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Organic Flashcards

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1
Q

What is the empirical formula?

A

The simplest whole number ratio of atoms of each element in a compound

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2
Q

What is molecular formula?

A

The true number of atoms of each element in a compound

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3
Q

What is the general formula?

A

All members of a homologous organic series follow the general formula

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4
Q

What is the structural formula?

A

Shows the structural arrangement of atoms within a molecule

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5
Q

What is the displayed formula?

A

Shows every atom and every bond in an organic compound

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6
Q

What is the skeletal formula?

A

Shows only the bonds in a compound and any non-carbon atoms (hydrogen is assumed to be bonded to carbon unless otherwise stated)

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7
Q

What is a homologous series?

A

Series of organic compounds which contain the same functional group

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8
Q

What do reaction mechanisms show?

A

The movement of electrons within a reaction

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9
Q

What are isomers?

A

Molecules with the same molecular formula but with a different arrangement of atoms within the molecule

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10
Q

What are structural isomers?

A

Have the same molecular form but different structural arrangement of the atoms, the chain of carbon can be straight or have branches

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11
Q

What are positional isomers?

A

Same molecular formula and functional group but the functional group is in a different position on the carbon chain

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12
Q

What are functional group isomers?

A

Same molecular formula but have different functional groups

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13
Q

What are stereoisomers?

A

Same molecular formula but different spatial arrangement

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14
Q

What type of isomerism is E-Z?

A

stereoisomerism

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15
Q

Why does E-Z isomerism arise?

A

Limited rotation around the carbon-carbon double bond

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16
Q

What is the E isomer in E-Z isomerism?

A

groups are apart

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17
Q

What is the Z isomer in E-Z isomerism?

A

groups are together

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18
Q

What is the Cahn-Inglod-Prelog (CIP) priority rules when it comes to E-Z isomerism?

A

Higher priority is given to the adjacent atom with the highest Ar and if they’re the same keep going down the chain till atom with higher Ar is reached

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19
Q

What is an ether functional group?

A

C-O-C

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20
Q

What is the general formula of alkanes?

A

Cn H2n+2

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21
Q

Are alkanes saturated or unsaturated?

A

Saturated hydrocarbons (only contain single bonds)

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22
Q

What is petroleum (crude oil)?

A

A mixture consisting mainly of alkane hydrocarbons

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23
Q

How can petroleum (crude oil) be separated?

A

Fractional distilliation

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24
Q

Why do different chain length alkanes have different boiling points?

A

The higher the Mr the greater the VDW and the higher the boiling point so the longer the carbon chain the higher the boiling point

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25
Q

How does fractional distillation of petroleum (crude oil) work?

A

The mixture is heated and vaporised and then fed into a fractionating column

The vapour rises and as it does it cools and condenses

It is then separated into its different fractions which can then be pumped away for their different uses

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26
Q

What is collected at the top of a crude oil fractionating column?

A

Short carbon chains

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27
Q

What is the order of crude oil fractions from top to bottom?

A

Refinery gases
Gasoline (petrol)
Naphtha
Kerosene
Diesel (gas oil)
Lubricating oil (mineral oil)
Fuel oil
Bitumen

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28
Q

How are refinery gases used?

A

Camping gas

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29
Q

How is gasoline used?

A

Petrol in cars

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30
Q

How is kerosene used?

A

jet fuel

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31
Q

How is diesel used?

A

Diesel fuel, central heating

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32
Q

How is fuel oil used?

A

Ships, power stations

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33
Q

How is Bitumen used?

A

Road surfacing

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34
Q

How is naphtha used?

A

Processed to make petrochemicals

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35
Q

What length of alkane carbon chains are more in demand?

A

Smaller chain alkanes

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36
Q

What type of reaction is cracking?

A

Decomposition

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37
Q

What is cracking?

A

The breaking down of longer carbon chain molecules into smaller more useful molecules

(breaking C-C bonds)

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38
Q

What are the two types of cracking?

A

Thermal and Catalytic

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39
Q

What does thermal cracking produce?

A

alkanes and alkenes

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40
Q

What does catalytic cracking produce?

A

Aromatic compounds and motor fuels

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41
Q

What are the conditions used in thermal cracking?

A

High temp - 1000°C
High pressure - 70 atm

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42
Q

What are the conditions used in catalytic cracking?

A

Zeolite catalyst
High temp - 450°C
Slight pressure

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43
Q

Why does using a zeolite catalyst in catalytic cracking cut costs?

A

Means the reaction can be done at low pressure and a lower temperature (also speeds up reaction)

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44
Q

Why do alkanes make good fuels?

A

Release a lot of energy when burned

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45
Q

What do we do with fuels?

A

Combust them

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46
Q

What are the products of complete combustion of alkanes?

A

CO2 and H2O

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47
Q

What are the products of incomplete combustion of alkanes?

A

CO and H2O

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48
Q

What are the products of incomplete combustion alkanes (when there’s even less O2)?

A

C(s) and H2O

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49
Q

What is the downside to burning alkanes?

A

Produces lots of pollutants

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50
Q

Whats the problem with carbon monoxide?

A

Poisonous as as it binds to the same sites on haemoglobin molecules as oxygen does so prevents oxygen being carried around the body

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51
Q

How is carbon monoxide removed from exhaust gases?

A

Using a catalytic converter

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52
Q

Whats the problem with burning fossil fuels?

A

Produces CO2 which is a greenhouse gas

(also non-renewable)

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53
Q

Whats the problem with greenhouse gases?

A

Really good at absorbing infrared radiation which means it isn’t all reflected as it ought to be which leads to the greenhouse effect and global warming

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54
Q

How are oxides of nitrogen produced in a car engine?

A

The high pressure and temperature causes the nitrogen and oxygen in the air to react together

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55
Q

What are carbon particulates?

A

Small fragments of unburned hydrocarbon that can cause serious respiratory problems

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56
Q

What is the problem when hydrocarbons and nitrogen oxides react in the presence of sunlight?

A

Forms ground-level ozone

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57
Q

Whats the problem with ground-level ozone?

A

Major component of smog, irritates peoples eyes and aggravates respiratory problems

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58
Q

What is the process of removing sulphur dioxide called?

A

Flue - gas desulphurisation

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59
Q

Whats the problem with SO2?

A

Acid rain which ruins habitats, destroys trees and vegetation, kills fish in lakes, corrodes buildings

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60
Q

What catalyst is used in a catalytic converter?

