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OCR A Level Chemistry > Topic 6 > Flashcards

Topic 6 Flashcards

1
Q

Draw an aldehyde group

A

google it

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2
Q

Draw an ester group

A

google it

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3
Q

Draw a haloalkane group

A

google it

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4
Q

Draw an alcohol group

A

google it

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5
Q

Draw an alkene group

A

google it

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6
Q

Draw a carboxylic acid group

A

google it

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7
Q

Draw a ketone group

A

google it

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8
Q

Draw an amine group

A

google it

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9
Q

What are aromatic hydrocarbons?

A

Aromatic hydrocarbons are when some or all of the carbons are found in a benzene ring

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10
Q

What are aromatic hydrocarbons also called?

A

Arenes

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11
Q

What is an alkyl group?

A

An alkyl group has a hydrogen group removed from the alkane chain

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12
Q

What are compounds with one substituent group?

A

.These are aromatic compounds with one substituent group that is mono-substituted on to a benzene ring

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13
Q

.If the substituent group is: An alkyl group (e.g. CH3), halogen (e.g. Br, Cl), or a nitro group (NO2)
.Then …

A

the parent group is classed as the benzene ring and the group added is considered the prefix

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14
Q

If the substituent group is: amine or an alcohol, then …

A

the parent group is classed as the functional group and benzene is classed as the prefix

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15
Q

What is the prefix for benzene?

A

phenyl

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16
Q

Draw Benzene carboxylic acid

A

google it or check notes

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17
Q

Draw Benzaldehyde

A

google it or check notes

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18
Q

Some molecules may contain more than one substituent group, so it may have ___ substituents bonded to it.

A

two

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19
Q

We number the benzene ring like you would a ____ chain

A

carbon

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20
Q

The substituent groups are listed in _____ order and using the ________ possible number.

A

alphabetical

smallest

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21
Q

Draw 2-chloro methylbenzene

A

google it or check notes

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22
Q

Draw 3-methylphenylamine

A

google it or check notes

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23
Q

When was Benzene discovered? and by who?

A

Discovered in 1825 by Michael Faraday

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24
Q

what is the percentage make up of benzene found by faraday? relative formula mass, and empirical formula

A

.92% carbon, 8% hydrogen
.It has a relative formula mass of 78
.Empirical formula found to be CH

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25
Q

What was weird about benzene when discovered?

A

.The structure was difficult to define

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26
Q

Who proposed the first structure of Benzene, what was it and did it work?

A

.Kekule’s proposed structure for benzene
.It was planar, cyclic with alternating double and single bonds which had 120’ bond angles
.But there were problems with this structure

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27
Q

What was the chemical evidence against Kekule’s benzene?

A

.Benzene would not react with bromine, hydrogen bromide, and sulfuric acid
.This tells us there are no double bonds in the molecule
.The molecule does not undergo electrophilic addition reactions

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28
Q

What was the bond length evidence against Kekule’s benzene?

A

.A carbon-carbon single bond length is 0.153nm
.A carbon-carbon double bond length is 0.134nm
.So you would expect benzene to be an irregular hexagon
.In 1922, Kathleen Lonsdale used x-ray diffraction to measure the bond length in benzene
.She found it had a regular shape
.She found that all the carbon-carbon bonds were the same length – 0.14nm
.Each bond is an intermediate between a single and double bond

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29
Q

What was the thermochemical evidence against Kekule’s benzene?

A

.The enthalpy of hydrogenation is defined as the change in enthalpy when 1 mole of unsaturated compound reacts with an excess of hydrogen to become fully saturated
.The molecule had an enthalpy of -208, Kekule’s model in theory should have had -360
.So it’s bonds are more stable than cycloalkenes, as it is less exothermic than expected

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30
Q

Describe the declocalised model of benzene

A

.Each carbon atom has 3 σ (normal) bonds
.This leaves a spare electron in 2p orbital
.120’ bond angle between carbon atoms
.Planar hexagonal molecule
.2p orbitals overlap above and below the ring
.To form pi bonds
.The electrons in the pi bonds are delocalised

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31
Q

Draw the delocalised model of bezene

A

check notes or google

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32
Q

Draw Kekule’s benzene model

A

Check notes or google

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33
Q

What is an electrophile?

A

An electrophile is an electron acceptor and can have a positive charge

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34
Q

What must an electrophile have to attack the stable benzene ring?

A

An electrophile has to have a strong positive charge to be able to attack the stable benzene ring, most compounds just aren’t polar enough

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35
Q

What does an electrophile need when attacking a benzene ring?

A

Needs a halogen carrier – iron, iron halides (e.g. FeCl3) or aluminium halides (e.g. AlCl3)

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36
Q

Br-Br: + AlBr3 

A

AlBr4- + Br+

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37
Q

In an electrophilic substitution reaction with benzene, what does the halogen carrier do?

A

The halogen carrier accepts a lone pair of electrons from a halogen atom, as the lone pair is pulled away from the polarisation increases forming a strong electrophile

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38
Q

What is halogenation?

A

when a hydrogen atom is substituted for a halogen on a benzene ring

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39
Q

Give an example of halogenation

A

bromine is substituted onto a benzene ring to make bromobenzene
C6¬H6 + Br2  AlBr3  C6H5Br + HBr

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40
Q

WHat is the mechanism to a halogenation?

A

Step 1 – creating the electrophile with the halogen carrier catalyst

Step 2 – electrophile accepts a long pair of electrons from the benzene ring to form a dative covalent bond, this forms as unstable intermediate, the intermediate breaks down to form the organic product

Step 3 – the catalyst is regenerated

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41
Q

Draw the halogenation of benzene with Br2 with the AlBr3 catalyst

A

check notes or google

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42
Q

Benzene reacts with nitric acid at what speed?

A

slowly

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43
Q

How can we increase the rate of reaction of benzene and nitric acid?

A

by using sulphuric acid as a catalyst and 50’C

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44
Q

What happens when benzene reacts with nitric acid?

