2.8 EXTRA QUESTIONS MS
 
1.	 	(i)	Cl2 ® 2Cl· / ½ Cl2 ® Cl·  (1)	1
(ii)	Cl·+ C6H5CH3 ® C6H5CH2· + HCl  (1)
C6H5CH2· + Cl2 ® Cl· + C6H5CH2Cl  (1)	2
 
(iii)	C6H5CHCl2 / C6H5CCl3 / C6H5 CHCHC6 H5 /
other correct possible answer  (1)	1
 
 [4]

2.	(a)	(i)	(free–)radical substitution	1
(both words required for the mark)
(ii)	uv light OR sunlight OR high temperature OR 150oC to 500oC	1
(iii)	Propagation	1
(ignore “chain”, “first”, “second” in front of the word propagation)
 
(iv)	Termination	1
·CH2CH3 + Br· ¾® CH3CH2Br 
OR 2·CH2CH3 ¾® C4H10	1
(penalise if radical dot is obviously on CH3, but not otherwise) 
(penalise C2H5·)
(credit 2Br· ¾® Br2)
(ignore “chain” in front of the word termination) 
 
(b)	(i)	Fractional distillation OR fractionation	1
(credit gas–liquid chromatography, GLC)
(ii)	CH3CH3 + 6Br2 ¾® C2Br6 + 6HBr	1
(credit C2H6 for ethane)
 [7]

3.	(a)	(i)	(free–) radical substitution	1
(both words required for the mark)
initiation Cl2 → 2Cl·	1
(credit correct half arrows, but penalise double headed arrows)
first propagation CH3Cl + Cl· → ·CH2Cl + HCl	1
second propagation ·CH2Cl + Cl2 → CH2Cl2 + Cl·	1
(penalise the absence of dots on radicals once only)
(penalise radical dot on Cl of CH2Cl once only)
 
(ii)	CH3Cl + Cl2 → CH2Cl2 + HCl	1
(penalise if any radicals appear in this equation)
 
(b)	M1:	mol C = 10.1/12.0 and mol Cl = 89.9/35.5	1
M2:	Ratio 0.842 : 2.53 OR 1: 3 OR CCl3	1
M3:	237.0/Mr of CCl3 = 237.0/118.5 = 2 Therefore C2Cl6	1
(correct answer gains full credit)
OR
M1:	237.0 × 10.1/100 and 237 × 89.9/100	1
M2:	Ratio 23.9/12.0 : 213/35.5 OR 2 : 6	1
M3:	C2Cl6	1
(correct answer gains full credit)
 
(c)	any two from CHBr3 or CBr4 or C2H2Br4 (or CHBr2CHBr2) or C2Br6
(or CBr3CBr3)	2
(ignore HBr or H2)
(ignore equations and ignore names when given in addition to formulae)
(penalise names alone)
[10]
4.	(a)	(i)	substitution or hydrolysis (1)
nucleophile (1)
 
(ii)	

 
		5
 
(b)	(i)	Type of reaction	elimination (1)
Role of reagent	base or proton acceptor (1)

(ii)	Structure of the alkene	(CH3)2C=C(CH3)CH2CH3 (1)
Mechanism

(iii)	Structure of second alkene	(CH3)2CHC(CH3)=CHCH3 (1)
Name	3,4-dimethylpent-2-ene (1)
Structure of third alkene	(CH3)2CHC(C2H5)=CH2 (1)
Name	2-ethyl-3-methylbut-1-ene(1)	10
[15]

5.		(i)	M1 curly arrow from lone pair of electrons on oxygen of hydroxide ion	1
(insist on a lone pair of electrons on the oxygen atom and a negative charge, but only credit this mark if the attack is to a correct H atom)
	M2 curly arrow from the middle of the C–H bond to the middle of 
the C–C bond.	1
(only credit this mark if the arrow originates from the correct
 C–H bond and if an attempt has been made at M1)
 
	M3 curly arrow from the middle of the C–Br bond towards/alongside 
the Br atom.	1
(credit M3 independently unless the bond breaking is 
contradicted by an additional arrow)
(penalise M3 curly arrow if the C–Br has a formal positive charge)
(ignore partial charges on the C–Br bond, but penalise if incorrect)
(credit full marks for an E1 mechanism, with M2 awarded for a correct curly arrow on the correct carbocation)
(award a maximum of two marks for an incorrect haloalkane) 
(ignore products) 

