OCR A Level Chemistry A Synthesis and analytical techniques June 2019 question paper H432/02

Which alkane has the highest boiling point?

A CH₃(CH₂)₅CH₃

B (CH₃)₃CCH(CH₃)₂

C CH₃(CH₂)₃CH(CH₃)₂

D (CH₃)₂CHCH₂CH(CH₃)₂

Butane reacts with chlorine in the presence of ultraviolet radiation to form a mixture of organic products.

Which equation shows a propagation step in the mechanism for this reaction?

A Cl₂ → •Cl + •Cl

B •Cl + •C₄H₈Cl → C₄H₈Cl₂

C C₄H₉Cl + •Cl → C₄H₈Cl₂ + •H

D •Cl + C₄H₉Cl → •C₄H₈Cl + HCl

Which types of bonds are broken and formed in the reaction of ethene and bromine?

What is the organic product of the reaction below?

What is the number of chiral carbon atoms in the steroid molecule below?

Phenol reacts with bromine.

Which is the least likely organic product?

Which compound shows 4 peaks in its carbon-13 NMR spectrum?

A student reacts 4.50 g of C₆H₅NH₂ with excess CH₃COCl in the reaction below.

C₆H₅NH₂ + CH₃COCl → C₆H₅NHCOCH₃ + HCl

M_r = 93.0 M_r = 135.0

The reaction produces 3.25 g of C₆H₅NHCOCH₃.

What is the percentage yield of C₆H₅NHCOCH₃?

A 49.8

B 68.9

C 72.2

D 95.4

A compound produces the¹³C NMR spectrum below.

Which compound could have produced this spectrum?

A Propane

B 2-Methylbutane

C 2-Methylpropan-1-ol

D 2-Methylpropan-2-ol

A carbonyl compound is reacted with NaBH₄.

Which compound(s) could be formed?

1 2-Methylpentan-2-ol

2 2-Methylpentan-1-ol

3 3-Methylpentan-2-ol

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1

Which chemical(s) can react with phenol?

1 Potassium hydroxide

2 Ethanoyl chloride

3 Nitric acid

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1

The structure of a compound used to treat influenza is shown below.

Which functional group(s) is/are in a molecule of the compound?

1 Ester

2 Secondary amide

3 Ketone

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1

This question is about unsaturated aldehydes and alcohols.

Outline the reaction mechanism for the formation of one of the organic products.

Include curly arrows and relevant dipoles.

Explain why one of the organic products forms in a much greater quantity than the other organic product.

Describe how the observations from a chemical test would distinguish between geraniol and citronellal.

What is the molecular formula of geraniol?

Explain why geraniol and citronellal are structural isomers of each other.

Explain the term stereoisomerism.

This question is about -amino acids, RCH(NH₂)COOH.

Table 17.1 shows the R groups in four amino acids.

In the boxes, draw the organic products for the reactions of serine shown below.

What is the R_f value of serine (ser) in solvent W?

Analyse the chromatograms to identify the unknown amino acid.

Explain your reasoning.

Name of unknown amino acid........

Explanation........

This question is about esters.

The structure of ester A is shown below.

What is the systematic name of ester A ?

Name the type of reactions of ester A shown in (ii).

A polyester is formed from 200 molecules of 4-hydroxybenzoic acid.

What is the relative molecular mass, M_r, of the polyester?

M_r =........ g mol⁻¹

* A student intends to synthesise ester C.

Plan a two-stage synthesis to prepare 12.75 g of ester C starting from 2-methylpropanal, (CH₃)₂CHCHO. Assume the overall percentage yield of ester C from 2-methylpropanal is 40%.

In your answer include the mass of 2-methylpropanal required, reagents, conditions and equations where appropriate.

Purification details are not required.

This question is about benzene.

Over time, the Kekulé and delocalised models have been used to describe the bonding and structure of a benzene molecule.

Describe, in terms of orbital overlap, the similarities and differences between the bonding in the Kekulé model and the delocalised model of benzene.

Experimental evidence led to the general acceptance of the delocalised model over the Kekulé model.

Describe two pieces of evidence to support the delocalised model of benzene.

Benzene can be used as the starting material for the synthesis of compounds D and E, shown below.

In the diagrams C₆H₅ is a phenyl group.

Compounds D and E can be converted into polymers.

Draw two repeat units of these polymers.

Two repeat units of polymer formed from D

Two repeat units of polymer formed from E

State the type of polymer formed from compounds D and E.

From compound D........

From compound E........

In the synthesis of compounds D and E, benzene is first reacted with ethanoyl chloride, CH₃COCl, to form phenylethanone, shown below.

The reaction takes place in the presence of aluminium chloride, Al Cl₃, which acts as a catalyst.

In the mechanism for this reaction,

• ethanoyl chloride first reacts with aluminium chloride to form the CH₃–C⁺=O cation

• the CH₃–C⁺=O cation then behaves as an electrophile.

Complete the mechanism for the reaction.

Include equations to show the role of the Al Cl₃ catalyst, relevant curly arrows and the structure of the intermediate.

Formation of electrophile........

Regeneration of catalyst........

Complete the flowchart for the synthesis of compounds D and E from phenylethanone.

This question is about reaction mechanisms.

Chemists use curly arrows in reaction mechanisms.

What does a curly arrow show in a reaction mechanism?

Draw structures to show the products in the reaction mechanism below.

Use the mechanism in (ii) to explain what is meant by heterolytic fission.

An incomplete reaction mechanism is shown below.

What is the role of OH − in this mechanism?

21* Analysis of an unknown organic compound produced the following results.

Elemental analysis by mass C: 73.17%; H: 7.32%; O: 19.51%

Mass spectrum Molecular ion peak at m / z = 164.0

Infrared spectrum

The numbers by the peaks are the relative peak areas.

Use the results to suggest one possible structure for the unknown compound.

Show all your reasoning.