A

The H atom is substituted for a nitro (NO2) group

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45
Q

C6H6 + HNO3  H2SO4 

A

C6H5NO2 + H2O

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46
Q

Draw the mechanism for benzene and nitric acid

A

check notes or google

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47
Q

Describe the steps of the mechanism for benzene and nitric acid

A

Step 1: Creating the electrophile with the sulphuric acid
Step 2: Electrophile accepts a lone pair of electrons from the benzene ring to form a dative covalent bond, this forms an unstable intermediate – the intermediate breaks down to form the organic product
Step 3: The catalyst is regenerated

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48
Q

Why is the reaction between benzene and nitric acid kept at 50’C?

A

so that only 1 nitro group attaches

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49
Q

What is alkylation?

A

.This is when a hydrogen atom is substituted for an alkyl group on a benzene ring
.Called the Friedel crafts reaction

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50
Q

In alkylation, what does the alkyl group need to be attached to?

A

a halogen

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51
Q

Give an example of alkylation

A

a methyl group is substituted onto a benzene ring to make methyl benzene

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52
Q

For alkylation, the halogen in the catalyst has to be what?

A

the same as the halogen the alkyl group is attached to

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53
Q

Draw the mechanism for attaching a methyl group to benzene

A

Check notes

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54
Q

What is Acylation?

A

.This is when a hydrogen atom is substituted for an acyl chloride group on a benzene ring
.Also called the Friedel crafts reaction

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55
Q

Draw the acyl chloride group?

A

check notes or google it

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56
Q

In an acylation reaction, Ethanoyl chloride reacts with benzene to make what?

A

phenylethanone

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57
Q

Draw the mechanism for benzene becoming phenylthanone

A

check notes

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58
Q

What are phenols?

A

Phenols are a type of organic chemical containing a hydroxyl group (-OH) functional group directly bonded to an aromatic ring

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59
Q

The simplest member of the phenols is ?

A

Phenol

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60
Q

Draw phenol

A

check notes or google

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61
Q

.Any compound that has an OH (hydroxyl) group bonded directly to a benzene ring is a what?

A

phenol

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62
Q

.If the compound doesn’t have a OH bond directly but still has an OH group it is classed as an ______, not a ______

A

alcohol, not a phenol

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63
Q

.Phenol is less soluble in water than alcohols, why?

A

due to its non-polar benzene ring

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64
Q

When dissolved in water, phenol partially dissociates to form what?

A

a phenoxide ion and a proton

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65
Q

As phenol only partially dissociates it is ______, other phenols also act as ________

A

a weak acid (pH4-6)

weak acids

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66
Q

.Ethanol doesn’t react with sodium hydroxide (strong ___) or sodium carbonate (weak ___)

A

base

base

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67
Q

Phenols and carboxylic acids will react with ____________________ (like aqueous sodium hydroxide)

A

solutions of strong bases

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68
Q

carboxylic acids are strong enough to react with a weak base like sodium carbonate, you would observe what?

A

a gas/bubbles

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69
Q

Draw the mechanism for phenol and sodium hydroxide

A

check notes or internet

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70
Q

Draw the mechanism for phenol and sodium

A

check notes or internet

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71
Q

Describe the bromination of phenols?

A

.Phenol reacts with aqueous solution of bromine (bromine water)
.A halogen carrier is not required and the reaction can be carried out at room temperature

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72
Q

Draw the mechanism of phenol and Br2

A

Check notes or internet

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73
Q

What does the bromination of phenol look like?

A

This reaction decolourises bromine water and forms a white precipitate

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74
Q

Why does phenol react more readily with bromine than benzene?

A

.One of the lone pairs of electrons on the p orbital of the O atom in the OH is partially delocalised into the ring
.This increases the electron density
.The electrophile becomes more polarised

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75
Q

Describe the nitration of phenol

A

.Phenol readily reacts with dilute nitric acid at room temperature
.It does not need halogen carrier
.Makes with 2-nitrophenol or 4-nitrophenol and water

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76
Q

Draw the nitration of phenol mechanism

A

check notes or internet

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77
Q

Many aromatic compounds can undergo a second substitution, what is this called?

A

a di-substitution

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78
Q

What is the directing effect?

A

The presence of substituted groups on a benzene ring will have an effect on the substitution of further groups – this is known as the directing effect

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79
Q

Substituted groups can be classified by the effect they have on the electron density of the ring, what are the classifications?

A
  • Electron donating – increases the electron density

- Withdrawing electrons – decrease electron density

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80
Q

What are electron donating substitition groups also known as, why?

A

.Side chains that increase electron density allow electrophiles to react faster than with benzene, so are ‘activating’ products

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81
Q

Give an example of an electron donating substitution group

A

.OH – O lone pair orbitals overlap with delocalised ring

.NH2 – N lone pair orbitals overlap with delocalised ring

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82
Q

Where do electron donating groups promote substitution?

A

.They increase the electron density at positions 2, 4, and 6
.So electrophiles are more likely to react at these positions
.The group directs substitution to positions 2, 4, and 6
.2, 4-directing
.The weaker position at 3 and 5 are rarely substituted

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83
Q

What are electron withdrawing substitition groups also known as, why?

A

.Side chains that decrease electron density slow electrophile reactions compared to benzene, so are ‘deactivating’ groups

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84
Q

Give an example of an electron withdrawing substitution group

A

.NO2 – O is more electronegative, drawing electrons away from the delocalised ring

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85
Q

Where do electron withdrawing groups promote substitution?

A

.It withdraws electron density at position 2, 4, and 6 – meaning that electrophiles are unlikely to react at these positions
.The group directs substitutes to position 3
.3- directing
.The weaker positions at 2 and 4 are rarely substituted

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86
Q

Where does NH2 direct?

A

2, 4

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87
Q

Where does OH direct?

A

2, 4

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88
Q

Where does OR direct?

A

2, 4

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89
Q

Where does F, CL, Br, and I direct?

A

2, 4

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90
Q

Where does R direct?

A

2, 4

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91
Q

Where does NO2 direct?

A

3

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92
Q

Where does COOH direct?

A

3

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93
Q

Where does CHO direct?

A

3

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94
Q

Where does COOR direct?

A

3

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95
Q

What is R?

A

An alkyl group

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96
Q

In a carbonyl group, what are the charges on the atoms?

A

The carbon is delta +

The oxygen is delta –

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97
Q

What is a carbonyl group?

A

C double bonded to O

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98
Q

What are aldehydes?

A

C=O group at the end of the carbon chain

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99
Q

How are aldehydes named?