A

Rhodium (or platinum)

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61
Q

What does the combustion of hydrocarbons containing sulfur lead to?

A

sulfur dioxide

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62
Q

What are the there steps of free-radical substitution?

A

Initiation
Propagation
Termination

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63
Q

What is produced in free radical substitutions?

A

Haloalkanes from alkanes and halogens

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64
Q

What is required for free radical substitution?

A

UV light

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65
Q

What is the initiation step of free radical substitution?

A

The break down of the halogen eg

Cl2 —> 2Cl* UV light

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66
Q

What is the propagation step? (Cl* and CH4 as example)

A

Hydrogen is replaced and the Cl* is reformed as a catalyst

Cl* + CH4 —> *CH3 + HCl

CH3 + Cl2 —> CH3Cl + Cl

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67
Q

What is the termination step in free radical substitution?

A

Two radicals join to end the chain reaction and form a stable product

eg *CH3 + *CH3 —> C2H6

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68
Q

What is the problem with CFC’s?

A

UV light from the sun causes CFC’s to break creating free radicals which then react with ozone in the atmosphere and deplete it

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69
Q

Which bond is stronger C-F or C-Cl?

A

C-F greater electronegative difference

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70
Q

Show how a chlorine radical depletes ozone?

A

Cl* + O3 —> O2 + ClO*

ClO* + O3 —> 2O2 + Cl*

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71
Q

What does the ozone layer do?

A

Protects us from UV radiation which can damage the skin and cause cancer (absorbs it)

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72
Q

Why were CFC’s banned?

A

As a result of research by different groups in the scientific community how provided evidence for legislation to ban the use of CFC’s as solvent and refrigerants

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73
Q

What do we now use instead of CFC’s?

A

Chemists have developed alternative chlorine free compounds

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74
Q

Why do halegenoalkanes contain polar bonds?

A

Halogens are more electronegative than carbon atoms so electron density is drawn towards the halogen

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75
Q

What is a nucleophile?

A

Species that contains a lone electron pair that is attracted to δ+ regions of molecules

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76
Q

Examples of nucleophiles

A

: C(-) ≡ N

:NH3

:OH

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77
Q

What mechanism means you get an alcohol from a halogenolalkane?

A

nucleophilic substitution

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78
Q

What mechanism means you get an amine from a halogenoalkane?

A

nucleophilic substitution

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79
Q

How does the carbon-halogen bond enthalpy influence the rate of reaction?

A

The greater the Mr of the halogen, the lower the bond enthalpy meaning it is broken more easily ∴ the rate is quicker

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80
Q

Why cant you have nucleophilic substitution with tertiary halogenoalkanes?

A

The nucleophile can only approach the carbon from the side with the halogen (as other side too crowded) but the halogen has a δ- charge so repels the nucleophile

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81
Q

What happens in nucleophilic substitution?

A

The nucleophile attacks the δ+ carbon bonded to the halogen (approached from opposite side to halogen) and then the carbon-halogen shared pair of electron are both given to the halogen to produce a halide

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82
Q

What is the role of the nucleophile in a nucleophilic substitution?

A

electron donor

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83
Q

What are the conditions needed for elimination?

A

High temperature
Ethanol (alcoholic) solvent
heat under reflux

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84
Q

What is the role of the nucleophile in elimination?

A

Proton acceptor (acts as a base)

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85
Q

How do you produce an alkene from a halogenoalkane?

A

elimination

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86
Q

What happens in an elimination mechanism?

A

Nucleophile attacks a hydrogen on the adjacent carbon to the halogen

That hydrogen-carbon bond then gives its electrons to the carbon-carbon bond (when nucleophile is :OH this makes a water molecule)

Then the electrons in the carbon-halogen bond gives both electrons to the halogen to make a halide

(like a waterfall affect)

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87
Q

Why does the proportion of water to ethanol matter when you have nucleophiles and halogenoalkanes?

A

water encourages substitution
ethanol encourages elimination

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88
Q

How do you favour nucleophilic substitution over elimination?

A

lower temp.
more dilute solutions
more water in the solvent mixture

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89
Q

How do you favour elimination over nucleophilic substitution?

A

higher temp.
conc. solutions
pure ethanol as solvent

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90
Q

What type of halogenoalkanes undergo elimination by a nucleophile under the right conditions? (primary, secondary or tertiary)

A

secondary and tertiary

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91
Q

What are alkenes?

A

Unsaturated hydrocabons

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92
Q

Why are alkenes unsaturated?

A

Contain a double covalent bond

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93
Q

Why is a carbon-carbon double bond susceptible to an attack from electrophiles?

A

Area of high electron density

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94
Q

How can you test for alkenes?

A

Add it to bromine water, turns solution from orange to colourless

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95
Q

What type of isomerism is common in alkenes?

A

E-Z stereoisomerism (restricted rotation around C=C)

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96
Q

What is an electrophile?

A

Electron pair acceptor (attracted to areas of high electron density)

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97
Q

Examples of electrophiles

A

HBr
Br2
H2SO4

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98
Q

What mechanism reaction produces alcohols and halogenoalkanes from alkenes?

A

electrophilic addition

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99
Q

What is electrophilic addition?

A

Electrophile attacks carbon double bond and forms a carbocation (always forms the most stable)

Then the nucleophile which formed from the electrophile bond breaking attacks the positively charged carbocation

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100
Q

What is a carbocation?

A

Carbon atom with only 3 bonds (has a positive charge)

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101
Q

What is the major product in electrophilic addition?

A

The product formed via the most stable carbocation

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102
Q

What does a tertiary carbocation mean?

A

The three bonds on the carbocation are all carbon-carbon single bonds

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103
Q

Why are tertiary carbocations more stable than secondary and primary ones?

A

Has more alkyl groups so greater inductive effect as each alkyl group pushes electrons onto the carbocation so spreads electrons more evenly round the molecule making it more stable

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104
Q

How do alkenes react with cold conc. sulfuric acid and what is the product called?

A

electrophilic addition

alkyl hydrogen sulfates

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105
Q

What happens when you react alkyl hydrogen sulfates with water and what are the conditions?

A

Make alcohols (and H2SO4)

Warm the reaction mixture

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106
Q

What are addition polymers produced from?

A

Alkenes when the double bond is broken to form a repeating unit

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107
Q

What is an addition polymer?

