Carboxylic Acids (CIE AS Chemistry)

Sour milk contains a compound called lactic acid (2-hydroxypropanoic acid) which has the molecular formula CH₃CH(OH)CO₂H.

Which of the following reactions could lactic acid undergo?

Apples contain a compound called malic acid.

Which substance will react with only one hydroxyl groups in malic acid under suitable conditions?

The natural bacterial fermentation of milk produces a compound called propanoic acid.

Propanoic acid is partly responsible for the flavour of Swiss cheese. Its structure is shown below:

Which starting materials could be used to produce propanoic acid?

 

	CH3CH2CN	CH3CH2CHO	CH3CH2CH2OH
A	✓	✓	✓
B	✓	✓	x
C	x	✓	✓
D	✓	x	x

 

Sirolimus is a drug used to treat patients after kidney transplants.

Sirolimus produces an equimolar mixture of two organic products, on reaction with hot aqueous sodium hydroxide.

What is the structural formula of the product with the lower relative molecular mass?

Compound K, C₅H₁₂O, is oxidised by acidified sodium dichromate (VI) to compound L.

Compound L reacts with butan-2-ol in the presence of a little concentrated sulfuric acid to give liquid M.

What could be the formula of liquid M?

Compound X can be made from 2-hydroxybutanoic acid.

What should be heated with 2-hydroxybutanoic acid in order to make compound X?

Oxaloacetic acid can be synthesised from fumaric acid in a two-step process involving the intermediate Z.

 

Each step involved can be achieved in the laboratory by a single reagent. 

What could be the intermediate Z and the reagent for step 2?

	Z	Reagent for step 2
A B C D	HO2CCH(OH)CH2CO2H HO2CCH(OH)CH2CO2H HO2CCHBrCH2CO2H HO2CCHBrCH(OH)CO2H	Fehling’s solution Warm acidified K2Cr2O7 Warm acidified KMnO4 Warm NaOH (aq)

Citric acid gives lemons and other citrus fruits their sour taste.

HO₂CCH₂C(OH)(CO₂H)CH₂CO₂H

        citric acid

What is the volume of 0.2 mol dm^–3 sodium hydroxide solution required to neutralise a solution containing 0.008 mol of citric acid?

The compound 2-ethyl-3-methylbutanoic acid gives rum it’s signature smell.

Which compound will produce 2-ethyl-3-methylbutanoic acid by heating under reflux with alcoholic sodium cyanide and subsequent acid hydrolysis of the reaction product?

Digestion of various foods and medicines can cause acidic compounds to pass through the body. The stomach wall can become sensitive to acidic compounds, resulting in stomach ulcers.

Which of the following is the most acidic compound?