Summary A* GRADE AQA A-Level Chemistry: Organic - Carboxylic acids and derivatives (3.3.9)

1. Carboxylic acids: -COOH (-oic acid)
carboxyl functional group = carbonyl + hydroxyl

weak acids: partially dissociate into carboxylate- + H+ in water

carboxylic acid + carbonate CO32- = salt + CO2 + H2O

Esterification
carboxylic acid + alcohol + conc sulphuric acid catalyst + heat ⇌ ester + water




Esters: -COO-
1. alkyl group from alcohol
2. -oate


hydrolysis – reflux
acid: dilute H2SO4 catalyst + water ⇌ alcohol + carboxylic acid = reversible
alkaline: dilute NaOH → alcohol + Nacarboxylate = irreversible



uses
- perfume & food flavouring – sweet smell
- glue & printing ink solvents: polar (polar solutes) + low boiling point (evaporate easily)
- plasticisers: make plastics more flexible



fats & oils = esters: fatty acids (long-chain carboxylic acids) + glycerol
- Animal fats: solid at room temp – saturated (pack closely) = high VDW
- Vegetable oils: liquid at room temp – unsaturated (don’t pack closely) = weak VDW

NaOH alkaline hydrolysis = glycerol + soap (sodium salt of long-chain carboxylic acid)



biodiesel: mixture of methyl esters of fatty acids (long-chain carboxylic acids)
vegetable oil + methanol + KOH catalyst → glycerol + methyl ester