A

Long chain molecule made from lots of monomers joined together

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108
Q

How do you name addition polymers?

A

Poly (alkene made from)

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109
Q

What polymer do you get in high temperature and pressure?

A

Branched chain polymers

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110
Q

What are the properties of branched chain polymers?

A

Weaker and more flexible (weak VDW)

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111
Q

What polymer do you get in low temperature and pressure?

A

Straight chain polymers

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112
Q

What are the properties of straight chain polymers?

A

Strong and rigid (strong VDW)

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113
Q

Why are polymers unreactive?

A

They’re saturated and non-polar

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114
Q

Why aren’t polymers biodegradable?

A

Very unreactive

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115
Q

How do you make a polymer more flexible?

A

Add plasticiser as it gets between the polymer chains and pushes them apart, reducing the intermolecular force strength which makes them easier to bend

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116
Q

Why do polymers make good plastics?

A

Unreactive, multiple strong non-polar bonds

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117
Q

What is a use of polythene?

A

Shopping bags

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118
Q

What does PVC stand for?

A

polychloroethene

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119
Q

What is PVC?

A

Waterproof polymer which has a long closely packed chain

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120
Q

What are the properties of PVC at room temperature?

A

hard and brittle

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121
Q

How is rigid PVC used?

A

Drainpipes, Window frames

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122
Q

How is plasticised PVC used?

A

Electrical cable insulation, flooring tiles and clothing (more flexible)

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123
Q

What are the two ways to make ethanol?

A

Fermentation

Hydration of ethene

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124
Q

What are the conditions of fermentation to produce alcohols?

A

Anaerobic (oxygen free)
yeast catalyst
temp. 30-40°C

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125
Q

What is the equation for fermentation to make alcohol?

A

C6 H12 O6 —> 2 C2 H5 OH + 2CO2

(yeast catalyst)

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126
Q

What are the advantages of fermentation to produce ethanol?

A

sugars renewable
cheap equipment

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127
Q

What are the disadvantages of fermentation to produce ethanol?

A

Batch process (its not continuous)
Ethanol needs distilling

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128
Q

What are the conditions needed for the hydration of ethene to make ethanol?

A

conc. acid (H3PO4 or H2SO4) catalyst
temp. 300°C
pressure 70 atm
(aqueous conditions)

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129
Q

What is the equation for the production of ethanol from the hydration of ethene?

A

C2H4 + H2O ⇌ C2H5OH

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130
Q

What are the advantages of ethanol production from the hydration of ethene?

A

Continuous process
Very high percentage yield (ethanol only product)
Produces purer product than fermentation

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131
Q

What are the disadvantages of ethanol production from the hydration of ethene?

A

ethene is non - renewable as comes from crude oil

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132
Q

What is ethanol used as?

A

biofuel

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133
Q

What is a biofuel?

A

fuel that’s made from biological material that’s recently died

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134
Q

What does carbon neutral mean?

A

no net release of CO2

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135
Q

Even if a reaction is carbon neutral why is the process not necessarily carbon neutral?

A

Transportation of reactants and products and machinery produce CO2

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136
Q

How is fermentation carbon neutral?

A

Glucose comes from photosynthesis:
6CO2 + 6H2O —> C6H12O6 + 6O2

Glucose is fermented to form ethanol:
C6H12O6 —> 2C2H5OH + 2CO2

Ethanol is combusted (used as a biofuel):
2C2H5OH + 6O2 —> 4CO2 + 6H2O

∴ 6CO2 in and 6CO2 out

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137
Q

Why is yeast needed in fermentation to make ethanol?

A

Produces an enzyme which converts glucose to ethanol and carbon dioxide

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138
Q

Why is fermenation to produce ethanol done at 30-40°C?

A

optimum temperature for the enzymes

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139
Q

How is ethanol separated from the products of fermentation?

A

fractional distillation

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140
Q

What are the advantages of biofuel?

A

Renewable energy source

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141
Q

What are the disadvantages of biofuel?

A

Petrol car engines would need to be modified

Land would need to be used to grow crops for fuel meaning it cant be used to grow food

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142
Q

Why does fermentation to make ethanol have to be anaerobic?

A

Must be anaerobic for the yeast to work

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143
Q

How do you classify an alcohol as primary, secondary or tertiary?

A

How many alkyl groups are attached to the carbon that’s bonded to the OH

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144
Q

What do you use to oxidise alcohols and whats the colour change?

A

acidified potassium dichromate ( K2 Cr2 O7 )
orange solution to green solution

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145
Q

What do primary alcohols oxidise to?

A

aldehydes

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146
Q

What do secondary alcohols oxidise to?

A

ketones

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147
Q

What do aldehydes oxidise to and what are the conditions?

A

carboxylic acid
heat under reflux

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148
Q

What do tertiary alcohols oxidise to?

A

they don’t easily oxidise

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149
Q

What is the only way to oxidise tertiary alcohols?

A

burn them

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150
Q

What do ketones oxidise to?

A

aren’t easily oxidised

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151
Q

What are the two tests to distinguish aldehydes and ketones?

A

Fehling’s solution
Tollen’s reagent

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152
Q

What do you observe when you add Fehling’s solution to aldehydes and ketones?

A

aldehyde - blue solution to brick red ppt
Cu 2+ —> Cu +

ketone - NVC

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153
Q

What do you observe when you add Tollen’s reagent to aldehydes and ketones?

A

aldehyde - silver mirror forms
Ag+ —> Ag

ketone - NVC

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154
Q

How do you get an aldehyde when oxidising a primary alcohol (eg ethanol)?

A

Distillation

Gently heat the alcohol with acidified potassium dichromate and use distillation apparatus as the aldehyde boils at a lower temp so is distilled off immediately

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155
Q

How do you get a carboxylic acid when oxidising a primary alcohol (eg ethanol)?

A

Reflux

The alcohol is heated under reflux with excess acidified potassium dichromate and vigorously oxidised. When aldehyde is produced it stays in the reaction mixture and is then oxidised to a carboxylic acid

156
Q

Equation for the oxidation of a primary alcohol?

A

1° alcohol + [O] —> aldehyde + H2O

aldehyde + [O] —> carboxylic acid + H2O

157
Q

Equation for the oxidation of a secondary alcohol?

A

2° alcohol + [O] —> ketone + H2O

158
Q

What type of mechanism means you get an alkene from an alcohol?