A

start from the aldehyde end, suffix ‘-al’

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100
Q

What are ketones?

A

C=O group somewhere along the carbon chain, never at the end

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101
Q

How are ketones named?

A

C=O carbon should have lowest possible number

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102
Q

Primary alcohols will oxidise to what?

A

aldehydes and carboxylic acids

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103
Q

What is needed to oxidise primary alcohols? What will be seen?

A

An oxidising agent, acidified potassium dichromate K2Cr2O7/H+, needs heat, colour change if there is a reaction to green

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104
Q

Forming Aldehydes , how?

A
  • Distillation
  • Only from primary alcohol
  • Product must be distilled off or it will oxidise further
  • Reaction mixture contains excess alcohol
  • Colour change from orange to green
  • Forms water
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105
Q

Forming Carboxylic Acids , how?

A
  • Reflux
  • From primary alcohol
  • Heated under reflux with excess of [O] – ensures reaction goes to completion
  • Colour change from orange to green
  • Doesn’t form water (unless from primary alcohol, but not if from aldehyde)
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106
Q

What is benzene called when it has a ketone group attached to carbon 1?

A

Phenyl ethanone

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107
Q

What is benzene called when it has an aldehyde group attached to carbon 1?

A

Phenyl methanal

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108
Q

Secondary alcohols will oxidise to what?

A

Ketones

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109
Q

Conditions for oxidation of secondary alcohols

A

an oxidising agent, acidified potassium dichromate

  • Heated under reflux with excess of [O], ensures reaction goes to completion
  • Colour change from orange to green
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110
Q

What do tertiary alcohols oxidise to?

A

Tertiary alcohols don’t oxidise at all

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111
Q

Draw the product of the oxidation of propan-2-ol

A

check notes

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112
Q

Conditions for reduction of aldehydes and ketones?

A

Reduction –
- Needs a reducing agent, NaBH4/H2O (sodium tetrahydridoborate)
- Contains BH4- ions which is a source of H- ions
• Need to warm it using water or ethanol as a solvent

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113
Q

What is a H- ion called?

A

A hydride ion

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114
Q

• Aldehydes and ketones can be reduced to their respective alcohols using what?

A

the reducing agent NaBH4

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115
Q

If reduced CH3CH2CHO, you would get what?

A

CH3CH2CH2OH

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116
Q

Reducing an aldehyde creates a what?

A

primary alcohol

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117
Q

Reducing a ketone creates a what?

A

Secondary alcohol

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118
Q

NaBH4 produces the nucleophile what?

A

H-

hydride ion

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119
Q

Draw the equation for the reduction of CH3CH2CHO

A

check notes

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120
Q

Draw the equation for the reduction of CH3CH2COCH2CH3

A

Check notes

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121
Q

Draw the mechanism for the reduction of CH3CH2CHO

A

check notes

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122
Q

Hydrogen cyanide can be added across the C=O bond of which two functional groups?

A

aldehydes and ketones

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123
Q

What is hydrogen cyanide?

A

HCN

a colourless and extremely poisonous liquid that cannot be safely used in labs

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124
Q

How is HCN used in labs? Why?

A
  • We use sodium cyanide and sulphuric acid to provide the hydrogen cyanide in the reactions
  • This makes it safer to carry out in a lab but it is still very dangerous
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125
Q

Why is the reaction of carbonyl compounds with HCN useful?

A

The reaction is very useful as it is a way of increasing the length of the carbon chain

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126
Q

How to name hydroxy nitriles

A
  • Need to include the carbon on the CN as part of the longest carbon chain

‘nitrile’ is the suffix

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127
Q

Draw the mechanism of the reduction of CH3CH2CH2CH2CHO

A

Check notes

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128
Q

Draw the mechanism of the reduction of CH3COCH3

A

check notes

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129
Q

Draw the equation for the reaction of CH3CH2CHO and HCN

A

Check notes

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130
Q

Draw the mechanism of the reaction of CH3CH2CHO and HCN

A

Check notes

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131
Q

Draw 2-hydroxybutanenitrile

A

check notes

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132
Q

What does tollens agent react with?

A
  • Tollens’ reagent oxidises aldehydes to carboxylic acids but does not oxidise ketones
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133
Q

How to form tollens agent

A
  • Tollens reagent = NaOH(aq) added to AgNO3 until a brown precipitate is formed, then add dilute NH3 until precipitate dissolves to form a colourless solution
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134
Q

What does a positive tollens agent test form

A

A silver mirror

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135
Q

WHat happens to silver ions in tollens test

A
  • Silver ions are reduced:

o Ag+(aq) + e-  Ag(s¬)

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136
Q

Draw the general formula for tollens test

A

cHECK NOTES

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137
Q

WHat is used to test for carbonyl compounds?

A

2-4, dinitrophenylhydrazine (2, 4-DNP or brady’s reagent)

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138
Q

In the carbonyl compound test, how is brady’s agent used?

A

Is dissolved in methanol and sulfuric acid

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139
Q

What colour does brady’s agent turn?

A
  • Reacts with carbonyl groups to form a bright orange precipitate
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140
Q

WHat does brady’s agent react with?

A
  • It only happens for compounds with a C=O bond, so aldehydes and ketones
  • Doesn’t work for COOH or esters
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141
Q

WHat is the orange precipitate from Bradys agent?

A
  • The orange precipitate is derivative of a carbonyl compound and can be used to identify an unknown compound with a carbonyl group
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142
Q

The method for identifying a carbonyl compound using bradys agent

A
  1. You are given an unknown compound with a carbonyl group
  2. Add 2,4-DNP to see an orange precipitate formed that is a derivative of the carbonyl group
  3. Filter off the crystals using a Buchner funnel and water pump
    This is an impure solid you need to have a pure solid, so we need to purify and then recrystallize
  4. Dissolve the crystals in the smallest amount of hot solvent (ethanol) to purify and then put the test-tube in ice water to allow the pure solid to recrystallize
  5. Filter off the crystals again using a Buchner funnel and water pump, this time you have a pure solid
  6. Find the melting point of the pure solid
  7. Compare to a known database of melting points for carbonyl derivatives to identify carbonyl
143
Q

Descibr carboxylic acids

A
  • A homologous series which contain the carboxyl functional group COOH
  • The bonds are in a planar arrangement
  • Include a carbonyl (C=O) group and a hydroxyl (O-H) group
144
Q

How to name carboxylic acids

A
  • Select the longest chain of C atoms containing the COOH group
  • Remove the e and add oic acid after the basic name
  • Number the chain starting from the end nearer the COOH group
  • As in alkanes, prefix with alkyl substituents
  • Side chain positions are based on the C in COOH being 1
145
Q

Why are carboxylic acids soluble in water?

