Carboxylic acids and derivatives (Organic) (complete) Flashcards
Give the chemical test for carboxylic acids
Add sodium carbonate - bubbles/effervescence.
What is esterification?
- The forming of esters when alcohols react with carboxylic acids.
Describe the process of esterification.
- Add alcohol to carboxylic acid (and conc acid catalyst).
- Slow reaction and reversible.
What is ester hydrolysis/saponification?
- The splitting of esters (acidic) - ester hydrolysis - slow and reversible
- The splitting of esters (+ NaOH )(alkali) - saponification - a salt of carboxylic acid formed and alcohol - used to form bars of soap.
Name some used of esters
- Food flavourings
- Perfumes
- Solvents
- Plasticisers
What is adulation?
- The insertion of an acrylic group into a compound.
Give the two types of acylation
- Acylation (water, alcohols, ammonia, amines)
- Friedel-Crafts acylation (aromatic)
Describe Friedel-Crafts acylation
- Reacting compound - Aromatics
- Reagants - acyl chloride, acid anhydride
- Catalyst - AlCl3 (aluminium chloride)
- Mechanism - electrophilic substitution
Describe Acylation (NOT friedel-crafts)
- Reactants - water, ammonia, amines, alcohols
- Reagants - acyl chloride, acid anhydride
- Mechanism - nucleophilic addition-elimination
How does an acyl chloride react when added to water?
- very violently, choking HCl fumes, crackling sound, exothermic, ethanoic acid produced.
How does an acyl chloride react when added to ethanol?
- very violent, choking HCl fumes, crackling sound, exothermic, ethyl ethanoate produced
How does an acyl chloride react when added to ammonia?
- very violent, crackling sound, exothermic, white fumes produced.
How does an acyl chloride react when added to phenylamine?
violent, crackling sounds exothermic, white fumes produced.
Describe the process of forming fatty acid salts (soap) and glycerol from lipids.
- Saponification - add 3 potassium hydroxide to the lipid.
Describe the process of forming biodiesel from lipids.
- Add 3 Methanol and potassium hydroxide to the lipid.
Why is ethanoic anhydride used not ethanoyl chloride for the industrial prep of aspirin?
- Ethanoic anyhydride is much less vigorous so a more easily controlled reaction. No corrosive HCl gas is produced, but ethanoic acid is which can be sold.
Why are acid anhydrides less reactive than acyl chlorides?
- Both O and Cl are more electronegative than C, however Cl is only pulling one shared pair of electrons towards itself. Oxygen is pulling two shared pairs, so the effect is not as strong. Cl-Cl bond breaks more easily than C-O bond.
Which is the best nucleophile for acylation?
- Amine > Ammonia > Alcohol > Water
- N has 7 protons attracting its own outer electrons, O has 8 protons so holds its own lone pair tighter than N. This makes O less able to act as a lone pair donor than N.
- Amines have a C chain which pushes electron density onto N. This electron pushing helps the lone pair to be released (repulsion) so makes amines better than ammonia at being a nucleophile (lone pair donor)
