Polymers

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WMP/Jan10/CHEM4

8 (c) Isomer Y is used in the production of the polymer Kevlar.

Y is first reduced to the diamine shown below.

8 (c) (i) Identify a suitable reagent or mixture of reagents for the reduction of Y to formthis diamine. Write an equation for this reaction using [H] to represent thereducing agent.

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8 (c) (ii) This diamine is then reacted with benzene-l,4-dicarboxylic acid to form Kevlar.Draw the repeating unit of Kevlar.

(2 marks)

NH2H2N

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8 (c) (iii) Kevlar can be used as the inner lining of bicycle tyres. The rubber used for theouter part of the tyre is made of polymerised alkenes.

State the difference in the biodegradability of Kevlar compared to that of rubbermade of polymerised alkenes.

Use your knowledge of the bonding in these polymer molecules to explain thisdifference.

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WMP/Jan10/CHEM4

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WMP/Jan12/CHEM4

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8 Common substances used in everyday life often contain organic compounds.

8 (a) State an everyday use for each of the following compounds.

8 (a) (i) CH3(CH2)17COO– Na+ .......................................................................................................(1 mark)

8 (a) (ii) CH3(CH2)19COOCH3 .........................................................................................................(1 mark)

8 (a) (iii) [C16H33N(CH3)3]+ Br– ........................................................................................................(1 mark)

8 (b) The following structures are the repeating units of two different condensation polymers.

For each example, name the type of condensation polymer. Give a common name fora polymer of this type.

8 (b) (i)

Type of condensation polymer ..........................................................................................

Common name ..................................................................................................................(2 marks)

8 (b) (ii)

Type of condensation polymer ..........................................................................................

Common name ..................................................................................................................(2 marks)

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CH2C CH2 OO

O

C

O

N CC

H O O

N

H

WMP/Jan12/CHEM4

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9

8 (b) (iii) Explain why the polymer in part (b) (ii) has a higher melting point than the polymer inpart (b) (i).

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WMP/Jun13/CHEM4

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5 (c) (iii) Suggest an alternative name for the term acidity regulator. Explain how a mixture of lactic acid and sodium lactate can act as a regulator when

natural processes increase the acidity in some foods.

Name ..................................................................................................................................

Explanation .........................................................................................................................

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5 (d) The cup shown is made from PLA, poly(lactic acid). PLA is the condensation polymer formed from lactic acid.

The polymer is described as 100% biodegradable and 100% compostable.

Compostable material breaks down slowly in contact with the moist air in a garden bin. This produces compost that can be used to improve soil.

The manufacturers stress that PLA cups differ from traditional plastic cups that are neither biodegradablenor compostable.

5 (d) (i) Draw a section of PLA that shows two repeating units.

(2 marks)

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WMP/Jun13/CHEM4

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5 (d) (ii) Name the type of condensation polymer in PLA.

............................................................................................................................................(1 mark)

5 (d) (iii) An intermediate in the production of PLA is a cyclic compound (C6H8O4) that is formedfrom two PLA molecules.

Draw the structure of this cyclic compound.

(1 mark)

5 (d) (iv) Traditional non-biodegradable plastic cups can be made from poly(phenylethene),commonly known as polystyrene.

Draw the repeating unit of poly(phenylethene).

(1 mark)

5 (d) (v) The manufacturers of PLA claim that the material will break down to compost in just 12 weeks.

Suggest one reason why PLA in landfill may take longer than 12 weeks to break down.

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WMP/Jan13/CHEM4

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4 (a) The tripeptide shown is formed from the amino acids alanine, threonine and lysine.

4 (a) (i) Draw a separate circle around each of the asymmetric carbon atoms in the tripeptide.(1 mark)

4 (a) (ii) Draw the zwitterion of alanine.

(1 mark)

4 (a) (iii) Give the IUPAC name of threonine.

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4 (a) (iv) Draw the species formed by lysine at low pH.

(1 mark)

Question 4 continues on the next page

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CH2N

H H

CH3

C N

O

C

H

C COOH

H

lysinethreoninealanine

H

CHOH

CH3

(CH2)4

NH2

C N

O

WMP/Jan13/CHEM4

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4 (b) The repeating unit shown represents a polyester.

4 (b) (i) Name this type of polymer.

............................................................................................................................................(1 mark)

4 (b) (ii) Give the IUPAC name for the alcohol used to prepare this polyester.

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4 (c) The repeating unit shown represents a polyalkene co-polymer. This co-polymer ismade from two different alkene monomers.

4 (c) (i) Name the type of polymerisation occurring in the formation of this co-polymer.

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4 (c) (ii) Draw the structure of each alkene monomer.

Alkene monomer 1 Alkene monomer 2

(2 marks)

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CH2 CH2 CH2O O C

O

CH2 CH2 CH2 C

O

C

H F

H F F

C C

F

C

F

CF3

WMP/Jan13/CHEM4

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4 (d) One of the three compounds shown in parts (a), (b) and (c) cannot be broken downby hydrolysis.

Write the letter (a), (b) or (c) to identify this compound and explain why hydrolysis ofthis compound does not occur.

Compound .........................................................................................................................

Explanation ........................................................................................................................

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............................................................................................................................................(2 marks)

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WMP/Jun14/CHEM4

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4 Kevlar is a polymer used in protective clothing. The repeating unit within the polymer chains of Kevlar is shown.

4 (a) Name the strongest type of interaction between polymer chains of Kevlar.[1 mark]

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4 (b) One of the monomers used in the synthesis of Kevlar is

An industrial synthesis of this monomer uses the following two-stage process starting from compound X.

Stage 1

Stage 2

4 (b) (i) Suggest why the reaction of ammonia with X in Stage 1 might be considered unexpected.

[2 marks]

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C

O

C

O

N

H

N

H

H2N NH2

Cl

X

NO2 + 2NH3 H2N NO2 + NH4Cl

H2N NO2 H2N NH2

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WMP/Jun14/CHEM4

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4 (b) (ii) Suggest a combination of reagents for the reaction in Stage 2.[1 mark]

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4 (b) (iii) Compound X can be produced by nitration of chlorobenzene.

Give the combination of reagents for this nitration of chlorobenzene. Write an equation or equations to show the formation of a reactive intermediate from

these reagents.[3 marks]

Reagents ............................................................................................................................

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Equation(s) .........................................................................................................................

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4 (b) (iv) Name and outline a mechanism for the formation of X from chlorobenzene and the reactive intermediate in Question 4 (b) (iii).

[4 marks]

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

Mechanism

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7 (b) Sections of two polymers, L and M, are shown.

7 (b) (i) Give the IUPAC name of a monomer that forms polymer L.[1 mark]

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7 (b) (ii) Give the IUPAC name of the monomer that forms polymer M.[1 mark]

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7 (b) (iii) Draw the section of a polymer made from a dicarboxylic acid and a diamine that isisomeric with the section of polymer M shown.

[1 mark]

7 (b) (iv) Explain why polymer L is non-biodegradable.[1 mark]

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(15)WMP/Jun15/CHEM4

7

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CH3 CH2

CH3

C C C C

H CH3

CH2

CH3

CH3

CH3

H

L

H H O H O

CCH2 CH2 N C N CCH2 C CH2

CH3

H

CH3

M