TOPIC 17 HW MS

1.	     (i)
          
1
          propan(e)-1,2,3-triol
          OR
          1,2,3-propan(e)triol
          OR
          Glycerol;
1
(ii)     CH3(CH2)16COONa  or  C17H35COONa or C18H35O2Na;
(ignore 3 in front of formula but not if indicating trimer)
1
(not just anion and penalise Na shown as covalently bonded) soap - 
allow with detergent but not detergent alone;
1
[4]
 
2.      X is CH3CN or ethanenitrile or ethanonitrile or methyl cyanide or
cyanomethane or ethyl nitrile or methanecarbonitrile
Not ethanitrile
but contradiciton of name and structure lose marks
1
          Y is CH3CH2NH2 or ethylamine or aminoethane or ethanamine
1
          Step 1: reagent      KCN not HCN/HCl
           condition      (aq)/alcohol - only allow condition if reagent
           correct or incomplete
2
          Step 2: reagent      H2                  LiAlH4        Na            Zn/Fe/Sn    Not NaBH4
            condition      Ni/Pt/Pd        ether        ethanol     HCl
2

         

Z is an amine or aminoalkane or named amine even if incorrect name for Z
            secondary (only award if amine correct)
1
   (Br–) + can be on N or outside brackets as shown
1
          nucleophilic substitution
1
[9]
 
3.	Mechanism

          Name of organic product: methylpropanoate (1)
5
          Notes
extra curly arrows are penalised
 alone loses M2 but can score M1 for attack on C+, similarly 
in M4, allow extra: Cl– attack on H, showing loss of H+
 [5]

          Organic points
(1)     Curly arrows: must show movement of a pair of electrons,
i.e. from bond to atom or from lp to atom / space
e.g.

(2)     Structures
penalise sticks (i.e. ) once per paper

Penalise once per paper
          allow CH3– or –CH3 or  or CH3
    or   H3C

4.    (a)     Melting range would be
         wide (>3 deg C) / not sharp
Allow melts over a range of temperatures.
1
below / before the true m.p.
Do not allow ‘above or below’.
1
(b)     Temperature on thermometer not the same as the sample
Allow sample heats up at a different / higher / lower rate than thermometer.
1
[3]

5.          (a)     

1

1
NB     The bonds shown in the structure must be correct
         Isomerism: E-Z isomerism
If written answer is correct, ignore incorrect labelling of structures.
If no written answer, allow correctly labelled structures.
1
         Both COOH groups must be on the same side/ close together/ cis
1
         No rotation about C=C axis
1
          Structure

1
(c)     e.g. 2NaOH + HO2CCHCHCO2H → NaO2CCHCHCO2Na + 2H2O
          Both H replaced
1
Balanced for atoms and charges
1
NB Allow ionic equations and      2NaOH + C4H4O4 → C4H2O4Na2+ 2H2O
     Allow one if structure incorrect but molecular formula
     correct
     Allow one for a correct equation showing one H replaced

 [8]
 6.     Advantage; reaction goes to completion, not reversible
or faster
                1
         Disadvantage; reaction vigorous/dangerous
(exothermic must be qualified)
          or HCl(g) evolved/toxic
or CH3COCl expensive
NB     Allow converse answers
     Do not allow reactions with other reagents e.g. water
     or ease of separation
1
 [2]
 
7.        (a)       

(allow 1 for amide even if not C4H7NO, i.e. RCONH2)
(if not amide, allow one for any isomer of C4H7NO which shows
geometric isomerism)
2
(b)      

1
[3]

 8.          (a)     (nucleophilic) addition-elimination;

(M3 for structure)
(M4 for 3 arrows and lone pair)
(M2 not allowed independent of M1, but allow M1 for correct attack
on C+ if M2 show as independent first.)
(+on C of C=O loses M2 but ignore δ+ if correct)
(Cl– removing Ft loses M4)
1

(If MS lost above for wrong C chain, do not penalise same error again here)
5

(b)     M1 CH3CH2COCl + H2O → CH3CH2COOH + HCl 1
(penalise wrong alkyl group once at first error)
1
M2 Mr of CH3CH2COCl = 92.5 1
(if Mr wrong, penalise M2 only)
1
          M3 moles of CH3CH2COCl = 1.48/92.5 = 0.016 1
1
M4 moles NaOH = 2 × 0.016 = 0.032 1
(allow for × 2 conseq to wrong no of moles)
1
M5 volume of NaOH = 0.032/0.42 = 0.0762 dm3 or 76.2 cm3 1
(with correct units)
(if ×2 missed in M4 lose M5 also)
1
[11]

 

9.      (a)     M1    CH3CH2CH2COOH
not C3H7COOH
1
M2    CH3CH2OH or C2H5OH
1
M3    CH3CH2CH2COOCH2CH3 + H2O
allow C3H7COOC2H5
penalise M3 for wrong products and unbalanced equation
1
M4    H2SO4 or HCl or H3PO4 conc or dil or neither
not HNO3
1
(b)     M1    CH3CH2CH2CH2OH
1
not C4H9OH
M2    (CH3CO) 2O
1
M3    → CH3COOCH2CH2CH2CH3 + CH3COOH
allow CH3COOC4H9
penalise M3 for wrong products and unbalanced equation
1
(c)     (nucleophilic) addition-elimination

not acylation alone
M2 not allowed indep of M1 but allow M1 for correct attack on C+
+C=O loses M2
only allow M4 after correct or v close M3
ignore Cl– removing H+
5

(d)

              (1)                                                              (1)                             (1)
ignore errors in initial triester
First mark for 3CH3OH
Third mark for all three esters
3
 [15]
10.      (a)     Nucleophilic substitution

1
          M1, M2 and M4 for arrows, M3 for structure of cation
(Allow M2 alone first, i.e. SN1 formation of carbocation)
(Penalise M4 if Br– used to remove H+)
4
(b)     Step 1        CH3CH2CH2CN   1
CH3CH2CH2Br + KCN → CH3CH2CH2CN + KBr balanced
1
                            (or CN–) (or Br–)
                   (not HCN)
1
Step 2        CH3CH2CH2CN + 2H2 → CH3CH2CH2CH2NH2
                     (or 4[H])
1
(c)            Lone pair (on N) (in correct context)
1
R group increases electron density / donates electrons /pushes
electrons / has positive inductive effect
1
(d)     CH3CH2N(CH3)2
1
[11]
 
11.	1-chloropropane        no visible change
Accept ‘small amount of precipitate’ or ‘precipitate forms slowly’.
1
  ethanoyl chloride        white precipitate
Accept ‘large amount of precipitate’ or ‘precipitate forms immediately’.
1
[2]

12.	A
[1]
13.	A
[1]
14.	C
[1]
15.	C
[1]
16.	D
[1]
17.	A
[1]
18.	D
[1]