18.1 Carboxylic acids Flashcards
Test
- reacts with carbonates to form CO2 gas which will turn limewater milky
Production of carboxylic acids
1) Oxidation of primary alcohols and aldehydes (by either acidified K2Cr2O7 or KMnO4 and reflux)
2) Hydrolysis of nitriles (by either dilute acid or dilute alkali, followed by acidification)
3) Hydrolysis of esters (by either dilute acid or dilute alkali, followed by acidification)
Oxidation of primary alcohols and aldehydes (by either acidified K2Cr2O7 or KMnO4 and reflux)
1) Primary alcohol = aldehyde + carboxylic acid
2) Aldehyde = carboxylic acid
Hydrolysis of nitriles (by either dilute acid or dilute alkali, followed by acidification)
1) Nitrile + acid (usually HCI) + water = carboxylic acid + ammonium chloride salt
2) Nitrile + alkali (hydrolysed) + water= sodium carboxylate salt + ammonia
- sodium carboxylate salt can be acidified to carboxylic acid
Hydrolysis of esters (by either dilute acid or dilute alkali, followed by acidification)
1) Ester + water (reversible rxn) = carboxylic acid + alcohol
2) Ester + alkali hydrolyzed (usually NaOH) + heat = sodium carboxylate salt + alcohol
*sodium carboxylate salt can be acidified to carboxylic acid
Dissociation of carboxylic acids
- eqm lies to the left
- they are weak acids that don’t fully dissociate in water + solution formed has a pH value of less than 7
- drawing in notes
Reactions of carboxylic acids
1) Redox reactions with reactive metals
2) Neutralisation reactions with alkalis
3) Acid-base reactions with carbonates
4) Esterification with alcohols
5) Reduction by LiAIH4
*reactions in notes
Redox reactions with reactive metals
carboxylic acid + M = salt + hydrogen gas
Neutralisation reactions with alkalis
carboxylic acid + NaOH = salt + water
Acid-base reactions with carbonates
carboxylic acid + carbonate = salt + water + CO2 gas
Esterification with alcohols (H2SO4 as a catalyst)
alcohol + carboxylic acid = ester + H2O
Reduction by LiAIH4
Carboxylic acid + [H] = primary alcohol + H2O