3.3.9 Carboxylic Acids and Derivatives Flashcards
1
Q
Draw the functional group of esters
A
2
Q
State the prefix / suffix of esters
A
-yl –oate
3
Q
Draw the functional group of acyl chlorides
A
4
Q
State the suffix of acyl chlorides
A
-oyl chloride
5
Q
Draw the functional group of amides
A
6
Q
State the suffix of amides
A
-amide
7
Q
Draw the functional group of acid anhydrides
A
8
Q
State the suffix of acid anhydrides
A
-oic anhydride
9
Q
Weak acids partially dissociate into ______ ion and ___ ion
A
Partially dissociate into carboxylate ion and H+ ion
10
Q
Write an equation to represent the dissociation of weak acids. Draw the displayed formula of the molecules.
A
11
Q
When carboxylic acids react with carbonates, what gas is formed?
A
CO2
12
Q
When carboxylic acids react with alcohols, what do they form?
A
Esters
13
Q
What functional group do esters have?
A
-COO-
14
Q
Describe how esters are made
A
- Esterification
- Made by heating carboxylic acid with alcohol in presence of strong acid catalyst
15
Q
Give an example of an acid catalyst that can be used in esterification
A
Concentrated sulfuric acid
16
Q
Write an equation for when alcohols react with carboxylic acids. Draw the molecules in displayed formula.
A
17
Q
Write an equation for when ethanoic acid reacts with ethanol. Draw the molecules in displayed formula. State the name of the ester.
A
ethyl ethanoate
1st part = alcohol
2nd part = carboxylic acid
18
Q
Name 4 uses of esters
A
- Perfumes
- Have sweet swell
- Food flavourings
- Flavour drinks and sweets
- Solvents
- Glues, drinking inks
- Plasticisers
19
Q
Explain why esters make good solvents
A
- Are polar liquids so lots of polar organic compounds will dissolve in them
- Got low boiling points = evaporate easily from mixtures
20
Q
Explain how esters act as plasticisers
A
Added to plastics during polymerisation to make plastic more flexible
21
Q
What happens to plastics over time after they have undergone polymerisation?
A
Over time, plasticiser molecules escape and plastic becomes brittle and stiff
22
Q
How do you convert an ester into an alcohol?
A
Hydrolysis
23
Q
Why is water not used when hydrolysing esters to alcohols? Name what substances you can use instead.
A
Using water to split up a substance is very slow, so an acid or alkali is often used to speed it up
24
Q
Esters are Hydrolysed to form Alcohols
Name 2 types of hydrolysis that can be used
A
- Acid Hydrolysis
- Base Hydrolysis
25
Describe how you can use acid hydrolysis to form an alcohol
* Reflux ester with dilute acid e.g. hydrochloric or sulfuric
* Splits ester in acid and alcohol
26
Describe how you can use base hydrolysis to form an alcohol
* Refluxing ester with dilute alkali e.g. sodium hydroxide
* Get carboxylate ion and an alcohol
27
Write an equation to show ethyl ethanoate undergoing acid hydrolysis. Draw molecules in displayed formula.
28
Write an equation to show ethyl ethanoate undergoing base hydrolysis. Draw molecules in displayed formula.
29
What are fatty acids essentially?
long chain carboxylic acids
30
What is formed when fatty acids combine with glycerol?
Esters = fats and oils
31
Fatty acids can be ______ or \_\_\_\_\_\_\_
Fatty acids can be _saturated (no double bonds)_ or _unsaturated (C=C double bonds)_
32
Most of fat or oil is made from _____ \_\_\_\_\_ chains
fatty acid
They give them many of their properties
33
What type of hydrocarbon chains do animal fats have?
Have mainly saturated hydrocarbon chains
34
What type of hydrocarbon chains do vegetable oils have?
Have unsaturated hydrocarbon chains
35
Explain why animal fats are solid at room temperature
* Saturated hydrocarbon chains fit neatly together = increase van der Waals forces between them
* Means you need higher temperature to melt them
36
Explain why vegetable oils are liquid at room temperature
* Double bond means mean chains are bent & don't pack together well = ↓ van der Waals forces
* Easier to melt
37
Draw an ester of glycerol and fatty acids
38
Describe how you can hydrolyse vegetable oils and animal fats and what this produces
* By heating ester with sodium hydroxide
* Produces glycerol, fatty acids and soap = sodium salt
39
Why are vegetable oils converted into biodiesel, before they can be used as vehicle fuels?