A

Carboxylic acids are polar molecules, electrons are drawn towards the oxygen atoms.
Hydrogen bonds form between the highly polarised hydrogen and oxygen atoms on the molecules.
This makes them soluble in water.

146
Q

As the carbon chain gets longer, carboxylic acids get less soluble, why?

A

this happens as the non-polar carbon chain having a greater effect on the overall polarity.

147
Q

Acid + Metal –>

A

Salt and hydrogen

148
Q

Acid + Metal Oxide –>

A

Salt and water

149
Q

Acid + Alkali –>

A

salt and water

150
Q

Acid + Metal Carbonate –>

A

Salt and water and carbon dioxide

151
Q

2HCl(aq) + 2Na(aq) –>

A

2NaCl(aq) + H2(g)

152
Q

2HCl(aq) + Na2O(s) –>

A

2NaCl(aq) + H2O(l)

153
Q

HCl(aq) + NaOH(aq) –>

A

NaCl(aq) + H2O(l)

154
Q

2HCl(aq) + Na2CO3(s) –>

A

2NaCl(aq) + H2O(l) + CO2(g)

155
Q

Carboxylic acids are ___ acids and take place in ____ reactions with metals and _______ reactions with bases (alkali’s, metal oxides and metal carbonates).

A

weak
redox
neutralisation

156
Q

In some reactions of carboxylic acids what is formed?

A

carboxylate salts

157
Q

What is a carboxylate salt?

A

One of the ions formed in the salt is a carboxylate ion.

158
Q

CH3COOH

A

CH3COO- + H+

159
Q

Ethanoic acid

A

Ethanoate ion + Hydrogen ion

160
Q

Name and give the structure of the 3 first carboxylate ions

A
  • Methanoate ion CHOO-
  • Ethanoate ion CH3COO-
  • Propanoate ion CH3CH¬2COO-
161
Q

Benzene with a carboxylic acid group when ionised becomes what?

A

a Benzoate ion NOT a benzanoate ion

162
Q

, Ethanoic acid + Sodium –>

A

Sodium ethanoate + Hydrogen

163
Q

Ethanoic acid + sodium 

A

sodium ethanoate + hydrogen

164
Q

Ethanol + sodium 

A

sodium ethoxide + hydrogen

165
Q

Sodium ethanoate written structure

A

Na+CH3COO-

166
Q

Sodium ethoxide writtren structure

167
Q

A derivative of carboxylic acid is what?

A

a compound that can be hydrolysed to form the parent carboxylic acid it was formed form.

168
Q

All carboxylic acid derivatives have a common sequence of atoms in their structure known as what?

A

an acyl group.

169
Q

Draw an acyl group

A

CHECK NOTES OR GOOGLE

170
Q

Draw an ester group

A

CHECK NOTES OR GOOGLE

171
Q

Draw an acyl chloride group

A

CHECK NOTES OR GOOGLE

172
Q

Draw an amide group

A

CHECK NOTES OR GOOGLE

173
Q

Draw an acid anhydride group

A

CHECK NOTES OR GOOGLE

174
Q

Draw

Ethanoic acid + methanol 

A

CHeck NOTES OR GOOGLE

175
Q

What is esterfication?

A

This is a reaction where an alcohol and a carboxylic acid react together to form an ester and water. It is a condensation reaction.

176
Q

Reagents and conditions for esterfication?

A

Reagents: catalyst (concentration H2SO4)
Conditions: warm

177
Q

Propanoic acid + ethanol 

A

ethyl propanoate + water

178
Q

What is special about esters?

A

Most esters have a pleasant odour.

Depending on the alcohol and acid used, many different fragrances can be made.

179
Q

What is an acid anhydride?

A

An acid anhydride is formed when water is removed from two molecules of carboxylic acid.

180
Q

2 ethanoic acids form what when water is removed?

A

ethanoic anhydride

181
Q

How can you make an ester using an alcohol?

A

You can form an ester using acid anhydride and an alcohol.

182
Q

Acid anhydride + alcohol 

A

ester + carboxylic acid

183
Q

Ethanoic anhydride + methanol 

A

methyl ethanoate + ethanoic acid

184
Q

Draw ethanoic anhydride + methanol

A

check notes

185
Q

What is hydrolysis?

A

Hydrolysis is the chemical breakdown of a compound in the presence of water or in aqueous solution

186
Q

What are the two types of hydrolysis?

A

There are two types:

  1. Acid hydrolysis
  2. Alkaline hydrolysis
187
Q

Describe the process of acid hydrolysis

A
  • Heated under reflux with dilute aqueous acid
  • Ester broken down by water using the acid as a catalyst
  • Reversible reaction
188
Q

Finish the equation

CH3COOCH3 + H2O HCl

A

CH3COOH + HOCH3

189
Q

Describe the process of alkaline hydrolysis

A
  • Reflux with aqueous alkali (NaOH or KOH)
  • Get a carboxylate salt and alcohol
  • Salt can be used to make soap – saponification
  • Irreversible
190
Q

Finish the equation

CH3COOCH3 + NaOH 

A

CH3COONa + HOCH3

191
Q

Draw an acyl group

A

check notes or google

192
Q

Draw an acyl chloride

A

check notes or google

193
Q

How to name an acyl chloride group

A

The primary suffix name is based on the longest carbon chain name (minus ‘e’) + ‘oyl chloride’ for the COCl
The carbon atoms are numbered from the C with the acyl functional group

194
Q

Draw propanoyl chloride

A

check notes or google

195
Q

Draw benzoyl chloride

A

check notes or google

196
Q

Amines can be classified as primary, secondary, and tertiary, how is this determined?

A

This is determined by the number of carbon alkyl (carbon chain) or aryl (benzene ring) attached to the N atom.

