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Organic Chemistry CHE230-001 EXAM 3
1.
Page 1 of 6
(50 pts) Draw the most likely product(s) to the right of the reactions and label them clearly A-J.
Hints: A-B, and E-J have stereochemical issues; in some cases you have to evaluate which is
the least hindered side of the molecules, in other cases cis versus trans etc. Pay attention to
regiochemistry—most stable carbocation. E and F are rearranged addition products. The bonds
that interact best with the carbocation are the ones most likely to shift to the most stable
carbocation. H is a racemic mixture of enantiomers, draw one enantiomer.
H2
Pd/C/CaO3/Pb
A
Lindlar catalyst
Na / NH3
B
1) BH3 / ether
2) H2O2 / NaOH / H2O
Na
C
O
O
H3O / H2O
D
H3O / H2O
E + F
diastereomers
1) OsO4, iPrOH
2) NaOH, H2O
OH
OH
OH
G
OH
OH
1) BH3 / ether
2) H2O2, NaOH, H2O
OH
H
O
OH
1) Cl2, H2O
2) NaOH, H2O
I
Cl
J
Organic Chemistry CHE230-001 EXAM 3
Page 2 of 6
2. (10 pts) Draw the starting material 2A. 2A has only 3 signals in its 13C NMR spectrum.
OH
1) O3, CH2Cl2
2) H2O2, H2O
O
2A
O
OH
3. (20 pts) Answer the following question in reference to the reaction energy diagrams below. The
labeled points on the reaction energy diagrams are either energies or chemical species,
depending on the sentence.
G
Energy
B
D
C
F
A
E
H
Reaction Coordinate
3a. ___C___ might be a catalytic intermediate or even a carbocation.
3b. __G-F__ This difference in energy might determine the rate of an SN2 reaction.
3c. ___E-A____This difference in energy might determine the ratio of product to starting material
of an E1 reaction.
3c. The Hammond postulate states that D is most similar in structure to ___C___.
Organic Chemistry CHE230-001 EXAM 3
Page 3 of 6
4. (10 pts) Rank the following carbocations by stability from 1-5. Use 1 as the most stable!
Pick the most stable 4 pts.
Pick the least stable 4 pts.
H2C
H
H
H
H
O
H
H
H
H
H3C
H
H H
H
O
H
4
H H
2
H
H
H
H
H3C
H
H
O
H
H3C
H
H
H
H
H H
3
H
H
O
H
H H
1
5. (10 pts) In general additions reactions of double and triple bonds are (exothermic or
endothermic)___exothermic______ because _________________
__More electrons in s-like orbitals in the product versus react. (one way to say)_
__Sigmabonds overlap better than pi-bonds to products are more stable. _______
___Another acceptable answer. ___________________________________________
6. (10 pts. bonus) Starting from molecules possessing five carbon atoms or less, draw the
chemical equations needed to show how you would synthesize 6A. Remember that the
conjugated bases of terminal alkynes can be used as nucleophiles in substitution reactions.
F3CCO3H
H2
lindlar cat
SN2
O
Na
Br
NaNH2
H
a possible route.
NH3