(ii)	Haloalkane/C2H5Br is made from ethane
OR haloalkane is not (readily) available
OR haloalkane is expensive 
OR it is (too) expensive/costly
OR (reaction) yield is too low/poor
OR it is too slow
OR a valid reference to nucleophilic substitution/alcohol formation
occurring as an alternative reaction.	1
(ignore references to temperature or to energy consumption)
(do not credit statements which refer to the idea that this route
is not chosen, because industry chooses another route e.g. cracking)
 
 [4] 
6.	
	(i)	M1: potassium cyanide OR KCN OR sodium Cyanide OR NaCN;	1
(ignore conditions - dissolved in (aq) or (alc) or KOH(aq) all work) (penalise HCN)
M2: propanenitrile;	1
(credit propan-1-nitrile OR propan nitrile, but not propanitrile)
(ii)	M1: ammonia OR NH3;	1
(If formula is written, insist that it is correct)
(ignore conditions, but penalise acidic)
M2: ethylamine;	1
(credit aminoethane)
(iii)	M1: curly arrow from lone pair on nitrogen of (correct formula for)
ammonia towards/alongside C atom of C-Br;	1
(penalise M1 if formula of ammonia is wrong or has a negative charge or has no lone pair or arrow is from negative charge)
	M2: curly arrow from C-Br bond towards/alongside side Br atom;	1
(credit M2 independently)
(penalise M2 if formal positive charge on C atom of C-Br)
 
	M3: correct structure of the ethylammonium ion;	1
(credit the structure drawn out with all four bonds around the nitrogen atom OR written as C2H5NH3+ OR CH3CH2NH3+)
	M4: curly arrow from the middle of one of the H-N bonds towards the
positive N atom;	1
(possible to credit M4 on an incorrect ethylammonium ion with no positive charge)
(ignore use of ammonia or bromide ion etc. to remove proton from ethylammonium ion)
(If the wrong haloalkane is used, award MAX. 3 marks for the mechanism) (If SN 1 mechanism is used, give full credit in which M1 is for a curly arrow from the lone pair of the N atom of (correct formula for) ammonia towards/alongside the positive carbon atom of CH3CH2+)
[8]

7.	(a)		1
 
(b)	(i)	

(ii)	(nucleophilic) elimination
	5
(c)	3–methylbut–1–ene  (1)	1

[7]

8.	 	(i)	Mechanism:

M1 and M2 independent
Curly arrows must be from a bond or a lone pair
Do not penalise sticks
Penalise M1 if  precedes (penalise this once)
Penalise incorrect d+ d– for M2
Penalise + on C atom for M2
Only allow M1 for incorrect haloalkane
	Role of the hydroxide ion: nucleophile (1)
	 electron pair donor
	 lone pair donor
NOT nucleophilic substitution

(ii)	Mechanism:

Only allow M1 and M2 for incorrect haloalkane unless RE on (i)
+ charge on H on molecule, penalise M1
M3 independent
M2 must be to correct C–C
M1 must be correct H atom
Credit M1 and M2 via carbocation mechanism
No marks after any attack of C Å by OH–
	Role of the hydroxide ion: base (1)	7
	 proton acceptor
	 accepts H+
[7]

9.	(a)	(i)	Structure: 
No credit for propan-1-ol even when named correctly
Credit propane-2-ol
	Name: propan-2-ol (1)
Not 2-hydroxypropane 
(ii)	Name of mechanism: nucleophilic substitution (1) (both words)
(NOT SN1 orSN2)
	Mechanism: 
penalise incorrect polarity on C-Br (M1)
Credit the arrows even if incorrect haloalkane
If SN1, both marks possible
	5
 
(b)	(i)	elimination (1)
(ii)	base (1)
OR proton acceptor
NOT nucleophile (base)
		2
[7]

10.	(a)	M1 NaOH OR KOH OR correct name	1
M2 aqueous or solution in water (ignore heat, reflux etc.)	1
(Penalise M1 for hydroxide ion alone, but mark on and credit M2)
(Credit M2 ONLY for H2O as reagent and heat / warm / T=50 to 100oC)
(NaOH(aq) scores M1 and M2 provided it is not contradicted)
(Penalise M2 if NaOH(aq) followed by concentrated or ethanol)
(Penalise M1 and M2 if followed by acid)
 
(b)	Ethanolic OR alcoholic OR CH3CH2OH / CH3OH solvent OR	1
aqueous ethanol/alcohol
OR higher temperature (must be comparative)
(Ignore heat or heat under reflux)
(Credit part (c) independently from part (b))
(Penalise “ethanoic”)
 [3]

11.		(i)	2–methylpropanenitrile (1)
(ii)	Reagent KCN (1)
Conditions alcoholic/aq (1)
(iii)	Name of mechanism 	nucleophilicsubstitution (1)
Mechanism 	
		7
 [7]

