Name
CHEM 0203 (Organic II)
Test 1 (2/16)
Spring 2011
Common solvents used in organic chemistry.
O
THF =
O
O
Et2O =
DMSO =
O
S
DMF =
N
O
1. _______
acetone =
1. (6 pts. ea.) Predict the outcome of the following reactions. Remember to use wedge and
dashed bonds to indicate the stereochemical outcome of the reaction where appropriate.
2. _______
3. _______
a.
CH3CH2SH
SN2
THF
4. _______
CH3OH
5. _______
Br
b.
SN1
Br
6. _______
7. _______
c.
H2O
SN1
8. _______
Br
2. For the following pairs of molecules (a. 4 pts.) circle the nucleophilic atom, and (b. 3 pts. ea.)
determine which is the better nucleophile under the given conditions.
CH3SNa
solvent: acetone
CH3SH
CH3SNa
substrate: 1-bromobutane
Cl–
Br–
solvent: THF
CH3ONa
substrate: 1-bromobutane
N
N
solvent: isopropanol
substrate: CH3OSO2CF3
solvent: THF
(–OSO2CF3 is an amazing leaving group)
substrate: 2-bromobutane
3. (10 pts.) Explain why increasing the concentration of the nucleophile in the following
reaction doesn't increase the rate of the reaction.
Br–
OH2
H2O
Br
9. _______
4. a. (4 pts.) Draw an SN2 reaction that shows that the stereochemistry of a chiral α-C is inverted.
b. (3 pts.) Include the transition state as part of the reaction.
c. (3 pts.) Explain why the stereochemistry of the α-C must be inverted.
5. (10 pts.) The synthesis of 3,3-dimethyl-2-butanol was attempted as indicated below, but 2,3dimethyl-2-butanol was produced instead.
OH
Br
Br
H2O
H2O
desired outcome
OH
actual outcome
Draw a mechanism that explains the observed outcome of the reaction.
6. (4 pts. ea.) Determine whether the following reactions would be likely to occur via an SN1, an
SN2, or a combination of SN1 and SN2 mechanisms.
I
CH3OH
Br
I–
acetone
OH2
Br–
H3O+
NH3
I
Et2O
7. a. (4 pts.) What can protic solvents do that aprotic solvents cannot?
b. (4 pts.) How can protic solvents encourage carbocation formation in an SN1 reaction?
8. (8 pts.) Which is the better leaving group, I– or Cl–? Explain your response.
9. With the help of an enzyme adrenaline is synthesized during the so-called "fight or flight"
response. The reaction is a biochemical example of nucleophilic substitution.
NH2
NH2
N
N
H
N
N
H
NH2
H
C
H
H
H
HO
HO
O
S
OH
H
OH OH
H
HO
S-adenosylmethionine
a. (3 pts.) Identify the atom that acts as the nucleophile.
b. (3 pts.) Identify the leaving group.
c. (3 pts.) Is this an SN2 or SN1 reaction. Explain your choice.
O
S
H
H
OH
O
epinephrine
(adrenaline)
H
H
OH OH
O
H3N
O
norepinephrine
(noradrenaline)
C
H
O
H3N
N
H
N
N
H
H
HO
N
N