Vegetable oils can't be burned directly in engines
40
Describe how vegetable oils are converted into biodiesel
* Involves reacting them methanol, using potassium hydroxide as a catalyst
* Get mixture of methyl esters of fatty acids
* = biodiesel
41
Write an equation representing vegetable oils being converted into biodiesel. Draw molecules in displayed formula.
42
State the functional groups of acyl chlorides
COCl
43
Name this molecule
44
Name this molecule
45
Name 4 substances acyl chlorides react with
* Water
* Alcohols
* Ammonia
* Primary amines
46
Describe how acyl chlorides react with water. Include its product.
A vigorous reaction with cold water, producing a carboxylic acid
47
Write an equation representing how ethanoyl chloride reacts with water. Draw the molecules in displayed formula.
48
Describe how acyl chlorides react with alcohols. Include its product.
A vigorous reaction at room temperature, producing an ester
49
Write an equation representing how ethanoyl chloride reacts with methanol. Draw the molecules in displayed formula.
50
Describe how acyl chlorides react with ammonia. Include its product.
A violent reaction at room temperature, producing an amide
51
Write an equation showing how ethanoyl chloride reacts with ammonia. Draw the molecules in displayed formula.
52
Describe how acyl chlorides react with primary amines. Include its product.
A violent reaction at room temperature, producing an N-substituted amide
53
Write an equation to show how ethanoyl chloride reacts with methylamine. Draw the molecules in displayed formula.
54
What happens in each reaction with acyl chlorides?
Cl is substituted by oxygen or nitrogen group & misty fumes of hydrogen chloride are given off
55
Acyl chlorides and ___ \_\_\_\_\_\_\_ react in the same way
Acid Anhydrides
56
What are acid anhydrides made from?
2 identical carboxylic acid molecules
57
State how you would name an acid anhydride if you know the name of the carboxylic acid
take away 'acid' and add 'anhydride'
58
Write an equation representing 2 ethanoic acids combining to form an acid anhydride. Draw the molecules in displayed formula.
59
Describe how reactions of acyl chlorides differ from reactions of acid anhydrides
Almost the same as those of acyl chlorides but reactions a less vigorous & get carboxylic acid formed instead of HCl
60
Write an equation representing how ethanoic anhydride reacts with methanol
61
What mechanism reaction are acyl chloride reactions?
Nucleophilic Addition-Elimination
62
Explain why acyl chlorides are easily attacked by nucleophiles
Both chlorine and oxygen draw electrons towards themselves, so carbon has slight positive charge
63
Draw the mechanism for nucleophilic addition-elimination reaction between ethanoyl chloride and methanol
64
Draw the nucleophile for water
H2O:
65
Draw the nucleophile for ammonia
:NH3
66
Draw the mechanism for when methyamine reacts with ethanoyl chloride
67
Aspirin is an \_\_\_
ester
68
Describe how aspirin is made
Made by reacting salicylic acid with ethanoic anhydride or ethanoyl chloride
69
Why is ethanoic anhydride used in industry to make aspirin instead of ethanoyl chloride?
* Cheaper than ethanoyl chloride
* Safer to use than ethanoyl chloride as it's less corrosive, reacts more slowly with water, and doesn't produce dangerous hydrogen chloride fumes
70
**Purifying Organic Compounds**
State when you can use separation
If product is insoluble in water, can use separation to remove any impurities that do dissolve in water
71
**Purifying Organic Compounds**
Describe a method for separation
1. Once reaction to form product is completed, pour the mixture into separating funnel & add water
2. Shake funnel and then allow it to settle
* Organic layer and aqueous layer (which contains any water soluble impurities) are immiscible (they don't mix) so separate out into 2 distinct layers
3. Can open tap and run each layer off into a separate container
72
**Purifying Organic Compounds**
State a method you can use to separate your product and impurities if they are both soluble in water
Solvent extraction
| (similar separation method)
73
**Purifying Organic Compounds**
Describe a solvent extraction method
1. Take organic solvent in which the product is more soluble in than it is in water
2. Add it to impure product solution & shake well
3. Product will dissolve into organic solvent = leaving impurities dissolved in water
4. Solvent containing product can be run off using separating funnel
74
If you use separation to purify a product, why does the product have to be dried?