A

elimination

159
Q

How are alkenes formed from the elimination of a water molecule from an alcohol used?

A

Addition polymers as they haven’t had to come from crude oil

160
Q

What catalyst is needed to form alkenes from the dehydration of alcohol?

A

conc. H2SO4
(conc. acid)

161
Q

How do you test for alcohols?

A

Add acidified potassium dichromate
turns from orange solution to green

(not for 3° alcohols)

162
Q

How do you test for aldehydes?

A

Add Tollen’s reagent and silver mirror will form

163
Q

How do you test for alkenes?

A

Add bromine water and shake
From orange solution to colourless

164
Q

How do you test for carboxylic acids?

A

Add sodium carbonate which will produce CO2, collect this gas and bubble through limewater which will go cloudy if gas is CO2

165
Q

What is High Resolution Mass Spectrometry?

A

More sensitive form of mass spectrometry which allows the Mr to be determined to several decimal places

166
Q

How do you make Tollen’s reagent? What is its formula

A

Silver nitrate and a few drops of sodium hydroxide and dilute ammonia solution

[Ag(NH3)2] +

167
Q

How does Infrared spectroscopy work?

A

Beam of IR radiation is passed through a sample

Different covalent bonds absorb different frequencies of IR radiation so the varying amounts of absorption can be measured and recorded

168
Q

What does the graph produced from IR spectroscopy show?

A

What frequencies of radiation the molecule is absorbing

169
Q

How can a molecule be identified from its IR absorption graph?

A

Fingerprint region - each molecules is unique

170
Q

How can an IR graph be used to find how pure a compound is?

A

Any impurities will produce extra peaks in the fingerprint region

171
Q

What causes global warming?

A

Molecules of greenhouse gases (eg CO2, CH4, H2O vapour) absorb IR radiation from the sun and they re-emit some towards earth

So the higher the conc. of greenhouse gases the greater the greenhouse effect

172
Q

What type of isomerism is optical isomerism?

A

stereoisomerism

173
Q

Why does optical isomerism arise?

A

Chirality in molecules

174
Q

What is a chiral centre?

A

A carbon with four different groups bonded around it so there is no line of symmetry to the molecule

175
Q

What are enantiomers?

A

Two isomers that are mirror images of each other and cant be superimposed

176
Q

What is plane polarised light?

A

Light that only vibrates in one direction

177
Q

What affect do enantiomers have on plane polarised light?

A

One rotates it 90° clockwise and the other 90° anticlockwise

178
Q

What is a racemic mixture?

A

Contains equal quantities of each enantiomer of an optically active compound

179
Q

How do you know if a mixture is racemic?

A

Doesn’t rotate plane polarised light

180
Q

Why do you get optical isomers when nucleophilic addition happens to aldehydes and unsymmetrical ketones?

A

Nucleophiles are able to attack a molecule with a carbonyl group from above or below the C=O bond

181
Q

How are chiral centres shown?

A

*

182
Q

What is the functional group of aldehydes?

A

-CHO

183
Q

What is the functional group of ketones?

A

RCOR’

184
Q

What do aldehydes reduce to?

A

primary alcohols

185
Q

What do ketones reduce to?

A

secondary alcohols

186
Q

What is the reaction mechanism when aldehydes are reduced to primary alcohols?

A

nucleophilic addition

187
Q

What is the reaction mechanism when ketones are reduced to secondary alcohols?

A

nucleophilic addition

188
Q

What is the reducing agent used to reduce aldehydes and ketones to alcohols?

A

NaBH4 (sodium borohydride) dissolved in water with methanol

189
Q

What is the overall equation for the reduction of aldehydes to primary alcohols?

A

RCHO + 2[H] —> RCH2OH

190
Q

What is the overall equation for the reduction of ketones to secondary alcohols?

A

RCOR’ + 2[H] —> RCH(OH)R’

191
Q

Where do the H- ions and H+ ions used in the nucleophilic addition that reduces aldehydes and ketones to alcohols come from?

A

:H- nucleophile comes from the NaBH4

H+ comes from either the water or the methanol

192
Q

What do you get when acidified KCN reacts with aldehydes and ketones?

A

hydroxynitriles

193
Q

What type of reaction mechanism is the reaction between KCN and aldehydes and carbonates?

A

nucleophilic addition

194
Q

What is a carbonyl compound?

A

Contains C=O

195
Q

Why do you need acidified KCN instead of just KCN when reacting with aldehyde and ketones?

A

Need a source of H+ ions

196
Q

Why is acidified KCN used instead of HCN in reactions?

A

HCN is hard to store as a gas and reacts to produce dangerous byproducts

197
Q

What type of isomerism often occurs in hydroxynitriles?

A

optical isomerism

198
Q

What are the dangers of using KCN?

A

Irritant

Extremely dangerous if ingested or inhaled

Can react with moisture to produce HCN which is a toxic gas

199
Q

What must you do when handling KCN?

A

Wear gloves, safety goggles, lab coat and do any reactions in a fume cupboard

200
Q

What is the overall equation between an aldehyde and KCN?

A

RCHO (aq) + KCN (aq) —> RCH(OH)CN (aq) + K+ (aq)

(also with H+ (aq) )
product - hydroxynitrile

201
Q

What is the overall equation between a ketone and KCN?

A

RCOR’ (aq) + KCN (aq) —> RC(OH)R’CN (aq) + K+ (aq)

(also with H+ (aq) )
product - hydroxynitrile

202
Q

Why do aldehydes and ketones have higher boiling points than alkanes with a similar Mr?

A

All have similar VDW as similar no. electrons but it is due to permanent dipole attractions between carbonyl groups on the neighbouring molecules

203
Q

Why do alcohols have a much higher boiling point than aldehydes and ketones with a similar Mr?

A

Aldehydes and ketones have permenant dipole attractions between carbonyl groups on neighbouring molecules but alcohols have hydrogen bonding between hyrdoxyl groups on neighbouring alcohol molecules

204
Q

Why are the boiling points of ketones slightly higher than aldehydes?

A

Aldehydes have the carbonyl group at the end which gives a longer non-polar part of the molecule so it has less effective permanent dipoles than ketones

205
Q

Why do branched chain aldehydes and ketones have a lower boiling point than straight chained ones?