12.	(a)	Name of mechanism: nucleophilic substitution (1)
Mechanism: 

Marks SN1 using same points
\ M2 requires  
		5
 
(b)	Role of potassium hydroxide: Base (1)
Mechanism: 
	5
[10]

13.		elimination (1)	1
 [1]

14.		(i)	CH3 CH2 CH2 CH2 CN (1)  Not C4 H9 CN
Pentanenitrile (1) 
allow pentanonitrile, ignore numbers
 
(ii)	Nucleophilic substitution (1)

SN1 mechanism
M1 formation of carbocation including  
M2 attack by :CN–
allow mechanism showing ‘Cl’
If ‘+’ onC’ lose M1
If K–CN shown lose M2
If d–c– lose M1
 
(iii)	C–F bond is strong (er) (1)  
Must imply C–F is stronger than C–Br bond
ignore references to electronegativity, bond polarity etc.
		6
 [6]

15.	(a)	(base) elimination	1
(penalise other words before ‘elimination’ e.g. nucleophilic)
M1: curly arrow from lone pair of electrons on oxygen of hydroxide ion	1
	(insist on a lone pair of electrons on the oxygen atom and a negative
charge, but only credit this mark if the attack is to a correct H atom)	1
	M2: curly arrow from the middle of the C-H bond to the middle
of the C–C bond	1
	(only credit this mark if the arrow originates from the correct C–H
bond and if an attempt has been made at M1)
	M3: curly arrow from the middle of the C–Br bond towards/alongside
the Br atom
	(credit M3 independently unless the bond breaking is contradicted
by an additional arrow)
(penalise curly arrow if the C–Br has a formal positive charge)
	(credit full marks for an E1 mechanism, with M2 awarded for a correct
curly arrow on the correct carbocation)
	(award a maximum of two marks for either an incorrect haloalkane or
an incorrect organic product)
	(maximum 2 marks for use of .sticks. for the haloalkane, unless RE
from 2(b), when credit can be given)

(b)	nucleophile or electron pair donor	1
(penalise ‘base’)
 
(c)	CH3CH2CH2CH2Br + 2NH3 → CH3CH2CH2CH2NH2 + NH4Br	2
(M1 correct product)
(M2 balanced equation using 2NH3 and leading to NH4Br)
	(penalise M1 for use of C4H9NH2 or for incorrect haloalkane,
but allow consequent correct balancing of equation with 2 moles
of ammonia)
(1–)butylamine	1
(credit 1–aminobutane and butyl–1–amine)
(award QoL mark for correct spelling)
[8]

16.		(i)	potassium or sodium hydroxide (or other specific strong base)  (1)
allow formula;   not just ‘hydroxide’
in ethanolic /alcoholic solution     (independent of first mark) (1)	2
allow ‘in ethanol’, not just ‘ethanol’/ ‘with ethanol’
ignore references to heat / pressure
 
(ii)	
structure of cyclohexene showing double bond  (1)
minimum structure needed is a ring with CH2 units implied
and double bond:
do not allow KOH over arrow
	equation correct overall    ie balanced 
allow ionic equation (1)	2
 
(iii)	elimination / dehydrohalogenation	1
ignore nucleophilic / electrophilic etc.
[5]

17.	
(a)	(i)	CH3CH2CH2Br  +  KCN  ®  CH3CH2CH2CN  +  KBr (1)	1
	allow C3H7Br	allow C4H7N
(ii)	nucleophilic substitution / SN2 (1)	1
(b)	CN–  or NC– (1)
	lone pair of electrons on C atom (1)	2
 
 [4]

18.	(a)	2-bromobutane;	1
 
(b)	Elimination;	1
(penalise “nucleophilic” OR “electrophilic” before the word “elimination”)
	M1: curly arrow from lone pair on oxygen of hydroxide ion to H atom
on correct C-H adjacent to C-Br;	1
(penalise M1 if KOH shown as covalent with an arrow breaking the bond)
	M2: curly arrow from single bond of adjacent C-H to adjacent single bond C-C;	1
(only credit M2 if M1 is being attempted to correct H atom)
	M3: curly arrow from C-Br bond to side of Br atom;	1
(credit M3 independently unless arrows contradict)
(Credit possible repeat error from 2(c)(iii) for M3)
(If the wrong haloalkane is used OR but-1-ene is produced, award MAX. 2 marks for the mechanism)
(If E1 mechanism is used, give full credit in which M1 and M2 are for correct curly arrows on the correct carbocation)
 
