CHE1502
EXAM PACK
Solutions, Explanations, workings, and references
+27 81 278 3372
,MAY 2017 CHE1502
SECTION B
Question 1 [20]
(a) Draw the resonance forms to show the delocalization of charges in the
following structure. Show the movement of electrons with curved arrows.
(4)
1 mark for each arrow
1 mark each for correct 2nd and 3rd structure
(b) Draw the Newman projection formulas of the MOST STABLE and LEAST
STABLE conformations of the following compound below. Label the
conformations accordingly.
, (6)
2 marks for each correct Newman projection and 1 mark for correct Least stable
and 1 mark for correct most stable label.
If Newman projections are wrong but most and/or least stable identification is
correct give 1 mark each.
(c) Draw the Lewis structure of any secondary alcohol and give the IUPAC of the
chosen compound.
(4)
Any secondary alcohol √
Lewis structure : all bonds and atoms must be shown and the electrons around
O √√
Correct IUPAC name √
(d) Formulate a detailed mechanism of the following nucleophilic substitution
reaction:
, Name the product according to the IUPAC nomenclature.
(6)
Firstly, carbocation formation:
√ √
Secondly, we redraw the carbocation (in 3-D format) and show the nucleophile
attacking from the bottom or top:
√ √ √ one of each step and the product
IUPAC name: 3-Methyl-3-methoxypentane √
Question 2 [20]
(a) Consider the following reaction:
EXAM PACK
Solutions, Explanations, workings, and references
+27 81 278 3372
,MAY 2017 CHE1502
SECTION B
Question 1 [20]
(a) Draw the resonance forms to show the delocalization of charges in the
following structure. Show the movement of electrons with curved arrows.
(4)
1 mark for each arrow
1 mark each for correct 2nd and 3rd structure
(b) Draw the Newman projection formulas of the MOST STABLE and LEAST
STABLE conformations of the following compound below. Label the
conformations accordingly.
, (6)
2 marks for each correct Newman projection and 1 mark for correct Least stable
and 1 mark for correct most stable label.
If Newman projections are wrong but most and/or least stable identification is
correct give 1 mark each.
(c) Draw the Lewis structure of any secondary alcohol and give the IUPAC of the
chosen compound.
(4)
Any secondary alcohol √
Lewis structure : all bonds and atoms must be shown and the electrons around
O √√
Correct IUPAC name √
(d) Formulate a detailed mechanism of the following nucleophilic substitution
reaction:
, Name the product according to the IUPAC nomenclature.
(6)
Firstly, carbocation formation:
√ √
Secondly, we redraw the carbocation (in 3-D format) and show the nucleophile
attacking from the bottom or top:
√ √ √ one of each step and the product
IUPAC name: 3-Methyl-3-methoxypentane √
Question 2 [20]
(a) Consider the following reaction:
