carboxylic acid derivatives 26.4

Question 1

What is a derivative of a carboxylic acid?

Answer 1

A compound that can be hydrolysed to form the parent carboxylic acid.

Question 2

What do esters , acyl chlorides, amides and acid anhydrides have in common?

Answer 2

They are all derivatives of carboxylic acids

Question 3

What is the acyl group ?

Answer 3

A carbon double bonded to an oxygen and single bonded to a carbon chain, (the spare bond in an acyl group bonds to chlorine or acid anhydride or amide group)

Question 4

Draw methyl ethanoate

Answer 4

See Pg 202 for answer

Question 5

How are acid anhydride molecules formed?

Answer 5

Removal of water between two carboxylic acids

Question 6

What is esterification?

Answer 6

The reaction of an alcohol with a carboxylic acid to form an ester.

Question 7

State the reagents and conditions for esterification

Answer 7

Alcohol + carboxylic acid —> ester
Reagents warmed
Small amount of conc. Sulfuric acid as catalyst

Question 8

Esters can be hydrolysed by aqueous acid or alkali, what is hydrolysis?

Answer 8

The chemical breakdown of a compound in the presence of water or in aqueous solution

Question 9

How do you carry out acid hydrolysis of an ester?

Answer 9

1. The ester is heated under reflux with dilute aqueous acid

2. The ester is broken down by water with the acid acting as a catalyst

Question 10

Name the products of acid hydrolysis

Answer 10

A carboxylic acid and an alcohol

Question 11

What is alkaline hydrolysis of an ester?

Answer 11

1. Known as saponification
2. Is irreversible
3. The ester is heated under reflux with aqueous hydroxide ions

Question 12

What is formed from alkaline hydrolysis?

Answer 12

A carboxylate ion and an alcohol

The ion often forms a salt with any + ions in solution

Question 13

How are acyl chlorides prepared?

Answer 13

Directly from their parent C. Acid by reaction with thionyl chloride SOCl2

Question 14

Name the products of preparation of an acyl chloride

Answer 14

Sulfur dioxide and hydrogen chloride

Both harmful gases

Question 15

Why might preparation of acyl chlorides be carried out in a fume cupboard?

Answer 15

Harmful gaseous products

Question 16

Why are acyl chlorides useful?

Answer 16

Very reactive, can be converted into esters and amides easily and with good yields.

Question 17

How do acyl chlorides react ?

Answer 17

With nucleophiles by loosing the chloride ion whilst retaining the C=O bond.

Question 18

Acyl chloride + alcohol —>

Answer 18

Ester

Question 19

Draw out the reaction for and name products of ethanoyl chloride + propan-1-ol

Answer 19

See Pg 205

Question 20

Why are acyl chlorides used to react with esters?

Answer 20

Carboxylic acids are not reactive enough to form esters with phenol
Acyl chlorides and acid anhydrides are more reactive and will produce esters with phenol

Question 21

Difference between ketone and esters?

Answer 21

Ketones have a carbonyl group bonded to 2 carbon chains

Esters have a carbonyl group bonded to 1 carbon chain 1 alkoxy group

Question 22

Draw the reaction of ethanoyl chloride + phenol and name the product

Answer 22

See Pg 205

Question 23

How do you convert acyl chloride back to carboxylic acid?

Answer 23

Add water (hydrolysis)

Question 24

What happens when you add water to acyl chlorides ?

Answer 24

Violent reaction takes place
Dense steamy HCl given of
Carboxylic acid formed

Question 25

Draw reaction for ethanoyl chloride + HCl and name products

Answer 25

See Pg 205