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A-Level Chemistry > Carbonyls and Carboxylic Acids > Flashcards

Carbonyls and Carboxylic Acids Flashcards

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1
Q

Where is the C=O situated in an aldehyde?

A

At the end of carbon chain

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2
Q

What is the number of the carbon with the =O in an aldehyde?

A

1

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3
Q

where is the C=O situated in a ketone?

A

Somewhere along the carbon chain

BUT NEVER AT THE END

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4
Q

What number should the C=O have in a ketone?

A

The lowest number

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5
Q

What are primary alcohols oxidised to?

A

Aldehydes

Carboxylic acids

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6
Q

What are secondary alcohols oxidised to?

A

Ketones

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7
Q

How do you oxidise a primary alcohol to a aldehyde?

A

Distillation

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8
Q

How do you oxidise a primary alcohol to a carboxylic acid?

A

Reflux

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9
Q

What are the two products of oxidising an alcohol?

A

Aldehyde/carboxylic acid/ketone + water

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10
Q

What are the conditions needed to oxidise a primary alcohol to an aldehyde?

A

Heat
Potassium dichromate
Excess of primary alcohol

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11
Q

Why do you need an excess of alcohol when oxidising a primary alcohol to a aldehyde?

A

So doesn’t further oxidise to a carboxylic acid

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12
Q

What colour does potassium dichromate turn when an alcohol has been oxidised?

A

Orange —-> green

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13
Q

What are the conditions needed to oxidise a primary alcohol to an carboxylic acid?

A

Heat
Excess [o] (potassium dichromate)
Primary alcohol

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14
Q

Why do you need an excess of [o] when oxidising a primary alcohol to a carboxylic acid?

A

To ensure the reaction is complete

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15
Q

What will not be produced if a carboxylic acid is produced via further oxidation?

A

Water

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16
Q

How can secondary alcohols be oxidised?

A

Distillation or reflux

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17
Q

What are the conditions needed for oxidising a secondary alcohol?

A

Heat
Excess [o]
Secondary alcohol

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18
Q

What can aldehydes be reduced to?

A

Primary alcohol

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19
Q

What is reducing agent is to reduce a ketone/aldehyde?

A

NaBH4/H2O

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20
Q

What is the name of NaBH4?

A

Sodium tetrahydrioborate

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21
Q

Why is the NaBH4 important?

A

Contains BH4 - which is the source of H- (hydride ion)

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22
Q

What are ketones and aldehydes reduced to?

A

Respective ion

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23
Q

What are the conditions needed for the reduction of ketones and aldehydes?

A

Warm it using ethanol or water as a solvent

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24
Q

What is the difference between an oxidising and reducing reaction?

A

Oxidising - [O]

Reducing =[H]

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25
Q

What are the products of reducing a ketone and aldehyde?

A

Just the alcohol

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26
Q

What happens in a carbonyl reaction?

A

Add hydrogen cyanide across C=O of aldehydes + ketones

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27
Q

Describe hydrogen cyanide

A

Colourless liquid

Extremely poisonous

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28
Q

What is the problem with HCN?

A

Cannot be safely used

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29
Q

What can be used instead to combat the problems of HCN?

A

Sodium cyanide for cyanide ion
Use H2SO4 for hydrogen ion
STILL VERY DANGEROUS

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30
Q

Why is using HCN very useful?

A

Increases the length of the carbon chain

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31
Q

What does the reaction of carbonyls with HCN produce?

A

Hydroxy nitrile

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32
Q

How do you name a hydroxy nitrile?

A

Need to include C on CN as part of longest chain
OH must be smallest number
eg. 2-hydroxybutanenitrile

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33
Q

What does tollens reagent do?

A

Oxidise aldehydes to carboxylic acids

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34
Q

What does tollens not oxidise?

A

Ketones

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35
Q

Describe the process of using tollens reagent

A 
NaOH(aq) added to AgNO3 
Until brown precipitate forms
Then add dilute NH3 until ppt dissolves to form colourless solution
Then add chemical and heat
Positive result = silver mirror
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36
Q

What is the positive result for tollens reagent?

A

Silver mirror

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37
Q

What is the equation for a positive result using tollens reagent?

A

Ag(aq) + e- —-> Ag(s)

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38
Q

What does 2,4 DNP react with?

A

Carbonyls

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39
Q

What is important about 2,4 DNP?

A

It only reacts with carbonyl with a C=O bond

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40
Q

What does 2,4 DNP not react with then if it only reacts with carbonyls with a C=O bond?

A

Carboxylic acids

Esters

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41
Q

Which carbonyls does 2,4 DNP react with?

A

Aldehydes

Ketones

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42
Q

What does 2,4 DNP form when it reacts with carbonyls?

