F324 June 2013 Unofficial Mark Scheme

F324-unofficial mark scheme (in progress)
Marks accounted for: 60/60

 Give the systematic name of the alcohol that is formed by this hydrolysis. (1)
 Propan(e)-1,2,3-triol
 What are the other monomers that make up this polymer? (3)
(Hydrolysed by hot NaOH)
 Two different carboxylic acids with COO-(Na+) - The monomers have COOH
as it's not referring to the hyrolysed products but the monomer units of
the polymer I'm pretty sure that the question said: "What are the other
products of this hydrolysis" or something along those lines
 One salt had a c=c double bond
 Why are people who drink a lot of goat's milk likely to suffer from CHD? (2)
 Fatty acids build up in the arteries and lead to CHD?
 Has trans isomer due to c=c double bond fatty acid linked to LDL's and
hence Atherosclerosis
 Trans-fatty acid in triglyceride of milk increases 'bad' cholesterol levels in
blood, resulting in increased risk of coronary heart disease and stroke
(straight from the spec)
 trans fatty acids can pack more tightly and hence have higher melting points
than cis fatty acids. --> so more likely to deposit on artery walls
 The other two molecules were fully saturated fatty acids which would also
lead to the formation of atheroma
 State how 4-aminophenol can behave as a base. (1)

 The lone pair on the Nitrogen atom in the amine group can accept a proton, forming
a dative covalent bond with it to give NH3+.
 NH2 + H+ ---> NH3+
 4-Aminophenol is produced by the reduction of 4-nitrophenol. Write an equation

to show the production of 4-aminophenol from 4-nitrophenol. Use [H] to
represent the reducing agent. (1)
 4-Nitrophenol + 6[H] = 4 Aminophenol + 2H20
 4-nitrophenol can be produced from 4-bromophenol. (4)

 Complete the mechanism for this reaction.
 Use +NO2 as the electrophile. Include any intermediate and the products.
 In the mechanism for this reaction, NO2 substitutes for Br on the ring.
 The flowchart below shows some reactions of 4-aminophenol. (Flowchart showing
4-aminophenol forming its ammonium salt in reaction I, forming 4-amino-3,5-
dibromophenol in reaction II, and reacting with Na in reaction III).
 Identity (typo in paper) the reagent in reaction I. (1)
 HCl
 Name the organic product of reaction II. (1)
4-amino-3,5-dibromophenol
As this is OCR I think that we should assume that they'll want the name to be
in alphabetical order. Agreed x1
 Write the equation for reaction II. (1)

C6H5(OH)NH2 + 2Br2 --> C6H5(OH)NH2Br2 + 2HBr
 In the box on the flowchart, draw the structure of the organic compound
formed by reaction III. (1)
 Sodium Phenoxide...
 The Sandmeyer reaction can be used to replace a diazonium group, N 2+, with a
halogen, X, on an aromatic ring. The reagent used for the reaction is a copper (I)
halide, CuX. Compound C shown below (azo dye shown), can be synthesised using
only 4-aminophenol and other standard laboratory reagents. The flowchart on the
next page shows this synthesis.
 State a possible use for compound C. (1)
 Dye/pharmaceutical
 On the flowchart on the next page: (5)
 State the reagents and conditions used for reaction 1
HNO2/NaNO2 and HCl and <10oC
 Suggest the structure of compound B
C6H4OHI (iodine and OH opposite)
 Suggest the reagent used for reaction 2

 CuI
 State the conditions used for reaction 3
 NaOh alkaline
 Alkaline conditions/ Ice or 10oC
 Phenol ? I think B was the phenol, so it's already in there
Also phenol isn't a condition - agreed x1
 (flowchart shows 4-aminophenol going to its diazonium ion

(compound A) in reaction 1, then going to compound B in reaction
2; A and B react to give the azo dye in reaction 3)
 Silk is a natural fibre. It is made up of two main polymers, fibroin and sericin. A
section of a fibroin strand is shown below. (Diagram below)
 Proteins are natural condensation polymers. State what is meant by a
condensation polymer. (1)
 Monomers join together due to the removal of a small molecule
(e.g. water)
 A student hydrolysed a sample of fibroin protein. She analysed the amino
acids that were formed from the hydrolysis. She found that fibroin
contained the amino acid glycine, H2NCH2COOH. Draw the structures of the
two other amino acids that make up the section of fibroin shown in the
diagram above. (2)
 H2N-CH(CH3)-COOH and H2N-CH(CH2OH)-COOH
 The isoelectric point of glycine is 5.8. Define the term isoelectric point and
draw the structure of glycine at its isoelectric point. (2)
 Isoelectric point is the pH at which an amino acid exists as a
zwitterion. (The pH at which an amino acid is bi-polar but has no
overall charge)
 H3N+C(H)(H)COO-
 The student then hydrolysed a section of sericin protein. She analysed the amino
acids formed using Thin-Layer Chromatography (TLC).
 Name the process by which TLC separates amino acids. (1)
 Adsorption
 The chromatogram the student obtained, and a table of Rf values for

