3.3.9 Carboxylic acids and derivatives Flashcards
What is the general formula of a carboxylic acid and what is the nomenclature (the suffix)?
CnH2n+1COOH or RCOOH
alkan + oic acid
What are the properties of carboxylic acids and why?
. high solubility in water because they can form hydrogen bonds with water
. high melting points because they can form dimers (two identical molecules linked together)
What happens to the solubility of RCOOH as the chain length increases?
As the chain length of RCOOH increases, there is a greater region of non-polar which can not dissolve in polar solvents and therefore cannot form hydrogen bonds between molecules
Why are carboxylic acids considered weak acids?
They only partially ionise in water. Due to this, the concentration of H+ is low, therefore less acidic.
(Equilibrium lies to the left, which means only a little bit turns into ions)
What forms when RCOOH reacts with metal?
salt + hydrogen
What forms when RCOOH reacts with metal oxide?
salt + water
What forms when RCOOH reacts with metal hydroxide?
salt + water
What forms when RCOOH reacts with metal carbonate?
salt+ water +carbon dioxide
what is the functional group of esters and what is its nomenclature?
RCOOR’
oate
What are the uses of esters
fragrances and flavourings
(fruitier and sweeter than aldehydes and ketones)
Plasticisers - more flexible
What factors affect the strength of the acid?
Length of alkyl group - inductive effect
COO becomes more negative, hence it wouldn’t released the H+ easily
Longer chain = weaker COOH
How are esters produced? include the conditions.
Carboxylic acid + alcohol —> ester + water
Using H2SO4 catalyst and heat
What is the reaction of acid hydrolysis of esters?
Ester + water <—-> Carboxylic acid + alcohol
Using strong acid catalyst
What is the reaction of alkaline hydrolysis of esters?
Ester + NaOH —> salt + alcohol
How do you produce oils/fats?
Oil + water <—> glycerol + (fatty)acid
Using H2SO4 catalyst and heat
What is the reaction of the alkaline hydrolysis of oils/fats?
Oil + alkali —> glycerol + soap
How do you produce biodiesel?
Oil + methanol —> glycerol + biodiesel
Using OH- catalyst
What are the Carboxylic acid derivatives and their physical properties?
Ester (RCOOR) - can react with water
Acyl chloride (RCOCl) - reacts violently with water
Acid anhydride (RCOOCOR) - reacts with water
What is the reaction of acid hydrolysis of oils/fats?
Oil+ water —> glycerol + fatty acids
Describe a soap molecule and how it works.
Polar (hydrophilic) head fern hydrogen bond with water
Non-polar (hydrophobic) tail forms VDWs with dirt/grease
Grease is pulled apart and
Soap emulsifies grease and oil allowing them to mix with water and can be washed away
Products of acyl chloride reacting with water.
Carboxylic acid + HCL
Products of acyl chloride reacting with alcohol.
Ester + HCL
Products of acyl chloride reacting with excess ammonia.
Primary amide + NH4Cl
Products of acyl chloride reacting with primary amine.
Secondary amide + RNH3Cl
