TOPIC 18 HW MS
1.       (a)     Cyclohexane evolves 120 kJ mol–1
 (expect triene to evole) 360 kJ mol–1 (1) or 3 × 120
360 – 208 = 152 kJ (1) NOT 150
152 can score first 2
QofL:   benzene lower in energy / more (stated) stable (1)
Not award if mentions energy required for bond breaking
     due to delocalisation (1) or explained
4
(b)     (i)      phenylamine weaker (1)
if wrong no marks
         lone pair on N (less available) (1)
delocalised into ring (1) or “explained”
3
(ii)     addition – elimination (1)

structure (1) M3
3 arrows (1) M4
N-phenyl ethanamide (1)
6
(iii)     conc HNO3 (1)
conc H2SO4 (1)
HNO3 + 2H2SO4 → O2 + H3O+ + 2HSO4– (1)

6
(iv)    peptide / amide (1)
NaOH (aq) (1)
HCl conc or dil or neither
H2SO4 dil NOT conc
NOT just H2O
2

          Notes
(a)     •    360 or 3 × 120 or in words (1);
•    152 NOT 150 (1);    (152 can get first two marks)
•    Q of L benzene more  stable but not award if ΔH values used to say
     that more energy is required by benzene for hydrogenation compared with
     the triene or if benzene is only compared with cyclohexene (1);
•    delocalisation or explained (1)
(b)     (ii)     or N-phenylacetamide or acetanilide
mechanism:  if shown as substitution can only gain M1
if CH3CO+ formed can only gain M1
lose M4 if Cl– removes H+
be lenient with structures for M1 and M2 but must be correct for M3
 alone loses M2
(iii)     No marks for name of mechanism in this part
if conc missing can score one for both acids (or in equation)
allow two equations
allow HNO3 + H2SO4 → NO2+ + HSO4– + H2O
ignore side chain in mechanism even if wrong
arrow for M1 must come from niside hexagon
arrow to NO2+ must go to N but be lenient over position of +
+ must not be too near “tetrahedral” Carbon
horseshoe from carbons 2-6 but don’t be too harsh
(iv)    reagent allow NaOH
HCl conc or dil or neither
H2SO4 dil or neither but not conc
not just H2O
[21]

2.     (a)     (i)      C6H6 + CH3CH2COCl → C6H5COCH2CH3 + HCl
OR
C6H6 + CH3CH2CO+ → C6H5COCH2CH3 + H+
allow C2H5
penalise C6H5–CH3CH2CO
allow + on C or O in equation
1
Phenylpropanone
OR ethylphenylketone OR phenylethylketone
Ignore 1 in formula, but penalise other numbers
1
AlCl3
can score in equation
1
CH3CH2COCl + AlCl3 → CH3CH2CO+ + AlCl4–
allow C2H5
allow + on C or O in equation
1
AlCl4– + H+ → AlCl3 + HCl
1

(ii)     electrophilic substitution
can allow in (a)(i) if no contradiction
1

M1 arrow from circle or within it to C or to + on C
horseshoe must not extend beyond C2 to C6 but can be smaller
+ not too close to C1
M2 penalise C6H5–CH3CH2CO (even if already penalized in (a)(i))
M3 arrow into hexagon unless Kekule
allow M3 arrow independent of M2 structure
ignore base removing H in M3
3
 [9]

3.	(a)      (i)     Conc HNO3
If either or both conc missing, allow one;
1
Conc H2SO4
this one mark can be gained in equation`
1
2 H2SO4 + HNO3  2 HSO4– + NO2+ + H3O+
1
OR     H2SO4 + HNO3  HSO4– + NO2+ + H2O
Allow + anywhere on NO2+
OR     via two equations
           H2SO4 + HNO3  HSO4– + H2NO3+
           H2NO3+  NO2+ + H2O
(ii)
•   ignore position or absence of methyl group in M1 but must be in     correct position for M2
•   M1 arrow from within hexagon to N or + on N
•  Allow NO2+ in mechanism
•   Bond to NO2 must be to N
•   horseshoe must not extend beyond C2 to C6 but can be smaller
•   + not too close to C1
•   M3 arrow into hexagon unless Kekule
•   allow M3 arrow independent of M2 structure
•   ignore base removing H in M3
•   + on H in intermediate loses M2 not M3
3

(b)     2C7H5N3O6      5H2O   +   3N2   +   7C   +   7CO
Or halved
1
[7]
 
4.     (a)    (i)      conc HNO3
1
conc H2SO4
allow 1 for both acids if either conc missing
1
HNO3 + 2H2SO4 → NO2+ + H3O+ + 2HSO4–
or HNO3 + H2SO4 → NO2+ + H2O + HSO4–
1
(ii)     electrophilic substitution CH3
1

horseshoe must not extend beyond C2 to C6 but can be smaller
+ must not be too close to Cl
3
(b)     Sn or Fe / HCl (conc or dil or neither)
or Ni / H2 not NaBH4 LiAlH4
1
(c)     (i)     NH3
1
Use an excess of ammonia
1
(ii)     nucleophilic substitution
1

4

[19]

5.     (a)     CH3CH2COCl OR CH3CH2CClO OR propanoyl chloride
OR (CH3CH2CO)2O OR propanoic anhydride
penalize contradiction in formula and name e.g. propyl chloride
could score in equation
1
AlCl3 or FeCl3 or names
could score in equation
1
CH3CH2COCl + AlCl3 → CH3CH2CO+ + AlCl4–
Allow RCOCl in equation but penalise above
allow + on C or O in equation
1
(b)

M1 arrow from circle or within it to C or to + on C
Horseshoe must not extend beyond C2 to C6 but can be smaller + not too close to C1
M3 arrow into hexagon unless Kekule
allow M3 arrow independent of M2 structure
Ignore base removing H in M3
3

(c)     Tollens or ammoniacal silver nitrate
1
		
penalise wrong formula
1
[8]
 
6.          (a)     CH3COCl  +  AlCl3  →  CH3O  +  AlCl 
                                        (1)                        equation (1)
2
penalise wrong alkyl group once at first error
position of + on electrophile can be on O or C or outside [ ]
penalise wrong curly arrow in the equation or lone pair on AlCl3  else ignore
Electrophilic substitution
NOT F/C acylation
1

horseshoe must not extend beyond C2 to C6 but can be smaller 
+ not too close to C1
M3 arrow into hexagon unless Kekule
allow M3 arrow independent of M2 structure
M1 arrow from within hexagon to C or to + on C 
+ must be on C of 
3

(b)     Nucleophilic addition
NOT reduction
1

M2 not allowed independent, but can allow M1 for attack of H– on C+ formed
4
          1–phenylethan(–1–)ol        or (1–hydroxyethyl)benzene
l
(c)     dehydration or elimination
1
(conc) H2SO4 or (conc) H3PO4 
allow dilute and Al2O3 
Do not allow iron oxides
1
[14]
 
7.	B
[1]
8.	D
[1]