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A2 Chemistry Unit 1 > Derivatives Of Carboxylic Acids > Flashcards

Derivatives Of Carboxylic Acids Flashcards

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1
Q

Definition of a monoester

A

An Ester which contains only one Ester group

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2
Q

Definition of tranesterification

A

A reaction where the alkyl group of an Ester is exchanged with the alkyl group of an alcohol

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3
Q

Definition of biodiesel

A

A fuel, similar to diesel, which is made from vegetable sources

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4
Q

What is the functional group of an Ester

A

R-COO-R

See notes

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5
Q

What is the functional group of acyl chlorides

A

See notes

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6
Q

How to name esters

A

Parent alcohol at start and parent acid at end

Eg ethanol and propanoic acid forms ethyl propanoate

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7
Q

How to draw esters

A

Acid then alcohol

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8
Q

Physical properties of esters

A
  1. Colourless
  2. Neutral
  3. Pleasant fruity smell
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9
Q

Describe the solubility of esters

A

⭕️ Small = fairly soluble ➡️ falls as chain increases
⭕️ can’t H bond with themselves
⭕️ H bond with water

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10
Q

What are the bonds in esters

A

Mostly VDW

Some permanent dipole dipole C=O

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11
Q

Describe the boiling points of esters compared to carboxylic acids

A

Lower than carboxylic acids ➡️ can’t H bond with themselves

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12
Q

Write the equation for the formation of esters via carboxylic acids and state conditions

A

See notes
Conc sulfuric acid
Reflux

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13
Q

Why is conc sulfuric acid needed in the preparation of esters via carboxylic acid

A

Removes water

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14
Q

Why is the formation of esters via carboxylic acids not the best

A

Less than 100% yield

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15
Q

Write the general equation for the formation of esters via acyl chlorides

A

See notes

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16
Q

Why is the formation of an Ester via acyl chlorides good

A
  1. Fast and no reflux
  2. Irreversible
  3. No catalyst needed
  4. Higher yield
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17
Q

Describe acid catalysed hydrolysis of esters

A

Heat under reflux with excess water and dilute HCl

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18
Q

State the products formed from acid catalysed hydrolysis of esters

A

Carboxylic acid

Alcohol

19
Q

Why is acid catalysed hydrolysis of esters a poor method

A
  1. Reversible

2. Some Ester left unhydrolysed

20
Q

Describe base catalysed hydrolysis of an Ester

A
  1. Reflux Ester with NaOH (aq)
  2. Sodium salt of acid produced
  3. Acid liberated from salt via addition of strong acid
21
Q

Why is base catalysed hydrolysis better than acid based hydrolysis

A

Irreversible

22
Q

How are acyl chlorides formed

A

When carboxylic acid reacts with PCl5

23
Q

Write the general equation for the formation of acyl chlorides

A

See notes

24
Q

What are the products when acyl chlorides react with alcohol

A

Ester and HCl

25
Q

What are the products when acyl chlorides react with water

A

Hydrolysis

Produces carboxylic acid and HCl

26
Q

Describe the structure of fats and oils

A

⭕️ triesters of glycerol and fatty acids

⭕️ formed via condensation reactions

27
Q

What does a glycerol and three fatty acids produce

A

A triglyceride and 3 waters

See notes

28
Q

Describe saturated fatty acids

A

⭕️ NO C=C
⭕️ fit compactly - strong vdw
⭕️ higher mp than unsaturated
⭕️ usually solid

29
Q

Describe unsaturated fatty acids

A

⭕️ one or more C=C
⭕️ cannot align compactly - tend to coil - due to C=C
⭕️ weak vdw low mp
⭕️ usually liquid

30
Q

What is the name for a fatty acid with one C=C

A

Monosaturated

31
Q

What is the name of a fatty acid with 2 or more C=C

A

Polysaturated

32
Q

Describe hydrogenation of oils and fats

A

⭕️ oils become fats - increase in vdw
⭕️ finely divided nickel catalyst
⭕️ 180 degrees
⭕️ H2 gas bubbled through

33
Q

Draw the structural equation of hydrogenation of oils and fats

A

See notes

34
Q

Name of hydrolysis of fats

A

Alkaline hydrolysis

Saponification

35
Q

Name the products of hydrolysis of fats

A

Glycerol
Sodium salt of fatty acid (soap)
See notes for structural equation

36
Q

Write the general equation for transesterification and state what happens

A

Swap alkyl group in an Ester for another
⭕️ alcohol + Ester ➡️ different alcohol + different Ester
See notes for structural equation

37
Q

Describe the two different forms of transesterification in fats

A
  1. Intramolecular - within same fat molecule

2. Intermolecular - between two fat molecules

38
Q

What is transesterification useful for

A

Produces biofuel and margarine

39
Q

What is biodiesel made from

A

Triglycerides in vegetable oils

40
Q

How is biodiesel made

A

Triglyceride heated with methanol

Presence of base (catalyst)

41
Q

What are the products of biodiesel reaction

A

Biodiesel

glycerol (used in other industries)

42
Q

Conditions for the formation of biodiesel

A

400K
Alkali
Glycerol
Catalyst

43
Q

Describe the method of preparing a carboxylic acid from an alcohol

A

See notes

A2 Chemistry Unit 1 (9 decks)

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