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3.3 Organic Chemistry > 3.3.9 Carboxylic acids and derivatives > Flashcards

3.3.9 Carboxylic acids and derivatives Flashcards

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1
Q

What is the general formula of a carboxylic acid and what is the nomenclature (the suffix)?

A

CnH2n+1COOH or RCOOH

alkan + oic acid

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2
Q

What are the properties of carboxylic acids and why?

A

. high solubility in water because they can form hydrogen bonds with water

. high melting points because they can form dimers (two identical molecules linked together)

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3
Q

What happens to the solubility of RCOOH as the chain length increases?

A

As the chain length of RCOOH increases, there is a greater region of non-polar which can not dissolve in polar solvents and therefore cannot form hydrogen bonds between molecules

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4
Q

Why are carboxylic acids considered weak acids?

A

They only partially ionise in water. Due to this, the concentration of H+ is low, therefore less acidic.

(Equilibrium lies to the left, which means only a little bit turns into ions)

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5
Q

What forms when RCOOH reacts with metal?

A

salt + hydrogen

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6
Q

What forms when RCOOH reacts with metal oxide?

A

salt + water

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7
Q

What forms when RCOOH reacts with metal hydroxide?

A

salt + water

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8
Q

What forms when RCOOH reacts with metal carbonate?

A

salt+ water +carbon dioxide

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9
Q

what is the functional group of esters and what is its nomenclature?

A

RCOOR’

oate

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10
Q

What are the uses of esters

A

fragrances and flavourings
(fruitier and sweeter than aldehydes and ketones)

Plasticisers - more flexible

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11
Q

What factors affect the strength of the acid?

A

Length of alkyl group - inductive effect
COO becomes more negative, hence it wouldn’t released the H+ easily

Longer chain = weaker COOH

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12
Q

How are esters produced? include the conditions.

A

Carboxylic acid + alcohol —> ester + water

Using H2SO4 catalyst and heat

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13
Q

What is the reaction of acid hydrolysis of esters?

A

Ester + water <—-> Carboxylic acid + alcohol

Using strong acid catalyst

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14
Q

What is the reaction of alkaline hydrolysis of esters?

A

Ester + NaOH —> salt + alcohol

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15
Q

How do you produce oils/fats?

A

Oil + water <—> glycerol + (fatty)acid

Using H2SO4 catalyst and heat

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16
Q

What is the reaction of the alkaline hydrolysis of oils/fats?

A

Oil + alkali —> glycerol + soap

17
Q

How do you produce biodiesel?

A

Oil + methanol —> glycerol + biodiesel

Using OH- catalyst

18
Q

What are the Carboxylic acid derivatives and their physical properties?

A

Ester (RCOOR) - can react with water

Acyl chloride (RCOCl) - reacts violently with water

Acid anhydride (RCOOCOR) - reacts with water

19
Q

What is the reaction of acid hydrolysis of oils/fats?

A

Oil+ water —> glycerol + fatty acids

20
Q

Describe a soap molecule and how it works.

A

Polar (hydrophilic) head fern hydrogen bond with water
Non-polar (hydrophobic) tail forms VDWs with dirt/grease
Grease is pulled apart and
Soap emulsifies grease and oil allowing them to mix with water and can be washed away

21
Q

Products of acyl chloride reacting with water.

A

Carboxylic acid + HCL

22
Q

Products of acyl chloride reacting with alcohol.

A

Ester + HCL

23
Q

Products of acyl chloride reacting with excess ammonia.

A

Primary amide + NH4Cl

24
Q

Products of acyl chloride reacting with primary amine.

A

Secondary amide + RNH3Cl

25
Q

Products of acid anhydride reacting with water.

A

2 Carboxylic acid

26
Q

Products of acid anhydride reacting with alcohol.

A

Ester + Carboxylic acid

27
Q

Products of acid anhydride reacting with ammonia.

A

Primary amide + Carboxylic acid

28
Q

Products of acid anhydride reacting with excess ammonia.

A

Primary amide + ammonium carboxylate

29
Q

Products of acid anhydride reacting with excess primary amine.

A

Secondary amide + alkyl-ammonium carboxylate

30
Q

What is the most reactive between Carboxylic acids, acyl chlorides and acid anhydride?

A

Acid chloride > acid anhydride > Carboxylic acids

31
Q

How is aspirin produced?

A

Reacting salicylic acid with Carboxylic acid derivative (generally ethanoic anhydride)

32
Q

Why do chemists generally use ethanoic anhydride rather than ethanoyl chloride when producing aspirin?

A

. Ethanoic anhydride is less reactive - less exothermic (easier to control)
. Ethanoyl chloride produces HCl (dangerous gas)
. Ethanoic anhydride is cheaper
. Ethanoic anhydride is easier to recycle

3.3 Organic Chemistry (16 decks)

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