A

Branching allows less interaction between molecules so less effective permanent dipole attractions

206
Q

Rank from lowest to highest boiling points aldehydes, alcohols, alkanes, carboxylic acids (all have similar Mr)

A

Alkanes (VDW)
Aldehydes (permanent dipoles)
Alcohols (hydrogen bonding)
Carboxylic acids

207
Q

How does solubility vary with carbon chain length of aldehydes and ketones?

A

Smaller chain lengths are more soluble

208
Q

Why do short chain aldehydes and ketones mix well with water (are soluble)?

A

Polar carbonyl groups are able to from hydrogen bonds with water molecules

209
Q

What is the functional group of carboxylic acids?

A

-COOH

210
Q

What is the reaction between carboxylic acids and carbonates?

A

carboxylic acid + carbonates —> salt + water + CO2

211
Q

What is the functional group of esters?

A

-COO-

212
Q

What is esterification?

A

Making esters by reacting carboxylic acids and alcohols

213
Q

What are the conditions needed for esterification?

A

Strong acid catalyst (H2SO4)
Heated under reflux

214
Q

What is the reaction between a carboxylic acid and an alcohol and whats it called?

A

Esterification or condensation

carbox. acid + alcohol ⇌ ester + water

(H+, reflux)

215
Q

How do you name esters?

A

alcohol - yl carbox. acid - oate

eg propyl butanoate

216
Q

What are some uses of esters?

A

Food flavouring
Perfumes
Solvents (they’re polar liquids so polar organic compounds dissolve in them)
Plasticisers

217
Q

How do you test for esters?

A

Smell them - usually smell sweet

218
Q

Why are esters used as solvents in glues and printing inks?

A

Have low boiling points so can easily evaporate from mixtures

219
Q

What is the problem with plasticisers over time?

A

They escape from the polymers causing the plastic to become brittle and stiff

220
Q

How does the solubility of carboxylic acids vary with carbon chain length?

A

Solubility decreases as chain increases due to the longer non-polar hydrocarbon chain

221
Q

Why are short chain carboxylic acids very soluble in water?

A

The highly polar carbonyl and hydroxyl groups can form hydrogen bonds with water

222
Q

What has a higher boiling point alcohols or carboxylic acids and why?

A

Carboxylic acids as forms two hydrogen bonds between molecules (both carbonyl and hydroxyl group are polar) where as alcohols only have one

223
Q

What is the reverse of esterification?

A

Hydrolosis

224
Q

What is the hydrolysis of esters?

A

The splitting of esters by the action of water

225
Q

What is the equation for the acid hydrolysis of esters?

A

ester + water ⇌ carboxylic acid + alcohol
(H+)

esters are not completely hydrolysed, an eqm. is set up

226
Q

What are the conditions for acid hydrolysis of esters?

A

heat under reflux with dilute H2SO4

227
Q

What hydrolysis of esters is faster, acidic or alkaline?

A

Alkaline

228
Q

What is the equation for the alkaline hydrolysis of esters?

A

ester + base(aq) —> carboxylate salt + alcohol

229
Q

What are the conditions for the alkaline hydrolysis of esters?

A

heat under reflux with NaOH(aq)

230
Q

What are vegetable oils and fats?

A

triesters

231
Q

What is the equation for the production of vegetable oils and fats?

A

glycerol + 3 fatty acids —> triglyceride + 3H2O

232
Q

What is glycerol?

A

propane - 1,2,3 - triol

233
Q

What are fatty acids?

A

Long chain carboxylic acids

234
Q

Which of animal fats and vegetable oil is saturated and unsaturated?

A

Animal fats - saturated (no C=C)

Veg. oil - unsaturated

235
Q

Why is vegetable oil liquid at room temperature and animal fats solid?

A

Animal fats are saturated so hydrocarbon chain fits nicely together which increases VDW

Veg oil is unsaturated so the hyrdocarbon chain is bent and doesn’t pack together well which decreases the VDW

236
Q

What is saponification?

A

Alkaline hydrolisis of fats into glycerol and the salts of the fatty acids present in the fat

237
Q

What conditions are needed for saponification?

A

heat under reflux with NaOH(aq)

238
Q

What is the reaction equation for saponification?

A

fat + 3NaOH —> glycerol + 3 sodium salts (soap)

239
Q

What is a soap and what properties does it have?

A

Salt of a long chain carboxylic acid

Hydrophobic and hydrophilic

240
Q

What is biodiesel?

A

Renewable fuel made from vegetable oils (eg rapeseed and palm)

241
Q

What is biodiesel made from?

A

Mixture of methyl esters of fatty acids

242
Q

What is trans-esterification?

A

Reacting an ester with an alcohol to produce a different ester and a different alcohol (eg production of biodiesel)

243
Q

What is the equation for the production of biodiesel?

A

triglyceride + 3 methanol —> mixture of methyl esters (3) + glycerol

244
Q

Glycerol is a bypoduct in the production of biodiesel, how can it be used?

A

Pharmaceuticals and cosmetics

245
Q

What are acid derivatives?

A

Compounds that are related to carboxylic acids, the OH group has been replaced by something else

246
Q

What are the three main derivatives?

A

acid anhydrides
acid chlorides
amides

247
Q

What is the functional group of acid chlorides?

A

-COCl

248
Q

How are acid chlorides named?

A
  • anoyl chloride
249
Q

How do acid chlorides react and why?

A

Violently/vigorously due to very polar -COCl group

250
Q

How are acid anhydrides formed?

A

When two identical carboxylic acid molecules join together and water is eliminated

251
Q

How are acid anhydrides named?

A

-anoic anhydride

252
Q

What is the functional group of an amide?

A
  • C(=O)N =
253
Q

How do you name amides with the functional group -C(=O)NH2

A

-anamide

254
Q

What is acylation?

A

The process in which an acyl group is added to a molecule

255
Q

What is an acylating agent?

A

The molecule providing the acyl group

eg acyl chlorides

256
Q

What type of mechanisms are acylations?

A

nucleophilic addition-elimination reactions

257
Q

What is the reaction between acyl chloride and alcohol?

A

acyl chloride + alcohol —> ester + HCl

258
Q

What are the observations when acyl chloride reacts with alcohol?

A

Vigorous reaction which produces steamy fumes of HCl, smell of ester

259
Q

What is the reaction between acid anhydrides and alcohol?