197
Q

Draw a primary amine

A

check notes or google

198
Q

Draw a secondary amine

A

check notes or google

199
Q

Draw a tertiary amine

A

check notes or google

200
Q

How to name amines

A

If the amine (NH2) group is on the end of the carbon chain, the suffix is amine. You add the suffix to the alkyl group.

If the amine (NH2) group is on any other carbon chain except carbon 1, the prefix is amino. You need to give the position of the amine group.

In secondary and tertiary amines that contain the same alkyl group you have a prefix di or tri.

201
Q

In secondary and tertiary amines that contain two or more different alkyl groups
The compound is named as an what?

A

N-substituted derivative

202
Q

Draw N-methl propylamine

A

check notes

203
Q

Draw N-ethyl N-methyl propylamine

A

check notes

204
Q

Amides can be classified as primary, secondary, or tertiary, how is this determined?

A

This is determined by the number of carbon atoms attached to the N atom

205
Q

Draw a primary, tertiary and secondary aminde (using R)

A

check notes

206
Q

Formula of propanamide

A

CH3CH2CONH2

207
Q

Formula of benzamide

208
Q

Formula of N-ethyl butanamide

A

CH3CH2CH2CONHCH2CH3

209
Q

Formula of N, N-dimethyl methanamide

A

CHON(CH3)CH3

210
Q

How are acyl chlorides made?

A

by reacting a carboxylic acid with thionyl chloride (SOCl2)

211
Q

CH3CH2COOH + SOCl2 

A

CH3CH2COCl + SO2 + HCl

212
Q

What would you see if HCl is produced as a product in carbonyl reactions?

A

Steamy white fumes

213
Q

Describe the reaction of acyl chloride and alcohols

A

With Alcohols to Form Esters

This is a vigorous reaction which happens at room temperature.

214
Q

Propanoyl chloride + propan-1-ol 

A

propyl propanoate + HCl

215
Q

Describe the reaction of acyl chloride and phenol

A

With phenol to form an aromatic ester
Esters are formed again during the esterification reaction between phenol and an acyl chloride
Phenol + acyl chloride ester + HCl

216
Q

Phenol + propanoyl chloride

A

phenyl propanoate + hydrogen chloride

217
Q

Describe the reaction of acyl chloride and water

A

With water to form carboxylic acid

This is a vigorous reaction with cold water

218
Q

Propanoyl chloride + water 

A

propanoic acid + hydrogen chloride

219
Q

Describe the reaction of acyl chloride and ammonia

A

With ammonia to form amides

This is a violent reaction at room temperature to form a primary amide

220
Q

Propanoyl chloride + ammonia 

A

propenamide + ammonium chloride

221
Q

Describe the reaction of acyl chloride and amines

A

With amines to form amides

This is a violent reaction at room temperature to form secondary amides

222
Q

Propanoyl chloride + methylamine 

A

N-methylpropanamide + methylammonium chloride

223
Q

Ester 1 ( C6H5COHCOOC(CH3)2 ) is less soluble than mandelic acid ( C6H5CH(OH)COOH ), why?

A

Hydrogen bonds are formed with water, between oxygen and hydrogen, mandelic acid has 2 OH groups (whilst ester 1 has 1), therefore more hydrogen bonds can be formed and so it is more soluble

224
Q

Define acid

A

Acid – In water, an acid releases hydrogen ions (H+) into solution

225
Q

Define base

A

Base – A base is a compound that neutralizes an acid, by accepting a hydrogen ion, to form a salt

226
Q

Define salt

A

Salt – A salt is the product of a reaction in which the H+ ions from the acid are replaced by the metal or ammonium ions

227
Q

HCl + OH-

228
Q

Bases donates _ electrons to the hydrogen ion to form a ___ ___ bond, bases can either have a ___ ___ or a ____ ___.

A

2
dative covalent
lone pair
negative charge

229
Q

How is ammonia a base?

A

Ammonia (NH3) is a base, it accepts a proton to become an ammonium ion.

230
Q

NH3 + HCl 

231
Q

Amines behave as ___ in chemical reactions

232
Q

How do amines behave as bases in chemical reactions?

A

The lone pair of electrons on the nitrogen accepts a proton (a hydrogen ion)
A dative covalent bond is formed, they form an ammonium ion

233
Q

Ethylamine + H+ 

A

Ethylammonium ion

234
Q

CH3CH2NH2 + H+ 

A

CH3CH2NH3+

235
Q

Ethylamine + HCl 

A

Ethylammonium chloride

236
Q

CH3CH2NH2 + HCl 

A

CH3CH2NH3Cl

237
Q

The strength of a base depends on how available the nitrogen’s lone pairs of electrons is, how?

A

A lone pair of electrons are more available if its electron density is higher
The higher density, the more available the lone pair, the stronger the base

238
Q

How strong of a base are aromatic amines? Why?

A

For aromatic amines, the benzene ring pulls the electrons towards the delocalized ring, electron density increases, weak base

239
Q

How strong of a base is ammonia? Why?

A

For ammonia, it doesn’t have an aromatic group to pull the lone pair away or an alkyl group to push the lone pair of electrons forward, base

240
Q

How strong of a base are aliphatic amines? Why?

A

For aliphatic amines (RNH2), the alkyl group pushes the electrons forward, towards the nitrogen, so the electron density increases, and the lone pair is more available, strong base

241
Q

How to form primary aliphatic amines?

A
  1. Ammonia has a lone pair of electrons on the N atom which allows it to act as a nucleophile in a reaction with a haloalkane, the product of this reaction is an ammonium salt
  2. Aqeous alkali (NaOH) is added to generate the amine from the salt
242
Q

Conditions for formation of primary aliphatic amines

A

For this reaction to happen, the conditions needed are:

  • Excess NH3
  • Ethanol as a solvent to prevent substitution of the haloalkane by water to make an alcohol – also called ethanolic ammonia
243
Q

What are the equations for the formation of ethylamine, using 1-chloroethane?

A

CH3CH2Cl + NH3  CH3CH2NH3+Cl-
1-chloroethane + ammonia  ethylammonium chloride

CH3CH2NH3+Cl- + NaOH  CH3CH2NH2 + NaCl + H2O
Ethylammonium chloride + sodium hydroxide  ethylamine + sodium chloride + water

244
Q

How are secondary aliphatic amines formed?