A

Orange precipitate

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43
Q

What is 2,4 DNP dissolved in?

A

Methanol + H2SO4

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44
Q

What is orange precipitate produced in carbonyl reaction with 2,4 DNP?

A

Derivative of the carbonyl

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45
Q

What can 2,4 DNP used to do?

A

Identify unknown compounds with a carbonyl group

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46
Q

What is the method for identifying carbonyls?

A

Add 2,4 DNP = orange ppt = derivative
Filter off crystals using Buchner funnel + water pump
Purify = dissolve crystals in smallest amount of hot solvent (ethanol)
Then put test tubes in ice water to recrystalise pure solid
Filter off crystals using a Buchner funnel + water pump
Find melting point of pure solids
Compare to known database of melting points for carbonyl derivatives

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47
Q

Why are the first set of crystals dissolved in carbonyl identification method?

A

Because they were impure and need a pure solid to identify melting point

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48
Q

What are the bonds arranged in a carboxylic acid?

A

Planar

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49
Q

How do you name a carboxylic acid?

A

Select longest chain of C atoms (containing COOH)

Number chain starting from end closest COOH

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50
Q

What is the name of a carboxylic acid with a 4 carbon chain?

A

Butanoic acid

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51
Q

Why is a carboxylic acid polar?

A

As electrons drawn towards O

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52
Q

Why are carboxylic acids soluble in water?

A

H bonds form between H + O atoms on molecule

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53
Q

Why does as the chain increases the solubility of carboxylic acid decreases?

A

Due to non-polar carbon chain having a greater effect on polarity overall

54
Q

What type of acid is a carboxylic acid?

A

Weak acid

55
Q

What is the ion formed called in reactions with carboxylic acids?

A

Carboxylate ion

56
Q

What is the formula of a methanoate ion?

A

HCOO-

57
Q

What is the formula of a ethanoate ion?

A

CH3COO-

58
Q

What is the formula of a propanoate ion?

A

CH3CH2COO-

59
Q

What ion is form when a carboxylate ion joins with a benzene ring?

A

Benzoate ion

60
Q

Why are the reactions with carboxylic acids redox reactions?

A

Because the hydrogen on the carboxylic acid goes from +1 to 0

61
Q

What are the products of ethanoic acid + sodium?

A

Sodium ethanoate + hydrogen

62
Q

What are the products of methanoic acid + sodium hydroxide?

A

Sodium methanoate + water

63
Q

What are the products of propanoic acid + calcium carbonate?

A

Calcium propanoate + water + carbon dioxide

64
Q

What is the problem with adding Na to acids?

A

Dangerous

Sodium ethanoate = not nice

65
Q

But what else can Na react with?

A

Alcohols

66
Q

What are the products of ethanol + sodium?

A

Sodium ethoxide + hydrogen

67
Q

What is a carboxylic acid derivative?

A

A compound that can be hydrolysed to form the patent carboxylic acid it was formed from

68
Q

What do all CA derivatives have in common?

A

A common sequence of atoms in their structure known as an acyl group

69
Q

What are the CA derivatives?

A

Ester
Acyl chloride
Acid anhydride
Amide

70
Q

What is esterification?

A

Carboxylic acid + alcohol —-> ester + water

71
Q

What type of reaction is esterification?

A

Condensation reaction

72
Q

What are the conditions needed for esterification?

A

H2SO4 catalyst

WARM conditions

73
Q

Why are esters useful?

A

Make pleasant odours

74
Q

What are esters used for?

A

Perfumes

75
Q

What are products of propanoic acid + ethanol?

A

Ethyl propanoate + water

76
Q

How is an acid anhydride formed?

A

When H2O is removed from 2 molecules of carboxylic acid

77
Q

How do you name an acid anhydride?

A

Acid + anhydride

eg. Ethanoic anhydride

78
Q

What is another way to form an ester?

A

Acid anhydride + alcohol —-> ester + carboxylic acid

79
Q

What are the products of propanoic anhydride + ethanol?

A

Ethyl propanoate + propanoic acid

80
Q

What is hydrolysis?

A

The chemical breakdown of a compound in the presence of water or in an aqueous solution

81
Q

What are the two types of hydrolysis?

A

Acid hydrolysis

Alkaline hydrolysis

82
Q

What are the conditions needed for acid hydrolysis?

A

Heated under reflux with dilute aqueous acid
Acid catalyst (HCl (aq))
Reversible reaction

83
Q

What is the general equation for acid hydrolysis?

A

Ester + water —-> carboxylic acid + alcohol

Reversible reaction

84
Q

What are the conditions needed for alkaline hydrolysis?

