18.1 carboxylic acids

State the ways in which carboxylic acids can be produced

1. oxidation of primary alcohols and aldehydes

2. Hydrolysis of nitriles

3. Hydrolysis of esters

Oxidation of primary alcohols & aldehydes

Acidified KMnO4 and reflux

First oxidised to aldehyde then to carboxylic acid

Acid Hydrolysis of nitriles

• Hydrolysis by dilute acid results in the formation of a carboxylic acid and ammonium salt

Alkaline hydrolysis of nitriles

• Hydrolysis by dilute alkali results in the formation of a sodium carboxylate salt and ammonia; Acidification is required to change the carboxylate ion into a carboxylic acid

Hydrolysis of esters

Hydrolysis of esters by dilute acid or dilute alkali and heat followed by acidification will reform the alcohol and the carboxylic acid

Acid vs alkaline hydrolysis of esters

• Hydrolysis by dilute acid is a reversible reaction where an equilibrium is established

• Hydrolysis by dilute alkali is an irreversible reaction as all the ester is broken down to form a sodium carboxylate salt and an alcohol; acidification is required to change the carboxylate ion into a carboxylic acid

Describe the ways in which carboxylic acids can react

1. Redox reactions with reactive metals

2. Neutralisation. Reaction with alkalis

3. Acid-base reaction

4. Esterification

5. Reduction

Redox reaction of carboxylic acids with reactive metals.

Produces salt and hydrogen gas

Neutralisation reaction with alkali

Salt and water

Acid base reactions with carbonates

Produces salt and water and carbon dioxide

Esterification with alcohols

H2SO4 as catalyst

Reduction by LiAlH4

Produced primary alcohols and water