Carboxylic acids and Derivatives Flashcards

1
Q

Why are carboxylic acids considered weak acids?

A

They only partially dissociate in water to make a carboxylate ion and a hydrogen ion.

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2
Q

How do carboxylic acids react with carbonates?

A

They form salt, water and carbon dioxide.

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3
Q

What is the test for a carboxylic acid?

A

You add sodium hydrogencarbonate and if there is fizzing then the acid is present.

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4
Q

What products are made when a carboxylic acid reacts with an alcohol?

A

An ester and water are made.

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5
Q

What conditions are needed for esterification?

A
  1. A strong acid catalyst like HCL.
  2. heated under reflux
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6
Q

What are the properties of esters?

A

They have a sweet smell meaning they can be used in cosmetics.
They are polar liquids that can be used as solvents to dissolve other polar substances.
They can be used as plasticiers.

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7
Q

What is hydrolysis?

A

The splitting of a substance using water.

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8
Q

Why is acid and alkali hydrolysis used?

A

Using just water to split up an ester takes too long so an acid or alkali is added to speed up the process.

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9
Q

What are the conditions needed for acid hydrolysis?

A
  1. Heat the solution under reflux.
  2. Have a dilute acid like HCL to act as a catalyst.
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10
Q

Why do you need to use a lot of water when doing acid hydrolysis?

A

Since the reaction is reversible a lot of water has to be added to shift the equilibrium to the right so you get lots of the product.

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11
Q

Write down the equation for the acid hydrolysis of methyl ethanoate.

A
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12
Q

What are the conditions needed for alkali hydrolysis?

A

You need warm dilute NaOH.
Remove the products using fractional distillation.
Heat under reflux.

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13
Q

Write down the equation for the alkali hydrolysis of methyl ethanoate.

A
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14
Q

What are animal fats and vegetable oils made up of?

A

They are esters of glycerol and fatty acids.

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15
Q

What is the actual name for glycerol?

A

propane-1,2,3-triol

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16
Q

What are fatty acids?

A

Long chain carboxylic acids.

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17
Q

Draw the structure of an animal fat.

A
18
Q

Why are fats usually solids at room temperature?

A

The fatty acids in fats are usually saturated meaning they fit closely together. This increases the number of van der Waals forces which require more energy to break.

19
Q

Why are oils usually liquids at room temperature?

A

The fatty acids in oils are mostly unsaturated meaning they don’t pack closely together. This means there are fewer van der Walls forces and less energy is needed to break them.

20
Q

How do you hydrolise fats and oils?

A

You heat with sodium hydroxide under reflux.

21
Q

What do you make in the hydrolysis of fats and oils?

A

glycerol and sodium salt.

22
Q

How do you convert the sodium salt back into a fatty acid?

A

You add a strong acid like HCl to it.

23
Q

What is biodiesel made out of?

A

A mixture of methyl esters.

24
Q

How do you make a methyl ester?

A

You react to the fatty acid with methanol.
You need a strong alkali like potassium hydroxide as a catalyst.

25
Q

What are the products of this reaction?

A

glycerol and a methyl ester.

26
Q

What is the functional group for acyl chlorides?

A

COCl

27
Q

What is the suffix used to name acyl chlorides?

A
  • oyl
28
Q

How do acyl chlorides react with water?

A

They produce a carboxylic acid and HCl.

29
Q

How do acyl chlorides react with alcohols?

A

They make an ester and HCl.

30
Q

How do acyl chlorides react with ammonia?

A

They make a primary amide and HCl.

31
Q

How does acyl chloride react with an amine?

A

They produce an N-substituted amine and HCl.

32
Q

What is an acid anhydride?

A

Two carboxylic acids joined together via a condensation reaction.

33
Q

How do you name acid anhydrides?

A
  1. Find the number of carbons on each side of the O.
  2. Name these carbon chains in alphabetical order.
  3. Add anhydride to the end.
34
Q

Why are reactions with acid anhydrides less vigorous than one with an acyl chloride?

A

Because acyl chloride produces HCl which is a strong acid and acid anhydrides produce a carboxylic acid which is a weak acid.

35
Q

How does an acid anhydride react with water?

A

It produces two molecules of carboxylic acid.

36
Q

How does an acid anhydride react with an alcohol?

A

It makes an ester and a carboxylic aid.

37
Q

How does an acid anhydride react with ammonia?

A

It makes a primary amide and a carboxylic acid.

38
Q

How does an acid anhydride react with an amine?

A

It makes an N-substituted amide

39
Q

What is the name of the mechanism for when an acyl chloride reacts with alcohol?

A

nucleophilic addition-elimination.

40
Q

How is aspirin made?

A

Reacting salicylic acid with ethanoic anhydride. This makes aspirin and ethanoic acid.

41
Q

What are the advantages of using an acid anhydride to make aspirin compared to acyl chloride?

A
  1. It is cheaper.
  2. It reacts more slowly and does not produce toxic HCl fumes.