OCR A Level Chemistry A Synthesis and analytical techniques June 2023 question paper H432/02

Which compound is used for proton exchange in NMR spectroscopy?

A CCl₄

B CDCl₃

C D₂O

D Si(CH₃)₄

Which compound reacts with 2,4-dinitrophenylhydrazine but does not react with Tollens’ reagent?

A C₆H₅COCOOH

B C₆H₅CH(OH)CHO

C CH₃COCHO

D CH₃CH₂CH(OH)CH₃

Propyne, CH₃C≡CH, is a member of the alkynes homologous series with the C≡C functional group.

What is the general formula of the alkynes?

A C_nH_2n–4

B C_nH_2n–2

C C_nH_2n

D C_nH_2n+2

The structure of the painkiller paracetamol is shown below.

Which functional groups are present in paracetamol?

A alcohol, amide

B alcohol, arene, ketone, amine

C phenol, amide

D phenol, ketone, amine

Oxymetazoline, shown below, is used as a decongestant in the treatment of colds.

How many H atoms are in one molecule of oxymetazoline?

A 23

B 24

C 25

D 26

Which statement supports the delocalised model of benzene and not the Kekulé model?

A Sigma bonds overlap to form a -system.

B The carbon-carbon bond lengths are all the same.

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

D Benzene is more reactive than alkenes with bromine.

What is the systematic name for the compound below?

A 3,5-dimethylocta-1,3,6-triene

B 3,5-dimethylocta-2,5,7-triene

C 4,6-dimethylocta-1,3,6-triene

D 4,6-dimethylocta-2,5,7-triene

For complete combustion, 0.100 mol of an alkane requires 22.8 dm³ of O₂, measured at RTP.

Which alkane has undergone complete combustion?

A pentane

B hexane

C heptane

D octane

Which compound has the greatest number of peaks in its proton NMR spectrum?

The infrared spectrum of an organic compound is shown below.

Which compound could have produced this spectrum?

Which compound reacts with ethanoyl chloride?

Which compound(s) is/are aliphatic?

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1

Which compound(s) is/are hydrolysed by HC l (aq) to produce butanoic acid?

1 CH₃CH₂CH₂COOCH₃

2 CH₃CH₂CH₂CH₂CN

3 CH₃CH₂CH₂CH₂Cl

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1

Which ion(s) contain(s) bond angles of approximately 120º?

1 CH₃COO^–

2 C₆H₅O^–

3 (CH₃)₃C⁺

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1

This question is about hydrocarbons.

The boiling points of some hydrocarbons containing 6 carbon atoms are shown below.

State and explain the trend in boiling points shown by these hydrocarbons.

2-methylpentane reacts with bromine by radical substitution.

A mixture of organic products is formed, including 3-bromo-2-methylpentane, and compounds A and B.

Complete the table below to show the mechanism for the formation of 3-bromo-2-methylpentane and three possible equations for termination.

In your equations, use structural or skeletal formulae and ‘dots’ (•) for the position of

Organic compound A is formed by the substitution of all 14 H atoms in 2-methylpentane by Br atoms.

Write the equation, using molecular formulae, for the formation of compound A from 2-methylpentane.

Organic compound B is formed by the substitution of some of the 14 H atoms in 2-methylpentane by Br atoms.

0.8649 g of compound B is heated until it is vaporised.

Under the conditions used:

• compound B has a volume of 72.0 cm³

• the molar gas volume is 40.0 dm³ mol^–1.

Determine a possible molecular formula of compound B.

This question is about alcohols.

An unsaturated alcohol has 6 carbon atoms and contains one C=C bond.

Construct an equation for the complete combustion of this alcohol.

Compound C, shown below, is refluxed with excess acidified potassium dichromate(VI) to form a single organic product and one other product.

Complete the equation for this reaction.

Compound C

Draw the structures of the three isomers of C₇H₁₀ formed from compound D.

A student converts compound D into a diiodoalkane.

Suggest suitable reagents for this reaction.

There are 4 structural isomers of C₄H₁₀O that are alcohols.

A student predicts that these structural isomers could be distinguished using carbon-13 NMR spectroscopy.

Explain whether the student is correct.

In your answer, show how the peaks in the carbon-13 NMR spectra are linked to the structure of each alcohol isomer.

Outline the mechanism for this reaction, including the role of H₂SO₄ as a catalyst.

Determine the percentage yield of 1,3-dinitrobenzene.

Give your answer to 3 significant figures.

Describe how to purify the impure crystals in Step 3.

This question is about aromatic compounds containing the –COOH and –OH functional groups.

Salicylic acid, shown below, is used in the manufacture of some important medicines.

Salicylic acid

Complete the flowchart for reactions of salicylic acid, by adding the organic products in each

PAS, shown below, is an antibiotic used to treat several diseases including tuberculosis (TB).

A student predicts that PAS could polymerise to form a polymer containing both ester and amide linkages.

Draw a section of this polymer.

The section should contain one amide and one ester linkage, which should be displayed.

For the treatment of TB, the maximum daily dosage of PAS that should be prescribed is 300 mg per kg of body mass.

A child weighs 20.0 kg.

Calculate the number of PAS molecules in the maximum daily dosage of PAS for this child.

This question is about -amino acids.

The general formula of an -amino acid is RCH(NH₂)COOH.

Most -amino acids show optical isomerism.

Explain the term optical isomerism.

The -amino acid valine has the R group of –CH(CH₃)₂.

What is the systematic name of valine?

Draw diagrams to show 3D structures of the optical isomers of valine.

How many optical isomers are possible for compound E ?

A student hydrolyses compound E with dilute hydrochloric acid, HC l (aq).

Draw the structures of the organic products formed by this hydrolysis.

This question is about reactions of acrolein, H₂C=CHCHO.

Acrolein reacts with sodium cyanide in acidic conditions, NaCN(aq) / H + (aq).

Outline the reaction mechanism for this reaction, showing the intermediate and the organic product.

The structure of acrolein has been provided.

Include curly arrows and relevant dipoles.

Name this type of mechanism.

23* An unknown organic compound is analysed.

The results are shown below.

Addition of 2,4-DNP No visible change

Elemental analysis by mass C, 66.63%; H, 11.18%; O, 22.19%

Mass spectrum Molecular ion peak at m / z = 144.0

IR spectrum

Proton NMR spectrum The numbers by each peak are the relative peak areas.

Use the information to identify the organic compound.

Show all your reasoning.