amino acids, are shown below. Estimate the Rf value for the amino acid
found at X. Hence identify the amino acid found at X. (2)
 About 0.56-0.58? 2.7/5.7
 Methionine
 Quiana is a synthetic polymer that can be spun into a soft, silky fabric. The
monomers used to make Quiana are shown below.
 Draw a repeat unit of the polymer formed. (2)
 Draw the structure of each of the monomers which form this polymer. (2)
 Draw the third monomer (1)
 Are either of these right?
 Compound E (alcohol found in oak wood) can be converted in compound G as shown in
the flowchart below. (E reacts with excess K2Cr2O7/H2SO4 under reflux to give F in reaction
1, F reacts to give G in reaction 2, which is basically E with a carboxylic acid replacing the
terminal -OH group).
 Complete the flowchart to show the structure of the organic compound F and the
reagent needed for reaction 2. (1)
 What would you observe during reaction 1? (1)
Orange to green solution
 In reaction 1, compound E was heated under reflux with excess
K2Cr2O7/H2SO4. Suggest why these conditions were used, rather than the
reaction mixture being distilled during the process. (1)
To produce a COOH as opposed to an aldehyde
 Name the type of reaction taking place in reaction 2. (1)
Oxidation
^ANSWER IS REDUCTION - Agreed
 Describe a chemical test that you could use to detect the presence of a carbonyl
group in an organic compound. (2)
 Reagent: Brady's reagent (2,4-DNP, H2SO4 and methanol). 2,4-DNP alone
should be fine
 Observation: Orange precipitate
 Compound E is a single stereoisomer.
 Draw the skeletal formula of one other stereoisomer of compound E and
state the type of stereoisomerism. (3) Pretty sure this was 2 marks 1 for
the isomer 1 for the type
 Optical isomerism

 4.56 g of compound E was converted into compound G using the method
shown in the flowchart. 3.15 g of compound G was formed. Calculate the
percentage yield of compound G. Give your answer to three significant
figures. The Mr of compound E is 160.0. (3)
 63.5%. (The mr value given was correct, the wedge represented a
CH3, not a H)
 Compound G is heated for several hours under reflux, in the presence of a
concentrated sulfuric acid catalyst. An ester and a small inorganic molecule
are formed.
Complete the equation to show the two products formed by this reaction.
(2)
Something like this?
This may well also get all the marks but the true formula was two of the
molecules joined together forming 2 ester bonds and 2 H2O
 Show that the molecular formula is C10H12O2 (2)
 Add the percentages together and minus from 100 to get percentage of O.
Multiply each of the percentages (divided by 100) by the Mr and then divide
that by the mass of each type of atom to get C5H60 x 2
 Calculate percentage of O by doing 100-(C+H)
 How many different carbon environments (types of carbon) are present in a
molecule of compound L? (1)
 7
 State why TMS was added. (1)
 To give a peak at 0ppm to calibrate spectrum against
 Standard
 The 1H NMR spectrum includes an integration trace. What information can be
deduced about compound L from the integration trace? (1)
 The number of protons in each proton environment
 Determine the structure of compound L, show all your reasoning. (7)
 ester
 (CH3)2CH0-0-C6H5

 Nmr
 proton peak at 2-3ppm
 Peak between 0.7-2.0 (multiplet)- 7 protons attached= CH(CH3)2
 peak at 6.9-8.0 -benzene ring ( no OH)
 Carbon nmr
 Carbon peak at-183ppm= 0=C----0

F324 June 2013 Unofficial Mark Scheme

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F324-unofficial mark scheme (in progress)

Marks accounted for: 60/60

(Hydrolysed by hot NaOH)

 State how 4-aminophenol can behave as a base. (1)

 4-Aminophenol is produced by the reduction of 4-nitrophenol. Write an equation

 4-nitrophenol can be produced from 4-bromophenol. (4)

 Write the equation for reaction II. (1)

HNO2/NaNO2 and HCl and <10oC

 Suggest the structure of compound B

C6H4OHI (iodine and OH opposite)

 Suggest the reagent used for reaction 2

 (flowchart shows 4-aminophenol going to its diazonium ion

 The chromatogram the student obtained, and a table of Rf values for

^ANSWER IS REDUCTION - Agreed

Something like this?

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