The structures of 3 molecules A, B and C extracted from plants are shown below.
CH CH2 CH C
CH3 C CH2 C C CH CH3
CH2 CH2 CH CH2 CH C
C O CH3
(a) Two of these molecules are constitutional isomers. Identify these molecules and give
their molecular formula.
(i) Molecules __ Molecular formula: ___________
(ii) Explain why they are constitutional isomers.
(b) Each of the three molecules has enantiomers (optical isomers).
(i) Circle the chiral carbon on each of the structures above (the carbon atom responsible
for the optical isomerism).
(ii) Draw the structural relationship between a pair of enantiomers using molecule A as
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(iii) Describe a measurement that could be made to distinguish between a pair of optical
(c) Explain how each of the solutions, acidified potassium permanganate, K2Cr2O7/H+(aq),
and BenedicW¶V VRlXWiRn, could be used to distinguish between molecules A and C. In
your answer, you should
x describe expected observations
x give a reason for the different reactions linked to the functional groups in the
molecules. (You are not expected to write structures for the reaction products)
x draw structures for any organic products .
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(d) Molecule B can be produced from reactions of Molecule D (below) in a two -step
Complete the table below to document the functional groups taking part in each reaction
step, the reagents needed for each reaction and the type of reaction occurring.
Reagents Type of
CH CH2 CH C
CH2 CH2 CH CH2 CH C
C O CH3
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(a) Complete the table below by giving the IUPAC systematic name or the structural
formula for each compound.
Compound Structural formula IUPAC systematic name
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(b) (i) Complete the following reaction scheme for molecule A by writing the appropriate
products in the boxes provided.
/ H+ Ag+
(ii) Compare and contrast the two reactions. In your answer you should include:
x the type of reaction that occurs
x a description of the changes observed when the reaction is carried out
x reasons for the difference in the products of the two reactions
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(c) (i) Molecule C can undergo a reaction to produce a molecule with the same
molecular formula at the final step. Complete the following reaction scheme with
the formula of the most likely products at each step.
(ii) In EACH of the steps for the reaction in (i), there are two possible products.
Give a reason for the two different products and explain why the product you
have drawn is the one most likely to be formed.
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(a) (i) Polyhydroxybutryrate (PHB) is a plastic used in food packaging. It is made from
renewable resources and is completely biodegradable. A portion of the structure of
this polymer with two repeating units is shown here:
In the box below, draw a monomer which could be reacted to form this polymer.
(ii) A different type of nylon polymer can be formed from two monomers:
ClOC(CH2)2COCl and H2N(CH2)6 NH2
In the box below, draw a single repeating unit of the resulting polymer chain and
give the formula of the other product.
(b) The nylon polymer chain can be broken down in the presence of acid or base.
Compare and contrast the reactions of this polymer with both dilute acid and base
solutions. In your answer, you should include:
x the name of the type of reaction occurring
x structural formulae of the products formed from both acidic and basic reactions
x reagents and conditions required.
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Question 3c continues on the next page
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(c) Complete the reaction scheme below to show the structural formulae of compounds B, D
and E and the missing reagents and conditions required at steps 1 and 2
(ii) Both molecules C and D above can be used for further reactions with alcohols in the
production of esters. Explain which would be the preferred option