Carboxylic Acids And Esters Flashcards
Physical properties of carboxylic acids
Every carboxylic acid has a different melting point
1. OH Bond forms hydrogen bonding which has a high melting point and boiling point compared to similar size alkanes.
2. The oxygen in carboxylic acids are polar whereas the hydrocarbon chain of a carboxylic acid is nonpolar so doesn’t dissolve in water.
A shorter carboxylic acid is more soluble than a longer carboxylic acid as the hydrocarbon chain part of the molecule is longer even though the COOH dissolves well this is cancelled out by the Insolublility of the chain
Naming esters
1.Chain with double carbon with Oxygen is the second part
2. The cabin after the single c-o is the first part
Forming esters
Carboxylic acid and alcohol
Condensation reaction - removal of a H2O ( remember Alcool as alcohol looses a h whereas carboxylic acid looses a OH)
Reversible reaction
Catalysed by a acid catalyst
2 ways of hydrolysing esters
- Hydrolysis which is the addition of H2O molecule
- Base hydrolysis using NaOH as a catalyst always forming a sodium oata and carboxylic acid
Key pints about base hydrolysis
Once the sodium ota is formed this increases the yield so equilibrium shifts it the left hand side to oppose increase in yield. This in an inappropriate method of you want to get carboxylic acid.
Uses of esters
Fats and oils such as triesters
Chemical name of glycerol
Propane-1,2,3-triol
Formation of triester(triglycerides)
3 Condensation reaction between glycerol and 3 fatty acids which are carboxylic acid chains forming a triester and 3 water molecules
Hydrolysis of tri esters
Hydrolysis with 3 water molecules to form carboxylic chain and glycerol
Base hydrolysis forming glycerol and sodium aota
Using methanol to form biodiesel
Use of sodium eg ethanoate
Soap
Polar head dissolves in water and non polar part dissolves into water and grease
Biodiesel
Hydrolysis of triesters into glycerol and 3 biodiesel molecules with CH3O attached
Other uses of esters
Flavouring
Perfumes
Acyl chloride
ROCl
Always oyl chloride
Acid anhydrides
RCOOR
Name in alphabetical order eg ethanoic propanoic anhydride
Name of reaction with nucleophile and acyl chloride
Nucleophilic addition elimination reaction.
4 nucleophile
Water
Alcohol
Ammonia
Amine
Formation of 4 things
Carboxylic acid
Ester
Amide
N substituted amide
Amide
C=O WITH NH2
RCONH2
Eg propanamide
N - substituted amide
RCONHR
Replace one H on nitrogen with R group
Acid anhydride acylation
Remove one of the groups on either side of the oxygen
Why are acylation of acid anhydride used more than acyl chloride
Doesn’t produce HCl fumes which are corrosive so safer
Cheaper
Less corrosive
