Y13 Organic Synthesis and Analysis
Homework Booklet

Name: ………………….
Class: …………

Mark = …./90  .…%

□	Textbook summary questions completed and handed in

Q1.          Synthetic dyes can be manufactured starting from compounds such as 4-nitrophenylamine.
A synthesis of 4-nitrophenylamine starting from phenylamine is shown below.

(a)     An equation for formation of N-phenylethanamide in Step 1 of the synthesis is shown below.
2C6H5NH2   +   CH3COCl   →   C6H5NHCOCH3   +   C6H5NH3Cl
N-phenylethanamide
(i)      Calculate the % atom economy for the production of N-phenylethanamide
(Mr = 135.0).
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(ii)     In a process where 10.0 kg of phenylamine are used, the yield of N-phenylethanamide obtained is 5.38 kg.
Calculate the percentage yield of N-phenylethanamide.
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(iii)     Comment on your answers to parts (i) and (ii) with reference to the commercial viability of the process.

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(7)

(b)     Name and outline a mechanism for the reaction in Step 1.
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(5)
(c)     The mechanism of Step 2 involves attack by an electrophile. Write an equation showing the formation of the electrophile. Outline a mechanism for the reaction of this electrophile with benzene.
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(4)
(Total 16 marks)
 
Q2.Acyl chlorides and acid anhydrides are important compounds in organic synthesis.
(a)     Outline a mechanism for the reaction of CH3CH2COCl with CH3OH and name the organic product formed.
Mechanism

 
 
Name of organic product ...............................................................................
(5)

(b)     A polyester was produced by reacting a diol with a diacyl chloride. The repeating unit of the polymer is shown below.

(i)      Name the diol used.
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(1)
(ii)     Draw the displayed formula of the diacyl chloride used.

 
(1)
(iii)     A shirt was made from this polyester. A student wearing the shirt accidentally splashed aqueous sodium hydroxide on a sleeve. Holes later appeared in the sleeve where the sodium hydroxide had been.
Name the type of reaction that occurred between the polyester and the aqueous sodium hydroxide. Explain why the aqueous sodium hydroxide reacted with the polyester.
Type of reaction ....................................................................................
Explanation ...........................................................................................
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(3)
(c)     (i)      Complete the following equation for the preparation of aspirin using ethanoic anhydride by writing the structural formula of the missing product.
 
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(1)

(ii)     Suggest a name for the mechanism for the reaction in part (c)(i).
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(1)

(iii)     Give two industrial advantages, other than cost, of using ethanoic anhydride rather than ethanoyl chloride in the production of aspirin.
Advantage 1 ..........................................................................................
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Advantage 2 ..........................................................................................
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(2)
(d)     Complete the following equation for the reaction of one molecule of benzene-1,2-dicarboxylic anhydride (phthalic anhydride) with one molecule of methanol by drawing the structural formula of the single product

(1)
(e)     The indicator phenolphthalein is synthesised by reacting phthalic anhydride with phenol as shown in the following equation.

(i)      Name the functional group ringed in the structure of phenolphthalein.
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(1)
(ii)     Deduce the number of peaks in the 13C n.m.r. spectrum of phenolphthalein.
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(1)

(iii)     One of the carbon atoms in the structure of phenolphthalein shown above is labelled with an asterisk (*).
Use Table 3 on the Data Sheet to suggest a range of δ values for the peak due to this carbon atom in the 13C n.m.r. spectrum of phenolphthalein.
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(1)
(f)      Phenolphthalein can be used as an indicator in some acid–alkali titrations.
The pH range for phenolphthalein is 8.3 – 10.0
(i)      For each acid.alkali combination in the table below, put a tick () in the box if phenolphthalein could be used as an indicator.
 
Acid	Alkali	Tick
box ()	
sulfuric acid	sodium hydroxide	 	
hydrochloric acid	ammonia	 	
ethanoic acid	potassium hydroxide	 	
nitric acid	methylamine	 	

(2)
(ii)      In a titration, nitric acid is added from a burette to a solution of sodium hydroxide containing a few drops of phenolphthalein indicator.
Give the colour change at the end-point.
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(1)
(Total 21 marks)
Q3.          (a)     Name and outline a mechanism for the reaction of CH3CH2NH2 with CH3CH2COCl
Name the amide formed.

