Carboxylic acids and esters Flashcards
What can the OH bond in carboxylic acids form? (1)
Form hydrogen bonding
Carboxylic acids can form hydrogen bonding. What does this mean about the melting and boiling point? (1)
They have relatively high MP and BP compared to similar sized alkanes
As the length of the hydrocarbon chain increases, what does this suggest about the solubility of acids?
Decreases
List 4 uses of esters (4)
Solvent for many reactions
Plasticisers (to make plastic objects more flexible)
Perfumes
Flavourings
What is the name of the reaction which forms esters?
Esterification
What is needed for esterification to take place? (4)
Carboxylic acids
Alcohol
Concentrated H2SO4 catalyst
Water is the by product
Esterification is a what kind of reaction?
Reversible
What are the two methods of ester hydrolysis? (2)
Acid catalysed hydrolysis
Base catalysed hydrolysis
Reagents and conditions of acid catalysed hydrolysis of esters (2)
Heat and reflux using a strong acid catalyst
Reagents and conditions of base catalysed hydrolysis of esters (2)
Warm aqueous NaOH
How to increase yield in base catalysed hydrolysis of esters (2)
Once the carboxylic acid forms it reacts with NaOH to form the salt of the acid
This increases yield as it shifts the position of the equilibrium to the right
What is the IUPAC name of glycerol (1)
propane-1,2,3-triol
What are tri-esters (in animal fats and vegetable oils)? (2)
The alcohol glycerol (propane-1,2,3-triol)
Which has formed ester links to 3 long carboxylic acids
Product of acid hydrolysis of tri-esters from fats and vegetable oils (2)
Form constituent carboxylic acids
Propane-1,2,3-triol (glycerol)
Product of base hydrolysis of tri-esters from fats and vegetable oils (2)
Constituent carboxylic acid salts
Propane-1,2,3-triol (glycerol)
Give one use of carboxylic acid salts formed from base hydrolysis of tri-esters from fats and oils (1)
soap
What is biodiesel and how is it formed? (2)
Mixture of methyl esters of long-chain carboxylic acids (formed from hydrolysis of tri-esters)
Produced by reacting vegetable oils with methanol in the presence of a catalyst
Reagents and conditions for the production of biodiesel (3)
Tri-ester
methanol
NaOH catalyst
What is biodiesel a mixture of?
Methyl esters
List 2 uses of biodiesel (2)
Conserve crude oil supplies
Reduce the amount of CO2 released (biodiesel is carbon neutral)
What are the different nucleophiles acyl chlorides react with?
Water
Alcohol
Ammonia
Amine
What is the name of the mechanism when acyl chlorides react with nucleophiles?
Nucleophilic Addition-Elimination
What is produced when acyl chlorides react with water? (2)
Carboxylic acid
HCL
What is produced when acyl chlorides react with an alcohol? (2)
Ester
HCL
What is produced when acyl chlorides react with ammonia? (2)
Amine
HCL
What is produced when acyl chlorides react with excess ammonia? (2)
Amine
NH4Cl
What is the functional group of amides?
RCONH2
What is the functional group in amines?
N
What is produced when acyl chlorides react with an amine? (2)
N-substituted amide
HCL but because an amine is present these react to form an ammonium chloride salt as the side product
What is the functional group of N-substituted amide?
RCONHR’
Why is it possible to form two organic products when a nucleophile attacks an acid anhydride (2)
Because the acid anhydride is asymmetrical
Nucleophile can attack either carbonyl group
Why are acid anhydrides used more often than acyl chlorides? (4)
Less corrosive
Don’t react with water
Safer as the side product is carboxylic acids whereas acyl chlorides produce HCL vapours
Cheaper
