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ORGANIC CHEMISTRY I (CHEM 323)
EXAM 3
November 26, 2013
There are five pages, NINE questions, and a total of 115 points in this exam, which gives an extra 15 points on top
of that required for a “perfect” paper. Please read each question carefully and possibly more than once.
Good luck…
(15)
1.
Give the major products for the reactions below. If the major product is a mixture of stereoisomers, show
all the stereoisomers (in a way they can be distinguished from one another).
1.1.
1.2.
1.3.
(12)
2.
The following reactions are regioselective and/or stereoselective. Provide structures for the missing final
major products. Show stereochemical features in a distinguishable manner (where appropriate).
2.1.
2.2.
Chem 323 Exam 3
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(8)
3.
Show how the following synthesis can be carried out stereoselectively.
More than one step may be required.
Show all reagents and intermediate products.
(12)
4.
Hydrogen cyanide, HCN, is not acidic enough to react with an alkene; therefore, the synthesis below
requires more than one step. Show all the steps of the synthesis in the right sequence. Give the reagents
used and the reaction conditions utilized (including acid base catalysis). Show the structures of all
intermediate products.
(12)
5.
For each pair of missing precursors below, one is an alkyl bromide and the other is an organic molecule in
its ionic form. Provide structures for the missing precursors from which the products shown are obtained in
high yields.
Question submitted by Motu
5.1.
5.2.
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6.
Circle the best correct answer (only ONE) for the multiple-choice questions below.
6.1.
Which one of the following statements suggests that the catalytic hydrogenation of an alkene is an
exothermic reaction?
(1)
(2)
(3)
(4)
6.2.
Hydrogen gas is flammable
A catalyst speeds up the reaction
Alkenes are more stable than alkanes
Alkanes are more stable than alkenes
In the following reaction the transition state of the rate determining step resembles
(1) The more reactive carbocation
(2) The epoxide starting material
(3) The more stable carbocation
(4) The epoxide in its chair form
(5) The transition state of an SN2 reaction
6.3.
What is the product of the reaction in question 6.2?
6.4.
Which of the organic products shown below is generated when 1-butanol is treated with
sodium hydride in a suitable solvent?
6.5.
The two reactions shown below are both carried out using bromine in an organic solvent. The
starting material for one is cis-3-hexene, and the other, trans-3-hexene. What is the relationship
between the two products A and B?
(1) identical compounds
(4) constitutional isomers
(2) enantiomers
(3) diastereomers
(5) no isomeric relationship
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6.6.
What is the leaving group in the reaction below?
6.7.
What is the molecular formula of a nine-carbon hydrocarbon with one ring and two double bonds
in its structure?
(1) C9H20
(2) C9H18
(3) C9H16
(4) C9H14
(5) C9H13
(17)
7.
Outline a step-wise mechanism for the following reaction. Show the structures of all the intermediates
formed and of the final product. Use curly arrows to illustrate bond cleavages and/or bond formations.
7.1.
The alkene below undergoes a very similar skeletal rearrangement. Give the structure of the final
product (no need for details of mechanism).
(12)
8.
Outline a retrosynthetic analysis for the target ketone below starting from the alkyl halide shown.
You do not need to give any reagents or reaction conditions, only the intermediate products in a sequential
way. Make sure that your transformations are selective and do not yield unwanted side products.
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9.
The reaction shown below can be carried out only in the presence of the macrocyclic molecule
(given under the chemical equation).
O
O
O
O
O
O
9.1.
The macrocyclic molecule is referred to as (fill in the blank) _________________________
9.2.
The macrocyclic molecule forms a host-guest complex with one of the species (or with one which
can be derived from those) above. Write the species which functions as the “guest”.
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15
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21
17
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0
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115
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