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AQA - A level Chemistry > Carboxylic acids and esters > Flashcards

Carboxylic acids and esters Flashcards

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1
Q

Solubility of carboxylic acids?

A
  • COOH group = soluble due to H bonding
  • hydrocarbon chain = non-polar
  • short chain carboxylic acids = soluble
  • long chain carboxylic acids = insoluble
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2
Q

Why do carboxylic acids act as acids?

A

They donate a proton

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3
Q

Carboxylic acids are weak acids. What does this mean?

A

Equilibrium lies to the left

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4
Q

How is an ester formed?

A

Carboxylic acid + alcohol

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5
Q

What catalyst is used in esterification?

A

H2SO4

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6
Q

3 facts about esterification reactions.

A
  • Water is always a product
  • Reversible reaction
  • catalyst is H2SO4
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7
Q

What is the name of the reaction that allows esters to be turned back into carboxylic acids and alcohols?

A

Hydrolysis reaction

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8
Q

What is meant by hydrolysis?

A

Breaking of a bond using water

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9
Q

What are the two types of hydrolysis?

A
  • Acid catalysed hydrolysis
  • Base catalysed hydrolysis
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10
Q

Acid hydrolysis of propylethanoate?

A

propylethanoate + water —> propan-1-ol + ethanoic acid
catalyst = H2SO4

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11
Q

What is an example of an acid catalyst?

A

HCl

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12
Q

What is an example of base catalyst?

A

Warm, aqueous NaOH

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13
Q

In which type of hydrolysis results in high yield of product?

A

Base hydrolysis

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14
Q

Base hydrolysis of propylethanoate?

A

propylethanoate + water —> propan-1-ol + ethanoic acid
ethnic acid + NaOH —> Sodium ethanoate
catalyst - NaOH

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15
Q

What is the IUPAC name for glycerol?

A

propane-1,2,3-triol

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16
Q

What is biodiesel?

A

Mixture of methyl esters

17
Q

Uses for esters?

A
  • Plasticisers
  • Perfumes
  • Flavourings
  • Solvents for many reactions
18
Q

What is an example of an acyl chloride?

A

ethanoyl chloride CH3COCl

19
Q

What is an example of an acid anhydride?

A

ethanoic anhydride

20
Q

Name CH3CH3COCl

A

propanoyl chloride

21
Q

Name CH3CH2CH2CH2CH2COCl

A

hexanoyl chloride

22
Q

What functional group is formed when an acyl chloride reacts with water?

A

Carboxylic acid

23
Q

What functional group is formed when an acyl chloride reacts with an alcohol?

A

Ester

24
Q

What functional group is formed when an acyl chloride reacts with ammonia?

A

Amide

25
Q

What functional group is formed when an acyl chloride reacts with an amine?

A

N-substituted amide

26
Q

suggest why aqueous ethanol is a suitable solvent when heating the coconut oil with KOH

give a safety precaution when heating the mixture. justify choice

A

reason
- allows to dissolve both oil and KOH

safety precaution
- use water bath for heating mixture

justification
- prevents risk of fire

27
Q

why are acylation with acid anhydrides more commonly used than acyl chlorides in industry

A
  • cheaper
  • less corrosive
  • don’t react with water
  • safer side product = carboxylic acid
  • acyl chloride produces HCl vapours
28
Q

describe briefly how you would determine melting point of aspirin

A
  • Sample in capillary / melting point tube
  • Heat in melting point apparatus
29
Q

write equation for reaction between butendioic acid and NaOH

A

2NaOH + HO2CCHCHCO2H → NaO2CCHCHCO2Na + 2H2O

30
Q

suggest why only one of two E/Z isomers of butendioic acid can readily form acid anhydride when warmed

A
  • both COOH groups must be on the same side
  • no rotation about C=C axis
31
Q

C = ester
D = carboxylic acid

identify reagent in test tube reaction to distinguish between C and D

A

reagent = NaHCO3

C observation = no observation
D = effervescence

32
Q

explain why ethanol chloride can readily react with nucleophiles

A
  • Large charge on carbonyl carbon atom due to bonding to O and Cl
  • Nucleophiles have electron pairs which can be donated
33
Q

one advantage using propanol chloride instead of propanoic acid in lab preparation of methyl propanoate from methanol

A
  • faster/bigger yield/no acid catalyst required
34
Q

Suggest why an excess of sodium hydroxide is used.

A

to ensure ester reacts completely

35
Q

equation for reaction between sodium benzoate and hydrochloric acid

A

C6H5COONa + HCl → C6H5COOH + NaCl

36
Q

Suggest two reasons why, in an industrial situation, ethanoic anhydride would be preferred to ethanoyl chloride in the production of paracetamol.

A

Any two from:
*        less exothermic reaction
*        easier to control
*        dangerous gas not evolved
*        ethanoic anhydride is a cheaper or more easily recycled reagent.

AQA - A level Chemistry (25 decks)

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