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Chemistry A level > 3.9 Carboxylic acids and derivatives > Flashcards

3.9 Carboxylic acids and derivatives Flashcards

1
Q

What is a carboxylic acid functional group

A

-COOH
C=O and C-OH

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2
Q

How do you name carboxylic acids

A

-oic acid

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3
Q

Are carboxylic acids soluble in water?
Why?
What influences their solublility

A

Yes
Acid group can form hydrogen bonds with water molecules

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4
Q

What are the imfs in carboxylic acids

A

Hydrogen bonds - very strong

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5
Q

What are esters (what are they formed from)
Func group
General formula

A

Formed from carboxylic acids and alcohols
RCOOR’ (C=O, C-O-C)

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6
Q

Write an equation for the reaction of ethanoic acid with propan-1-ol

A

CH3COOH + CH3CH2CH2OH –> CH3COOHCH2CH2CH3 + H2O

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7
Q

How do you name esters

A

Start with the group that has replaced the hydrogen, then the acid part eg propyl (from alcohol) ethanoate (from carboxylic acid)

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8
Q

What characteristic physical properties do esters have

A

Volatile
Pleasant fruit smells eg pear drops

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9
Q

What are some uses of esters

A

Flavourings, perfumes, solvents, plasticisers

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10
Q

Write an equation for the equilibrium formed by a ethanoic acid in solution

A

CH3COOH(aq) <–> CH3COO-(aq) + H+(aq)

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11
Q

How could you distinguish carboxylic acids from other -OH containing compounds

A

Add NaHCO3, acids will produce sodium salt, water and carbon dioxide

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12
Q

Write an equation for the reaction of ethanoic acid with NaOH

A

CH3COOH + NaOH –> H2O + CH3COO-Na+

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13
Q

What catalyst is needed for the formation of esters from alcohols and carboxylic acids

A

Concentrated strong acid eg H2SO4

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14
Q

What catalyst is needed for the hydrolysis of esters

A

Dilute strong acid eg H2SO4

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15
Q

Which alcohol forms the esters that make up animal and vegetable oils

A

Glycerol / propane-1,2,3-triol

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16
Q

What are the products of hydrolysing fats and oils

A

Glycerol and sodium salts of the acids that make up the ester

17
Q

What are the uses of glycerol and sodium salts

A

Soaps and cleaning products

18
Q

Common uses of glycerol

A

Solvent in many medicines
Solvent in food industry eg food colourings
Plasticising

19
Q

How do you make biodiesel (general equation and conditions)

A

NaOH catalyst
60 degrees C
Lipids + 3CH3OH –> 3 methyl esters + glycerol

20
Q

What does transesterification meam

A

Converting one type of ester to another

21
Q

What is a problem with producing biodiesel

A

Crops that could be used to make food are being used to make fuel

22
Q

What are carboxylic acid derivatives

A

Molecules that have the acyl group as part of their structure, formed from carboxylic acids

23
Q

Name 2 acid derivatives and give their functional groups

A

Acyl chlorides: RCOCl
Acid anyhdrides: RCOOCR / (RCO)2O

24
Q

Are acyl chlorides or acid anhydrides more reactive

A

Acyl chlorides

25
Q

What is the name of the mechanism by which acyl chlorides and acid anhydrides acylate nucleophiles

A

Addition-elimination

26
Q

Draw the mechanism for the reaction of ethanoyl chloride and ammonia

A

Google

27
Q

Draw the mechanism for the reaction of ethanoyl chloride and methylamine

A

Google

28
Q

Draw the mechanism for the reaction of ethanoyl chloride and ethanol

A

Google

29
Q

Draw the mechanism for the reaction of ethanoyl chloride and water

A

Google

30
Q

What is a commercially important acylation reaction

A

The manufacture of aspirin

31
Q

What are the advantages of using ethanoic anhydride as an acylating agent over ethanoyl chloride

A

It is cheaper, less corrosive and does not react as readily with water
It is safer, as ethanoic acid is produced, rather than HCl which is corrosive

32
Q

What would you observe in a mtp determination if the samples was not pure

A

Samples melts over a large range (more than 3 degrees C)
Sample’s melting point is below the accepted value due to impurities disrupting structure

33
Q

What conditions are needed to form methyl esters from an acid anhydride or acyl chloride

A

React with methanol and heat gently under reflux

34
Q

When purifying by recrystallisation, why is the minimum volume of hot solvent used

A

So that a saturated solution is created, so that as many crystals will fall out of solution as possible when it is cooled

35
Q

Why is the solution filtered hot when purifying by recrystallisation

A

To remove insoluble impurities and ensure that the crystals do not form in the filter paper

36
Q

Why is the solution cooled in an ice bath when purifying by recrystallisation

A

To ensure that as many crystals as possible fall out of solution - higher yield

37
Q

Why are the crystals washed with cold water when purifying by recrystallisation

A

To remove soluble impurities

38
Q

How would you separate the crystals from the reaction mixture when purifying by recrystallisation

A

Filter under reduced pressure using a Buchner funnel

Chemistry A level (36 decks)

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