A2 LEVEL CHEMISTRY

CARBONYL COMPOUNDS
CARBOXYLIC ACIDS AND ESTERS

TEST

Answer all questions
Max 57 marks

	
Name		…………………………………………………………..

Mark		……../57	……....%	Grade ………

1.	Hydroxyethanal, HOCH2CHO, is sometimes referred to as the ‘first sugar’ as it is the simplest possible molecule that contains both an aldehyde group and an alcohol group.
	A biochemist investigated some redox reactions of hydroxyethanal and found that several different products were produced.
(a)	The biochemist reacted hydroxyethanal with Tollens’ reagent.
(i)	State what the biochemist would see when hydroxyethanal reacts with Tollens’ reagent.
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[1]
(ii)	Write the structural formula of the organic product formed when hydroxyethanal reacts with Tollens’ reagent.

[1]
(b)	The biochemist also reacted hydroxyethanal with acidified dichromate by heating under reflux.
	Write an equation for this oxidation.
	Use [O] to represent the oxidising agent.

[2]
 (c)	The biochemist then reduced hydroxyethanal using aqueous NaBH4.
(i)	Write the structural formula of the organic product.
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[1]
(ii)	Outline the mechanism for this reduction.
	Use curly arrows and show any relevant dipoles.

[4]
[Total 9 marks]
2.	An unknown colourless liquid with molecular formula C4H8O was thought to be one of butanal, but-3-en-1-ol, or butanone.

(a)	State a simple chemical test that would positively identify:
(i)	butanal only;
reagent .................................................................................................
observation ...........................................................................................
organic product .....................................................................................
[3]
(ii)	but-3-en-1-ol only.
reagent .................................................................................................
observation ...........................................................................................
type of reaction .....................................................................................
[3]
 (b)	Butanal and butanone both react with 2,4-dinitrophenylhydrazine to produce mixtures containing orange precipitates.
	Outline how the mixtures containing these orange precipitates can be used to distinguish between butanal and butanone.
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[3]
[Total 9 marks]

3.	An ester D with the formula, CH3CH2COOCH2CH(CH3)2, is used in rum flavouring.
(a)	Draw a displayed formula of ester D.

[2]
(b)	Outline how you could obtain a sample of ester D, starting with a named carboxylic acid and a named alcohol.
	Include any essential reaction conditions and write an equation for the reaction. You do not need to include any details of the separation or purification of the ester.

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[6]
(c)	State a spectroscopic method that could be used to confirm that a sample of ester D has a molecular mass of 130.
	Explain how you would obtain the molecular mass of D from the spectrum.
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[2]
[Total 10 marks]
4.	Benzoic acid and phenylmethanol will react with each other in the presence of a suitable catalyst.
(i)	State a suitable catalyst for this reaction.
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[1]
(ii)	Draw the displayed formula of the organic product.

[2]
[Total 3 marks]
 
5.	Aspirin and paracetamol are commonly available painkillers.

	Aspirin and paracetamol can be prepared using ethanoic anhydride, (CH3CO)2O.
	Some examples of the reactions of ethanoic anhydride are shown below.
	reaction 1	(CH3CO)2O + CH3OH → CH3COOCH3 + CH3COOH
	reaction 2	(CH3CO)2O + CH3NH2 → CH3CONHCH3+ CH3COOH
	reaction 3	(CH3CO)2O + C6H5OH →  CH3COOC6H5 + CH3COOH
	Draw the structure of a compound that could react with ethanoic anhydride to form aspirin.

[Total 1 mark]

6.	Compound A is used to add the flavour of mushrooms to foods.

(a)	(i)	Apart from the benzene ring, name the two functional groups in compound A.
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[2]
(ii)	Draw the skeletal formula of compound A.

[1]
(iii)	Deduce the molecular formula of compound A.
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[1]
 (b)	Compound B is a stereoisomer of compound A.
	Explain what is meant by the term stereoisomerism. Use compounds A and B to illustrate your answer.
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[2]

(c)	If the food is cooked for a long time, naturally occurring acids catalyse the hydrolysis of compound A.
	Draw structures to show the two organic compounds formed by the acid hydrolysis of compound A.

[2]
(d)	The hydrolysis of compound A can be monitored by sampling the mixture at regular intervals, separating the components, and recording their infra-red spectra.
(i)	State two absorptions that would be expected in the infra-red spectrum of compound A, and identify the parts of the molecule responsible for each.
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[2]
(ii)	Suggest a wavenumber range within the spectrum that could be used to clearly distinguish compound A from the products formed by the hydrolysis reaction.
	Explain your answer.
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[2]
[Total 12 marks]

7.	The demand for ‘natural’ shampoos and detergents has led to the development of more biodegradable detergents such as sorbitan monolaurate, which is made from plants.
		
(i)	Suggest a type of reaction that could break down sorbitan monolaurate when it is washed into drains and rivers.
	Explain your answer and state the type of organic products formed.
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[3]
(ii)	Suggest one other reason why detergents such as sorbitan monolaurate are regarded as ‘environmentally friendly’.
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[1]
[Total 4 marks]

 8.	Explain why triglycerides are soluble in non-polar solvents and not in water.
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[Total 3 marks]

9.	Linoleic acid, C17H31COOH, is an unsaturated fatty acid found in triglycerides from sunflower oil.
(i)	Draw the structure of the triglyceride made from linoleic acid, C17H31COOH, and propane-1,2,3-triol. Show clearly all the bonds in the ester groups.

[2]
(ii)	Deduce the number of carbon to carbon double bonds in a molecule of the triglyceride.
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[1]
[Total 3 marks]

10.	Complete the reactions by drawing structural formulae in each of the boxes provided.
(i)	CH3CHO	
[1]
(ii)	H3CCOOCH2CH3 
[2]
 [Total 3 marks]