6.1.3: Carboxylic acids and esters

Question 1

What is the functional group of a carboxylic acid?

Answer 1

-COOH (C=O and C-OH)

Question 2

How do you name carboxylic acids?

Answer 2

-oic acid

Question 3

Are carboxylic acids soluble in water? Why? What

influences their solubility

Answer 3

Yes. Acid group can form hydrogen bonds with water molecules

Question 4

What are the intermolecular forces in carboxylic

acids?

Answer 4

Hydrogen bonds in solid state - very strong.

Question 5

What are esters (what are they formed from)?

Functional group, general formula?

Answer 5

Formed from carboxylic acids and alcohols.

RCOOR’ (C=O, C-O-C)

Question 6

Write an equation for the reaction of ethanoic acid with propan-1-ol

Answer 6

CH3COOH + CH3CH2CH2OH → CH3COOCH2CH2CH3 + H2O

Question 7

How do you name esters?

Answer 7

Start with the alcohol group that has replaced the hydrogen, then acid part e.g. propyl (from alcohol) ethanoate (from carboxylic acid)

Question 8

What characteristic physical properties do esters

have?

Answer 8

Volatile, pleasant fruity smells e.g. apple, pear

drops

Question 9

What are some uses of esters?

Answer 9

Flavourings, perfumes (both for longer chains), solvents (short chains), plasticisers

Question 10

How could you distinguish carboxylic acids from other -OH containing compounds?

Answer 10

Add NaHCO3, acids will produce sodium salt, water and carbon dioxide.

Question 11

Write an equation for the reaction of ethanoic acid

with NaOH.

Answer 11

CH3COOH + NaOH → H2O + CH3COO-Na+

Question 12

Write an equation for the reaction of ethanoic acid

with Na2CO3

Answer 12

2CH3COOH + Na2CO3 → 2CH3COO-Na+ + H2O + CO2

Question 13

Write an equation for the reaction of ethanoic acid with

calcium oxide

Answer 13

2CH3COOH + CaO → (CH3COO)2Ca + H2O

Question 14

What catalyst is needed for the formation of esters

from alcohols and carboxylic acids?

Answer 14

Concentrated strong acid e.g. H2SO4

Question 15

What catalyst is needed for the hydrolysis of esters?

Answer 15

Dilute strong acid e.g. H2SO4

Question 16

What is an alternative method of hydrolysis?

Answer 16

Base hydrolysis

Question 17

What are the advantages of base hydrolysis?

Answer 17

Reaction goes to completion due to neutralisation
by base - more product in the mixture than acid
catalysed hydrolysis.

Question 18

What are carboxylic acid derivatives?

Answer 18

Molecules that have the acyl group as part of their structure, formed from carboxylic acids

Question 19

Name two acid derivatives and give their functional

groups.

Answer 19

Acyl chlorides: RCOCl

Acid anhydrides: RCOOCR / (RCO)2O

Question 20

How do you form an acyl chloride?

Answer 20

React a carboxylic acids with SOCl2

Question 21

If the nucleophile is ammonia for the acylation of acyl
chlorides or acid anhydrides, what are the products
of the reaction?

Answer 21

an amide

Question 22

Write an equation for the reaction of ethanoyl

chloride and ammonia

Answer 22

CH3COCl + 2NH3 → CH3CONH2 + NH4Cl

Question 23

If the nucleophile is a primary amine, what are the
products of the acylation of acyl chlorides or acid
anhydrides?

Answer 23

N-substituted amide

Question 24

Write an equation for the reaction of ethanoyl

chloride and methylamine

Answer 24

CH3COCl + CH3NH2 → CH3CONHCH3 + CH3NH3Cl

Question 25

If the nucleophile is an alcohol, what are the products of the acylation of acyl chlorides or acid anhydrides?

Answer 25

an ester

Question 26

Write an equation for the reaction of ethanoyl | chloride and ethanol

Answer 26

CH3COCl + CH3CH2OH → CH3COOCH2CH3 + HCl

Question 27

If the nucleophile is water, what are the products of | the acylation of acyl chlorides or acid anhydrides?

Answer 27

Carboxylic acid (hydrolysis produces an ester linkage)

Question 28

What is the name of this reaction (the acylation of acyl chlorides/acid anhydrides with water as a nucleophile)?

Answer 28

hydrolysis

Question 29

Write an equation for the reaction of ethanoyl | chloride and water.

Answer 29

CH3COCl + H2O → CH3COOH + HCl