OCR A Level Chemistry A Synthesis and analytical techniques June 2017 question paper H432/02

A chemist compares the rates of hydrolysis of 1-chloropropane and 1-bromopropane in ethanol.

Which reagent in aqueous solution should be used?

A Silver chloride

B Silver nitrate

C Potassium chloride

D Potassium nitrate

How can the molecule below be described?

A Aromatic and alicyclic

B Aliphatic and unsaturated

C Aromatic and unsaturated

D Alicyclic and saturated

Complete combustion of an organic compound forms 40 cm³ of carbon dioxide and 40 cm³ water vapour, under the same conditions of temperature and pressure.

Which molecular formula could the organic compound have?

A C₃H₈

B C₂H₂O

C C₂H₄O

D C₂H₃N

Which type of reaction has the greatest atom economy?

A Substitution

B Hydrolysis

C Elimination

D Addition

Four atoms, 1–4, are labelled in the structure below.

Which atom has a trigonal planar arrangement of bonds around it?

A Atom 1

B Atom 2

C Atom 3

D Atom 4

Which molecule is a secondary amine?

What is the number of chiral centres in the molecule below?

What is the molecular formula of the compound below?

Equal amounts of the four compounds are added to the same volume of water.

Which compound would produce the most acidic solution?

A CH₃CONH₂

B CH₃COOH

C CH₃COOCH₃

D CH₃COCl

The compound below is analysed by¹H NMR spectroscopy.

How many peaks are observed in the¹H NMR spectrum?

A 5

B 4

C 3

D 2

0.1 mol of HOOCCH₂COOH are reacted with 0.1 mol of aqueous NaOH.

How many molecules of water are formed?

A 6.02 × 10²²

B 3.01 × 10²²

C 6.02 × 10²³

D 3.01 × 10²³

Which reagents could be used to prepare CH₃CH₂CONHCH₃?

A CH₃CH₂COCl + CH₃NH₂

B CH₃CH₂CONH₂ + CH₃Br

C CH₃CH₂COONa + CH₃NH₂

D CH₃CH₂COCH₃ + NH₃

Ethane reacts with chlorine by radical substitution to form chloroethane.

Which radical(s) is/are present in the mechanism?

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1

Which compound(s) is a/are structural isomer(s) of C₆H₁₂O₂?

1 hexanoic acid

2 ethyl butanoate

3 propyl propanoate

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1

This question is about unsaturated hydrocarbons.

Compound A and compound B are isomers.

Compound A has a lower melting point than compound B.

Suggest why.

Compound C, CH₃CH₂CH=CHCH₂CH₂OH, exists as cis and trans stereoisomers.

Name compound C.

Define the term stereoisomers.

Draw the structures of the cis and trans stereoisomers of compound C.

The C=C group in an alkene contains a -bond.

Complete the diagram below to show how p-orbitals are involved in the formation of a -bond.

Compound D, shown below, reacts with hydrogen bromide by electrophilic addition. A mixture of two organic compounds, E and F, is formed.

compound D

Suggest how an HBr molecule can act as an electrophile.

Draw the structures of the two organic compounds E and F.

Outline the mechanism of the reaction between compound D and hydrogen bromide to form either compound E or compound F.

Include curly arrows and relevant dipoles.

Which of E or F is the major organic product?

Explain your answer.

Major organic product........

Explanation........

Myrcene, C₁₀H₁₆, is a naturally occurring hydrocarbon containing more than one carbon-carbon double bond.

Reaction of 204 mg of myrcene with hydrogen gas produces a saturated alkane.

Calculate the volume of hydrogen gas, in cm³ and measured at RTP, needed for this reaction.

Show your working.

-Carotene is a naturally occurring unsaturated hydrocarbon found in carrots. A -carotene molecule contains 40 carbon atoms, has two rings, and a branched chain.

0.0200 mol of -carotene reacts with 5.28 dm³ of hydrogen gas to form a saturated hydrocarbon.

Using molecular formulae, construct a balanced equation for this reaction.

Include relevant calculations and reasoning.

Equation........

This question is about the chemistry of aromatic compounds.

