AMINO ACIDS, POLYMERS, ORGANIC SYNTHESIS AND BIOCHEMISTRY
 
1.    (a)    2,6-diaminohexanoic acid
Ignore additional , or – or spaces.
1
(b)    (i)      

NB both N must be protonated.
Allow −NH3+    allow CO2H    Allow −+H3N.
Penalise – C4H8 – here.
1
(ii)     

Allow CO2−.
Allow −H2N.
Allow –COONa but penalise O–Na bond shown.
1
(iii)    

Allow CO2CH3.
Allow −NH3+ or –H2N.
1
(c)     
OR
OR
Dipeptide, not repeating unit /.
Allow CO2H Allow –H2N.
Allow –CONH–.
1
 [5]

2.         (a)     (i)  
	
		 Allow –CONH- or - COHN -
Mark two halves separately
lose 1 each for missing trailing bonds at one or both ends or error in peptide link or either or both of H or OH on ends
1
Not allow –(C6H12)–
Ignore n
1
(ii)     M1 in polyamides - H bonding
1
M2 in polyalkenes - van der Waals forces
Penalise forces between atoms or van der Waals bonds
1
M3 Stronger forces (of attraction) in polyamides
Or H bonding is stronger
(must be a comparison of correct forces to score M3)
Do not award if refer to stronger bonds
1

(b)     (i)      (nucleophilic) addition elimination

Minus sign on NH2 loses M1
1
M2 not allowed independent of M1, but allow M1 for correct attack on C+
+ rather than + on C=O loses M2
If Cl lost with C=O breaking, max 1 for M1
M3 for correct structure with charges but
lp on O is part of M4
only allow M4 after correct/ very close M3
For M4, ignore NH3 removing H+ but lose
M4 for Cl removing H+ in mechanism,
but ignore HCl as a product
4
(ii)     N-methylpropanamide
Not N-methylpropaneamide
1
(c)     
 
Allow –CONH– or –COHN–
1

(d)     (i)      2-amino-3-hydroxypropanoic acid
1
(ii)     
 
Must be salts of aspartic acid
allow –CO2–
allow NH2–
1
(iii)     Penalise use of aspartic acid once in d(iii) and d(iv)
 
allow –CO2H
allow +NH3–
don’t penalize position of + on NH3
1
(iv)    Penalise use of aspartic acid once in d(iii) and d(iv)
(Br–)
allow –CO2–
must show C-N bond
don’t penalize position of + on N(CH3)3
1
[16]
 
3.       (a)     polyamide or nylon (2,4)
(allow nylon without numbers but if numbers are present they must be correct)
1
condensation
1

(b)     
1
(c)     ionic bonding in aminoethanoic acid
(can only score if includes that aminoethanoic is ionic)
1
stronger attractions than Hydrogen bonding in hydroxyethanoic acid
(e.g. stronger Hydrogen bonding in aminoethanoic acid scores 0)
(mention of electrostatic forces between molecules scores 0)
1
[5]
 
4.      (a)     (i)      hydrolysis
not hydration
1
(ii)     2-aminopropanoic acid
ignore alanine
QoL
1
(iii)

allow –CO2–
allow +NH3–
don’t penalize position of + on NH3
1
(iv)    

allow –CO2–
allow +NH3–
don’t penalize position of + on NH3
1

(b)     (i)

allow –CO2H
allow limit as 
+ on N or outside [ ]
1
(ii)

allow –CO2H allow –CONH– or –COHN–
allow NH2–
allow limit as 
1
[6]
 
5.       (a)     3-hydroxypropanoic acid
allow 3-hydroxypropionic acid
must be correct spelling
1

(b)     (i)      must show trailing bonds

or can start at any point in the sequence, e.g.

not allow dimer
allow –O–CH2CH2COOCH2CH2CO–
or –CH2CH2COOCH2CH2COO–
ignore ( ) or n
NB answer has a total of 6 carbons and 4 oxygens
1
(ii)     condensation (polymerisation)
Allow close spelling
1
(c)     (i)      C=C or carbon-carbon double bond
1
(ii)

must show ALL bonds including O–H
1
(iii)     must show trailing bonds

allow polyalkene conseq on their c(ii)
ignore n
1
(d)
allow NH3+—
allow COO–
1
(e)     (i)
	
In (e), do not penalise a slip in the number of carbons in the -CH2CH2- chain, but all must be bonded correctly
NB two carboxylate groups
Allow COONa or COO– Na+ but not covalent bond to Na
allow NH2–
1
(ii)
In (e), do not penalise a slip in the number of carbons in the
-CH2CH2- chain, but all must be bonded correctly
NB two ester groups
allow NH2– or +NH3–
1
(iii)
		
In 4(e), do not penalise a slip in the number of carbons in the -CH2CH2- chain, but all must be bonded correctly
allow anhydride formation on either or both COOH groups (see below) with or without amide group formation

1
 [10]

6.       (a)     (i)      	H2/Ni or H2/Pt or Sn/HCl or Fe/HCl (conc or dil or neither)
			allow dil H2SO4
			ignore mention of NaOH
Not NaBH4
Not LiAlH4
Not Na/C2H5OH
not conc H2SO4 or any HNO3
1
					(Or 6H2)
allow C6H4(NO2)2 etc ,
allow NO2– NH2–
i.e. be lenient on structures, the mark is for balancing equ
1
(ii)

allow –CONH
ignore [ ]n as in polymer
1st mark for correct peptide link
2nd mark for the rest correct including trailing bonds
2
(iii)     M1 Kevlar is biodegradeable but polyalkenes not
allow Kevlar is more biodegradeable
1
M2 Kevlar has polar bonds/is a (poly) amide/has peptide link
comment on structure of Kevlar
1
M3 can be hydrolysed/attacked by nucleophiles/acids/
bases/enzymes
1
M4 polyalkenes non polar/has non-polar bonds
comment on structure of polyalkenes but not just strong bonds
1
[8]

 
7.