 

 

(6)

(b)     Haloalkanes such as CH3Cl are used in organic synthesis.
Outline a three-step synthesis of CH3CH2NH2 starting from methane. Your first step should involve the formation of CH3Cl
In your answer, identify the product of the second step and give the reagents and conditions for each step.
Equations and mechanisms are not required.
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(6)
(Total 12 marks)
 
Q4.Benzene reacts with ethanoyl chloride in a substitution reaction to form C6H5COCH3.
This reaction is catalysed by aluminium chloride.
(a)     Write equations to show the role of aluminium chloride as a catalyst in this reaction.
Outline a mechanism for the reaction of benzene.
Name the product, C6H5COCH3.
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(6)
(b)     The product of the substitution reaction (C6H5COCH3) was analysed by mass spectrometry. The most abundant fragment ion gave a peak in the mass spectrum with m/z = 105.
Draw the structure of this fragment ion.

 
(1)

(c)     When methylbenzene reacts with ethanoyl chloride and aluminium chloride, a similar substitution reaction occurs but the reaction is faster than the reaction of benzene.
Suggest why the reaction of methylbenzene is faster.
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(2)
(Total 9 marks)

Q5.Baking powder contains sodium hydrogencarbonate and an acid or a mixture of acids. One acid that may be in baking powder is 2,3-dihydroxybutanedioic acid. This has the molecular formula C4H6O6 and it is often referred to as tartaric acid.
(a)     Draw the structural formula of tartaric acid.

 

(1)
(b)     Write an equation for the reaction of tartaric acid (C4H6O6) with sodium hydrogencarbonate to form a salt, carbon dioxide and water.
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(1)
(c)     Substances that contain carbonate or hydrogencarbonate ions can be used to confirm the presence of an acid.
Identify one other substance that could be used to confirm the presence of acid groups in tartaric acid.
State the observation you would make when this other substance is added to an aqueous solution of tartaric acid.
Substance ......................................................................................................
Observation ....................................................................................................
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(2)
(d)     It is known that tartaric acid contains alcohol and carboxylic acid functional groups only. 
A test can be used to show that tartaric acid contains secondary alcohol groups, not tertiary alcohol groups.
(i)      Identify a reagent for this test and state the observation you would make for each type of alcohol.
Reagent ................................................................................................
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Observation for secondary alcohol .......................................................
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Observation for tertiary alcohol .............................................................
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(3)
(ii)     Suggest why this test cannot be used to distinguish between a primary alcohol and a secondary alcohol.
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(1)
(e)     Baking powder usually contains starch. Starch is added to absorb any water vapour that may come into contact with the baking powder when the container is opened.
Deduce a reason why this water vapour needs to be absorbed.
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 (1)
(f)     Sodium hydrogencarbonate in baking powder forms carbon dioxide during the production of bread and cakes.
Suggest one advantage of having an acid in baking powder.
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		(1)
(g)     Safety information indicates that tartaric acid and its salts can act as muscle toxins. 
These can cause paralysis and possible death.
Suggest one reason why the use of tartaric acid in baking powder is not a hazard to health.
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(1)
(Total 11 marks)

Q6.A sample of 2-methylpropan-2-ol was contaminated with butan-2-ol. The student separated the two alcohols using chromatography.
Identify a reagent or combination of reagents that the student could use to distinguish between these alcohols. State what would be observed for each alcohol.
Reagent(s) ..............................................................................................................
Observation with 2-methylpropan-2-ol ....................................................................
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Observation with butan-2-ol ....................................................................................
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(Total 3 marks)

Q7.Ethanoic acid, propyl ethanoate and propan-1-ol are all colourless liquids. Esters do not give a positive result with any of the usual tests for functional groups.
State how you could use chemical tests to show the presence of ethanoic acid and propan-1-ol in a mixture of the acid, the alcohol and the ester.
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(Total 4 marks)

Q8.Describe how you could distinguish between the compounds in the following pairs using one simple test-tube reaction in each case.
For each pair, identify a reagent and state what you would observe when both compounds are tested separately with this reagent.
(a)     

Reagent .........................................................................................................
Observation with R.........................................................................................
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Observation with S.........................................................................................
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(3)

(b)     

Reagent .........................................................................................................
Observation with T.........................................................................................
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Observation with U.........................................................................................
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(3)

(c)     

Reagent .........................................................................................................
Observation with V.........................................................................................
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Observation with W........................................................................................
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(3)
(Total 9 marks)

Q9.This question refers to the reaction sequence below.
 
