Carboxylic acids and their derivatives

Question 1

Which is more reactive: acid chlorides or acid anyhydrides?

Answer 1

Acid chlorides.

Question 2

Water, alcohols, amines and ammonia can all act as nucleophiles in acylation. What is the order of strength of their nucleophilic ability?

Answer 2

Weakest to strongest: -Water -Alcohol -Ammonia -Amine Tip: consider how much repulsion the lone pair receives.

Question 3

Why is ethanoic anhydride preferred as an acylating agent compared to ethanoyl chloride?

Answer 3

Ethanoic anhydride is: -Cheaper -Less corrosive -Reacts with water less easily -It is safer as ethanoic acid is produced as a byproduct instead of steamy HCl fumes.

Question 4

What is one use of acylation reactions?

Answer 4

The production of aspirin.

Question 5

What are some uses of esters? (3 uses)

Answer 5

-Perfumes/flavourings -Plasticisers for polymers -A solvent for polar organic substances (e.g ethyl ethanoate in glues and printing inks)

Question 6

There are two conditions for the hydrolysis of esters. What are they?

Answer 6

1. With acid: -Dilute acid (HCl) as a reagent -Heat under reflux 2. WIth sodium hydroxide: -Dilute sodium hydroxide as a reagent -Heat under reflux

Question 7

Which condition of the hydrolysis of esters gives the better yield and why?

Answer 7

Sodium hydroxide as a reagent with heat under reflux because after the formation of an acid and alcohol a carboxylate salt is formed which prevents the reaction from taking place in the opposite direction so the reaction goes to completion. When acidic conditions and heat under reflux is used the reaction can be reversible which ensures a bad yield.

Question 8

In terms of this topic, what are fats and oils?

Answer 8

Fats and oils are esters of glycerol and long chain carboxylic acids (fatty acids)`.

Question 9

What is the formula and IUPAC name of glycerol?

Answer 9