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Exam 2013, questions and answers
Chemistry B (University of South Africa)
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CHE 1502 MAY/JUNE 2013 MEMORANDUM SECTION B
Question 1 (a)
Draw the Newman projections of the different conformations of 1-bromopropane viewing along the C1-C2- bond. Label the most stable and least stable conformation. (6)
CH3
Br
H H
H H
H Br
Br CH3
H
H
H H
H CH3
Br
H H
Least stable
(b)
H
H
H
H CH3
Most stable
Write the detailed mechanism of the following reaction: H2O ethanol Br
OH
(4) The mechanism of the reaction:
+ Br
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Br
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H2O O H
H
+ O H
Br
H
HBr
OH
Question 2 (a)
Draw the structure of any secondary alcohol. (2)
(b)
Draw the geometric isomers of 3-methyl-2-pentene. Give the IUPAC name of each isomer (4)
(E)-3-Methyl-2-pentene
(Z)-3-Methyl-2-pentene
(c)
Give the mechanism of the reaction of HCl with CH3CH=CH2 (4) The reaction mechanism is:
CH3CH
CH2
+
H
Cl
CH3CH
CH3
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+
Cl
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CH3CH
CH3
+
Cl
CH3CHCH3 Cl
]
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