First mark for correct ester link second mark for the rest including trailing bonds
If ester link wrong, lose second mark also
2
Adv        reduces landfill
saves raw materials
lower cost for recycling than making from scratch
reduces CO2 emissions by not being incinerated
not allow cost without qualification
ignore energy uses
1
Disad     difficulty/cost of collecting/sorting/processing
product not suitable for original purpose, easily contaminated
not allow cost without qualification
ignore energy uses
1
[4]
 
8.	(a)     (i)     (As a) soap
Allow washing, cleaning, degreasing, detergents
1
(ii)     (Bio)diesel or biofuel or fuel for cars/lorries
Allow to make soap
1
(iii)    (Cationic) surfactant /detergent /fabric softener /germicide / shampoos /(hair) conditioners /spermicidal jelly
Allow cleaning
1

(b)     (i)     (Poly)ester
1
Terylene OR PET
Allow polyester
1
(ii)     (Poly)amide
1
Kevlar OR nylons
Ignore numbers with nylons Allow polyamide(e)
1
(iii)    (Independent marks)
CE = 0
Hydrogen bonding in b(ii)
1
Imfs in (b)(ii) are stronger
OR
H bonding stronger than dipole–dipole/van der Waals/ dispersion/London
forces in b(i)
1
[9]
 
9.      (a)     (i)      hexane-1,6-diamine or 1,6-diaminohexane (allow ammine)
or 1,6 hexan(e)diamine (1)
(ii)     
Allow –CONH–
2
(b)     (i)      
(ii)     
2

(c)     (i)      quaternary ammonium bromide salt (1)
(not ion, not compound)
Allow quarternery
(ii)     Reagent: CH3Br or bromomethane (1)
penalise CH3Cl but allow excess for any halomethane
         Condition: excess (CH3Br) (1)
(iii)     nucleophilic substitution (1)
4
[8]
 
10.          (i)      Single reagent
If wrong single reagent, CE = zero
Incomplete single reagent (e.g. carbonate) or wrong formula (e.g.NaCO3) loses reagent mark, but mark on
For “no reaction” allow “nothing”
Different reagents
If different tests on E and F; both reagents and any follow
on chemistry must be correct for first (reagent) mark.
Reagent must react: i.e. not allow Tollens on G (ketone) – no reaction.
Second and third marks are for correct observations.
i.e. for different tests on E and F, if one reagent is correct and one wrong, can score max 1 for correct observation with correct reagent.
PCl5 PCl3
SOCl2
1
E ester
Na2CO3/NaHCO3 named carbonate
metal e.g.Mg
no reaction
no reaction
named indicator
no effect
No reaction
1

F acid
Na2CO3/NaHCO3 named carbonate
Effervescence or CO2
metal e.g.Mg
Effervescence or H2
named indicator
acid colour
fumes
1
(ii)     Single reagent
If wrong single reagent, CE = zero
Incomplete single reagent (e.g. carbonate) or wrong
formula (e.g.NaCO3) loses reagent mark, but mark on
For “no reaction” allow “nothing”
Different reagents
If different tests on E and F; both reagents and any
follow on chemistry must be correct for first (reagent) mark.
Reagent must react: i.e. not allow Tollens on
G (ketone) – no reaction.
Second and third marks are for correct observations.
1
i.e. for different tests on E and F, if one reagent is correct
and one wrong, can score max 1 for correct observation
with correct reagent.

G ketone
AgNO3
no reaction
Na2CO3/NaHCO3 named carbonate
water
no reaction
named indicator
no effect
Named alcohol
no reaction
Named amine or ammonia
no reaction
1
H Acyl chloride
AgNO3
(white) ppt
Na2CO3/NaHCO3 named carbonate
Effervescence or CO2 or fumes or exothermic
water
fumes
named indicator
acid colour
Named alcohol
Smell or fumes
Named amine or ammonia
fumes
1
Allow iodoform test or Brady’s reagent (2,4,dnph) test (both positive for G)

(iii)     Single reagent
If wrong single reagent, CE = zero
Incomplete single reagent (e.g. carbonate) or wrong
formula (e.g.NaCO3) loses reagent mark, but mark on
For “no reaction” allow “nothing”
Different reagents
If different tests on E and F; both reagents and any follow
on chemistry must be correct for first (reagent) mark.
Reagent must react: i.e. not allow Tollens on
G (ketone) – no reaction.
Second and third marks are for correct observations.
i.e. for different tests on E and F, if one reagent is correct
and one wrong, can score max 1 for correct observation
with correct reagent.
1
J Primary alcohol
K2Cr2O7/ H+
goes green
KMnO4/ H+
decolourised / goes brown
Lucas test (ZnCl2/HCl)
Penalise missing H+ but mark on
1
K Tertiary alcohol
K2Cr2O7/ H+
No reaction
KMnO4/ H+
no reaction
Lucas test (ZnCl2/HCl)
Rapid cloudiness
1
If uses subsequent tests e.g. Tollens/Fehlings, test must be on product of oxidation
 [9]