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A-level Chem > Carboxylic acids and esters > Flashcards

Carboxylic acids and esters Flashcards

1
Q

What is the functional group of a caroxylic acid/

A

-COOH

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2
Q

What is the general formula for a carboxylic acid/

A

CnH2n+1COOH

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3
Q

Describe the 2 stage synthesis of carboxylic acids from alkenes. Include the name of the reactions and the reagents and conditions.

A
  1. Alkene to alcohol: hydration / H2O(g) / concentrated H3PO4(aq).
  2. Alcohol to carboxylic acid: oxidation / reflux / K2Cr2O7(aq) / concentrated H2SO4(aq)
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4
Q

*Draw a diagram displaying the solubility/ hydrogen bonding of butanoic acid.

A

*Refer to notes.

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5
Q

Describe and explain how the solubility of carboxylic acids changes as carbon chain length changes (2 points).

A
  1. Solubility of carboxylic acids decreases with increasing carbon chain length because hydrocarbon chains are non-polar, so cannot form hydrogen bonds with the polar water.
  2. They can only form induced dipole-dipole interactions with each other.
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6
Q

What two things does the solubility of carboxylic acids depend on?

A
  1. The number of carboxylic acid groups, i.e. number of hydrogen bonds.
  2. The number of carbons in the chain.
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7
Q

METAL + ACID… Write an overall and ionic equation for the reaction between Na (metal) and ethanoic acid. Name the salt and type of reaction.

A

Overall: CH3COOH(aq) + Na(s) …. CH3COONa(aq) + 1/2H2(g)
Ionic: H+(aq) + Na(s) …. Na+(aq) + 1/2H2(g)
Salt formed: sodium ethanoate.
Type of reaction: redox.

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8
Q

METAL OXIDE + ACID…Write the overall and ionic equations for the reaction between MgO (metal oxide) and ethanoic acid. Name the salt formed and the type of reaction.

A

Overall: 2CH3COOH(aq) + MgO(s) …. (CH3COO)2Mg(aq) + H2O(l)
Ionic: 2H+(aq) + MgO(s) …. Mg^2+(aq) + H2O(l)
Salt formed: magnesium ethanoate.
Type of reaction: neutralisation.

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9
Q

ACID + ALKALI…Write the overall and ionic equation for the reaction between KOH (alkali) and ethanoic acid. Name the salt formed and the type of reaction.

A

Overall: CH3COOH(aq) + KOH(aq) …. CH3COOK(aq) + H2O(l)
Ionic: H+(aq) + OH-(aq) …. H2O(l)
Salt formed: potassium ethanoate.
Type of reaction: neutralisation.

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10
Q

CARBONATES + ACID…Write the overall and ionic equation for the reaction of CaCO3 (carbonate) and ethanoic acid. Name the salt formed and the type of reaction.

A

Overall: 2CH3COOH(aq) + CaCO3(s) …. (CH3COO)2Ca(aq) + H2O(l) + CO2(g)
Ionic: 2H+(aq) + CaCO3(s) …. Ca^2+(aq) +H2O(l) + CO2(g)
Salt formed: calcium ethanoate
Type of reaction: test for carboxylic acids.

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11
Q

What is the positive result to test for a carboxylic acids?

A

White precipitate forms.

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12
Q

Does Na and a carboxylic acid react?

A

Yes

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13
Q

Does NaOH(aq) and a carboxylic acid react?

A

Yes

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14
Q

Does Na2CO3 and a carboxylic acid react?

A

Yes

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15
Q

Does Na and phenol react?

A

Yes

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16
Q

Does NaOH(aq) and phenol react?

A

Yes

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17
Q

Does Na2CO3 and phenol react?

A

No reaction

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18
Q

Does Na and an alcohol react?

A

Yes

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19
Q

Does an alcohol and NaOH(aq) react?

A

No reaction.

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20
Q

Does an alcohol and Na2CO3 react?

A

No reaction.

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21
Q

*What is the functional group of an ester?

A

*Refer to notes.

22
Q

What are the two main uses of esters?

A
  1. Perfumes.
  2. Flavourings.
23
Q

Definition of condensation reactions. Give an example of a condensation reaction.