A

acid anydride + alcohol —> ester + carboxylic acid

260
Q

What are the conditions for acylation involving acyl chloride?

A

Anhydrous to prevent the hydrolysis of acyl chloride, reacts vigorously with water

261
Q

What is the reaction between acyl chloride and water?

A

acyl chloride + water —> carboxylic acid + HCl

262
Q

What is the reaction between acid anhyrdride and water?

A

acid anhydride + water —> 2 carboxylic acids

263
Q

What is the reaction between acyl chloride and ammonia?

A

acyl chloride + ammonia —> amide + HCl

HCl and excess ammonia can further react to make ammonium salt (NH4Cl)

264
Q

What is the reaction between acid anhydride and ammonia?

A

acid anhydride + ammonia —> amide + carboxylic acid

(Carboxylic acid and ammonia can further react to make ammonium salt)

265
Q

What is a N-substituted amide?

A

When one of the hydrogens of an amine has been substituted

266
Q

What is the reaction between acyl chloride and a primary amine?

A

acyl chloride + primary amine —> n-sub. amide + HCl

267
Q

What is the reaction between acid and anhydride and a primary amine?

A

acid anhydride + primary amine —> n-sub. amide + carboxylic acid

(carboxylic acid will then react with the excess amine to produce a salt)

268
Q

What type of organic compound is asparin and what is it made from?

A

ester

salicylic acid and ethanoic anhydride

269
Q

What are the industrial advantages of using ethnic anhydride to acylate rather than ethanol chloride?

A

less corrosive

less vulnerable to hydrolysis (less reactive)

less hazardous to use as gives a less violent reaction

cheaper

doesn’t produce corrosive HCl fumes

270
Q

What is the molecular formula of benzene?

A

C6H6

271
Q

What are the lengths of the carbon bonds in benzene?

A

All an intermediate length between carbon-carbon single and double bonds

272
Q

Describe the bonds on each carbon atom in benzene, accounting for all 4 outer electrons?

A

Forms two carbon-carbon bonds either side

One carbon-hydrogen bond

The remaining outer electron from the p-orbital is delocalised to form a central ring above and below the ring of carbon atoms

273
Q

Why is benzene more stable than the theoretical compound cyclohexa-1,3,5-triene?

A

Delocalised ring of electrons means the electron density is more evenly spread around the molecule which reduces electron repulsion

274
Q

Why is the ΔH of hydration of benzene less exothermic than expected and what does a less exothermic reaction mean?

A

More energy must have been put in to break the bonds in benzene which suggests its more stable (due to the delocalised electron ring)

275
Q

Does benzene favour substitution or addition?

A

Substitution

276
Q

Why does benzene favour substitution reactions over addition?

A

In addition reactions the electrons from the delocalised system in benzene would need to bond with wahtevers being added so the delocalised ring would be broken so it would loose its stability

In substitution the organic product formed retains the ring of delocalised electrons

277
Q

Why doesn’t benzene decolourise bromine water like you might expect it to?

A

Doesn’t undergo an addition reaction as the delocalised ring would get broken

278
Q

Whats an arene?

A

An aromatic compound - contains a benzene ring as part of its structure

279
Q

What intermolecular forces does benzene have?

A

Only VDW
its a non-polar molecule

280
Q

What type of reaction mechanism do you get when reacting something with benzene?

A

Electrophilic substitution

281
Q

What is Friedel-Crafts acylation?

A

When the benzene ring acts as a nucleophile leading to an attack on R-COCl (makes phenylketones)

282
Q

How does AlCl3 act as a catalyst in Friedel-Crafts acylation?

A

R-COCl + AlCl3 —> R-C(+)O + AlCl4-

AlCl4- + H+ —> HCl + AlCl3

makes a reactive intermediate

283
Q

What is nitration?

A

When you warm benzene with conc. nitric and sulfuric acid and get nitrobenzene

284
Q

What are the conditions for nitration?

A

conc. nitric and sulfuric acid
warmed

285
Q

Show how you form the electrophile NO2 + from conc. nitric and sulfuric acid?

A

HNO3 + H2SO4 —> H2NO3+ + HSO4-

HNO3+ —> NO2 + + H2O

286
Q

How do you get a monosubstitution in nitration?

A

temp 55°C as when temp is greater you get multiple substitutions

287
Q

How are nitration reactions useful?

A

Nitro compounds can be used as explosives egTNT (trinitrotoluene or 2,4,6-trinitromethylbenzene

Nitro compounds formed can be reduced to form aromatic amines that are used to manufacture dyes and pharmaceuticals

Organic synthesis

288
Q

What is the overall equation for the reaction between benzene and conc. nitric acid in the presence of a catalyst?

A

C6H6 + HNO3 —> C6H5NO2 + H2O

289
Q

What is the nitrile functional group?

A

C≡N

290
Q

How can you ‘prepare’ primary amines?

A

Nucleophilic substitution of halogenoalkanes :NH3 acts as a nucleophile

reduction of nitriles

291
Q

What are the conditions needed for the nucleophilic substitution of halogenoalkanes with ammonia to make primary amines?

A

heated in a sealed flask with excess ammonia in ethanol

292
Q

What is the nucleophilic substitution reaction equation for halogenooalkanes and ammonia?

A

halogenoalkane + 2 ammonia —> primary amine + ammonium salt

293
Q

What are the two ways you can reduce a nitrile to make primary amines?

A

CATALYTIC HYDROGENATION
Hydrogen in the presence of a nickel catalyst with high temp and high pressure

STRONG REDUCING AGENT IN A NON-AQUEOUS SOLVENT
eg LiAlH4 in dry ether followed by dilute acid

294
Q

Which method is preferred for making primary amines - nuc. sub of halogenoalkane with NH3 or reduction of nitriles?

A

Reduction of nitriles gives better yield as primary amine is only product

100% atom economy

295
Q

How do you ‘prepare’ aromatic amines?

A

Reduction of nitro compounds
eg nitro benzene to make phenylamine

296
Q

What conditions are needed when reducing nitrocompounds eg nitrobenzene?

A

heat under reflux with tin and excess conc. HCl, followed by addition of conc. NaOH

297
Q

How are aromatic amines used?

A

To manufacture dyes

298
Q

What is the inductive effect?

A

An electron pushing effect - alters the electron density distribution in a molecule

299
Q

What is the inductive effect in benzene amines eg phenylamine?

