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chemistry module 1 > Derivatives of Carboxylic acids > Flashcards

Derivatives of Carboxylic acids Flashcards

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1
Q

What are the derivatives of Carboxylic acids

A

Esters, fats and acyl chlorides

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2
Q

What is the ester functional group?

A

-COO-

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3
Q

How are esters formed

A

Formed from the condensation reaction between a carboxylic acid and alcohol or from the elimination reaction between an alcohol and acyl chloride.

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4
Q

What are some properties of esters?

A

Esters are liquids with a fruity odour, immiscible and mostly non polar.

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5
Q

How are esters named?

A

Esters names are based on the alcohol converted to acyl chloride and the acid converted to the salt name
e.g. Ethanol and Propanoic acid → ethyl propanoate
Methanol and Ethanoic acid → Methyl ethanoate

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6
Q

What happens to the solubility of esters as chain length increases

A

Solubility decreases as chain length increases. There are H bonds between the carbonyl group and water molecules but as the chain length increases the bonds are less effectively formed.

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7
Q

What happens to boiling point as chain length increases?

A

As ester chain length increases boiling point increases, greater number of electrons, more induced dipoles therefore stronger Van der Waals forces of attraction between molecules.

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8
Q

What are the two ways esters can be formed?

A
  1. Formed from an alcohol and carboxylic acid.

2. Formed from an alcohol and an acyl chloride

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9
Q

Draw the formation of an ester from ethanol and propanoic acid and describe

A

in book
Concentrated sulfuric acid is added to remove water and promote the formation of the ester
The mixture is heated and distilled and the ester collected

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10
Q

Draw the formation of an ester from ethanol and propanoyl chloride and describe

A

in book

This reaction produces a much higher yield of the ester, as the HCl is gaseous and removed.

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11
Q

What are the two ways esters can be hydrolysed

A

Acid catalysed hydrolysis - heated under reflux with dilute HCl
Base catalysed hydrolysis - heated under reflux with sodium hydroxide solution

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12
Q

Write the eqn for the acid catalysed hydrolysis of methyl ethanoate

A

in book

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13
Q

Write the eqn for the base catalysed hydrolysis of ethyl methanoate

A

in book

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14
Q

What is the method of preparation of ethyl ethanoate

A
  1. Place a mixture of the alcohol and concentrated sulfuric acid in a pear shaped flask
  2. Add a mixture of the alcohol and carboxylic acid slowly form a dropping funnel
  3. Swirl the mixture
  4. Add antibump granules and arrange the apparatus for distillation
  5. Heat the mixture gently and collet the distillate 2ºC pf the boiling point
  6. Place in a separating funnel and rinse with Sodium carbonate solution
  7. Remove lower aqueous layer and add anhydrous calcium chloride to the upper organic layer
  8. Filter to remove calcium chloride
  9. Redistill and collect distillate 1ºC either side of the BP
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15
Q

How are acyl chlorides produced

A

Produced when a carboxylic acid reacts with phosphorus pentachloride. All are highly reactive

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16
Q

What happens when you react an acyl chloride with water?

A

The corresponding carboxylic acid and hydrogen chloride is produced.

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17
Q

What are the observations when ethanoyl chloride is reacted with water

A

Fizzes, misty fumes produced.

18
Q

What are some proerties of ethanoyl chloride?

A

It is a colourless, corrosive liquid. An open bottle of ethanoyl chloride fumes in contact with moist air and HCl is produced

19
Q

What are fats?

A

Fats are triesters of propane-1,2,3-triol (glycerol) and fatty acids.

20
Q

What is the structure of glycerol?

A

in book

21
Q

What are fatty acids?

A

Carboxylic acids with long hydrocarbon chains

22
Q

What is Stearic acid?

A

CH3(CH2)16COOH. It is saturated as it contains no C=C, and its systematic name is Octadecanoic acid

23
Q

What is Oleic acid?

A

CH3(CH2)7CH=CH(CH2)7COOH. Unsaturated as it contains C=C. It is a Z isomer. Its systematic name is (9Z)-octadec-9-enoic acid

24
Q

How is a fat formed?

A

1 mol of glycerol reacts with 3 mol of fatty acids to form 1 mol of fat and 3 moles of water

25
Q

Show the formation of a fat from glyerol and fatty acids

A

in book

26
Q

Show the formation of gylceryl tristearate

A

in book

27
Q

How do fats and oils come about?

A

If a fat has a large proportion of C=C bonds it will be an oil. The more C=C the weaker the Van der Waals

28
Q

Saturated fats in the diet

A

LDL, provide energy and insulation, increase risk of CHD

29
Q

Unsaturated fats in the diet

A

HDL, reduces risk of CHD,

30
Q

What are the two reactions of fats and oils

A
  1. Hydrogenation of unsaturated fats

2. Hydrolysis of fats

31
Q

What are the conditions for the hydrogenation of fats

A

They react with hydrogen in the present of finely divided nickel catalyst at 180ºC

32
Q

How many moles of H2 does it take to saturated an unsaturated fat?

A

It takes 1 mol of H2 per C=C

33
Q

What are two ways fats can be hydrolysed?

A

Acid or base, base is the most common and it is called saponification

34
Q

What does saponification produce?

A

Produced glycerol and the sodium or potassium salt of the fatty acid.

35
Q

Draw the saponification of glyceryl tristearate

A

in book

36
Q

What is transesterification

A

The process of swapping an alkyl group in an ester for a different alkyl group.

37
Q

What can transesterification be between?

A

An ester and an alcohol or an ester and carboxylic acid.

38
Q

What does transesterification produce ?

A

Margarine or a biodiesel

39
Q

Draw the transesterification between triglyceride and methanol (excess)

A

in book

40
Q

Draw intramolecular exchange and intermolecular exchange

A

in book

41
Q

What are the conditions for inter/intramolecular exchange

A

Occurs at 400K in the presence of an alkali (NaOH), glycerol and a catalyst (Sodium methoxide, CH3ONa)

chemistry module 1 (10 decks)

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