CHEM 203 Study Guide - Proton Nuclear Magnetic Resonance, Magnesium Bromide, Sn2 Reaction

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7 Feb 2013
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CHEM 203 Midterm #2-Nov. 14, 2006
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CIRCLE YOUR LECTURE SECTION: DAKE: MWF 9 AM CIUFOLINI MWF 2 PM
MOLECULAR MODELS MAY BE USED
1
2
3
4
5
raw total
total
18
10
14
6
10
70
10
1. (18 marks) Answer each of the following parts.
a) Draw the structure of:
e.g.: CH3I, Br
IBr
Br
etc.
,
e.g.: Cl
e.g.: Br
• an alkyl halide that is likely
to undergo SN2 reaction when
treated with CH3ONa
• an alkyl halide that is likely
to undergo E2 reaction when
treated with CH3ONa
• an alkyl halide that is likely
to undergo nucleophilic
substitution by the SN1
mechanism
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b) Circle any compound in the series below that has only two singlets in its 1H NMR spectrum.
CH3
CH3CO
OCH3
OCH3
OCH3
H3CO O
CH3CH3
OCH3
none of these
all of these
c) Provide the structures of:
i) a hydrocarbon containing at least 5 carbon
atoms that is a good substrate for radical
chlorination
ii) a hydrocarbon containing at least 5 carbon
atoms that is a poor substrate for radical
chlorination
e.g.:
,
CH3C
CH3
CH3
CH3
e.g.:
etc.
,
,
d) Treatment of 1,2-dibromoethane with magnesium metal in an ether solvent produces ethylene
gas and magnesium bromide (below). Using arrows to represent electron movement, provide a
reasonable mechanistic rationale for this known process.
Br Br
Mg°
ether
CH2=CH2 + MgBr2
Mg
Br Br
Mg
Br Br then, either:
Mg
Br Br Br Mg Br Br MgBr
SET
or
Mg
Br Br Br Br MgBr
followed by:
SET
MgBr
Br MgBr Br
MgBr
CH2=CH2 + Br + MgBr MgBr2
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e) The 1H NMR spectrum of unknown organic compound A is shown below. Circle the structural
formula of A.
O
O O O O
CH3O O
O O
O O
O O
O
O
CH3O
O O
O
relative ratio under 2 2 3 2 3
signals:
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