A

Benzene ring draws the electron density away from the nitrogen, lone pair of electrons on the nitrogen get partially delocalised on the ring, so are much less available

300
Q

What is the inductive effect in alkyl groups?

A

They push the electron density towards the atom so for example towards the nitrogen making the lone pair more available

301
Q

What is base strength?

A

How available the lone pair of electrons are

302
Q

What is the strongest and weakest base from ammonia, aromatic amine (phenylamine) and a primary amine?

A

strongest - primary amine (lone pair most available )

weakest - aromatic amines (lone pair least available)

303
Q

Are amines strong or weak bases?

A

Weak

304
Q

How do amines act as nucleophiles?

A

The lone electron pair on the N is attracted to δ+ regions

305
Q

When do nucleophilic substitution reactions with halegonalkanes and amines stop and why?

A

When a quaternary ammonium ion has been formed (from sub. of tertiary amine) as it cannot act as nucleophile as there is no lone pair on the N

306
Q

When carrying out nucleophilic substiturions to make amines with halogenoalkanes and ammonia how do you favour the production of primary amines?

A

Excess ammonia

This means its unlikely for a halogenoalkane to react with a primary amine and for further substitutions to occur as there are large amounts of ammonia available to react with instead

307
Q

When carrying out nucleophilic substiturions to make amines with halogenoalkanes and ammonia how do you favour the production of quaternary ammonium salts?

A

Excess halogenoalkanes

This ensures all the ammonia will react with halogenoalkanes and then the amines formed will continue to react with the unused halogenoalkanes until quaternary ammonium salts have been made

308
Q

How are quaternary ammonium salts used?

A

Cationic surfactants eg detergents, hair conditioner, fabric softners

As they have a positive and negative end meaning the two ends are attracted to other substances which prevents static from building up on surfaces

309
Q

What is the equation for the nucleophilic addition-elimination reaction between acyl chlorides and amines?

A

acyl chlorides + amines —> N-sub. amides + HCl

310
Q

What is the equation for the nucleophilic addition-elimination reaction between acid anhydrides and amines?

A

acid anhydride + amine —> N-sub. amide + carboxylic acid

311
Q

What is a polymer?

A

A very long chain molecule comprising of several monomers

312
Q

What is condensation polymerisation?

A

When two monomers form a link and a water molecule is lost

313
Q

What are the three types of condensation polymers?

A

polyamides
polyesters
polypeptides

314
Q

What are polyamides made from?

A

Dicarboxylic acids and diamines

315
Q

Why are polyamides strong?

A

Commonly formed from long chain molecules which provides them with strength

316
Q

What is an amide linkage?

A

-CONH -

(-C(=O)NH-) carboxyl groups of dicarboxylic acid and amino groups of diamines

317
Q

What are the two polyamide examples?

A

Nylon 6,6
Kevlar

318
Q

How is Nylon 6,6 used?

A

Clothing, carpet, rope, airbags, parachutes

319
Q

What is Nylon 6,6 made from?

A

1,6-diaminohexane
hexanedioic acid

320
Q

How is Kevlar used?

A

Bulletproof vests, boat construction, car tyres

321
Q

What is Kevlar made from?

A

1,4-diaminobenzene
benzene-1,4-dicarboxylic acid

322
Q

What are polyesters made from?

A

Dicarboxylic acids and diols

323
Q

What is an ester linkage (in polyesters)?

A

-COO-

(-C(=O)O-) carboxyl groups of dicarboxylic acid and hydroxyl groups of diols

324
Q

What is an example of a polyester?

A

Trylene (PET)

325
Q

How is Trylene used?

A

Plastic bottles, clothing, sails

326
Q

What is Trylene made from?

A

benzene-1,4-dicarboxylic acid
ethane-1,2-diol

327
Q

What are polypeptides made from?

A

amino acids

328
Q

How are condensation polymers broken down into their constituent molecules?

A

hydrolysis

329
Q

What intermolecular forces do you get in condensation polymers?

A

VDW, permanent dipoles and hydrogen bonding

330
Q

Why are condensation polymers stronger than addition polymers?

A

They have polar bonds eg C-N and C=O so they have hydrogen bonds as well as VDW

331
Q

Why are addition polymers non-biodegradable?

A

Non-polar carbon chains which make them unreactive and inert

332
Q

How do we dispose of addition polymers?

A

Have to be burned

333
Q

Are condensation polymers biodegradeable?

A

Yes

334
Q

Why are condensation polymers biodegradable?

A

They have polar bonds so they’re susceptible to nucleophile attacks by water (hydrolysis)

(can be broken down by naturally occuring water and moisture)

335
Q

What are the advantages of burying (landfill) polymers?

A

cheap and easy

336
Q

What are the disadvantages of burying (landfill) polymers?

A

Plastic decomposes to release methane (greenhouse gas)

Takes up space

Takes a long time to decompose

337
Q

What are the advantages of burning polymers to dispose of them?

A

Gets rid of them

Heat can be used to generate electricity

338
Q

What are the disadvantages of burning polymers to dispose of them?

A

Can release toxic gas which has to be removed
CO2 produced which is a greenhouse gas

339
Q

What are the advantages of recycling polymers?

A

Cuts down on landfill

Saves raw materials (oil is non-renewable)

Produces less CO2 than burning plastic

340
Q

What are the disadvantages of recycling polymers?

A

Labour intensive sorting plastic

Expensive (costs more than landfill)

Plastic can become contaminated

341
Q

What does NMR stand for?

A

Nuclear Magnetic Resonance

342
Q

What is NMR spectroscopy?

A

An analytical technique that allows the structure of a molecule to be determined by analysing the energy of each bond environment

343
Q

When does an atom have nuclear spin and what does this cause the atom to have?

A

When there is an odd number of nucleons in its nucleus and causes it to have a weak magnetic field

344
Q

What does an atoms environment depend on?

A

All the groups its connected to, going right along the molecule

345
Q

What is NMR actually measuring?

A

Normally nuclei spin in random directions (so their magnetic field cancels out) but when placed in a strong external magnetic field they either align with the field or opposed to it.

Nuclei aligned with the field are at a slightly lower energy level.

Radio waves of the right frequency can give those nuclei enough energy to flip up to the higher energy level

NMR can measure the adsorption of the sample

346
Q

What does chemical shift depend on?

A

The molecular environment

347
Q

What is chemical shift measured in?

