 No Brain Too Small  CHEMISTRY 
AS 90698 Describe aspects of organic chemistry
Polymers
(2011:2)
Nylon 6,6 is a polymer with the following structure:
(a)
Circle an amide linkage in the structure above.
(b)
Draw TWO monomers that could have formed this polymer.
(c)
Nylon 6 is formed from the monomer H2N – (CH2)5 – CO2H.
(d)
(i)
Name this monomer.
(ii)
Draw THREE repeating units of the Nylon 6 polymer chain.
Nylon is used for making ropes for climbing and abseiling. The ropes come with a warning label
attached, such as that shown below.
WARNING!!!
Nylon Rope: Do not allow to
come in contact with acids or
their vapours
Discuss why this warning label is attached to nylon rope when purchased.
Include in your answer:
•
the type of reaction that would occur
•
relevant organic structural formulae
•
any changes to the properties of the nylon rope
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(2010: 3(c))
(c)
The polymer commonly known as Kevlar is used to make bullet-proof vests and bicycle tyres.
It can be made in a condensation reaction from either of the following pairs of monomers:
However, the second pair of monomers needs to be heated for the polymerisation reaction to take
place.
Note:
is a benzene ring and should be treated as a hydrocarbon chain. It is not a functional
group and does not change during the reaction.
Discuss these polymerisation reactions.
Your answer should include:
•
a repeating unit of the polymer chain
•
reasons for the choice of monomers
•
identification of the functional group in the polymer
•
a reason why this is classified as a condensation reaction
•
a comparison of the two pairs of monomers, including the reason that the second reaction will
not take place without heating.
(2009:3)
(a)
Kodel is a polymer with the following structure:
(i)
(ii)
(b)
Identify TWO monomers for this structure.
Explain why this type of polymer is known as a condensation polymer.
Compound X is a polymer which can be hydrolysed to give a single monomer, Compound Y, which
has the molecular formula C3H6O3.
Compound Y will turn blue litmus red, and can exist as enantiomers (optical isomers). It will react
with acidified potassium dichromate to form Compound Z, which has the molecular formula C 3H4O3.
Compound Z does not react with Tollens’ reagent.
(i)
(ii)
Draw the structures of Compounds Y and Z.
Draw a section of the polymer, Compound X, showing at least two repeating units.
 No Brain Too Small  CHEMISTRY 
(2008:2)
Amino acids are the building blocks that make up proteins. Alanine and valine are amino acids which can
combine to form dipeptides.
(a)
Draw the structure of a possible dipeptide formed from the combination of alanine and valine.
(b)
Complete the following reaction scheme to show the organic products of the hydrolysis of the
dipeptide below using :
(i)
dilute hydrochloric acid solution
(ii)
dilute sodium hydroxide solution.
(2007:2 (c))
(c)
Lactic acid is able to form a condensation polymer in the presence of dilute sulfuric acid.
Monomer:
Draw three repeating units of this polymer.
 No Brain Too Small  CHEMISTRY 
(2006:2)
(a)
(b)
The reaction scheme below shows formation of a section of a nylon polymer chain. Complete the
reaction scheme by:
(i)
identifying reagents 1, 2 and 3,
(ii)
drawing the structures of compounds P and Q,
(iii)
drawing a single repeating unit for the nylon polymer formed.
Nylon is used as a fibre to manufacture ropes and fabrics. These products can be damaged if they
come into contact with acidic solutions. Teflon is a polymer formed from F2C=CF2 and is not affected
by contact with acidic solutions.
Discuss why nylon is affected by acidic solutions while Teflon is not. Use structural formulae and
equations where appropriate.
 No Brain Too Small  CHEMISTRY 
(2005:3)
(a)
(b)
Gluthathione (GSH) is one of the most common small peptides in animals, plants and bacteria.
(i)
Draw a circle around one of the amide (peptide) groups.
(ii)
Draw structures of the products of the hydrolysis of this compound using alkaline conditions
(NaOH) and compare with the structures of the hydrolysis products under acidic conditions.
Consider the following statement.
Polyesters are polymers that can be made from two different monomers or from a single monomer.
