Carboxylic acids and derivatives

7.1 Carboxylic acids and derivatives

Carboxylic acids are produced when 1° alcohols/aldehydes are oxidised.

- COOH

- carboxylic acids fewer than 6C are water-soluble (water molecules can H bond with functional group)

- in aq soln they are only slightly ionised = they are weak acids

test for presence:

- Na2CO3(aq) + carboxylic acids -> CO2

IUPAC nomenclature:

carboxylic acid: -oic acid

ester (C=O): -oate

amide: -amide

7.2 Esters

Preparation (esterification):

- alcohol + carboxylic acid -> ester (in presence of conc. strong acid catalyst)

- C-O bond breaks in acid

- an e.g. of a condensation reaction (H2O is the small molecule removed)

- reversible reactions: eq. can be shifted right if water is distilled or if a large excess of alcohol is used

- also used as plasticisers, increasing the flexibility of polymers

test for presence of alcohol or carboxylic acid

- warmed carboxylic acid in presence of conc sulphuric acid

- if remaining mixture has a sweet smell, this confirms presence of alcohol

plasticisers

- long polymer chains

- C-Cl bond is very polar

- high intermolecular attraction = strong, rigid plastic

- plasticisers molecules penetrate between polymer chains and increase distance between them

- polar effects are weakened = rigidity is reduced = polymer chains can slide over each other and plastic is soft and pliable

- over time, plasticiser evaporates causing 'leather' to lose its flexibility and crack

Hydrolysis of esters:

Content of the notes (1)