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Chemistry A Level > Chapter 31,32 and 33 - Synthesis, Analysis, Chromatography and structure determination > Flashcards

Chapter 31,32 and 33 - Synthesis, Analysis, Chromatography and structure determination Flashcards

1
Q

What is the test for the C=C bond

A

Bromine water
Turns from Orange to Colourless

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2
Q

What is the test for Aldehydes and Primary, Secondary Alcohols

A

Acidified K2Cr2O7
Turns from orange to green

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3
Q

What are the tests for aldehydes

A

Tollens reagent - Silver Mirror formed
Fehlings Solution - Brick Red Precipitate

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4
Q

What is the test for Carboxylic acids

A

NaHCO3 or Na2CO3
CO2 gas formed

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5
Q

What is the test for Haloalkanes

A

Hydrolysis with NaOH then acidified AgNO3
Chlorine - White
Bromine - Cream
Iodine - Yellow Precipitate

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6
Q

What is the test for acyl Chlorides

A

Addition of water
White fumes

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7
Q

What is chromatography

A

It is method used to separate and identify the components in a mixture

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8
Q

What are the 2 phases of chromatography

A

Stationary phase
Mobile Phase

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9
Q

What is the stationary phase

A

It is a solid (or liquid supported on a solid)

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10
Q

What is the mobile phase

A

A liquid or a gas

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11
Q

What do the phases do

A

The mobile phase flows through the stationary phase and carries the components of a mixture with it
Different components travel at different rates which leads to separation of the mixture

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12
Q

How do you do for paper or thin layer chromatography

A

Draw a pencil line near the bottom of the paper
Stand the paper in a layer of solvent in a covered beaker with the solvent under the line
When the solvent gets near the top, remove the paper from the beaker and allow to dry

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13
Q

What happens during the chromatography

A

As the solvent travels up the paper the different components of the mixture dissolve in it and travel up at different rates

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14
Q

What does the rate at which a component travels up the paper depend on

A

Their relative affinities for the mobile or stationary phase

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15
Q

What does the number of spots of a mixture show

A

The number of substances in the mixture

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16
Q

How are components identified

A

Calculating the Rf value and comparing to standard values
Must be obtained under the same conditions using the same solvent

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17
Q

What is the formula for the Rf value

A

Distance spot moved / Distance solvent moved

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18
Q

What happens if the components are colourless

A

They can be revealed by UV light or chemical staining agents e.g. Iodine or Ninhydrin

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19
Q

How do you carry out column chromatography

A

A column is filled with an inert solid (stationary phase)
Sample mixture introduced at top
A liquid solid is then applied from the top (mobile phase)
Substances separate going down the column

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20
Q

What is the retention time for a column chromatography

A

The time taken to come out the bottom of the column

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21
Q

How do you carry out Gas-Liquid Chromatography

A

Long coiled tube packed with a solid or solid coated with a liquid (Stationary Phase)
The sample is vaporised and injected into instrument
An inert gas (mobile phase) carries the sample through the instrument under pressure and high temp

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22
Q

What is the retention time for a Gas-Liquid Chromatography

A

Time taken to travel through the tube

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23
Q

What makes a substance move quickly

A

A stronger affinity for the mobile phase

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24
Q

For Carbon 13 NMR, how does it work

A

Different carbon atoms in different carbon environments give signals at different chemical shift values

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25
Q

How is a chemical shift measured

A

It is measured in parts per million relative to a reference compound

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26
Q

What is the reference point in Carbon 13 NMR

A

Tetramethylsilane (TMS)
Chemical shift = 0.00 ppm

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27
Q

What does a C13 NMR tell you

A

Number of carbon environments
Type of chemical environments

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28
Q

What shows the number of carbon environments

A

Number of signals

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29
Q

What shows the type of chemical environments for carbon’s

A

Position of the signals

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30
Q

What happens during H1 NMR

A

The hydrogen atoms in different chemical environments give signals at different chemical shifts
Measured in parts per million
Reference compound TMS

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31
Q

What is TMS

A

It is tetramethylsilane
Non-toxic
Inert
Produces a single peak - Lots (12) of equivalent H to) give one signal
Signal in an area away from other typical H signals / peak upfield from others
Low Boiling Point (26 degrees) - easily removed from sample

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32
Q

What are the solvents used in H1 NMR

A

Solvents that don’t contain hydrogen
TMS
Deuterated solvent (where the H’s are replaced with Deterium, an isotope of H)

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33
Q

Why do hydrogen’s in different chemical environments give different chemical shifts

A

Atom’s nuclei experience the magnetic field differently depending on how well their electrons shield them
Electronegative atoms draw electrons away from the H so the H feel the magnetic field more leading to higher frequency and chemical shift

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34
Q

What does low resolution H1 NMR provide information about

A

Number of signals
Position of signals
Intensity of Signals
Splitting

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35
Q

What does the number of signals shows

A

Number of H environments

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36
Q

What does the position of signals show

A

The chemical environment of H atoms

37
Q

What does the intensity of signals show

A

Relative number of H’s causing the signal

38
Q

What are the different types of H1 NMR

A

Low and high resolution

39
Q

What is different about the high resolution NMR

A

Each signal is split into a more complex pattern

40
Q

What does the splitting pattern depend on

A

The number of chemically different H’s on adjacent atoms

41
Q

Why does the splitting pattern happen

A

The spins of adjacent H’s interact with each other in a process called spin-spin coupling

42
Q

What does the number of peaks in the splitting pattern mean

A

The number of chemically different adjacent H’s + 1

43
Q

What does the NMR look like for 0 neighbouring H

A

1 peak ‘singlet’