Which one of the following is not involved in the reaction sequence?
A       esterification
B       hydrolysis
C       nucleophilic addition
D       reduction
(Total 1 mark)

Q10.This question concerns the preparation of the plastic poly(methyl 2-methylpropenoate) (Perspex), starting from propanone.
 
Which one of the following sets of reagents is not suitable for the step indicated?
A       Step 1 HCN (NaCN then dilute HCl)
B       Step 2 hot ethanolic KOH
C       Step 3 warm aqueous H2SO4
D       Step 4 CH3OH with an acid catalyst
(Total 1 mark)

Q11.Refer to the following reaction sequence:
 
Which one of the following types of reaction is not involved in the above sequence?
A       acylation
B       oxidation
C       reduction
D       dehydration
(Total 1 mark)
Q12.Refer to the following reaction sequence:
 
Which one of the following types of reaction mechanism is not involved in the above sequence?
A       electrophilic addition
B       electrophilic substitution
C       addition−elimination
D       elimination
(Total 1 mark)

Q13.Refer to the following reaction sequence:
 
Which one of the following would be the most appropriate to carry out Step 2?
A       H2 / Ni
B       Sn / HCl
C       NaBH4
D       Fe / HCl
(Total 1 mark)

M1.          
 
Mark
Range	The marking scheme for this part of the question includes an overall assessment for the Quality of Written Communication (QWC). There are no discrete marks for the assessment of QWC but the candidates’ QWC in this answer will be one of the criteria used to assign a level and award the marks for this part of the question
Descriptor
an answer will be expected to meet most of the criteria in the level descriptor	
4-5	–    claims supported by an appropriate range of evidence
–    good use of information or ideas about chemistry, going beyond those given in the question
–    argument well structured with minimal repetition or irrelevant points
–    accurate and clear expression of ideas with only minor errors of grammar, punctuation and spelling 	
2-3	–    claims partially supported by evidence
–    good use of information or ideas about chemistry given in the question but limited beyond this
–    the argument shows some attempt at structure
–    the ideas are expressed with reasonable clarity but with a few errors of grammar, punctuation and spelling	
0-1	–    valid points but not clearly linked to an argument structure
–    limited use of information or ideas about chemistry
–    unstructured
–    errors in spelling, punctuation and grammar or lack of fluency	

(a)     (i)      Mr of C6H5NH2 = 93    Mr of CH3COCl = 78.5
total Mr of reagents = 264.5
1
% atom economy =  × 100 QWC
1
=  × 100 = 51.0 %
1
(ii)     expected yield =  × 0.5 × 135 = 7.26 kg
1
% yield =  × 100 = 74.1 %
1
(iii)     Although yield appears satisfactory (74%) % atom economy
is only 51% QWC
1
nearly half of the material produced is waste and must be
disposed of QWC
1
(b)     (nucleophilic) addition-elimination
1

QWC (2)
4
(c)     HNO3 + 2H2SO4 → NO2+ + H3O+ + 2HSO4–
1

3
[16]
 
M2.(a)
•         M2 not allowed independent of M1, but allow M1 for correct          attack on C+
•         + rather than δ+ on C=O loses M2
•         If Cl lost with C=O breaking, max1 for M1
•         M3 for correct structure with charges but lp on O          is part of M4
•         only allow M4 after correct/very close M3
•         ignore Cl – removing H+
4
1
(b)     (i)      pentane-1,5-diol
Second ‘e’ and numbers needed
Allow 1,5-pentanediol but this is not IUPAC name
(ii)
Must show ALL bonds
1
(iii)     All three marks are independent
M1 (base or alkaline) Hydrolysis   (allow close spelling)
1
Allow (nucleophilic) addition-elimination or saponification
M2 δ+ C in polyester
1
M3 reacts with OH– or hydroxide ion
1
Not reacts with NaOH
1
(c)     (i)
Allow CH3COOH or CH3CO2H
1
(ii)     (nucleophilic) addition-elimination
Both addition and elimination needed and in that order
OR
(nucleophilic) addition followed by elimination
Do not allow electrophilic addition-elimination / esterification
Ignore acylation
1
(iii)     any two from: ethanoic anhydride is
•         less corrosive
•         less vulnerable to hydrolysis
•         less dangerous to use,
•         less violent/exothermic/vigorous reaction OR more controllable rxn
•         does not produce toxic/corrosive/harmful fumes (of HCl) OR does not
produce HCl
•         less volatile
NOT COST
List principle beyond two answers
2
(d)

