100%
CHE2613
EXAM PACK
DISTINCTION QUALITY
UNISA EXAM
, lOMoARcPSD|59991305
UNIVERSITY EXAMINATIONS
October / November 2025
CHE2613
Organic Chemistry II
100 Marks
Duration 2 Hours
EXAMINERS:
FIRST: K.G Lesenyeho
SECOND: Prof. C. A. Summers
Instructions:
This a closed book examination.
Make sure to tick the honour pledge box before submission.
Students found cheating/ copying/ plagiarizing will be disqualified.
IRIS tool will be used to monitor and maintain academic integrity during an examination
Ensure that IRIS installed on your computer
Examination paper will be accessed on https://myexams.unisa.ac.za
Please ensure that you are always connected to the internet.
, lOMoARcPSD|59991305
Question 1
1.1 Use electron factors to rank the following according to increasing intermediate
stability when each molecule is reacted with 1 mol of HBr.
a) b) c)
(8)
Tertiary carbocation,
stabilised by inductive effect
H Br
a)
Tertiary allylic carbocation,
stabilised by both inductive
and resonance effects
H Br
b)
Tertiary allylic carbocation,
stabilised by both inductive
and resonance effects
Secondary carbocation,
stabilised by inductive effect
c)
H Br
Order of increasing stability: c < a <b
, lOMoARcPSD|59991305
(ii) Give the major product that will form in the reaction described in (i) above
(3)
Br
1.2 The reaction shown below produces a racemic mixture
Br
CH3OH
a) Propose a mechanism to account for the formation of a racemic mixture.
CHE2613
EXAM PACK
DISTINCTION QUALITY
UNISA EXAM
, lOMoARcPSD|59991305
UNIVERSITY EXAMINATIONS
October / November 2025
CHE2613
Organic Chemistry II
100 Marks
Duration 2 Hours
EXAMINERS:
FIRST: K.G Lesenyeho
SECOND: Prof. C. A. Summers
Instructions:
This a closed book examination.
Make sure to tick the honour pledge box before submission.
Students found cheating/ copying/ plagiarizing will be disqualified.
IRIS tool will be used to monitor and maintain academic integrity during an examination
Ensure that IRIS installed on your computer
Examination paper will be accessed on https://myexams.unisa.ac.za
Please ensure that you are always connected to the internet.
, lOMoARcPSD|59991305
Question 1
1.1 Use electron factors to rank the following according to increasing intermediate
stability when each molecule is reacted with 1 mol of HBr.
a) b) c)
(8)
Tertiary carbocation,
stabilised by inductive effect
H Br
a)
Tertiary allylic carbocation,
stabilised by both inductive
and resonance effects
H Br
b)
Tertiary allylic carbocation,
stabilised by both inductive
and resonance effects
Secondary carbocation,
stabilised by inductive effect
c)
H Br
Order of increasing stability: c < a <b
, lOMoARcPSD|59991305
(ii) Give the major product that will form in the reaction described in (i) above
(3)
Br
1.2 The reaction shown below produces a racemic mixture
Br
CH3OH
a) Propose a mechanism to account for the formation of a racemic mixture.