Benzoic acid can be nitrated by concentrated nitric acid in the presence of concentrated sulfuric acid as a catalyst, as shown in Equation 17.1.

The organic product of this reaction is 3-nitrobenzoic acid.

Outline the mechanism for this nitration of benzoic acid.

Show how H₂SO₄ behaves as a catalyst.

* A chemist carries out the reaction in Equation 17.1 using 4.97 g of benzoic acid.

The chemist obtains 3-nitrobenzoic acid as an impure solid.

The chemist purifies the solid to obtain 4.85 g of 3-nitrobenzoic acid.

Describe a method to obtain a pure sample of 3-nitrobenzoic acid from the impure solid, determine the percentage yield and check its purity.

A student investigates the relative ease of nitration of phenol, benzene, and benzoic acid.

The student finds that the conditions required for the nitration of each compound are different, as shown in Table 17.1.

State the trend in the relative ease of nitration of phenol, benzene, and benzoic acid.

Apply your knowledge of the bonding in arenes to explain the trend in part (b)(i).

A student synthesises 3-bromophenylamine, shown below, starting from nitrobenzene.

Complete the flowchart showing the structure of the intermediate and the formulae the reagents for each stage.

Another student attempts the same synthesis but carries out reduction before bromination. The student was surprised to find that two structural isomers of 3-bromophenylamine had been formed instead of the desired organic product.

Explain this result and suggest the structures of the two isomers that formed.

Explanation........

Structures

This question is about organic compounds containing nitrogen.

Sodium cyanide, NaCN, can be reacted with many organic compounds to increase the length of a carbon chain.

1-Chloropropane, CH₃CH₂CH₂Cl, reacts with ethanolic sodium cyanide by nucleophilic substitution.

Outline the mechanism for this reaction.

Include curly arrows, relevant dipoles and the structure of the organic product.

Compound G is used to synthesise compounds H and I as shown in the flowchart below.

Complete the flowchart showing the structure of compound G and the formulae of the reagents for Reaction 2 and Reaction 3.

Compound H reacts with dilute hydrochloric acid to form a salt.

Explain why compound H can react with dilute hydrochloric acid and suggest a structure for the salt formed.

Explanation........

Structure

Compound I is the monomer for the biodegradable polymer J.

Draw two repeat units of polymer J and suggest a reason why it is biodegradable.

The repeat unit of Nylon 6,6 is shown below.

Draw the structures of two monomers that can be used to form Nylon 6,6.

A sample of Nylon 6,6 has a relative molecular mass of 21500.

Estimate the number of repeat units in the sample.

Give your answer as a whole number.

This question is about alcohols.

Construct an equation for the complete combustion of an unsaturated alcohol with 5 carbon atoms.

Many alcohols, including ethanol, are soluble in water.

Explain, with the aid of a diagram, why ethanol is soluble in water.

Include relevant dipoles and lone pairs.

The solubility of hexan-1-ol and hexane-1,6-diol in water is shown below in Table 19.1

Explain the difference in solubility of hexan-1-ol and hexane-1,6-diol.

Alcohols are important in organic synthesis and can be formed by the reduction of carbonyl compounds.

Complete the flowchart by filling in each box.

What is the name of compound K ?

Butan-1-ol can be oxidised to form two different organic products, depending on the reaction conditions used.

Describe both oxidation reactions of butan-1-ol.

For each reaction include

• the structure of the organic product

• a balanced equation

• the essential reaction conditions.

In your equations you may use [O] to represent the oxidising agent.

A chemist analyses a naturally occurring aromatic compound.

The percentage composition and mass spectrum of the compound are shown below.

Percentage composition by mass: C, 70.58%; H, 5.92%; O, 23.50%.

Mass spectrum

Determine the molecular formula of the compound.

Show your working.

Qualitative tests are carried out on the aromatic compound. The results are shown below.

Determine the functional groups in the compound. Explain your reasoning.

Functional groups........

Explanation........

The carbon-13 NMR spectrum of the compound is shown below.

Using the spectrum and the results from (a) and (b), determine the structure of the compound. Explain your reasoning.

Structure of compound