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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
How is a chemical shift measured
It is measured in parts per million relative to a reference compound
26
What is the reference point in Carbon 13 NMR
Tetramethylsilane (TMS) Chemical shift = 0.00 ppm
27
What does a C13 NMR tell you
Number of carbon environments Type of chemical environments
28
What shows the number of carbon environments
Number of signals
29
What shows the type of chemical environments for carbon's
Position of the signals
30
What happens during H1 NMR
The hydrogen atoms in different chemical environments give signals at different chemical shifts Measured in parts per million Reference compound TMS
31
What is TMS
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
32
What are the solvents used in H1 NMR
Solvents that don't contain hydrogen TMS Deuterated solvent (where the H's are replaced with Deterium, an isotope of H)
33
Why do hydrogen's in different chemical environments give different chemical shifts
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
34
What does low resolution H1 NMR provide information about
Number of signals Position of signals Intensity of Signals Splitting
35
What does the number of signals shows
Number of H environments
36
What does the position of signals show
The chemical environment of H atoms
37
What does the intensity of signals show
Relative number of H's causing the signal
38
What are the different types of H1 NMR
Low and high resolution
39
What is different about the high resolution NMR
Each signal is split into a more complex pattern
40
What does the splitting pattern depend on
The number of chemically different H's on adjacent atoms
41
Why does the splitting pattern happen
The spins of adjacent H's interact with each other in a process called spin-spin coupling
42
What does the number of peaks in the splitting pattern mean
The number of chemically different adjacent H's + 1
43
What does the NMR look like for 0 neighbouring H
1 peak 'singlet'
44
What does the NMR look like for 1 neighbouring H
2 peaks 'doublet'
45
What does the NMR look like for 2 neighbouring H
3 peaks 'triplet'
46
What does the NMR look like for 3 neighbouring H
4 peaks 'quartet'
47
What is different about OH groups in H1 NMR
H's on OH groups do not couple with adjacent hydrogen atoms
48
What are OH hydrogen's always seen as in NMR
a singlet
49
What does the area under a signal represent in H1 NMR
It is proportional to the number of hydrogen atoms present
50
What ways can the relative area of the signals be shown as
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
What is taken into account when designing the synthesis of a particular molecule (Target Molecule)
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
How do you convert from benzene to cyclohexane
H2 and Ni catalyst Reduction
53
How do you convert from benzene to nitrobenzene
Concentrated HNO3 Concentrated H2SO4 Electrophilic substitution
54
How do you convert from a nitrobenzene to a aminobenzene
HCl and Sn catalyst Reduction
55
How do you convert from a benzene to a benzene ketone
RCOCl or (RCO)2O AlCl3 catalyst Acylation Electrophilic substitution
56
How do you convert from a benzene ketone to a benzene alcohol
Reduction - Nucleophilic addition NaBH4
57
How do you convert from an aminobenzene to a benzene amide
RCOCl/ (RCO)2O nucleophilic addition elimination
58
How do you convert from an alkene to an Alkyl hydrogensulphate
Concentrated H2SO4 Electrophilic addition
59
How do you go from an alkene to an alkane
H2 Ni catalyst Electrophilic addition
60
How do you convert from an alkane to Carbon dioxide and water
Combustion
61
How do you convert from an Alkyl Hydrogensulphate to an alcohol
H2O warm Hydrolysis
62
How do you convert from an alcohol to an alkene
Conc H2SO4 Heat Elimination
63
How do you convert from an alkene to an alcohol
Steam Conc H3PO4 Electrophilic Addition
64
How do you convert from a haloalkane to an alkene
NaOH in ethanol Elimination
65
How do you convert from an alkene to a haloalkane
HX or X2 Electrophilic addition
66
How do you convert from an alkane to a haloalkane
Halogen UV light Free Radical Substitution
67
How do you convert from a ketone to a hydroxynitrile
HCN Nucleophilic addition
68
How do you convert from an alcohol to a ketone
K2CR2O7/H+ Secondary alcohol Oxidation
69
How do you convert a ketone to an alcohol
NaBH4 or H2/Ni heat Reduction - Nucleophilic addition
70
How do you convert a haloalkane into an Alcohol
NaOH in aqueous solution Nucleophilic substitution
71
How do you convert from a haloalkane to an amine
concentrated NH3 Nucleophilic Substitution
72
How do you convert from an amine to a secondary,tertiary amine and quaternary salt
XS NH3 Nucleophilic Substitution
73
How do you convert from a hydroxynitrile to an amino acid
H2 and Ni catalyst Reduction
74
How do you convert from an alcohol to an ester
Carboxylic acid and conc H2SO4 Or Acyl Chloride Or Acid Anhydride Esterfication
75
How do you convert from an aldehyde to an alcohol
NaBH4 Primary Alcohol Reduction - Nucleophilic addition
76
How do you convert from a primary alcohol to an aldehyde
K2CR2O7 / H+ Distillation Oxidation
77
How do you convert from a haloalkane to a nitrile
KCN Reflux Nucleophilic substitution
78
How do you convert from a nitrile to an amine
H2 and Ni catalyst Reduction
79
How do you convert from an ester to a salt and alcohol
NaOH Saponification
80
How do you convert from a carboxylic acid to an ester
Alcohol and conc H2SO4 Warm Esterification
81
How do you convert from a carboxylic acid to an aldehyde
NaBH4 Reduction - Nucleophilic addition
82
How do you convert from an aldehyde to a carboxylic acid
K2Cr2O7/H+ Reflux Oxidation
83
How do you convert from a carboxylic acid to a salt and carbon dioxide
NaHCO3 acid-base
84
How do you convert from an acyl chloride to a carboxylic acid
Water Addition-elimination
85
How do you convert from an acyl chloride to an ester
ROH Addition-elimination
86
How do you convert from an acyl chloride to an amide
Conc NH3 Addition elimination
87
How do you convert from an acyl chloride to a N-substituted amide
Amine Addition-elimination
88
What does CCl4 and CDCl3 do
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
What is the observation of an ester
A sweet smell

Chemistry A Level (20 decks)

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