Chem 352 Winter 2006 students:

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Chem 352 Winter 2006 students We are behind my
anticipated schedule. You should make a
composite exam in the following way On
the 351 sample final exam try questions 1, 4-7,
17, 23-25 On this exam (352 1) try only
questions 1-4, 15-17
You should review alkene nomenclature and the use
of cis/trans and E/Z designations.
Also read the slides How to draw a
mechanism which are found with the PowerPoint
lecture slides. (Merged mechanisms are OK by
me.)
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D. PAVIA CHEM 352
SAMPLE EXAM ONE
1. Give the expected major product in each of the
following reactions.
Br2
1M H2SO4
A
B
H2O
H2O
conc
HBr
HCl
peroxides
C
D
2. Write the structure of the alkyne whose
hydration product would be
b)
a)
3
3. It is difficult to synthesize an alkene from
an alkyne. How can the following reaction be
accomplished? Show specific reagents and
explain.
4. Show the reactions you would use to prepare
the following compounds starting with any
alkene that you wish. Be sure your method
gives the desired compound as the major
compound.
a)
b)
c)
4
5. Give the expected result for each of the
following reactions.
KOH
ethanol / heat
KOH
ethanol / heat
KOH
ethanol / heat
5
KOH / EtOH
heat
6
NaOEt / EtOH
heat
NaOEt / EtOH
heat
KOH / EtOH
heat
7
6. Which of the following compounds will react
with the fastest rate when allowed to undergo
solvolysis (elimination) in warm ethanol?
Explain briefly.
a)
b)
c)
7. What kind of elimination reaction takes place
in Problem 6?
__________
8. Draw comparative energy profile curves
(overlaid) for each of the compounds in
Problem 6.
8
9. Classify each of the following reactions as
either E1, E2 or E1cb.
9
10.
Draw a complete mechanism for the following
reaction. Include electron pairs, formal
charges, and curved arrows. Also be sure to mark
the rate-determining step.
11. How could you prepare the following
compound? Give a method.
10
12. Name the following compounds.
a) NaOCH2CH3
c)
b)
13. Show what reactions you would use to convert
1-pentene to 2-pentyne.
14. E2 eliminations always follow the Zaitsev
Rule. True or false? Explain your answer.
11
a) 1-Butene reacts with concentrated HCl at a
faster rate than any 2-butene.
15.
b) cis-2-butene reacts (same reagent) faster than
trans-2-butene.
c) All three alkenes give the same major product.
d) The reaction forming the product is exothermic
in each case.
e) The same intermediate is formed in each case.
Draw an energy profile that explains the
difference in the rates of reaction for these 3
alkenes. All three compounds may be drawn on the
same set of coordinates.
HINT. Remember the heats of hydrogenation
studies on these three alkenes.
12
16.
Consider the two isomeric alkenes
2-butene and 2-methyl-1-propene.
a) Which alkene would you expect to react fastest
with concentrated HCl?
b) Draw two energy profiles (one for each
reaction) to illustrate (explain) your
answer.
c) What is the most important mechanistic reason
that your choice reacts fastest?
HINT Think about intermediates.
13
17.
Draw a complete mechanism, showing the formation
of the correct major product, for the following
reaction.
Show all steps, all intermediates, all unshared
pairs, and all charges where appropriate.
Use curved arrows to indicate electron
movement. Pay attention to stereochemistry.
in methanol (no water)
3M
CH3
H2SO4
CH3OH

(HINT H2SO4 ionizes completely in CH3OH.)