4.5 Carboxylic Acids & Esters

Question 1

Describe decarboxylation & draw it

Answer 1

• removal of CO2 molecule
• shortening carbon chains
• heat with soda lime

Question 2

Describe the solubility of carboxylic acids

Answer 2

• soluble
• become less soluble as number of chains/branches increases

Question 3

Draw the dissociation of a carboxylic acid

Question 4

Draw the ester functional group

Question 5

How are esters made?

Answer 5

• condensation reaction between alcohols and carboxylic acids

Question 6

Draw condensation reaction forming an ester

Question 7

How are acid chlorides made?

Answer 7

Carboxylic acid + SOCl2

Question 8

How are acid anhydrides made?

Answer 8

Carboxylic acid + carboxylic acid

Question 9

Draw acid hydrolysis of ethyl ethanoate

Question 10

Draw the base hydrolysis of ethyl ethanoate (saponification)

Question 11

Differentiate between saturated and unsaturated fats

Answer 11

Saturated: don’t have double bonds
Unsaturated: have double bonds

Question 12

Test for carboxylic acids

Answer 12

• add a metal carbonate
• if CA present should see effervescence

Question 13

How are amides formed from carboxylic acids?

Answer 13

• react ammonium carbonate with carboxylic acid
• form ammonium salt which is dehydrated to form an amide

Question 14

Mechanism of formation of ethanamide

Question 15

How do you produce a nitrile from an amide?

Answer 15

Add P4O10 or dehydrate it

Question 16

Why might products made from esters be considered environmentally friendly?

Answer 16

Made from a renewable source

Question 17

Why are triglycerides soluble in non-polar solvents and not in water?

Answer 17

• VdW between triglycerides
• VdW form between triglycerides and solvent
• cannot H bond to water due to the long carbon chains involvement

Question 18

What is meant by stereoisomerism?

Answer 18

Same structural formula but different arrangement

Question 19

Conditions for ester formation

Answer 19

H2SO4, heat & reflux

Question 20

Reagent for benzene containing compound to carboxylic acid

Answer 20

Alkaline potassium manganate

Question 21

What is meant by reflux?

Answer 21

Process involving continued evaporation and condensation

Question 22

How would you purify benzoic acid?

Answer 22

• dissolve in minimum of hot water
• allow to cool then filter and dry

Question 23

How would you know if something was pure?

Answer 23

• compare melting point to literature values
• use chromatography

Question 24

Reagents and conditions for acid hydrolysis of esters

Answer 24

• dilute sulphuric acid
• heat under reflux

Question 25

Reagents and conditions for base hydrolysis of esters

Answer 25

- aqueous NaOH - heat under reflux

Question 26

Mechanism for nucleophilic reaction of ethanoyl chloride and water

Question 27

Describe the formation of amides from carboxylic acids

Answer 27

- react acid with basic ammonia and heat - convert to nitrile by heating with P4O10

Question 28

Describe the formation of nitriles from aliphatic halogenoalkanes

Answer 28

- KCN, alcohol solvent - heat under reflux - nucleophilic substitution

Question 29

Draw the formation of nitriles from halogenoalkanes

Question 30

Describe the hydrolysis of nitriles

Answer 30

- alkaline conditions - heated under reflux with NaOH to give carboxylate ion - mixture acidified to give carboxylic acid

Question 31

Describe the hydrolysis of amides

Answer 31

- heat under reflux with aqueous NaOH - sodium carboxylate ion and nitrogen containing compound

Question 32

Describe methods by which nitriles can be reduced to primary amines

Answer 32

- LiAlH4 in ethoxyethane (used for aromatic) - sodium in ethanol - hydrogen gas and nickel