carboxylic acid derivatives 26.4 Flashcards
What is a derivative of a carboxylic acid?
A compound that can be hydrolysed to form the parent carboxylic acid.
What do esters , acyl chlorides, amides and acid anhydrides have in common?
They are all derivatives of carboxylic acids
What is the acyl group ?
A carbon double bonded to an oxygen and single bonded to a carbon chain, (the spare bond in an acyl group bonds to chlorine or acid anhydride or amide group)
Draw methyl ethanoate
See Pg 202 for answer
How are acid anhydride molecules formed?
Removal of water between two carboxylic acids
What is esterification?
The reaction of an alcohol with a carboxylic acid to form an ester.
State the reagents and conditions for esterification
Alcohol + carboxylic acid —> ester
Reagents warmed
Small amount of conc. Sulfuric acid as catalyst
Esters can be hydrolysed by aqueous acid or alkali, what is hydrolysis?
The chemical breakdown of a compound in the presence of water or in aqueous solution
How do you carry out acid hydrolysis of an ester?
- The ester is heated under reflux with dilute aqueous acid
2. The ester is broken down by water with the acid acting as a catalyst
Name the products of acid hydrolysis
A carboxylic acid and an alcohol
What is alkaline hydrolysis of an ester?
- Known as saponification
- Is irreversible
- The ester is heated under reflux with aqueous hydroxide ions
What is formed from alkaline hydrolysis?
A carboxylate ion and an alcohol
The ion often forms a salt with any + ions in solution
How are acyl chlorides prepared?
Directly from their parent C. Acid by reaction with thionyl chloride SOCl2
Name the products of preparation of an acyl chloride
Sulfur dioxide and hydrogen chloride
Both harmful gases
Why might preparation of acyl chlorides be carried out in a fume cupboard?
Harmful gaseous products
Why are acyl chlorides useful?
Very reactive, can be converted into esters and amides easily and with good yields.
How do acyl chlorides react ?
With nucleophiles by loosing the chloride ion whilst retaining the C=O bond.
Acyl chloride + alcohol —>
Ester
Draw out the reaction for and name products of ethanoyl chloride + propan-1-ol
See Pg 205
Why are acyl chlorides used to react with esters?
Carboxylic acids are not reactive enough to form esters with phenol
Acyl chlorides and acid anhydrides are more reactive and will produce esters with phenol
Difference between ketone and esters?
Ketones have a carbonyl group bonded to 2 carbon chains
Esters have a carbonyl group bonded to 1 carbon chain 1 alkoxy group
Draw the reaction of ethanoyl chloride + phenol and name the product
See Pg 205
How do you convert acyl chloride back to carboxylic acid?
Add water (hydrolysis)
What happens when you add water to acyl chlorides ?
Violent reaction takes place
Dense steamy HCl given of
Carboxylic acid formed
Draw reaction for ethanoyl chloride + HCl and name products
See Pg 205
