Edexcel A Level Chemistry

Topic Questions

A LevelChemistryEdexcelTopic Questions7. Advanced Organic Chemistry (A Level Only)7.2 Organic Chemistry II: Carbonyl Chemistry

7.2 Organic Chemistry II: Carbonyl Chemistry

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Hard
1a1 mark

This question is about redox reactions.

Name the ion with formula PO subscript 3 superscript 3 minus end superscript. Include the relevant oxidation number.

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1b1 mark

State what happens to a reducing agent during a reaction, in terms of oxidation number and electrons.

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1c1 mark

Identify the species that is the strongest reducing agent from the list of standard electrode potentials in the Data Booklet.

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1d3 marks

Manganese(IV) oxide, MnO2, and manganate(VII) ions, MnO4–, react in alkaline solution to form manganate(VI) ions, MnO42–.

i)
Write the ionic equation for this reaction.

State symbols are not required.

(2)

ii)
Give a reason why this reaction is not disproportionation.

(1)

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1e5 marks

Sodium tetrahydridoborate(III), NaBH4, is used in organic chemistry.
It is an alternative reagent to lithium tetrahydridoaluminate(III) for the reduction of carbonyl compounds.

i)
Draw a dot-and-cross diagram of the BH4– ion.

Use crosses (×) for the boron electrons, dots (•) for the hydrogen electrons and triangles (increment) for the additional electron forming the negative ion.

(1)

ii)
The BH4– ions reduce carbonyl compounds to alcohols in aqueous solution.

Complete the mechanism for the reduction of propanone to propan-2-ol by adding curly arrows, and any relevant lone pairs and dipoles.

(4)

q5eii-9cho-al-3-june-2019-qp-edexcel-a-level-chem

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2a2 marks

This question is about some carbonyl compounds with the molecular formula C5H10O.

Describe a chemical test, and its result, to distinguish between pentan-2-one, CH3CH2CH2COCH3, and pentan-3-one, CH3CH2COCH2CH3.

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2b6 marks

Pentan-2-one reacts with hydrogen cyanide in the presence of cyanide ions to form 2-hydroxy-2-methylpentanenitrile.

q8b-9cho-al-3-oct-2021-edexcel-a-level-chem
i)
Draw the mechanism for the reaction between pentan-2-one and hydrogen cyanide in the presence of cyanide ions.

Include curly arrows and any relevant lone pairs.

(4)

ii)

The product of this reaction, 2-hydroxy-2-methylpentanenitrile, has a chiral center.
Explain why a racemic mixture of 2-hydroxy-2-methylpentanenitrile is formed in this reaction.

(2)

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2c4 marks

An aldehyde with molecular formula C5H10O has a 13C NMR spectrum with three peaks.
The high resolution 1H NMR spectrum of this aldehyde has two peaks and neither of them is split.

Deduce the displayed formula of this aldehyde.
Justify your answer by referring to both NMR spectra.

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2d6 marks

Describe the oxidation and reduction reactions of pentanal and pentan-3-one.

Include the reagents and the structures of the organic products formed in any reactions that take place.

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