Condensation polymerisation

Which statement concerning nylon-6,6 is correct?

In which polymer does hydrogen bonding occur between the polymer chains?

Acrylonitrile, H₂C=CHCN, can be used as a starting material for the synthesis of butane-1,4-diamine, as shown in this reaction scheme.

Use IUPAC rules to name isomer W.

Reaction 1 produces a mixture of W and two other isomers.

Draw the structures of the two other isomers.

Explain, by considering the mechanism of this reaction, why all three isomers are formed.

The reaction scheme is repeated here.

Identify the reagent that is warmed with isomer W in reaction 2.

State the other reaction condition needed.

State the reagent and reaction conditions needed for reaction 3.

Give an equation for reaction 3.

Reagent and conditions

Equation

An incomplete equation for the formation of nylon 4,6 from five molecules of butane-1,4-diamine and five molecules of hexanedioic acid is shown.

Deduce the values of x and y in this equation.

Figure 6 shows a section of the nylon 4,6 polymer molecule.

Figure 6

Draw, on Figure 6, another section of nylon 4,6 polymer showing two hydrogen bonds between the two sections.

Proteins are polymers made from amino acids. Part of the structure of a protein is shown.

–Cys–Ser–Asp–Phe–

Each amino acid in the protein is shown using the first three letters of its name.

Identify the type of protein structure shown.

Tick (✓) one box.

Draw a structure for the –Cys–Ser– section of the protein. Use the Data Booklet to help you answer this question.

Name the other substance formed when two amino acids react together to form part of a protein chain.

The general structure of an amino acid is shown.

R represents a group that varies between different amino acids. R groups can interact and contribute to protein structure.

Explain why the strength of the interaction between two cysteine R groups differs from the strength of the interaction between a serine R group and an aspartic acid R group.

Use the Data Booklet to help you answer this question.

Deduce the type of interaction that occurs between a lysine R group and an aspartic acid R group.

Suberoyl chloride, ClOC(CH₂)₆COCl, is commonly used in the manufacture of polymers.

Which compound can form a polymer with suberoyl chloride?

This question is about ethanedioic acid (HOOCCOOH) and the ethanedioate ion (⁻OOCCOO⁻).

Ethanedioic acid reacts with propane-1,3-diol (HOCH₂CH₂CH₂OH) to form a polyester.

Draw the repeating unit of this polyester.

Explain why polyesters are biodegradable but polyalkenes are not biodegradable.

Sodium ethanedioate is used to find the concentration of solutions of potassium manganate(VII) by titration. The equation for this reaction is

A standard solution is made by dissolving 162 mg of Na₂C₂O₄ (M_r = 134.0) in water and making up to 250 cm³ in a volumetric flask.

25.0 cm³ of this solution and an excess of sulfuric acid are added to a conical flask. The mixture is warmed and titrated with potassium manganate(VII) solution. The titration is repeated until concordant results are obtained.

Calculate the concentration, in mol dm^–3, of the potassium manganate(VII) solution.

Figure 1 shows the 25.0 cm³ pipette used to measure the sodium ethanedioate solution.

On Figure 1, draw the meniscus of the solution when the pipette is ready to transfer 25.0 cm³ of the sodium ethanedioate solution.

Potassium manganate(VII) is oxidising and harmful. Sodium ethanedioate is toxic.

Suggest safety precautions, other than eye protection, that should be taken when:

• filling the burette with potassium manganate(VII) solution

• dissolving the solid sodium ethanedioate in water.

Filling the burette

Dissolving the solid

State the colour change seen at the end point of each titration.

Figure 2 shows the burette containing potassium manganate(VII) solution.

Give two practical steps needed before recording the initial burette reading.

When Na₂C₂O₄(aq) is added to a solution containing [Fe(H₂O)₆]³⁺ ions, a reaction occurs in which all six water ligands are replaced by ethanedioate ions.

Explain why the replacement of the water ligands by ethanedioate ions is favourable. In your answer refer to:

• the enthalpy and entropy changes for the reaction

• how the enthalpy and entropy changes influence the free-energy change for the reaction.

Which polymer has hydrogen bonding between the polymer chains?

Which is the repeating unit of a polyamide?

Which forms a polymer with ClOC(CH₂)₈COCl?

Which polymer has hydrogen bonding between its chains?

The repeating unit of a polymer is shown.

Which monomer or pair of monomers could be used to make this polymer?

The structure of part of a polyester chain is shown.

Which statement correctly explains why plastics made from this polyester only soften at high temperatures?

Give the full IUPAC name of isomer P.

A sample of P was mixed with an excess of oxygen and the mixture ignited. After cooling to the original temperature, the total volume of gas remaining was

When this gas mixture was passed through aqueous sodium hydroxide, the carbon dioxide reacted and the volume of gas decreased to 155 cm³

Both gas volumes were measured at 25 °C and 105 kPa

Write an equation for the combustion of P in an excess of oxygen and calculate the mass, in mg, of P used.

The gas constant R = 8.31 J K⁻¹ mol⁻¹

Mass of P used mg

Isomer Q (C₆H₁₀O₂) is a cyclic compound. The infrared spectrum of Q is shown in Figure 4 and the¹³C NMR spectrum of Q is shown in Figure 5.

Use these spectra and Tables A and C in the Data Booklet to deduce the structure of Q. In your answer, state one piece of evidence you have used from each spectrum.

Structure of Q.

Evidence from Figure 4

Evidence from Figure 5

Isomers R and S are shown.

Although the¹³C spectra of R and S both show the same number of peaks, the spectra can be used to distinguish between the isomers.

Justify this statement using Table C from the Data Booklet.

Give the number of peaks for each isomer.

Justification

Although the¹H spectra of R and S both show the same number of peaks, the spectra can be used to distinguish between the isomers.

Justify this statement using the splitting patterns of the peaks.

Give the number of peaks for each isomer.

Justification

The action of heat on 5-hydroxyhexanoic acid can lead to two different products.

On gentle heating, 5-hydroxyhexanoic acid loses water to form a cyclic

Under different conditions, 5-hydroxyhexanoic acid forms a polyester.

Draw the structure of T.

Draw the repeating unit of the polyester and name the type of polymerisation.

Structure of T

Repeating unit of polyester

Type of polymerisation

Isomer U is shown.

The polymer formed by U and the polymer formed by 5-hydroxyhexanoic acid in Question 10.6 both contain ester groups that can be hydrolysed.

Draw the repeating unit of the polymer formed by U.

Justify the statement that, although both polymer structures contain ester groups, the polymer formed by U is not biodegradable.

Repeating unit of polymer formed by U.

Justification