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ORGANIC CHEMISTRY I (CHEM 115/CNED 013)
EXAM #3
November 18, 2002
Name:_____________________________________
Please read each question carefully before you begin. Your exam should have a total of 9 pages.
You will have two hours in which to complete this exam; be sure to save time to check your
answers after you’re finished. The backs of the pages may be used for rough work, but your
answers should be written clearly on the front of the page in the spaces provided. Molecular models
and non-programmable calculators may be used. Show your work clearly, and you may receive
partial credit for partially correct answers. Good luck!
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1. (10 pts total, 5 each) Provide an IUPAC name or structure for the following.
CH3
H
C
H
C
C
C
C
CH3
C
__________________________________
__________________________________
2. (20 pts total) Hydrobromination of 1-methylcyclohexene with HBr yields different products
with the molecular formula C7H13Br depending on the reaction conditions. Provide the structures of
all product(s) under each set of reaction conditions, paying careful attention to both regiochemistry
and stereochemistry.
HB
C7H13Br
r
OR
O
(R
t)
ea
h
+
HB
(da
rk)
r
Briefly explain the modern-day rationale behind Markovnikov's rule.
C7H13Br
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3. (20 pts) Draw step-by-step mechanisms to explain the two following reactions. Make sure that
you use arrows to denote all bond breaking and bond forming steps, and show the structure for each
intermediate.
O
H
H + , H 2O
HO
O
OH
-
OH , H2O
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4. (60 pts) For each of the following reactions, fill in the missing reagents or major product(s) to
complete the transformations. If more than one step is necessary, list the reagents sequentially
above the arrow as 1,2,3 etc. Whenever necessary, you should specify the stereochemistry of the
product(s) in your structure(s).
C
H2, Pt
C
cis-3-hexene
1. OsO4
trans-3-hexene
2. H2O2
KMnO4
OH, H2O
(hot, conc.)
2-pentyne
KMnO4
OH, H2O
(cold, dilute)
H3CH2C
H
H
CH3
5
O
CH2
C
O
C
H
C
H
C
CH2CH3
C
O3
C
H2O
H3C
CH3
5. (50 pts total, 25 each) Unknowns A, B and C each contain exactly 5 Carbon atoms. Based on
the IR and MS data provided, determine the molecular structures for 2 out of 3 of them and draw
them in the boxes below. Note: If the structure is incorrect, some partial credit may be awarded
ONLY IF you make a clear itemized list stating how you deduced specific bits of info (e.g. this
peak/fragment suggests functional group X, molecular weight, molecular formula, the absence of
this peak/fragment means X etc.) This information should be clearly written in the box marked
“relevant info”.
Unknown A
Unknown B
Unknown C
CH3
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Unknown A
Peaks Observed in the Mass Spectrum: 86 (s), 71 (s), 57 (l), 29 (l), 15 (s) {s, m, l = relative
intensities}
Relevant Info
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Unknown B
Peaks Observed in the Mass Spectrum: 86 (s), 71 (s), 57 (l), 29 (l), 15 (s) {s, m, l = relative
intensities}
Relevant Info
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Unknown C
Peaks Observed in the Mass Spectrum: 152 & 150 (1:1 ratio, s), 137 & 135 (1:1 ratio, s), 109 &
107 (1:1 ratio, s), 71 (l), 57 (s), 43 (l) {s, m, l = relative intensities}
Relevant Info
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6. (40 pts total, 20 each) Propose multi-step syntheses for 2 out of 3 of the compounds shown
below. You can use any reagents you like, however all carbon atoms in the product must originate
from one or more of the following: propyne, iodomethane, diiodomethane and 1-iodopropane.
You do not need to show the mechanisms, but you do need to show the structure of each important
intermediate.
Br
O
H
OH
H
Br
1. _____/10
2. _____/20
3. _____/20
4. _____/60
5. _____/50
6. _____/40
TOTAL: ______/(200)