Elimination reactions

This question is about spectral analysis.

Compound K, C₄H₁₀O, is refluxed with H₂SO₄ to form a mixture of compound L and compound M.

The infrared spectrum of compound K is shown.

Compound L and compound M are analysed using¹³C NMR spectroscopy.

• The¹³C NMR spectrum of compound L has 4 peaks.

• The¹³C NMR spectrum of compound M has 2 peaks.

Suggest the functional group in compound K, showing your reasoning, and suggest possible structures for compound K, compound L and compound M.

Functional group........

* An unknown organic compound N is analysed and produces the following results.

Elemental analysis by mass

C, 62.07%; H, 10.34%; O, 27.59%

Mass spectrum

The numbers by the peaks are the relative peak areas.

Determine the structure of the compound N, showing all your reasoning.

This question is about reactions of alcohols.

There are 4 structural isomers of C₄H₁₀O that are alcohols: CH₃CH₂CH₂CH₂OH CH₃CH₂CHOHCH₃ (CH₃)₂CHCH₂OH (CH₃)₃COH

Alcohols take part in many different types of reaction, including

• elimination

• oxidation

• substitution

• esterification.

For each type of reaction, choose appropriate reagent(s) and/or catalyst, and show the organic product formed.

Elimination reaction of CH₃CH₂CH₂CH₂OH

Reagent(s) and/or catalyst

organic product

Oxidation reaction of CH₃CH₂CHOHCH₃

Reagent(s) and/or catalyst

organic product

Substitution reaction of (CH₃)₂CHCH₂OH

Reagent(s) and/or catalyst

organic product

Esterification reaction of (CH₃)₃COH

Reagent(s) and/or catalyst

organic product

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.

This question is about the chemistry of aromatic compounds.

What chemical test(s) could be used to confirm the presence of the phenol group in compounds K and L ?

A student thought that¹³C NMR spectroscopy could be used to distinguish between compounds J, K and L.

Explain, with reasoning, whether the student is correct.

Compound J is substituted at the 2-and 4-positions by chlorine in the presence of a catalyst.

Outline the mechanism for the 4 substitution of compound J by chlorine in the presence of a catalyst.

Show the role of the catalyst.

Compounds K and L react with chlorine much more readily than compound J.

Explain why.

Compound J, C₆H₅CH₂CH₂OH, is reacted with acidified potassium dichromate(VI) under reflux to form organic product M.

Write an equation for this reaction.

Use [O] to represent the oxidising agent and show the structure of M.

A two-stage synthesis of an amine from compound J is shown below.

Add the reagents for each stage of this synthesis.

Compound J

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

Which structure could be formed?

Which alcohol reacts with an acid catalyst to form a mixture of stereoisomers?

A 3-methylbutan-2-ol

B pentan-1-ol

C 2-methylhexan-2-ol

D heptan-4-ol

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 reactions of organic compounds containing carbon, hydrogen and oxygen.

A chemist investigates two reactions of alcohol A, shown below.

What is the systematic name of alcohol A ?

What is the structural formula of alcohol A ?

The chemist heats alcohol A with an acid catalyst to form a mixture containing alkenes.

Draw the structures of the two alkenes formed in this reaction.

The chemist heats alcohol A with sodium chloride and sulfuric acid.

Construct a balanced equation for this reaction. Show structures for the organic compounds in your equation.

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.