 [5]
19.	(a)	(i)	CH3Cl + 2Cl2 ® CHCl3 + 2HCl (1)
(ii)	step in which radicals are used and formed (1)
(iii)	CH3Cl + Cl· ® ·CH2Cl + HCl (1)
(iv)	·CHCl2 + Cl2 ® CHCl3 + Cl·	4

(b)	Equation 	CH3Cl + 2NH3 ® CH3NH2 + NH4Cl (1)
Mecanism
	5
[9]

20.		CH4 + Cl2 ® CH3Cl + HCl (1)
Initiation: Cl2 ® 2Cl. (1)
Propagation: CH4 + Cl. ® CH3. + HCl (1)
	 CH3. + Cl2 ® CH3Cl + Cl. (1)
Termination: Cl. + Cl. ® Cl2 (1)
	or CH3. + CH3. ® C2H6	5
[5]

21.	Reaction 5	NH3 (1)	1
For Reaction 4; credit dil H2SO4 OR H2SO4(aq) OR HCl (aq) but NOT steam and NOT NaOH(aq)
 [1]
22.		nucleophilic substitution	1
(both words needed)
	Mechanism M1 curly arrow from lone pair on oxygen of hydroxide	1
ion to C atom of C-Br
Mechanism M2 curly arrow from C-Br bond to side of Br atom	1
(a possible repeat error here from Question 4a)
(award a maximum of one mark for the wrong haloalkane)
(credit an SNl mechanism in which Ml will be a curly arrow from the lone pair on oxygen of the hydroxide ion to the correct positive carbon atom)
	Y is susceptible to attack by hydroxide ions for one of the following reasons	1
	o	the C-Br bond is polar
o	the carbon atom is partially positive (or shown as such)
o	the carbon atom is electron deficient
 [4]

23.	(a)	Reaction 2: NaOH OR KOH (1) M1	alcohol (ic) OR ethanol (ic)(1) M2
ignore heat
Condition mark linked to correct reagent but award M2 if OH– or base or alkali mentioned
	2
(b)	Mechanism:

Award M3  independently 
M1 and M2 must be to / from correct places
E1 mechanism possible in which M2 
Name: of mechanism = elimination (1)
NOT dehydrohalogenation
Ignore “base” OR “nucleophilic” before elimination
Reason: Reaction 2 has (very) low yield (1)	5
QoL	OR chloroethane has to be made (from ethane)
	OR chloroethane is expensive
	OR chloroethane is not redily available
 [7]
24.	(a)	Alcohol: Reaction = Substitution (/ hydrolysis) (1)
Ignore reference to nucleophilic, but electrophilic give zero
	Alcohol: Role = nucleophile (/ lone pair donor) (1)
	Alkene: reaction = elimination (1)
Ignore ref to nucleophilic or electrophilic
	Alkene: base (/ proton acceptor) (1)	4
 
(b)	Alcohol = butan-2-ol  (1)
Not 2-hydroxybutane or but-2-ol
	Appropriate structure for CH3CH(OH) CH2CH3 (1)
Brackets not essential
SN2 version	SN1 version	
– bond is polar	C–Br bond is polar (1)	
Lone pair of OH–	C–Br bond breaks (1)	
Attacks the Cd+	forming carbocation / carbonium ion (1)	
M1 can be scored from a diagram, M2 and M3 from written
explanation only	5
 
 [9]
25.		(i)	2-chloro(-2-)methylpropane / (2)methyl 2 chloropropane (1)	1
(ii)	appropriate unambiguous formula for either but-1-ene or but-2-ene (1)
appropriate unambiguous formula for the remaining structural isomer
allow 1 mark if candidate draws cis and trans but-2-ene (1)	2
(iii)	unambiguous structure for 2-methylpropan-1-ol – may be
from mechanism (1)
	curly arrow / attack by OH–         curly arrow from lone pair or
charge only (1)
do not allow if Na -OH 
	curly arrow from bond to Cl / dipole shown on
C-Cl bond / intermediate showing 3 full and 2 partial bonds to C (1)
	loss of Cl– 	NaCl or Na+:Cl– (1)
– not allowed		4
 
	if SN1 mechanism given: 
first mark as above - independent
second mark for correct carbocation formed including curly
arrow from C to Cl or CS+ –ClS –
	third mark for hydroxide attack as above
final mark not available (wrong mechanism)
penalise missing proton once only
[7]

26.		

	                                                            CH3CH=C(CH3)2 (1)

CH3CH2C(OH)( CH3)2  (1)         2-methylbut-2-ene  (1)
2-methylbutan-2-ol  (1)          also loss of H+ from CH3  (1) 
	
14
 
[14]