A

The primary amine can react with the haloalkane to make a secondary amine.

245
Q

What are the equations for the formation of di-ethyl amine, using 1-chloroethane and ethylamine?

A

This is a two stage reaction:
1. CH3CH2NH2 + CH3CH2Cl  (CH3CH2)2NH2+Cl-
Ethyl amine + 1-chloroethane  Di-ethyl ammoniumchloride
2. (CH3CH2)2NH2+Cl- + NaOH  (CH3CH2)2NH + NaCl + H2O
Di-ethyl ammoniumchloride + sodium hydroxide  Di-ethyl amine + sodium chloride + water

246
Q

The secondary amine can react with the haloalkane to make a tertiary amine, what is the two step reaction for this? Using 1. (CH3CH2)2NH + CH3CH2Cl

A
  1. (CH3CH2)2NH + CH3CH2Cl  (CH3CH2)3NH+Cl-
    Secondary amine + haloalkane  salt (triethyl ammonium chloride)
  2. (CH3CH2)3NH+Cl- + NaOH  (CH3CH2)3N + H2O + NaCl
    Salt + sodium hydroxide  tertiary amine + water + sodium chloride
247
Q

Draw the mechanism for CH3Cl + CH3CH2NH2

A

CHECK NOTES

248
Q

Phenylamine is made by the reduction of _____

A

nitrobenzene

249
Q

C6H5NO2  _____  C6H5NH2

A

reduction with concentrated HCl and Sn in reflux

250
Q

What is the two step reaction for the formation of phenylamine from nitrobenzene?

A
  1. C6H5NO2 + 7[H]  C6H5NH3+Cl- + 2H2O
    Nitrobenzene + reducing agent  phenyl ammonium chloride (a salt) + water
  2. C6H5NH3+Cl- + NaOH  C6H5NH2 + NaCl + H2O
    phenyl ammonium chloride (a salt) + sodium hydroxide  phenylamine + sodium chloride + water
251
Q

C6H5NO2 + 6[H] 

A

C6H5NH2 + 2H2O

252
Q

What are aminos?

A

Amino are organic compounds containing amine and carboxylic acid functional groups, the side R chain is specific to each amino acid

253
Q

Draw the general displayed formula for an amino acid

A

check notes

254
Q

What is the general written formula for amino acids?

A

RCH(NH2)COOH

255
Q

What are the three types of amino acids and how do they differ?

A 
-	Alpha-amino acids
o	2 carbons
-	Beta-amino acid
o	3 carbons
-	Gamma-amino acids
o	4 carbons
256
Q

Write the formula for glycine and state its proper name

A 
o	HCH(NH2)COOH
o	Proper name is 2-amino ethanoic acid
257
Q

Write the formula for alanine and state its proper name

A 
o	H3CH(NH2)COOH
o	Proper name is 2-amino propanoic acid
258
Q

Write the formula for phenylalanine and state its proper name

A 
o	H5C6H2CCH(NH2)COOH
o	2-amino, 3-phenyl propanoic acid
259
Q

How is an amino acid both a proton donor and acceptor?

A

Amino acids contain an acid group (COOH) and a base group (NH2)
The COOH is a proton donor, and the NH2 is a proton acceptor

260
Q

As amion acids are both proton donors and acceptors, what can they do?

A

This means it can react with itself so the H+ ion from the COOH is donated to the NH2, this forms an ion called a zwitterion

261
Q

What is the charge on a zwitterion?

262
Q

Zwitterions only form at their specific isoelectric point, what is an isoelectric point?

A

pH at which an amino acid exists as a zwitterion

263
Q

What is the isoelectric point affected by?

A

Different R groups

264
Q

Draw the general formula for the formation of zwitterions

A

check notes

265
Q

Alanine’s isoelectric point is ?

266
Q

Draw the formation of alanine’s zwitterion

A

check notes

267
Q

What happens to zwitterions in acidic conditions?

A

a lower pH, it is in acidic conditions, and so H+ ions are added wherever they can be

268
Q

What happens to zwitterions in basic conditions?

A

At pH 7.01, a higher pH, it is in alkaline conditions, and so H+ ions are removed wherever they can be

269
Q

Draw the product of an alanine zwitterion in acidic conditions

A

check notes

270
Q

Draw the product of an alanine zwitterion in basic conditions

A

check notes

271
Q

What is glutamic acid’s isoelectric point?

272
Q

Draw the product of an glutamic acids zwitterion in basic conditions

A

Check notes

273
Q

Draw the product of an glutamic acids zwitterion in acidic conditions

A

Check notes

274
Q

What is lysine’s isoelectric point?

275
Q

Draw the product of an lysine’s zwitterion in acidic conditions

A

Check notes

276
Q

Draw the product of an lysineds zwitterion in basic conditions

A

check notes

277
Q

What’s the equation for alanine (R=CH3) and HCL?

A

H3CCH(NH2)COOH + HCl  CH3CH(N+H3)COOH Cl-

278
Q

What’s the equation for alanine (R=CH3) and NaOH?

A

CH3CH(NH2)COOH + NaOH  CH3CH(NH2)COO-Na+ + H2O

279
Q

What’s the equation for alanine (R=CH3) and methanol?

A

CH3CH(NH2)COOH + CH3OH  CH3CH(NH2)COOCH3 + H2O

280
Q

WHat are stereoisomers?

A

Stereoisomers are species with the same structure but a different arrangement of atoms in space

281
Q

WHich one of E-but-2-ene, and Z-but-2-ene is trans?

A

E-but-2-ene

282
Q

What is superimpose?

A

to place or lie over another and they are the same

283
Q

What does it mean if you can or cannot superimpose two molecules of the same structure?

A

If you can superimpose, they are identical, and cannot form an optical isomer
If you cannot superimpose, they are not identical, and can form an optical isomer

284
Q

When you have 4 different groups attached to a carbon, the molecule shows what?

A

optical isomerism

285
Q

WHat are chiral centres?

A

Carbon atoms with 4 different groups attached are called chiral centers

286
Q

Where does the word chiral come from?

A

Chiral is the Greek word for hands

287
Q

Draw 2-bromobutane and identify the chiral centre

A

check notes

288
Q

Draw 2, 3-dimethyl pentane and identify the chiral centre

A

check notes

289
Q

Draw chloroethanoic acid and identify the chiral centre

A

check notes (there is no chiral centre)

290
Q

How to draw optical isomerism?