A

δ
parts per million relative to TMS

348
Q

What is the structure of TMS?

A

Si (CH3)4
tetramethylsilane

349
Q

What does a peak at δ=0 on a NMR spectra graph mean?

A

TMS has been added to the sample

350
Q

Why is TMS sometimes added too samples when using NMR spectroscopy and what properties make it okay to add?

A

Calibration purposes

Inert, non-toxic, volatile (won’t react with sample and can be easily removed)

351
Q

What does the area under each peak on a proton NMR spectra represent?

A

Corresponds to the relative no. of H atoms in each environment

352
Q

What does the no. of splits in a peak on a proton NMR show?

A

The no. of hydrogen atoms on the adjacent carbon

353
Q

What three things do you need to look at when studying a proton NMR spectra?

A

Chemical shift value

Ratio of the areas under peaks

Splitting patterns

354
Q

What do we use when the area under the peaks on a proton NMR are too difficult to distinguish?

A

Integration trace

Shown instead and the heights are proportional to the no. of H atoms in each environment

355
Q

What must be done to samples when carrying out proton NMR?

A

Dissolved in non-hydrogen containing solvents
(must be non-hydrogen so it doesn’t produce any δ peaks)

356
Q

What solvents can be used to dissolve proton NMR samples? examples and why

A

CCl4 (doesn’t contain any hydrogens)

Deuterated solvents (2H atoms as they have 2 nucleons so have no nuclear spin and ∴ no magnetic field)

357
Q

What is chromatography?

A

An analytical technique used to separate and identify component molecules of a mixture

358
Q

What does the separation in chromatography depend on?

A

The solubility in the mobile phase

The retention by the stationary phase

359
Q

What is the mobile phase in chromatography and what state is it in?

A

When the molecules can move
Liquid or gas

360
Q

What is the stationary phase in chromatography and what state is it in?

A

When the molecules can’t move
Solid or a liquid on a solid support

361
Q

How does solubility affect the distance moved by a compound in chromatography?

A

More soluble the further it moves with the mobile phase

362
Q

How does a compounds affinity to the stationary phase affect the distance it moves in the mobile phase?

A

The greater the affinity the shorter the distance moved

363
Q

What are the three types of chromatography?

A

Thin Layer Chromatography (TLC)
Column Chromatography
Gas Chromatography

364
Q

What is Thin Layer Chromatography used for?

A

Separating mixtures

365
Q

Describe the set up of Thin Layer Chromatography and the reasoning for certain elements

A

A metal plate with a thin layer of silica (or alumina) is placed in a beaker with solvent. Solvent is below the baseline (where mixture being tested is) so that it doesn’t dissolve the sample

Watch glass lid is placed on beaker to prevent the solvent from evaporating

366
Q

What do you do with the TLC plate once the solvent has travelled to the top of the plate?

A

Remove plate from beaker

Use a pencil to mark how far the solvent travelled - this line is the solvent front

Place the plate in a fume cupboard and leave it to dry (fume cupboard prevents any toxic or flammable gases from escaping the room)

367
Q

What is the solvent front in TLC?

A

Where the solvent travelled to on the TLC plate

368
Q

What is a chromatogram and how is it used?

A

The product of TLC and the position of spots on a chromatogram can be used to calculate Rf values and determine the components of a mixture

369
Q

What do you need to do if carrying out TLC with colourless chemicals?

A

Use a TLC plate with a special fluorescent dye that glows when UV light shines on it

Expose the chromatogram to iodine vapour (its a locating agent so sticks to chemicals and shows them as brown spots)

370
Q

How do you expose a chromatogram to iodine vapour?

A

Leave it in sealed jar with a couple of iodine crystals

371
Q

How do you calculate the Rf value?

A

Rf = distance moved by molecule / distance moved by solvent

372
Q

What do Rf values depend on?

A

Specific molecule

Composition of TLC plate

Composition of solvent

Temperature

373
Q

What does the number of spots on a chromatogram tell you?

A

The no. compounds present in a mixture

374
Q

What is Column Chromatography used for?

A

To seperate out solutions

375
Q

How is Column Chromatography set up?

A

A vertical glass column is set up with a solid, powdered substance (eg aluminium oxide) that acts as the stationary phase.

A solvent containing the mixture being separated is then added tot he column and moves down.

Each compound moves at different speeds so is collected at different times

376
Q

Why do different molecules drain out the column during Column Chromatography at different times?

A

Varying affinities of the molecules to the stationary phase means they have different retention times

377
Q

How can molecules be identified from Column Chromatography?

A

The different retention times can be compared to known values

378
Q

How is Gas Chromatography used?

A

To separate mixtures of volatile liquids?

379
Q

What is the stationary phase of Gas Chromatography?

A

Solid or a solid coated in a viscous liquid that’s been packed into a long tube that is built into an oven

380
Q

What is the mobile phase of Gas Chromatography?

A

Unreactive gas (eg nitrogen)

381
Q

Describe the setup of Gas Chromatography and explain the reasoning for some of the elements

A

A tube thats coiled up to save space in a temp. controlled oven so that it can happen under pressure and at a high constant temp.

The carrier gas is fed into the tube and the sample is also injected into the tube

The other end of the tube is attached to a detector and recorder

382
Q

What does the retention time of Gas Chromatography depend on?

A

How much time the molecule spends moving along with the carrier gas and how much time it spends stuck to the viscous liquids

383
Q

What does the detector and recorder of Gas Chromatography produce?

A

A graph of recorder response against retention time

Each molecule has a unique retention time that can be compared to known retention times

Area under each peak tells you the relative amount of each compound present in the mixture

384
Q

What are some uses of Gas Chromatography?

A

Find the level of alcohol in blood or urine (accurate enough to be used as evidence in court)

Find proportion of various esters in oils used in paints. Picture restorers then know exactly what paint was originally used)

385
Q

What can you combine with Gas Chromatography to make a very useful analytical technique?

A

Mass Spectrometry

386
Q

How does Gas Chromatography - Mass Spectrometry (GC-MS) work?

A

A sample is separated using Gas Chromatography but instead of going to a detector, the separated components are fed into a mass spectrometer

387
Q

What are the advantages of Gas Chromatography - Mass spectrometry?

A

The components separated out can be positively identified

Computers can be used to match the mass spectrum for each component of the mixture against a database - the process can be automated

Chemistry (10 decks)

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