.

59
Q

How do you calculate the Rf value of a sample of unknown amino acid in paper chromatography.

A

Distance travelled by spot vs distance travelled by solvent.

60
Q

Why do spots spread out as the solvent moves up the paper.

A

Different forces of attraction between the two phases.

61
Q

How can you use a measured Rf value to identify an amino acid?

A

Use a table of known values.

62
Q

Why do you need to use ninhydrin to reveal amino acids?

A

Because their solutions are colourless.

63
Q

What are the products of the reaction between ninhydrin and an amino acid?

A

Ammonia, aldehydes, CO2 and hydrindantin.

64
Q

What does hydrindantin react with to produce Ruhemann’s purple?

A

Ammonia and ninhydrin.

65
Q

Why do most α-amino acids rotate plane polarised light?

A

Because they have a chiral carbon with 4 different groups attached.

66
Q

Name the two types of polymerisation.

A

Addition and condensation.

67
Q

Briefly explain how alkenes join up to form addition polymers.

A

The double bonds of the monomers open up, join together and make long chains.

68
Q

What happens was molecules link together in condensation polymerisation?

A

A small molecule, usually water, is lost.

69
Q

Give three examples of condensation polymers.

A

Polyesters, polyamides and polypeptides.

70
Q

What are the requirements for monomers to undergo condensation polymerisation?

A

They have to have at least two functional groups that can form a link.

71
Q

What is the name of the polymer made from propenamide monomers?

A

Poly(propenamide).

72
Q

What is polyethenol made from?

A

Ethenol monomers.

73
Q

What special property does polyethenol have?

A

It is water soluble and breaks down at around 40ºC.

74
Q

Why is polyethenol very soluble?

A

Because it forms many hydrogen bonds with water along its chain.

75
Q

Explain two uses for polyethenol.

A

Bags for soiled bed linen in hospitals so washing can be put in the machine without touching it, reducing the risk of infection. They’re also used in dishwasher liquitabs, which break down and release the detergent.

76
Q

Give two examples of the link in condensation polymers.

A

Ester link and amide link.

77
Q

What are the reagents required to make a polyamide?

A

Dicarboxylic acids and a diamines.

78
Q

What does an amide link contain?

A

-CONH-

79
Q

What is Nylon 6,6 made from?

A

1,6-diaminohexane and hexanedioic acid.

80
Q

Give three properties of nylon.

A

Strong, elastic and abrasion resistant.

81
Q

Give three uses of nylon.

A

Ropes, carpets and clothes.

82
Q

What is KEVLAR made from?

A

Benzene-1,4-diamine and benzene-1,4-dicarboxlyic acid.

83
Q

Give two properties of KEVLAR.

A

Light and five times stronger than steel.

84
Q

Where is KEVLAR used?

A

Bulletproof vests.

85
Q

Name three physical property of polyamides.

A

High tensile strength, can be used at high temperatures and resistant to most chemicals except acids.

86
Q

What are the reagents required to make polyesters?

A

Dicarboxlyic acids and diols.

87
Q

What is PET, Terylene made of?

A

Benzene-1,4-dicarboxlyic acid and ethane-1,2-diol.

88
Q

Give three physical properties of polyesters.

A

They’re strong, flexible and abrasion resistant.

89
Q

What are proteins?

A

Condensation polymers of amino acids.

90
Q

Whats the difference between a polyamide and a protein (polypeptide)?

A

They have the same peptide link but proteins are made from amino acids and have a repeating amino acid unit.

91
Q

What do you get when two amino acids join together?

A

A dipeptide and water.

92
Q

What is the link in proteins?

A

The peptide bond, -CONH-