Halogenoalkanes

This question is about reactions of haloalkanes.

Haloalkanes can react with potassium cyanide to form new carbon–carbon bonds.

Outline the mechanism for the reaction of 2-bromopropane with cyanide ions.

Show curly arrows, relevant dipoles and products.

Name this type of mechanism.

The table below shows the boiling points of propan-1-ol and 1-bromopropane.

Propan-1-ol can be reacted to form 1-bromopropane.

Suggest suitable reagents for this reaction.

The reaction to form 1-bromopropane from propan-1-ol is carried out in a flask.

After the reaction, the flask contains a mixture of an organic layer (density = 1.35 g cm^–3) and an aqueous layer (1.04 g cm^–3).

Describe how to obtain pure 1-bromopropane from the mixture.

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 haloalkanes.

Haloalkanes can be synthesised by reacting alkanes with halogens in the presence of ultraviolet radiation.

An alkane reacts with bromine to form 2-bromo-2-methylpropane.

Write the equation for this reaction, showing the structures of the organic compounds.

Name the reaction mechanism and the type of bond fission that occurs.

Equation

Name of reaction mechanism........

Type of bond fission........

Describe two limitations of the synthesis of 2-bromo-2-methylpropane from an alkane and bromine.

This question is about the analysis of organic compounds.

Determine the R_f value of propan-1-ol.

Show your working.

Write an equation for the alkaline hydrolysis of 1-bromopropane.

Show structures of organic compounds.

A student investigates the alkaline hydrolysis of 1-chloropropane using the same method as for 1-bromopropane.

Predict, with reasons, how the appearance of the reaction mixture in the chromatogram produced after 20 minutes would be different when 1-chloropropane is used instead of 1-bromopropane.

Suggest why propan-1-ol is run alongside the reaction mixture.

Write the formula of the species causing the colours after refluxing with acidified dichromate(VI

Green solution........

Orange solution........

* The student is provided with further information about compounds F– I.

• They all have the molecular formula C₅H₁₀O.

• One of the compounds is alicyclic.

• The other compounds are unbranched.

Use this further information and the student’s observations in Table 5.1 to answer the following.

• How do the observations provide evidence for the possible functional groups in compounds F– I ?

• Suggest a possible structure for each of the compounds F– I.

Show your reasoning.

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.

Which statement is correct for the different rates of hydrolysis of RC l and RBr?

A RBr is hydrolysed faster because C l is more electronegative than Br.

B RBr is hydrolysed faster because the C–C l bond enthalpy is greater than C–Br.

C RC l is hydrolysed faster because C l is more electronegative than Br.

D RC l is hydrolysed faster because the C–Br bond enthalpy is greater than C–C l.

Compounds 1, 2 and 3 are heated with NaOH(aq).

Which compound(s) react(s)?

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1

This question is about organic acids.

Table 18.1 shows the R groups in four amino acids.

Most amino acids show optical isomerism.

Explain the term optical isomerism.

Draw 3-D diagrams to show the optical isomers of alanine.

How many optical isomers does threonine have?

Ibuprofen, shown below, is used as a painkiller.

What is the molecular formula of ibuprofen?

One ibuprofen tablet contains 400 mg of ibuprofen.

Calculate the number of ibuprofen molecules in one ibuprofen tablet.

Give your answer to 3 significant figures.

Tablets based on ibuprofen and lysine are now available from pharmacies.

These tablets are claimed to act faster than ibuprofen by being absorbed into the body more quickly than ibuprofen alone.

One type of these tablets contains a salt of ibuprofen and the amino acid lysine (R = –(CH₂)₄NH₂) in a 1:1 molar proportion.

Suggest why tablets based on a salt of ibuprofen should act faster in the body than ibuprofen.

Which of the following reactions produce propan-1-ol?

1 The alkaline hydrolysis of 1-chloropropane.

2 The acid hydrolysis of propyl methanoate.

3 The acid hydrolysis of propanenitrile.

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1

This question is about organic compounds containing nitrogen.

Salt H, (CH₃)₂CHNH₃Cl, is used in the manufacture of garden weedkillers.

The flowchart shows the synthesis of the salt H from propanone.

Complete the flowchart. Show structures for organic compounds.

Aspartame, shown below, is an artificial sweetener commonly used as a sugar substitute.

Aspartame contains several functional groups.

Apart from the benzene ring, name the functional groups in aspartame.

A sample of aspartame is hydrolysed with aqueous acid.

Draw the structures of the three organic products of the complete acid hydrolysis aspartame.

What is the organic product of the reaction below?

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 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 the hydrolysis of haloalkanes.

The rate of hydrolysis of a haloalkane depends on the halogen present.

State and explain how the halogen in the haloalkane affects the rate of hydrolysis.

A student hydrolyses a haloalkane, E, using the following method.

• 0.0100 mol of haloalkane E is refluxed with excess NaOH(aq) to form a reaction mixture containing an organic product F.

• The reaction mixture is neutralised with dilute nitric acid.

• Excess AgNO₃(aq) is added to the reaction mixture. 1.88 g of a precipitate G forms.

Organic product, F, has a molar mass of 74.0 g mol⁻¹ and has a chiral carbon atom.

Draw a labelled diagram to show how the student would carry out the hydrolysis of haloalkane E.

Analyse the information to identify E, F and G.

Show your working.

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

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.