CHAPTER 19: Carboxylic Acids and
Derivatives I
19.1 Carboxylic Acids
19.2 Reactions of Carboxylic Acids
19.3 Esters
Learning outcomes:
(a) describe the formation of carboxylic acids from alcohols, aldehydes and nitriles.
(b) describe the reactions of carboxylic acids in the formation of:
(i) salts, by the use of reactive metals, alkalis or carbonates.
(ii) esters.
(iii) acyl chlorides.
(c) describe the formation of esters from carboxylic acids, using ethyl ethanoate as an example.
(d) describe the acid and base hydrolysis of esters.
(e) state the major commercial uses of esters, e.g. solvents, perfumes, flavourings.
, 19.1 Carboxylic Acids
Introduction to carboxylic acids
1) Carboxylic acids are compounds that contain the -COOH group.
2) Examples of carboxylic acids:
3) Salts of carboxylic acids are called carboxylate salts. The formation of
carboxylate salts shows that carboxylic acids are acidic. A carboxylate salt is
formed upon the removal of H⁺ from -COOH group, leaving -COO⁻.
Physical properties of carboxylic acids
1) Carboxylic acids have higher melting and boiling points than the
corresponding alcohols.
i. This is because in a pure carboxylic acid,
hydrogen bonding can occur between two
molecules of acid to produce a dimer.
ii. This doubles the size of the molecule,
making the van der Waals' forces stronger.
iii. Hence more energy is required to overcome these forces of attraction.
2) Small carboxylic acids are soluble in water.
i. This is because carboxylic acid is capable of forming
hydrogen bond with water molecule.
ii. However, the solubility decreases as the number of
carbon atoms increases. This is because the presence of
long hydrocarbon tail disrupts the effectiveness of
hydrogen bonding.
Derivatives I
19.1 Carboxylic Acids
19.2 Reactions of Carboxylic Acids
19.3 Esters
Learning outcomes:
(a) describe the formation of carboxylic acids from alcohols, aldehydes and nitriles.
(b) describe the reactions of carboxylic acids in the formation of:
(i) salts, by the use of reactive metals, alkalis or carbonates.
(ii) esters.
(iii) acyl chlorides.
(c) describe the formation of esters from carboxylic acids, using ethyl ethanoate as an example.
(d) describe the acid and base hydrolysis of esters.
(e) state the major commercial uses of esters, e.g. solvents, perfumes, flavourings.
, 19.1 Carboxylic Acids
Introduction to carboxylic acids
1) Carboxylic acids are compounds that contain the -COOH group.
2) Examples of carboxylic acids:
3) Salts of carboxylic acids are called carboxylate salts. The formation of
carboxylate salts shows that carboxylic acids are acidic. A carboxylate salt is
formed upon the removal of H⁺ from -COOH group, leaving -COO⁻.
Physical properties of carboxylic acids
1) Carboxylic acids have higher melting and boiling points than the
corresponding alcohols.
i. This is because in a pure carboxylic acid,
hydrogen bonding can occur between two
molecules of acid to produce a dimer.
ii. This doubles the size of the molecule,
making the van der Waals' forces stronger.
iii. Hence more energy is required to overcome these forces of attraction.
2) Small carboxylic acids are soluble in water.
i. This is because carboxylic acid is capable of forming
hydrogen bond with water molecule.
ii. However, the solubility decreases as the number of
carbon atoms increases. This is because the presence of
long hydrocarbon tail disrupts the effectiveness of
hydrogen bonding.
