1 out of 7
Chemistry 220b, Section 1
Exam 3 (75 pts)
Thursday, April 3, 2008
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This Exam is closed book and closed notes
NOTE: It is difficult for me to give you partial credit if you do not show your work!
Neatness counts
Good Luck !!
2 out of 7
1-10. Multiple Choice. Give the best answer for the following. (30 pts)
1.
The pKa of tert-butanol is 18. Which of the following carbonyl compound undergoes αdeprotonation with potassium tert-butoxide to give the highest concentration of the corresponding
enolate?
a)
b)
O
c)
O
O
pKa ~ 20
2.
d)
O
O2N
OC(CH3)3
pKa ~ 5.1
O
(H3C)3CO
pKa ~ 11
OC(CH3)3
pKa ~ 19
Which of the following sequences can be used to synthesize 6-methyl-2-heptanone.
O
6-methyl-2-heptanone
a)
O
H
O
b)
THF
H3CO Na
H3COH
O
H3CO
H3O+
BrMg
NaOH,
H2O
H3O+, !
OCH3
Br
H3CO Na
H3COH
O
c)
!
O
H
d)
O
O
OCH3
H3CO Na
H3COH
NaOH,
H 2O
H3O+, !
Br
3. Which is the correct order of predicted acidity from most acidic to least acidic?
OH
OH
a)
>
OH
OH
>
>
H 3C
O2N
Cl
OH
c)
OH
>
OH
>
Cl
O2N
>
OH
OH
>
Cl
OH
>
H 3C
OH
OH
O2N
O2N
Cl
>
d)
>
OH
OH
b)
OH
OH
>
H3C
O
>
H 3C
3 out of 7
4.
Which of the following is a feasible way to make 2-aminopentane?
O
HN
a)
LiAlH4, then H2O
b)
2) LiAlH4
then H2O
1) CN
Br
O
d)
5.
N
Br
c)
NaOH, H2O
O
None of the above; i.e., a, b, and c, are not feasible ways to make 2-aminopentane
Which of the following is a feasible way to make 3-nitrophenyl ethyl ether.
a)
H3CH2C-O
Na+
+
F
O 2N
b)
O
Na+
+
H3CH2C-Br
O 2N
c)
d)
6.
OCH2CH3
+ HNO3 + H2SO4
All of the above; i.e., a, b, and c, are all feasible ways to make 3-nitrophenyl ethyl ether
Which Fischer projection corresponds to the Haworth formula of tagalose shown below?
HOH2C
OH
O
OH
HO
H
H
H
Tagalose
a)
7.
HO
HO
H
H
CHO
H
H
OH
OH
CH2OH
b)
CH2OH
O
HO
H
H
OH
H
OH
CH2OH
CH2OH
c)
CH2OH
O
HO
H
HO
H
H
OH
CH2OH
CH2OH
OH
O
H
OH
HO
H
CH2OH
d)
H
The Fischer projection of pseudoephedrine, 2-methylamino-1-phenylpropan-1-ol, is shown. Assign
the correct stereochemistry to the Fischer projection.
H
H3CHN
a) (1S, 2S)
OH
H
CH3
b) (1R, 2R)
pseudoephedrine,
2-methylamino-1-phenylpropan-1-ol
c) (1S, 2R)
d) (1R, 2S)
4 out of 7
8.
Which is the product of the following reaction?
H
HO
H
H
H3CO
H
HO
H
H
9.
b)
H
a)
CHO
OH
H
OH
OH
CH2OH
OCH3
OH
H
OH
OH
CH2OH
H3COH, H+
c)
H3CO
H3CO
H3CO
H3CO
H3CO
H3CO
H3CO
O
OCH3
d)
H3CO
HO
HO
HO
O
OH
O
HO
OCH3
Which of the following carbohydrates reacts with NaBH4 to give an optically inactive product?
a)
H
H
H
CHO
OH
OH
OH
CH2OH
b)
HO
H
H
CHO
H
OH
OH
CH2OH
c)
HO
HO
H
CHO
H
H
OH
CH2OH
d)
None of the above.
i.e., the products from the
reaction of a, b, or c with NaBH4
will be optically active
10. Which are products from the Kiliani-Fischer chain extension reaction (1. HCN 2. H2, Pd/BaSO4,
H2O) of D-glyceraldehyde (an aldotriose)
a)
CHO
H
OH
H
OH
CH2OH
b)
H
H
CHO
OH
OH
CH2OH
H
H
CHO
OH
OH
CH2OH
c)
d)
CHO
H
OH
H
OH
CH2OH
+
CHO
HO
H
+
H
OH
CH2OH
+
HO
HO
CHO
H
H
CH2OH
+
HO
H
CHO
H
OH
CH2OH
+
CH2OH
O
H
OH
CH2OH
CHO
HO
H
HO
H
CH2OH
+
H
HO
CHO
OH
OH
CH2OH
5 out of 7
11. Provide the reagent(s) and any other necessary reactants for the following reactions (12 pts)
NH2
1) H3C-I (excess)
2) Ag2O, then !
O
(H3CH2C)2NH,
NaB(CN)H3
H
N
Cl
H
N
CH3
Cl2, FeCl3
O
Br
OH
1) NaNO2, H2SO4
2) H2O, !
Cl
CH3
O
Br
NH2
Cl
OCH3
12.
H
N
OCH3
Give the product of the following reactions. Stereochemistry is as shown. (12 pts)
Br
1) Na+ N32) LiAlH4, then H2O
NH2
O
OH
H3C
O
Cl
H 3C
O
H 3C
N
O
HO
H
H
CHO
H
OH
OH
CH2OH
OH
! (~200!°C)
HNO3, !
HO
H
H
CH3
CO2H
H
OH
OH
CO2H
6 out of 7
13.
Synthesize m-bromobenzylamine starting from benzene. (12 pts)
CH2NH2
~ 6 steps
Br
NO2
HNO3, H2SO4
Br2, FeBr3
NH2
NO2
N2
NaNO2, H2SO4
H2, Pd/C
Br
Br
Br
CN
CH2NH2
LiAlH4, then H2O
Cu(CN)
Br
Br
14. Give a complete, stepwise mechanism for the following reaction. (9 pts)
O
O
O
CO2CH3
H3CO Na , H3COH
H3CO
OCH3
H H
H3CO
O
H3CO
O
O
OCH3
OCH3
CO2CH3
7 out of 7
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Problem
1-10:_______ (30 pts)
11:_______ (12 pts)
12:_______ (12 pts)
13:_______ (12 pts)
14:________ (9 pts)
Total out of 75: _________