∵ organic layer will end up containing trace amounts of water
75
Describe how you can remove water from a purified product by drying it
1. Add anhydrous salt (e.g. magnesium sulfate or calcium chloride)
2. When you first add salt to organic layer = clumps together
* Keep adding drying agent until it disperses evenly when you swirl the flask
3. Filter mixture to remove solid drying agent
* Pop a piece of filter paper into a funnel that's in a flask and pour mixture into filter paper
76
When removing water from a purified product by drying it, why is anhydrous salt used?
Salt is used as drying agent = binds to any water present to become hydrated
77
Describe a way, other than by drying it, to remove impurities from a product of a reaction.
* Can remove some of these by washing the product
* (Adding another liquid and shaking)
* ∵ product can be contaminated with leftover reagents or unwanted side products
78
Describe how you could remove acid from an impure product in solution.
* Aqueous sodium hydrogencarbonate can be added to impure product in solution to remove acid from it
* Acid reacts with sodium hydrogencarbonate to give CO2 gas and organic product can be removed using separating funnel
79
How can volatile liquids can be purified?
By distillation
80
Describe how distillation works
* Works by gently heating a mixture in distillation apparatus
* Substances will evaporate out of mixture in order of increasing boiling point
81
Describe how you can purify volatile liquids by distillation
1. Connect a condenser to round bottomed flask containing your impure product in solution
2. Place thermometer in neck of flask so bulb sits next to entrance to condenser
* Temperature on thermometer will show boiling point of substance that's evaporating at any given time
3. Heat impure product
4. When product you want to collect boils, place a flask at open end of condenser to collect your pure product
82
When purifying volatile liquids by distillation, why should you use an electric heater?
Many organic chemicals are flammable
83
State how organic solids can be purified
Recrystallisation
84
Describe how organic solids can be purified via recrystallisation
1. Dissolve impure solid in minimum hot solvent
* Don't add too much solvent = want saturated solution of impure product
2. Filter hot solution through heated funnel
* To remove any insoluble impurities
3. Leave solution to cool down slowly
* Crystals of product will form as it cools
4. Filter mixture under reduced pressure
* To remove liquid containing soluble impurities from crystals
5. Wash crystal with ice-cold solvent
* To remove any soluble impurities from their surface
6. Leave your purified crystals to dry
85
Describe how you could remove liquid containing soluble impurities from crystals by filtering a mixture under reduced pressure
Pour mixture into filter paper lined Büchner funnel (flat bottomed funnel with holes in base) that's sitting in side-arm flask attached to vacuum line
86
**Recrystallisation**
Why does crystals of product form as the solution cools?
* As solution cools, solubility of product falls
* Reaches point where it can't stay in solution = forms pure crystals
87
What are good indicators of purity?
Melting and boiling points
88
Pure substances have ______ melting and boiling points
specific
89
What happens to substance's melting and boiling point when it's impure?
Melting point is lowered and boiling point is raised
90
What happens substance's melting and boiling point when it's very impure?
Melting and boiling will occur across a wide range of temperatures
91
What type of apparatus can you use to accurately determine the melting point of an organic solid?
Melting point apparatus
92
Describe how you can use melting point apparatus to accurately determine the melting point of an organic solid
1. Pack small sample of solid into glass capillary tube and place it inside the heating element
2. Increase the temperature until sample turns from solid to liquid
3. Measure a melting range (range of temperatures from where solid begins to melt to where it has melted completely)
4. Can look up the melting point of substance in data books and compare it to your measurements
5. Impurities in sample will lower the melting point and broaden the melting range
93
Pure substances melt \_\_\_\_\_
sharply
94
Give an observation that occurs during esterification
Sweet smell/oily layer
95
Recrystallisation
Why shouldn't you add too much solvent when dissolving the solid?
Want saturated solution of impure product
96
Recrystallisation
Why do you filter hot solution through a heated funnel?
To remove any insoluble impurities
97
Recrystallisation
Why do you leave the solution to cool down slowly?
More crystals of product will form as it cools/decreases solubility of solid
98
Recrystallisation
Why do you filter the mixture under reduced pressure?
To remove liquid containing soluble impurities from crystals
99
Recrystallisation
Why do you wash the crystal with ice-cold solvent?
To remove any soluble impurities from their surface