A

Reflux with aqueous alkali (NaOH/KOH)

Irreversible reaction

85
Q

What is the general equation for alkaline hydrolysis?

A

Ester + NaOH —-> carboxylate salt + alcohol

86
Q

What can the salt produced in alkaline hydrolysis be used to make?

A

Soap

87
Q

What products are produced in the acid hydrolysis of methyl ethanoate + water?

A

Ethanoic acid + methanol

88
Q

What products are produced in the alkaline hydrolysis of methyl ethanoate + NaOH?

A

Sodium ethanoate + ethanol

89
Q

How do you name acyl chlorides?

A

Add “oyl chloride” for COCl part

No. C atoms from C with acyl

90
Q

What is called when a benzene ring is attached to COCl?

A

Benzoyl chloride

91
Q

What is the name of CH3CH2COCl?

A

Propanoyl chloride

92
Q

What can amines be classed as?

A

Primary, secondary or tertiary

93
Q

If the NH2 is on the end carbon what is the suffix?

A

Amine

94
Q

What is the name of CH3NH2?

A

Methylamine

95
Q

If the NH2 is on any other carbon than carbon one what is the prefix?

A

Amino

96
Q

If the prefix is amino what must you do when naming it?

A

You must number the carbon the amino appears on

97
Q

What is the name of CH3CHNH2CH3?

A

2-amino propane

98
Q

In secondary and tertiary amines how are they named different?

A

The suffix is always amine
Name alphabetically
Must use “N” to symbolise it is attached to the N
eg. N,N - dimethylamine

99
Q

What can amides be classes as?

A

Primary, secondary or tertiary

100
Q

What do amides contain?

A

Double bond O

101
Q

How do you name amides?

A

Suffix = always amide

102
Q

What must you do when naming a secondary or tertiary amide?

A

Include “N” in the name

103
Q

What is the name of CH3CH2CONH2?

A

Propanamide

104
Q

What is it called when a benzene ring is joined to a amide group?

A

Benzamide

105
Q

What is the name of CH3CH2CH2CONHCH2CH3?

A

N- ethyl butanamide

106
Q

How is an acyl chloride made?

A

By reacting carboxylic acid + thionyl chloride

107
Q

What is the formula of thionyl chloride?

A

SOCl2

108
Q

What is formed when you reaction propanoic acid + thionyl chloride?

A

Propanoyl chloride + sulphur dioxide + HCl

109
Q

What is the general formula for synthesis of an acyl chloride?

A

Carboxylic acid + thionyl chloride —-> acyl chloride + SO2 + HCl

110
Q

What will be produced in the synthesis of an acyl chloride?

A

Steamy white fumes

111
Q

When you react an acyl chloride + alcohol what will the products be?

A

Ester + HCl

112
Q

Describe the reaction of an acyl chloride + alcohol?

A

Vigorous reaction at R.T

113
Q

What products are formed when propanoyl chloride + propanol?

A

Propyl propanoate + HCl

114
Q

What will be produced in the reaction of acyl chloride + alcohol?

A

Steamy white fumes

115
Q

When you react an acyl chloride + phenol what will the products be?

A

Aromatic ester + HCl

116
Q

What is different about the reaction between phenol + acyl chloride?

A

Reversible reaction

117
Q

What will be produced in the reaction of acyl chloride + phenol?

A

Steamy white fumes

118
Q

When you react an acyl chloride + water what will the products be?

A

Carboxylic acid + HCl

119
Q

Describe the reaction of acyl chloride + water

A

Vigorous reaction with cold water

120
Q

What products are formed when propanoyl chloride + H2O?

A

Propanoic acid + HCl

121
Q

What will be produced in the reaction of acyl chloride + water?

A

Steamy white fumes

122
Q

When you react an acyl chloride + ammonia what will the products be?

A

Amide + ammonium chloride

123
Q

Describe the reaction of acyl chloride + ammonia

A

Violent reaction at R.T to form a primary amide

124
Q

What products are formed when propanoyl + NH3?

A

Propanamide + NH3Cl

125
Q

When you react an acyl chloride + amine what will the products be?

A

Amide + alkyl (eg. methyl)ammonium chloride

126
Q

Describe the reaction of acyl chloride + amine

A

Violent reaction at R.T to form a secondary amide

127
Q

What products are formed when propanoyl + methylamine?

A

N- methyl propanamide + methyl ammonium chloride

128
Q

Which acyl chloride reaction produces a primary amide?

A

Acyl chloride + NH3

129
Q

Which acyl chloride reaction produces a secondary amide?

A

Acyl chloride + amine

130
Q

Which acyl reactions don’t produce steamy white fumes and why?

A

NH3
Amine
Because HCl isn’t produced

A-Level Chemistry (26 decks)

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