OCR A Level Chemistry A Synthesis and analytical techniques November 2021 question paper H432/02

2-Methylbutane is reacted with chlorine by radical substitution.

What is the number of structural isomers with the molecular formula C₅H₁₁Cl that could be formed?

A 2

B 3

C 4

D 5

Which type(s) of stereoisomerism is/are shown by 2,4-dimethylhex-2-ene?

A E / Z isomerism only.

B Optical isomerism only.

C Both E / Z isomerism and optical isomerism.

D Neither E / Z isomerism nor optical isomerism.

Which sample contains the greatest number of carbon atoms?

A 20.0 g C₆H₅OH

B 30.0 g C₂H₅COOH

C 40.0 g CH₃CHO

D 50.0 g CH₃OH

What is the correct equation for the incomplete combustion of butan-1-ol?

CH₃CH₂COOCH₃ is heated with aqueous sodium hydroxide to produce two organic products.

What are the two organic products?

A CH₃CH₂COOH and CH₃OH

B CH₃CH₂COONa and CH₃OH

C CH₃CH₂COOH and CH₃ONa

D CH₃CH₂COONa and CH₃ONa

Menthol, shown below, is heated with an acid catalyst.

Which structure could be formed?

Which compound contains a bond angle of approximately 120º?

A CH₃CH₂CN

B CH₃CH(OH)CH₃

C CH₃COOCH₂CH₂CH₃

D CH₃CH₂CH₂NH₂

Which reaction is not a reduction?

A TLC chromatogram for two compounds is shown below.

What is the R_f value for the compound that is most strongly adsorbed onto the stationary phase?

A 0.25

B 0.33

C 0.69

D 0.78

Which compound could have produced the IR spectrum below?

A (CH₃)₂CHCHO

B (CH₃)₂CHCOOH

C CH₃CH(OH)CH=CH₂

D CH₃COCH(OH)CH₃

Which peak would be in the mass spectrum of propanal, CH₃CH₂CHO, but not in the mass spectrum of propanone, CH₃COCH₃?

A m / z = 15

B m / z = 29

C m / z = 43

D m / z = 58

Which compound(s) has/have four peaks in a¹³C NMR spectrum?

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1

Which of the following statement(s) provide(s) evidence for the delocalised model of benzene rather than the Kekulé model?

1 The enthalpy change of hydrogenation is more exothermic than expected.

2 Benzene only reacts with bromine in the presence of a halogen carrier.

3 The carbon-carbon bonds all have the same length.

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1

Compounds 1, 2 and 3 are heated with NaOH(aq).

Which compound(s) react(s)?

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1

But-1-ene, H₂C=CHCH₂CH₃, and buta-1,3-diene, H₂C=CH–CH=CH₂, are unsaturated compounds used to make many organic products.

But-1-ene and buta-1,3-diene have -bonds and -bonds.

How many - and -bonds are in one molecule of buta-1,3-diene?

-bonds:........ -bonds:........

But-1-ene is reacted with hydrogen bromide, forming a mixture of two saturated organic products.

One of the organic products is formed in a much greater quantity than the other organic product.

Explain why one organic product is formed in a much greater quantity than the other organic product.

Buta-1,3-diene is reacted with an excess of hydrogen bromide, forming a mixture of saturated organic products.

How many saturated organic products could be present in this mixture?

A student thought that buta-1,3-diene can show stereoisomerism.

The student drew out skeletal formulae for the stereoisomers of buta-1,3-diene:

Explain the term stereoisomerism.

Explain, with a reason, whether the student is correct or incorrect.

‘Diels-Alder’ reactions are used in the synthesis of many important organic compounds.

The Diels-Alder reaction of buta-1,3-diene with ethene is shown below.

Add curly arrows to the diagram below to complete the mechanism for this Diels-Alder reaction.

Two more Diels-Alder reactions of buta-1,3-diene are shown below.