1
(e)     (i)      ester
Do not allow ether
Ignore functional group/linkage/bond
1
(ii)     12 or twelve (peaks)
1
(iii)     160 – 185
Allow a number or range within these limits
Penalize extra ranges given
Ignore units
1
(f)     (i)      sulfuric acid	sodium hydroxide		
hydrochloric acid	ammonia	X or blank	
ethanoic acid	potassium hydroxide		
nitric acid	methylamine	X or blank	
4 correct       scores 2
3 correct       scores 1
2 or 1 correct   scores 0
2
(ii)     Pink to colourless
Allow ‘red’ OR ‘purple’ OR ‘magenta’ instead of ‘pink’
Do not allow ‘clear’ instead of ‘colourless’
1
[21]

M3.          (a)     (nucleophilic) addition-elimination
1

4
N-ethylpropanamide
minus on NH2 loses M1
M2 not allowed independent of M1, but allow M1 for correct attack on C+
+C=O loses M2
only allow M4 after correct or very close M3
lose M4 for Cl– removing H+ in mechanism, but ignore HCl as a product
Not N-ethylpropaneamide
1
(b)     CH3CN or ethan(e)nitrile or ethanonitrile
not ethanitrile
but allow correct formula with ethanitrile
1
for each step wrong or no reagent loses condition mark
contradiction loses mark
1
Step 1    Cl2
uv or above 300 °C
wrong or no reagent loses condition mark
1
Step 2    KCN
1
aq and alcoholic (both needed)
allow uv light/(sun)light/uv radiation
1
Step 3    H2/Ni or LiAlH4 or Na/C2H5OH
not CN– but mark on
NOT HCN or KCN + acid, and this loses condition mark
NOT NaBH4
Sn/HCl (forms aldehyde!)
ignore conditions
1
[12]
 
M4.(a)     CH3COCl   +   AlCl3    CH3CO+   +   AlCl4–
Allow RHS as 
Allow + on C or O in equation but + must be on C in mechanism below
Ignore curly arrows in equation even if wrong.
1
AlCl4– + H+  AlCl3 + HCl
1

