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

Question 1

What is an amine?

Answer 1

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

Question 2

Give an example of a tertiary amine.

Answer 2

Trimethlyamine

Question 3

Give an example of an aromatic amine.

Answer 3

Phenylamine.

Question 4

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

Answer 4

More fishy.

Question 5

What happens when you add small amines to water?

Answer 5

They dissolve to form alkaline solutions.

Question 6

What makes small amines very soluble in water?

Answer 6

They hydrogen bonds that it forms with water.

Question 7

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

Answer 7

It decreases because the london forces between amines increase.

Question 8

Give the equation to show ethylamine dissolving in water.

Answer 8

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

Question 9

What happens when you react an acid with an amine?

Answer 9

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

Question 10

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

Answer 10

CH3CH2NH2 + HCl → CH3CH2NH3+Cl-

Question 11

What do amines form with copper(II) ions?

Answer 11

Complex ions.

Question 12

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

Answer 12

Insoluble copper hydroxide forms.

Question 13

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

Answer 13

A deep blue solution forms.

Question 14

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

Answer 14

They can’t fit six around the copper ion.

Question 15

What happens when amines are reacted with acyl chlorides?

Answer 15

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.

Question 16

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

Answer 16

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

Question 17

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

Answer 17

Add ethanoyl chloride to a concentrated aqueous solution of amine.

Question 18

Describe the reaction and product of the acylation of amines.

Answer 18

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

Question 19

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

Answer 19

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.

Question 20

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

Answer 20

Unreacted phenylamine.

Question 21

What functional group do amides have?

Answer 21

-CONH2

Question 22

Why do amides behave differently from amines?

Answer 22

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

Question 23

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

Answer 23

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

Question 24

What is the name of H2NCONH2?

Answer 24

Urea.

Question 25

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

Answer 25

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

Question 26

How can you make aromatic amines?

Answer 26

Reducing nitro commands.

Question 27

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

Answer 27

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

Question 28

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

Answer 28

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

Question 29

Name the catalyst used when reducing nitrobenzene.

Answer 29

Tin, Sn.

Question 30

What name the products of reducing nitrobenzene.

Answer 30

Phenylamine and H2O.

Question 31

What is the azo group?

Answer 31

-N=N-

Question 32

Where is the azo group commonly found?

Answer 32

Manmade azo dyes.

Question 33

What does the azo group link in most azo dyes?

Answer 33

Two aromatic groups.

Question 34

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

Answer 34

The azo group forms part of the delocalised electron system.

Question 35

How are different colours of azo dyes created?

Answer 35

Combining different phenols and amines.

Question 36

What causes the colours of azo dyes?

Answer 36

The light absorption by the delocalised system.

Question 37

What do diazonium compounds contain?

Answer 37

-N+≡N

Question 38

How are ago dyes made?

Answer 38

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

Question 39

How can you make phenylamine into a diazonium salt?

Answer 39

React it with nitrous acid, HNO2.

Question 40

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

Answer 40

Because it is unstable.

Question 41

Give the equation for the reaction producing nitrous acid.

Answer 41

NANO2 + HCL → HNO2 + NaCl.

Question 42

Give the reagents and conditions needed to create benzenediazonium chloride.

Answer 42

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

Question 43

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

Answer 43

To prevent phenol forming.

Question 44

What does the skeletal formula of benzenediazonium chloride look like?

Answer 44

⬡-N+≡N Cl-

Question 45

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

Answer 45

Because they're very unstable and decompose quickly.

Question 46

How do you make sodium phenoxide solution?

Answer 46

Dissolve phenol in sodium hydroxide solution.

Question 47

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

Answer 47

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

Question 48

What makes phenol a coupling agent?

Answer 48

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

Question 49

What makes azo dyes fit for purpose.

Answer 49

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

Question 50

What is an amino acid?

Answer 50

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

Question 51

Why are amino acids amphoetic?

Answer 51

Because ethyl have both acidic and basic properties.

Question 52

What is an α-amino acid?

Answer 52

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

Question 53

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

Answer 53

RCH(NH2)COOH

Question 54

What is significant about glycine?

Answer 54

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

Question 55

What is a zwitterion?

Answer 55

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

Question 56

When do zwitterions exist?

Answer 56

Near to the amino acid's isoelectric point.

Question 57

What is an amino acid's isoelectric point?

Answer 57

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

Question 58

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

Answer 58

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.

Question 59

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

Answer 59

Distance travelled by spot vs distance travelled by solvent.

Question 60

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

Answer 60

Different forces of attraction between the two phases.

Question 61

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

Answer 61

Use a table of known values.

Question 62

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

Answer 62

Because their solutions are colourless.

Question 63

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

Answer 63

Ammonia, aldehydes, CO2 and hydrindantin.

Question 64

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

Answer 64

Ammonia and ninhydrin.

Question 65

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

Answer 65

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

Question 66

Name the two types of polymerisation.

Answer 66

Addition and condensation.

Question 67

Briefly explain how alkenes join up to form addition polymers.

Answer 67

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

Question 68

What happens was molecules link together in condensation polymerisation?

Answer 68

A small molecule, usually water, is lost.

Question 69

Give three examples of condensation polymers.

Answer 69

Polyesters, polyamides and polypeptides.

Question 70

What are the requirements for monomers to undergo condensation polymerisation?

Answer 70

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

Question 71

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

Answer 71

Poly(propenamide).

Question 72

What is polyethenol made from?

Answer 72

Ethenol monomers.

Question 73

What special property does polyethenol have?

Answer 73

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

Question 74

Why is polyethenol very soluble?

Answer 74

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

Question 75

Explain two uses for polyethenol.

Answer 75

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.

Question 76

Give two examples of the link in condensation polymers.

Answer 76

Ester link and amide link.

Question 77

What are the reagents required to make a polyamide?

Answer 77

Dicarboxylic acids and a diamines.

Question 78

What does an amide link contain?

Answer 78

-CONH-

Question 79

What is Nylon 6,6 made from?

Answer 79

1,6-diaminohexane and hexanedioic acid.

Question 80

Give three properties of nylon.

Answer 80

Strong, elastic and abrasion resistant.

Question 81

Give three uses of nylon.

Answer 81

Ropes, carpets and clothes.

Question 82

What is KEVLAR made from?

Answer 82

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

Question 83

Give two properties of KEVLAR.

Answer 83

Light and five times stronger than steel.

Question 84

Where is KEVLAR used?

Answer 84

Bulletproof vests.

Question 85

Name three physical property of polyamides.

Answer 85

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

Question 86

What are the reagents required to make polyesters?

Answer 86

Dicarboxlyic acids and diols.

Question 87

What is PET, Terylene made of?

Answer 87

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

Question 88

Give three physical properties of polyesters.

Answer 88

They're strong, flexible and abrasion resistant.

Question 89

What are proteins?

Answer 89

Condensation polymers of amino acids.

Question 90

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

Answer 90

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

Question 91

What do you get when two amino acids join together?

Answer 91

A dipeptide and water.

Question 92

What is the link in proteins?

Answer 92

The peptide bond, -CONH-