Carboxylic Acids & Derivatives

Question 1

What do esters end in

Answer 1

“-anoate”

Question 2

Why do esters have a lower boiling point than carboxylic acids and alcohols

Answer 2

Because esters can only form hydrogen bonds with water and not with eachother. But alcohols/carboxylic acids can form H bonds with both

Question 3

How do you form an ester and what conditions

Answer 3

Esterification:
Carboxylic acid + alcohol -> ester + water

• dynamic equilibrium
• reagent: H2SO4 Catalyst
• condition: heat under reflux

Question 4

Describe hydrolysis of an ester into a carboxylic acid in the presence of an acid

Answer 4

• reagent - Dilute HCl
• condition - heat under reflux
• reversible reaction

Question 5

Describe hydrolysis of an ester into a carboxylic acid in the presence of an alkali (saponification)

Answer 5

• reagent - EXCESS dilute NaOH
• condition - heat under reflux
• forms a carboxylate salt
• not reversible

Question 6

Why is saponification not reversible

Answer 6

Cannot be attacked by weak nucleophiles eg alcohols

Question 7

What are the 4 common uses of esters

Answer 7

• solvents
• plasticisers
• perfumes
• food flavourings

Question 8

Why are esters used for perfumes

Answer 8

• Soluble in alcohol
• Non toxic
• Volatile
• Doesn’t react with water

Question 9

Why can esters be used as solvents

Answer 9

• they’re polar

Question 10

How can esters be used as plasticisers

Answer 10

• added to pure polymers to make them more flexible and reduces intermolecular forces

Question 11

What’s propane-1,2,3-triol

Answer 11

Glycerol

Question 12

Glycerol + fatty acids =?

Answer 12

Esters which make fats and oil

Question 13

What are fats and oils at room temp and what type of bonds will they have

Answer 13

Fats - higher VDWs so solids (has all single bonds)
Oils - lower VDWs liquids (has double bonds)

Question 14

How can soap (sodium salt) be made

Answer 14

Hydrolysis of Fats and oils by heating with NaOH

Question 15

What is biodiesel and how can it be made

Answer 15

It is a mixture of fatty acids made from methyl esters
Made by:
- Oil + methanol
- using KOH catalyst

Question 16

What is used ethanoic anhydride or acid chlorides and why

Answer 16

Ethanoic anhydride
- it is cheaper
- less corrosive
- less vulnerable to hydrolysis
- less dangerous