Discuss this statement, using the structures of specific monomers and the polyesters that can be
made from them, to illustrate your answer. Your answer should demonstrate a clear understanding
of the highlighted terms.
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Answers to collated questions
(2011:2)
(a)
(b)
One link is circled.
One set of monomers (can be in any order)
(c)
(i)
6-amino hexanoic acid
(ii)
(d)
The acid would hydrolyse the rope. This would cause the amide linkages to break and form the
monomers. The rope would lose strength.
OR products from nylon 6,6.
(2010:3 (c))
The repeating group is:
The monomers have functional groups at both ends, so can react to form a long chain. (Mention of diacid
chloride, diacid, diamine sufficent).
The acid chloride and amine react to give an amide functional group or peptide bond.
The reaction is a condensation reaction, since a small molecule (HCl or H2O) is released.
When the amine and the acid are used without heating, a proton transfer (acid-base reaction) occurs and
hence polymerisation does not occur until the reaction is heated.
The acid chloride is more reactive than the carboxylic acid.
 No Brain Too Small  CHEMISTRY 
(2009:3)
(a)
(i)
(ii)
A small molecule, such as H2O or HCl, is eliminated when the monomers join.
(b)
OH
O
H3C CH
(i)
Compound Y
(ii)
Polymer (Compound X)
O
O
C OH
O
O
CH
CH3
H3C C
Compound Z
C
O
O
O
CH
C
C OH
O
CH3
CH C
CH3
O
(2008:2)
O
H3C
O
CH3
H3C CH CH C NH CH C OH
NH2
(a)
(b)
NH2 O
O
H3C CH C NH CH C OH
HC
H3C
CH3
or
The amide linkage is hydrolysed with both acidic and basic hydrolysis.
(i)
Under acidic conditions the products would be:
+
NH3
A.
(ii)
HO
CH2 CH
O
O
C OH
+
B.
H3N
CH2
Under alkaline conditions, the products would be:
O
HO CH2
C.
(2007:2 (c))
C OH
O
CH C
NH2
H2N
O
-
D.
CH2 C
O
-
 No Brain Too Small  CHEMISTRY 
(2006:2)
(a)
(i)
Reagent 1
NaOH (KOH, OH- )
Reagent 2
SOCl2, PCl3, PCl5
Reagent 3
NH3
(ii)
Compound P HOOC(CH2)4COOH
Compound Q HCl
(iii)
Repeating unit is an amide linkage, ie –HN(CH2)6NHOC(CH2)4CO–
(b)
Nylon is easily hydrolysed with acidic solutions as the amide bonds are broken and so monomer
molecules are reformed.
–HN(CH2)6NHOC(CH2)4CO– + H+
↓
+NH (CH ) NH +
3
2 6
3
+ HOOC(CH2)4COOH
Monomer molecules acceptable (i.e. NH2(CH2)6NH2 and ClOC(CH2)4COCl).
(c)
Teflon is not hydrolysed as the chain involves a series of C–C single bonds that are not easily broken.
(2005:3)
(a)
(i)
(ii)
Under alkaline conditions products
would be
OR
The structures above with COO– instead of COONa
Under acidic conditions the NH2 group would be protonated (to NH3+ ) in each case and COOH
would be present instead of COO– / COONa.
 No Brain Too Small  CHEMISTRY 
(b)
•
A polymer is a long chain molecule formed when many molecules or units (ie monomers) link
together.
•
Polyester chains are formed by condensation with the loss of H2O or HCl at each ester linkage.
•
Polyesters contain ester linkages.
•
A single monomer must be a hydroxyl alkanoic acid or hydroxy alkanoyl chloride eg
HO(CH2)4COOH / HO-R-COOH or HO(CH2)4COCl / HO-R-COCl
•
Two different monomers can be a diol and a dioic acid / a diol and a dioyl chloride / two
different hydroxy alkanoic acids / two different hydroxy alkanoyl chlorides eg
HOOC(CH2)nCOOH + HO(CH2)mOH
ClOC(CH2)nCOCl + HO(CH2)mOH
HOOC(CH2)nOH+ HOOC(CH2)mOH
ClOC(CH2)nOH+ ClOC(CH2)mOH