A
  • Put chiral carbon in middle and draw groups off of it
  • Use wedges, dashes, and lines as usual
  • Draw it like a tetrahedron
  • Mirror it
291
Q

For a substance that can undergo optical isomerism, the different optical isomers are called what?

A

enantiomers

292
Q

What is a racemic mixture?

A

A racemic mixture is when you have a mixture of a substances enantiomers together.

293
Q

Draw the optical isomerism of CH3 C (OH) Cl

A

check notes

294
Q

If a molecule has 1 chiral center, there will be _ isomers.

295
Q

If a molecule has 2 chiral centers, there will be _ isomers.

296
Q

For every chiral center, there are ___ possible isomers.

297
Q

Draw the isomers of CH3 C (Cl) C (OH) Br

A

CHECK NOTES

298
Q

What is a condensatio reaction?

A

A condensation reaction is when small molecules join to form a larger molecule with a loss of another small molecule – usually H2O or HCl

299
Q

What are some examples of condensatio reactions?

A 
-	H2O
o	Carboxylic acid and alcohol
o	Carboxylic acid and amine
-	HCl
o	Acyl chloride and alcohol
o	Acyl chloride and amine
300
Q

What are the two important condensation polymers made on a large scale?

A

Polyesters and polyamides

301
Q

What are common starting materials for condensation polymers?

A

carboxylic acids

302
Q

What is condensation polymerisation?

A
  • Condensation polymerization is when monomers join together to form a polymer with a loss of another small molecule – usually H2O or HCl
303
Q

How are polyesters formed?

A
  • To make a polyester – monomers are joined together by ester linkages to form a long chain (polymer)
  • There are two ways of linking them
  • From one monomer
    o Must contain a COOH and a OH group
  • From two monomers
    o Must contain two COOH groups and the other contains two OH groups
304
Q

Draw the monomer, polymer (3 units), repeat unity, and overall equation for poly(glygolic acid), HOCH2COOH

A

check notes

305
Q

In condensation polyesters, what do the monomers have to be?

A
  • One monomer has to be a diol (two OH groups)

- One monomer has to be a dicarboxylic acid (two COOH groups)

306
Q

Draw the monomers, polymer, repeat unit, and overall equation for the polyester of Benzene 1, 4 dicarboxylic acid, and ethan 1,2-diol

A

check notes

307
Q

How to form a poly amide

A

To make a polyamide, monomers are joined by amide linkages to form a long chain (polymer)
There are two ways of linking them:
1. From one monomer
a. Must contain a COOH and an NH2 group (also be formed from an acyl chloride and an amine group)
2. From two monomers
a. One contains two COOH groups (or acyl chloride) and the other contains two NH¬2 groups

308
Q

What can undergo condensation reactions as they have both a COOH group and an NH2 group?

A

amino acids

309
Q

Alanine CH3CH(NH2)COOH, monomer, polymer, repeat unit and overall equaiton

A

check notes

310
Q

What do you need for a di monomer polyamide?

A
  • One monomer has to be a diamine (two NH2 groups)

- One monomer has to be a dicarboxylic acid (two COOH groups) or diacyl group

311
Q
  • Condensation polymers can be reversed by hydrolyzing with water, but this is slow, so what is added?
A
  • Condensation polymers can be reversed by hydrolyzing with water
  • It would take a long time with water alone so an acid or base is added
312
Q

Which hydrolysis do polyesters and polyamides prefer?

A
  • Polyesters prefer hydrolysis with a base

- Polyamides prefer hydrolysis with an acid

313
Q

Draw the acid hydrolysis of COC6H6CO OCH2CH2CH2O

A

Check notes

314
Q

Draw the alkali hydrolysis of COC6H6CO OCH2CH2CH2O

A

check notes

315
Q

What is formed in alkaline hydrolysis of polyesters and polyamides?

A

dicarboxyate salt

316
Q

Draw the alkali hydrolysis of COC6H6CO NHC6H6NH

A

Check notes

317
Q

Draw the acid hydrolysis of COC6H6CO NHC6H6NH

A

Check notes

318
Q

Why are reactions that form carbon-carbon bonds important?

A

Reactions that form carbon to carbon bonds are important in chemistry as it is a way of making new compounds with more carbon atoms.

319
Q

What are the two ways of forming nitriles?

A

There are two ways:

  1. From aldehydes and ketones
  2. From haloalkanes
320
Q

Haloalkana and NaCN equation, name type of reaction, and mechanism

A

CHECK NOTES

321
Q

We can use nitriles as intermediates to help us create other organic substances, what can be made and what are the steps used?

A

We can make:
1. Amines
2. Carboxylic acids
We use reduction and hydrolysis reactions to create them.

322
Q

Reduction of nitriles, product, reagents, equation with propananitrile as organic reagent

A
  • Forms amines
  • Reagents are:
    o H2
    o Nickel Catalyst

CH3CH2CN + 2H2 –> Ni –> CH3CH2CH2NH2

323
Q

Hydrolysis of nitriles, product, reagents, equation with propananitrile as organic reagent

A
  • Forms carboxylic acids
  • Reagents are:
    o Heat
    o Dilute aqueous acid (usually HCl)

CH3CH2CN + 2H2O + HCl –> CH3CH2COOH + NH4+Cl-

324
Q

What is oil of wintergreen?