A

A reaction in which two small molecules react together to form a larger molecule with the elimination of a small molecule, such as water.
Example: esterification reactions.

24
Q

List the three ways to make esters

A
  1. Carboxylic acids + alcohol …./…. ester + water.
  2. Acid anhydride + alcohol …. ester + carboxylic acid.
  3. Acyl chloride + alcohol …. ester + HCl.`
25
Q

What are the reagents and conditions for the esterification of carboxylic acids with alcohols?

A

Carboxylic acids and alcohol.
Reflux and concentrated H2SO4(aq).

26
Q

*Write an equation for the reaction between ethanoc acid and 2-methylpropan-1-ol. Name the ester formed.

A

*Refer to notes.
2-methylpropylethanoate.

27
Q

Describe an acid anhydride.

A

Made from two carboxylic acids that join together by the loss of a water molecule.

28
Q

*Write the equation for the reaction between ethanoic anhydride and methanol.

A

*Refer to notes.

29
Q

What are the conditions for the esterification reaction between an alcohol and acid anyhride?

A

Dry

30
Q

What are the advantages to using an alcohol and acid anhydride to form an ester?

A

Increased yeild and no catalyst or heat required.

31
Q

What are the reagents and conditions of the reaction to form an acyl chloride from carboxylic acids?

A

Thionyl chloride, SOCl2
Dry

32
Q

*Write an equation for the reaction between CH3CH2COOH and SOCl2. Name the products.

A

*Refer to notes.
Propanoyl chloride, hydrogen chloride, sufur dioxide gas.

33
Q

What are acyl chlorides used in the synthesis of? (3 points).

A
  1. Esters (including from phenols which won’t work from carboxylic acids).
  2. Carboxylic acids.
  3. Primary and secondary amides.
34
Q

What are the main advantages of using acyl chlorides?

A
  1. Better yields.
  2. No use of heat or catalyst.
35
Q

What reagent is reacted with an acyl chlroide to form an ester?

A

A primary alcohol.

36
Q

What are the conditions for esterification with an acyl chloride and alcohol?

A

Dry and room temperature.

37
Q

Write an equation for the reaction between ethanoyl chloride and propan-1-ol. Name the products.

A

*Refer to notes.
Propylethanoate, hydrogen chloride.

38
Q

What are the reagents for the esterification of phenol?

A

Phenol and an acyl chloride as carboxylic acids are not reactive enough to form esters with phenols.

39
Q

What are the conditions for the esterfication of phenol?

A

Dry and room temperature.

40
Q

Write an equation for the reaction between ethanoyl chloride and phenol. Name the products.

A

*Refer to notes.
Phenyl ethanoate and hydrogen chloride.

41
Q

What are the reagents for the reaction to form carboxylic acids?

A

An acyl chloride and water.

42
Q

What are the conditions for the reaction between an acyl chloride and water to form a carboxylic acid?

A

Room temperature.

43
Q

Write an equation for the reaction between ethanoyl chloride and water. Name the products.

A

*Refer to notes.
Ethanoic acid and hydrogen chloride.

44
Q

What is the observation for reactions that product hydrogen chloride?

A

Misty white flame.

45
Q

State two ways esters can be hydrolysed.

A
  1. Hot aqueous acid hydrolysis.
  2. Hot aqueous alkaline hydrolysis.
46
Q

What is the reagent used when hydrolysing esters using hot aqueous acid?

A

HCl(aq) SOURCE OF WATER.

47
Q

What is the reagent used when hydrolysing esters using hot alkaline hydrolysis?

A

NaOH(aq) SOURCE OF WATER

48
Q

What are the conditions in which esters are hydrolysed?

A

Reflux

49
Q

Write an equation for the hydrolysis of methyl propanoate in hot aqueous acid hydrolysis.

A

*Refer to notes.

50
Q

Write a reaction for the hydrolysis of methyl propanoate in hot alkaline hydrolysis.

A

*Refer to notes.

51
Q

What are the products formed when an ester is hydrolysed?

A

Carboxylic acid and alcohol.

A-level Chem (30 decks)

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