In the boxes, draw the organic product of each reaction.

This question is about haloalkanes and polymers.

Freon-13, is a CFC with the molecular formula CCl F₃. In the upper atmosphere, the presence of Freon-13 can lead to ozone depletion.

Explain, with the aid of equations, how Freon-13 can lead to this ozone depletion.

Use ‘dots’ (•) to show the position of unpaired electrons.

An oligomer is a polymer with a low molecular mass and a small number of repeat units.

An oligomer made from 2-chloro-1,1,2-trifluoroethene is used as a lubricating oil.

Draw the repeat unit of this oligomer.

The boiling point of the lubricating oil can be increased by increasing the number of repeat units.

Explain this statement.

A polymer can be made from the monomers:

• 1,4-diaminobutane

• benzene-1,4-diacyl dichloride.

Draw the structures of these monomers and one repeat unit of the polymer.

This question is about organic acids.

Table 18.1 shows the R groups in four amino acids.

Most amino acids show optical isomerism.

Explain the term optical isomerism.

Draw 3-D diagrams to show the optical isomers of alanine.

How many optical isomers does threonine have?

Ibuprofen, shown below, is used as a painkiller.

What is the molecular formula of ibuprofen?

One ibuprofen tablet contains 400 mg of ibuprofen.

Calculate the number of ibuprofen molecules in one ibuprofen tablet.

Give your answer to 3 significant figures.

Tablets based on ibuprofen and lysine are now available from pharmacies.

These tablets are claimed to act faster than ibuprofen by being absorbed into the body more quickly than ibuprofen alone.

One type of these tablets contains a salt of ibuprofen and the amino acid lysine (R = –(CH₂)₄NH₂) in a 1:1 molar proportion.

Suggest why tablets based on a salt of ibuprofen should act faster in the body than ibuprofen.

This question is about organic synthesis.

Prenal, shown below, is used in the synthesis of some pharmaceuticals.

What is the systematic name for prenal?

* A student intends to synthesise compound A using the two-stage route below.

(chloromethyl)benzene Compound A

Plan a two-stage synthesis to prepare 5.44 g of compound A starting from (chloromethyl)benzene, C₆H₅CH₂Cl. Assume that the overall percentage yield of compound A from (chloromethyl)benzene is 25%.

In your answer, include the mass of C₆H₅CH₂Cl required, reagents, and equations where appropriate.

Purification details are not required.

This question is about reactions of phenol.

Complete the mechanism below for Stage 1 and Stage 2.

Show curly arrows, the structure of the intermediate and the missing formulae on the dotted lines.

Two molecules of salicylic acid can react together in the presence of an acid catalyst to form compound B.

Compound B has three rings and a molecular formula of C₁₄H₈O₄.

Write the equation for this reaction showing the structures of organic compounds.

A student reacts phenol with nitric acid and sulfuric acid at 100 °C to form impure crystals of an organic compound, C. The student purifies the crystals by recrystallisation.

Describe how the student could recrystallise the impure crystals to obtain a pure sample of C.

The pure sample of C is analysed to give the following results.

Percentage composition by mass: C, 31.44%; H, 1.31%; N, 18.34%; O, 48.91%.

The mass spectrum of C shows a molecular ion peak at m / z = 229.0

The¹³C NMR spectrum of C is shown below.

The table shows directing effects for different groups in the electrophilic substitution of aromatic compounds.

Analyse all the information to suggest the structure for C.

Show all your reasoning.

compound C

21* Compounds D, E and F are isomers with the molecular formula C₅H₁₀O. One of the compounds is alicyclic.

A student carries out test-tube tests on the compounds. The observations are shown below.

¹³C NMR spectrum of D
Compound D has 3 peaks at / ppm: 24, 36, 73.

¹H NMR spectra of E and F The integration data has been omitted.

Compound E

Compound F

Analyse the observations and results to identify the structures of D, E and F.

Explain your reasoning.