A

Starting reagent for formation of aspirin, IUPAC name of Methyl-2-hydroxybenzoate and check notes for displayed formula

325
Q

How to synthesise aspirin from oil of wintergreen

A

Stage 1 – Preparing the Organic Substances –
- 2-hydroxybenzoic acid would need to be prepared from oil of wintergreen
- Add NaOH
- This would be done under reflux
- After 30 minutes, leave the mixture to cool
- Add hydrochloric acid to neutralise the mixture
Stage 2 – Preparing the Aspirin –
- React the 2-hydroxybenzoic acid (salicylic acid) with ethanoic anhydride
- Add drops of concentrated acid
- Warm the mixture in a water bath until the solid dissolves
- Cool the mixture
- Filter under reduced pressure using the Buchner apparatus
- Slowly add the minimum amount of hot solvent (ethanol) into the impure aspirin
- The sample will dissolve
- Cool the mixture to allow recrystallisation
- Filter under reduced pressure using the Buchner apparatus
- Wash the purified aspirin in cold water (as aspirin is not very soluble in cold water)
- Place a small sample of aspirin in a melting point tube
- Use melting point apparatus – set to 130’C
- Insert sample into melting point apparatus
- Slowly increase the temperature, record the range over when it starts to melt
- Impurities lower the melting point and widen the range

326
Q

Explain how a time of flight spectrometer works

A
  1. injection
  2. vaporization
  3. ionisation chamber
  4. acceleration area
  5. drift region
  6. detector
327
Q

Describe and explain fragments in mass spectrometry

A
  • Excess energy from the ionization process can be transferred to the molecular ion and cause it to split (fragment)
  • When it fragments:
    o It produces a smaller positive ion and radical
    o The smaller positive ion is detected
    o Fragment ions can be broken down further still
328
Q

What does a CH bond do when it absorbs IR?

329
Q

What does a HCH bond do when it absorbs IR?

330
Q

Each bond in IR spectroscopy vibrates with a unique freuquency, which is picked up by what?

A

the spectrometer

331
Q

What does vibration in IR spectroscopy depend on?

A
  • Bond strength
  • Bond length
  • Mass of the bonded atom
332
Q

What are the types of movement found in IR spectroscopy?

A
  • Symmetrical stretching
  • Antisymmetrical stretching
  • Scissoring
  • Rocking
  • Wagging
  • Twisting
333
Q

How to identify alcohols with IR spectorscopy?

A

Primary alcohol = 1050
Secondary alcohol = 1100
Tertiary alcohols = 1150
OH bond = 3200-3640

334
Q

Mr of CH3+

335
Q

Mr of C2H5+

336
Q

Mr of C3H7+

337
Q

Mr of OH+

338
Q

Mr of C4H9+

339
Q

Equation of formation of C6H14+ in hexane mass spectrometry

A

C6H14  C6H14+ + e-

340
Q

Equation of formation of C4H9+ in hexane mass spectrometry

A

C6H14+  C4H9+ + •C2H5

341
Q

How to check for polarity on a molecule?

A

Ask the two questions:
Are the surrounding atoms the same?
Is there a long pair on the central atom?
If the answer is yes to both its polar, if its no to both its polar, if its yes to one and no to the other its non-polar

342
Q

Rf =

A

distance of pigment / solvent front

343
Q

What does the Rf value tell you?

A

Generally if the Rf values are the same, they are the same substance (there are exceptions)

344
Q

Problems with Rf values

A
  • Components can have similar Rf values

- The unknown substance is new and there is no previous chemical to compare it with

345
Q

What is Thin Layer Chromatography (TLC)?

A
  • TLC is very similar to paper chromatography
  • Rather than using chromatography/filter paper the stationary phase is a thin uniform layer (usually silica gel) coated on a piece of plastic, metal, or glass
  • The mobile phase is a liquid which acts as a solvent for the substances you are trying to separate or analyze
346
Q

Steps of TLC

A
  1. A base line is drawn in pencil across the plate and dots of the substances are placed along the line
  2. The plate is placed in a beaker of the solvent such that the level of the solvent is below the line and the solvent moves up the plate
  3. A lid is placed to ensure the atmosphere in the tank is saturated with the often volatile solvent which climbs up the plate causing the mixture to separate
  4. As the solvent front moves up the plate the mixture separates into its different components
  5. The solvent reaches near to the top of the plate and the plate is removed
  6. The solvent front is noted and the solvent is left to evaporate
347
Q

What happens if the substances are colorless in TLC?

A
  • Using UV Light
    o The stationary phase has a chemical added to it which will fluorescence under UV light, the spots need to be circled while under the light
  • Chemically
    o The chromatogram is dried and sprayed with a ninhydrin spray, amino acids react and turn a purple/brown colour
    o You can also use iodine crystals, the chromatogram is dried and placed in an enclosed container with a few iodine crystals, the iodine vapor in the container may either react with the pots on the chromatogram, or simply stick more to the spots than to the rest of the plate, either way the substances you are interested in may show up as brownish spots
348
Q

How does TLC work?

A
  • Silica gel is a form of silicon dioxide (silica)
  • The silicon atoms are joined via oxygen atoms in a giant covalent structure
  • However, at the surface of the silica gel, the silicon atoms are attached to -OH groups
  • The surface of the silica gel is very polar and, because of the -OH groups, can form hydrogen bonds with suitable compounds around it as well as van der waals dispersion forces and dipole-dipole attractions
  • With a solid stationary phase, the pigments are adsorbed onto the surface of the solid particles or fibers
  • The relative forces of attraction between the stationary phase, the mobile phase, and the pigment mean that separation happens
349
Q

Define adsorption

A

Adsorption – is the adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved solid to a surface

350
Q

Which pigments will move how much in TLC?

A 
-	Insoluble pigment
o	Won’t move
-	Strong forces of adsorption
o	More polar so won’t move a lot
-	Weak forces of adsorption
o	Less polar so will move a lot
351
Q

When will the Rf value stay the same?

A
  • Providing the temperature, stationery phase, and solvent stay the same, the Rf value will stay the same on repeats
352
Q

What is Gas liquid chromatography?

A
  • In GLC a long column is often filled with a liquid compound
  • In thinner tubes, the stationary phase is coated to the inside surface of the tube
  • The sample is vaporized and pushed through the column by an inert carrier gas (most often nitrogen or helium)
353
Q

How does gas-liquid chromatography (GLC) work?

A
  • Depending on the solubility of the different compounds in the stationary liquid phase, their boiling points and the temperature of the column, the different compounds will travel through the GLC column at different speeds
  • The length of time a compound remains in the column is known as the retention time
  • It is calculated from the time the sample is injected until the maximum peak heigh for that compound is observed on the display/chromatogram
  • Compare to a known database to find the molecule
354
Q

Explain how to find the proportion of components in GLC?

A

The area under the peaks can be used to calculate the composition of the mixture
Area of triangle = ½ x base x height
Work out individual areas and add them together
Work out percentage of area taken up by each peak

OCR A Level Chemistry (17 decks)

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