i pledge on my honor that i have neither given nor …...chemistry 220b, section 1 name _____ exam 2...
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Chemistry 220b, Section 1 Name ______________________________ Exam 2 (100 pts) Thursday, February 26, 2015 Chapters 13, 15-19 Write and sign the VU Honor Pledge:
I pledge on my honor that I have neither given nor received unauthorized aid on this examination
_____________________________________ signature
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
Stereochemistry counts are indicated
Good Luck !!
I. M. Honest
page 2 of 8
1 – 15. Multiple Choice. Choose the best answer for each of the following questions. (60 pts) 1. Which structure is most consistent with the following 1H NMR spectrum?
2. Which structure is most consistent with the following IR spectrum?
3. What is the product of the following reaction?
H
O
OH
O
OH
O
OH
Oa) b) c) d)
a) b) c) d)H
O
OCH3
OO
N
O
a) b) c) d)
O+ NH2
HN
HNHN
NN
H+
page 3 of 8
4. What is the product of the following reaction?
5. What is the product of the following reaction?
6. What is the product from the following reaction?
7. What is the product from the following reaction?
8. What is the best reagent for the following reaction?
a) b) c) d)
O
O
O
N
NH2+
NH
OOH
OH
ONH
N
OH
a) b) c) d)
O
OCH2CH3
OCH2CH3 OH
OH
H3C-MgBr(excess)
OOCH2CH3
then H3O+
a) b) c) d)
O+
Cl
O
O OH NaHCO3
O
O
O
O
OO OH
a) b) c) d)
+O
OH OHH+
O
O
O
OO
O
OH O
OHO
a) H2NNH2, KOH, H2O c) H2, Pd/C
b) LiAlH4, THF, then H3O+ d) , H+HO
OH
O
page 4 of 8
9. Which combination of reactants will give (E)-3-methyl-3-hexene as the product?
10. What is the best reagent for the conversion of a primary amide to a nitrile?
a) P4O10, heat b) H3O+, heat c) H2, Pd/C d) NaCN, then H3O+
11. Which reaction or reaction sequence does not affords phenylacetic acid?
12. What is the order of reactivity, from most reactive to least reactive, for the following reaction?
OPh3P
++
OPh3P
++
(2 equivalents)
Br +
a)
b)
c)
d) all of the above; i.e., a, b, and c will all afford (E)-3-methyl-3-hexene
Ph3P+
O
NH2C
N
Br Mg(0), THF CO2 H3O+ OH
O
OHCH2Cl2
OH
O
Br – CN H3O+ OH
Oa)
b)
c)
d) none of the above; i.e., a, b, and c are all afford phenylacetic acid
NH
Cr2O7-2
+ 2
H3C X
O
X= OH, Cl, O2CCH3, OCH3
+ H3C NH
CH3H3C N
O+ H–X
H3C OH
O>
H3C Cl
O>
H3C O
O O
CH3>
H3C OCH3
O
H3C Cl
O>
H3C OCH3
O>
H3C O
O O
CH3>
H3C OH
O
H3C Cl
O>
H3C O
O O
CH3>
H3C OH
O>
H3C OCH3
O
H3C O
O O
CH3 H3C Cl
O>>
H3C OCH3
O
H3C OH
O>
a)
b)
c)
d)
page 5 of 8
13. Arrange the following carboxylic acids from the highest pKa value to lowest pKa value.
14. Which structure is an intermediate in the saponification of an ester?
15. Which structure is not an intermediate in the formation of a ketal?
O
OHO
OH
O
OHF
O
OHF> > >
>
a)
b)
c)
d)
O
OH
O
OH
O
OHF
O
OHF> > >
O
OH
O
OH
O
OH
O
OH> >
FF
>O
OH
O
OH
O
OH
O
OH> >
FF
OCH3
O+ NaOH
O
O– Na+ + H3COH
a) b) c) d)
+
+ –+
O
OHOCH3
HO
OHOCH3
H
–O
OH
OCH3
H
OCH3
HO
O
+ H2O
O H+OHO
OOHO OH+ H+
O –H+ OHO OHa) b) c) d)
OOH+
page 6 of 8
16. The following transformations cannot be done in a single step. Complete the following by providing the correct reagents and the structure of the intermediate. (18 pts)
17. Give a complete, stepwise mechanism for the acid-catalyzed reaction of propionic acid and
methanol to afford methyl propionate. (12 pts)
3-hexyne
Br O
B2H6, THF; then H2O2, NaOH, H2O O
Ph3P=CH2
NaCNCN
H3C-MgBr, THFthen H3O+
OH
OH A
OH
OH
H3C OH
OHHO
OH3C
H :A–
OHHO
OH3C
H AOH2
HO
OH3C
OCH3
OOCH3
OH :A–
page 7 of 8
18. A molecule with the formula C12H17NO2 has the IR, 1H and 13C NMR spectra shown below. Provide a structure that is consistent with the data. Please circle your final answer. (10 pts)
13C NMR: δ 168.1, 154.2, 132.5, 125.8, 114.5, 64.6, 41.5, 23.1, 14.8, 11.2 13C NMR: δ 168.1 : C=O, ester, acid, amide (acid is eliminated since there is no OH in IR)
C=O ~1660 cm-1
amide, possibly conjugated.
N-H
p-disubstitutedbenzene
Amide N-H
X H2C-CH3
X H2C-H2C-CH3
O
NH
O
page 8 of 8
___________________________________________________________________________________
Problem 1-15:_______ (60 pts)
16:_______ (18 pts)
17:_______ (12 pts)
18:_______ (10 pts)
Total out of 100: ______________