44
Q

What does the NMR look like for 1 neighbouring H

A

2 peaks ‘doublet’

45
Q

What does the NMR look like for 2 neighbouring H

A

3 peaks ‘triplet’

46
Q

What does the NMR look like for 3 neighbouring H

A

4 peaks ‘quartet’

47
Q

What is different about OH groups in H1 NMR

A

H’s on OH groups do not couple with adjacent hydrogen atoms

48
Q

What are OH hydrogen’s always seen as in NMR

49
Q

What does the area under a signal represent in H1 NMR

A

It is proportional to the number of hydrogen atoms present

50
Q

What ways can the relative area of the signals be shown as

A

Indicate the relative intensities of the signals from a whole number ratio
Measure an integration trace in order to calculate the whole number ratio - measure the distance between the 2 lines

51
Q

What is taken into account when designing the synthesis of a particular molecule (Target Molecule)

A

Availability and cost of a suitable starting material
The number of stages needed to convert the starting material into the target molecule
% yield at each stage of the process
The possibility of competing reactions
Safety considerations in scaling up the process to manufacturing proportions

52
Q

How do you convert from benzene to cyclohexane

A

H2 and Ni catalyst
Reduction

53
Q

How do you convert from benzene to nitrobenzene

A

Concentrated HNO3
Concentrated H2SO4
Electrophilic substitution

54
Q

How do you convert from a nitrobenzene to a aminobenzene

A

HCl and Sn catalyst
Reduction

55
Q

How do you convert from a benzene to a benzene ketone

A

RCOCl or (RCO)2O
AlCl3 catalyst
Acylation
Electrophilic substitution

56
Q

How do you convert from a benzene ketone to a benzene alcohol

A

Reduction - Nucleophilic addition
NaBH4

57
Q

How do you convert from an aminobenzene to a benzene amide

A

RCOCl/ (RCO)2O
nucleophilic addition elimination

58
Q

How do you convert from an alkene to an Alkyl hydrogensulphate

A

Concentrated H2SO4
Electrophilic addition

59
Q

How do you go from an alkene to an alkane

A

H2
Ni catalyst
Electrophilic addition

60
Q

How do you convert from an alkane to Carbon dioxide and water

A

Combustion

61
Q

How do you convert from an Alkyl Hydrogensulphate to an alcohol

A

H2O warm
Hydrolysis

62
Q

How do you convert from an alcohol to an alkene

A

Conc H2SO4
Heat
Elimination

63
Q

How do you convert from an alkene to an alcohol

A

Steam
Conc H3PO4
Electrophilic Addition

64
Q

How do you convert from a haloalkane to an alkene

A

NaOH in ethanol
Elimination

65
Q

How do you convert from an alkene to a haloalkane

A

HX or X2
Electrophilic addition

66
Q

How do you convert from an alkane to a haloalkane

A

Halogen
UV light
Free Radical Substitution

67
Q

How do you convert from a ketone to a hydroxynitrile

A

HCN
Nucleophilic addition

68
Q

How do you convert from an alcohol to a ketone

A

K2CR2O7/H+
Secondary alcohol
Oxidation

69
Q

How do you convert a ketone to an alcohol

A

NaBH4 or H2/Ni heat
Reduction - Nucleophilic addition

70
Q

How do you convert a haloalkane into an Alcohol

A

NaOH in aqueous solution
Nucleophilic substitution

71
Q

How do you convert from a haloalkane to an amine

A

concentrated NH3
Nucleophilic Substitution

72
Q

How do you convert from an amine to a secondary,tertiary amine and quaternary salt

A

XS NH3
Nucleophilic Substitution

73
Q

How do you convert from a hydroxynitrile to an amino acid

A

H2 and Ni catalyst
Reduction

74
Q

How do you convert from an alcohol to an ester

A

Carboxylic acid and conc H2SO4
Or Acyl Chloride
Or Acid Anhydride
Esterfication

75
Q

How do you convert from an aldehyde to an alcohol

A

NaBH4
Primary Alcohol
Reduction - Nucleophilic addition

76
Q

How do you convert from a primary alcohol to an aldehyde

A

K2CR2O7 / H+
Distillation
Oxidation

77
Q

How do you convert from a haloalkane to a nitrile

A

KCN
Reflux
Nucleophilic substitution

78
Q

How do you convert from a nitrile to an amine

A

H2 and Ni catalyst
Reduction

79
Q

How do you convert from an ester to a salt and alcohol

A

NaOH
Saponification

80
Q

How do you convert from a carboxylic acid to an ester

A

Alcohol and conc H2SO4
Warm
Esterification

81
Q

How do you convert from a carboxylic acid to an aldehyde

A

NaBH4
Reduction - Nucleophilic addition

82
Q

How do you convert from an aldehyde to a carboxylic acid

A

K2Cr2O7/H+
Reflux
Oxidation

83
Q

How do you convert from a carboxylic acid to a salt and carbon dioxide

A

NaHCO3
acid-base

84
Q

How do you convert from an acyl chloride to a carboxylic acid

A

Water
Addition-elimination

85
Q

How do you convert from an acyl chloride to an ester

A

ROH
Addition-elimination

86
Q

How do you convert from an acyl chloride to an amide

A

Conc NH3
Addition elimination

87
Q

How do you convert from an acyl chloride to a N-substituted amide

A

Amine
Addition-elimination

88
Q

What does CCl4 and CDCl3 do

A

Act as a solvent for H NMR
Both have no H atoms so give no signals in spectrum
CCl4 non polar so good solvent for non-polar molecules
CDCl3 polar covalent molecule so good solvent for polar organic compounds

89
Q

What is the observation of an ester

A

A sweet smell

Chemistry A Level (20 decks)

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