• M1 arrow from within hexagon
to C or to + on C
• + must be on C of RCO in mechanism
• + in intermediate not too close to C1
• gap in horseshoe must be centred approximately around C1
• M3 arrow into hexagon unless Kekule
• allow M3 arrow independent of M2 structure
• ignore base removing H for M3
• NO mark for name of mechanism
3
Phenylethanone             ignore 1 in name, penalise other numbers
Note: this is the sixth marking point in (a)
1
(b)
+ must be on C
But allow [C6H5CO]+
1
(c)     M1 about electrons
methyl group has (positive) inductive effect OR increases electron density on 
benzene ring OR pushes electrons OR is electron releasing
Ignore reference to delocalisation
1
M2 about attraction
electrophile attracted more
or benzene ring better nucleophile
Allow intermediate ion stabilised
M2 only awarded after correct or close M1
1
[9]
M5.(a)     HOOC—CHOH—CHOH—COOH
Any suitable structural formula.
Displayed formula not required but bond sequences must be correct if shown.
1
(b)     C4H6O6  +  NaHCO3  →  C4H5O6Na  +  CO2  +  H2O
OR
C4H6O6  +  2NaHCO3  →  C4H4O6Na2  +  2CO2  +  2H2O
Allow equations based on the structural formula.
Allow multiples including fractions.
Allow any structure for C4H6O or C4H5O6Na
1
(c)     Suitable named indicator (eg litmus, methyl orange, Universal Indicator) / identified reactive metal (Mg, Zn or Fe)
Do not allow phenolphthalein without explanation of how a colour change would be seen.
Incorrect reagent, chemical error = 0 / 2
1
Appropriate colour in acid (eg red) / gas evolved
1
(d)     (i)      Reagent: Acidified potassium dichromate (solution)
If incomplete (correct) reagent, lose M1 but mark on.
Incorrect reagent, chemical error = 0 / 3
Allow acidified potassium manganate(VII)
1
Obs: orange to green
Purple to colourless (solution).
1
Obs: no (visible) change
Allow ‘no visible reaction’, but do not allow ‘no reaction’ without qualification.
1
(ii)     Both would give the same result / both oxidised by reagent / both react with the reagent or similar
Allow consequential answer from (i).
Chemical error if reagent in (i) is incorrect, 0 / 1
1
(e)     The water would allow the tartaric acid and sodium hydrogencarbonate to react (before use)
Ignore any reference to water reacting with the ingredients.
Ignore references to prevention of ‘caking’ or ‘clumping’.
Ignore references to shelf life without qualification.
1
(f)     Acid reacts (with NaHCO3 / Na2CO3) to form CO2
Allow ‘neutralises (NaHCO3 / Na2CO3) to form CO2’.
1
(g)     It is only used in very small quantities
Allow ‘decomposes in the reaction’.
Do not allow ‘reacts’ without qualification.
Ignore reference to formation of salts.
1
[11]
M6.Acidified potassium dichromate
Accept words or formulae.
Accept acidified potassium permanganate.
Accept Lucas reagent (conc HCl, ZnCl2) (cloudy in 5 mins for 2°, instantly for 3°).
Mark on for incomplete reagent.
Incorrect reagent CE = 0 / 3
Inclusion of Tollen’s etc with acidified potassium dichromate is incorrect reagent.
Not no reaction.
Either
Obs with 2-methylpropan-2-ol
No visible change
1
Obs with butan-2-ol
Orange to green (both colours needed)
1
or
 
 	Obs with 2-methylpropan-2-ol	orange	
 	Obs with butan-2-ol	green	

[3]

M7.Identification of acid by suitable method eg named indicator, named carbonate, specified reactive metal
Ignore any reference to the smell of the ester.
1
with expected results
Do not allow the use of any instrumental method eg i.r. or n.m.r.; must be a chemical test.
1
Identification of alcohol by suitable method eg oxidation by acidified potassium dichromate(VI)
1
with expected results
1
[4]
M8.In each section
•        If wrong or no reagent given, no marks for any observations;
•        Penalise incomplete reagent or incorrect formula – but mark observations
•        Mark each observation independently
•        Allow no reaction for no change / no observable reaction in all three parts, but not none or nothing
•        Q says one test. If two tests are given, score zero
(a)
  	 	K2Cr2O7 / H+	KMnO4 / H+	Lucas test (ZnCl2 / HCl)	
1
  	R
Primary alcohol	(Orange) goes green Penalise wrong starting colour	(purple) goes colourless / decolourises allow goes brown	No cloudiness	
1
  	S
Tertiary alcohol	no change / no observable reaction	no change / no observable reaction	Rapid cloudiness	
1
Allow acidified potassium manganate and acidified potassium dichromate without oxidation numbers
(b)
 
 	 	Na2CO3 / NaHCO3 named carbonate	metal eg Mg	named indicator	
PCl5      PCl3
      SOCl2
Named alcohol + HCl / H2SO4
1

 	T
ester	no change / no observable reaction	no change / no observable reaction	no effect	
no change / no observable reaction
1
  	U
Acid	Effervescence or (CO2) gas formed	Effervescence or (H2) gas formed	acid colour	
Fumes / (HCl) gas formed
Sweet smell
1
(c)
  	 	Fehling’s / Benedict’s	Tollens’ / [Ag(NH3)2]+	 	
K2Cr2O7/ H+	

I2 / NaOH
1
 	V
Ketone	no change / no observable reaction	 	
no change / no observable reaction	

no change / no observable reaction	

Yellow ppt
1
 	W
aldehyde	Red ppt	Silver mirror	 	
(Orange) goes green Penalise wrong starting colour	

no change / no observable reaction
1
[9]
M9.D
[1]
M10.B
[1]
M11.B
[1]
M12.A
[1]
M13.C
[1]