CH318N Exam 2 Key (1)
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Transcript of CH318N Exam 2 Key (1)
UTID: ________________________ 03/23/2009
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CH318N-Exam II
Objective Test SectionIdentify the choice that best completes the statement or answers the question. There is only one correct answer; please carefully bubble your choice on the scantron sheet. (3pts. ea; 75 pts this section)
1. Which combination(s) of alkyl bromide and carbonyl compound can be used to prepare the following product by addition of the Grignard reagent derived from the alkyl bromide to the carbonyl compound?
a. only 1 and 2b. only 3 and 4c. only 2 and 3d. only 1, 2 and 3
2. What is the major organic product obtained from the following reaction?
a. 1b. 2c. 3d. 4
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3. What is the major organic product of the following sequence of reactions?
a. 1b. 2c. 3d. 4
4. Which combination(s) of alkyl bromide and carbonyl compound can be used to prepare the following product by addition of the Grignard reagent derived from the alkyl bromide to the carbonyl compound?
a. only 1b. only 3c. only 1 and 3d. only 2 and 4
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5. What is the major organic product obtained from the following reaction?
a. 1b. 2c. 3d. 4
6. Which of the following compounds is a 3° amide?
a. 1b. 2c. 3d. 4
7. What is the major organic product obtained from the following reaction?
a. 1b. 2c. 3d. 4
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8. What is the major organic product obtained from the following reaction?
a. 1b. 2c. 3d. 4
9. What is the major organic product obtained from the following reaction?
a. propiophenone, PhCOCH2CH3
b. 3-phenyl-2-butanolc. 2-phenyl-2-butanold. 3-phenylbutanone
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10. What is the major organic product obtained from the following reaction?
a. 1b. 2c. 3d. 4
11. Which of the following has the highest boiling point?a. hexaneb. pentanalc. butanoic acidd. 1-pentanol
12. What is the relationship between the following two structures?
a. tautomersb. constitutional isomers, but not tautomersc. resonance structuresd. stereoisomers
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13. What is the major organic product obtained from the following reaction?
a. 1b. 2c. 3d. 4
14. What is the major organic product obtained from the following reaction?
a. 2,3-dimethyl-3-heptanolb. 2,4-dimethyl-4-heptanolc. 2,5-dimethyl-4-heptanold. 2,5-dimethyl-3-heptanol
15. What is the approximate pKa value of acetic acida. 5b. −2c. 15d. 35
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16. What is the major organic product obtained from the following reaction?
a. 1b. 2c. 3d. 4
17. What is the best choice of reagent(s) to perform the following transformation?
a. 1. LiAlH4; 2. H3O+
b. H2, Ptc. 1. NaBH4; 2. H2Od. NaH
18. What is the major organic product obtained from the following reaction?
a. 1b. 2c. 3d. 4
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19. What is the major organic product obtained from the following sequence of reactions?
a. 1b. 2c. 3d. 4
20. What is the major organic product of the following sequence of reactions?
a. 1b. 2c. 3d. 4
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21. Which of the following carboxylic acids undergoes the most rapid thermal decarboxylation reaction?
a. 1b. 2c. 3d. 4
22. What is the major organic product obtained from the following reaction?
a. 1b. 2c. 3d. 4
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23. What is the major organic product obtained from the following reaction?
a. 1b. 2c. 3d. 4
24. What of the following is the correct assignment of the classes of the following compounds?
a. 1 = ester; 2 = imide; 3 = amideb. 1 = ester; 2 = ester; 3 = imidec. 1 = lactone; 2 = anhydride; 3 = imided. 1 = lactone; 2 = ester; 3 = amide
25. What is the major organic product obtained from the following reaction?
a. 4-methyl-1-penteneb. 2-methyl-2-pentenec. (Z)-3-methyl-2-pentened. (E)-3-methyl-2-pentene
ID: A
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CH318N-Exam IIAnswer Section
MULTIPLE CHOICE
1. ANS: A PTS: 3 2. ANS: B PTS: 3 3. ANS: B PTS: 3 4. ANS: B PTS: 3 5. ANS: D PTS: 3 6. ANS: A PTS: 3 7. ANS: C PTS: 3 8. ANS: A PTS: 3 9. ANS: C PTS: 3 10. ANS: A PTS: 3 11. ANS: C PTS: 3 12. ANS: C PTS: 3 13. ANS: C PTS: 3 14. ANS: C PTS: 3 15. ANS: A PTS: 3 16. ANS: B PTS: 3 17. ANS: B PTS: 3 18. ANS: C PTS: 3 19. ANS: C PTS: 3 20. ANS: B PTS: 3 21. ANS: C PTS: 3 22. ANS: B PTS: 3 23. ANS: B PTS: 3 24. ANS: C PTS: 3 25. ANS: B PTS: 3
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KEY PART 2: Free Style Answer Format (75 pts in this section) 1) Multi-step synthesis: Provide the products for the multistep synthesis below. Indicate any relevant stereochemistry (cis, trans, racemate, etc.). (8 pts)
2) Wittig reagents: The use of Wittig reagents is illustrated by the sequence below. Show the products in this sequence; note that the Wittig reagent must be prepared first, then condensed with the carbonyl compound (n-butyraldehyde). (8 pts)
BrPPh3
PPh3 PPh3 PPh3
nBuLi
O
H
H
Must show 2 resonance structures
1)
2) H2O
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KEY 3) Mechanism: Provide a mechanism for the following transformation. Show all important flows of electrons, charges and intermediates. Where indicated, (in the structure boxes)- draw the intermediates. (3 pt each structure-n-a-box; resonance structures, 1 pts ea)
H3C CH3
CO
NH2
H
H3C CH3
CO
NH2
H
CO
NH2
H
H3C CH3
CO
NH2
H
OH
HH3C
CO NH2
H
OH
H3C CH3
CHO NH2
HO H
H3C CH3
CHO NH3
O H
H3C
CHO NH3
O
H3C CH3
C
HONH4
Protonated Amide-must show 3 resonancestructures for full credit
Water attacks theprotonated amide
Intramolecularproton transfer
Elimination ofammonia
Acid Basereaction togive finalproducts
CH3H3C
CH3
CH3
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KEY
4) Multi-step synthesis: Provide the reagents for the multistep synthesis below. Note, although there may be several correct reagents for each transformation, you need only provide one method. (8 pts)
1. CH3MgBrEt2O
2. H3O+
CrO3H2SO4
O
H
H2N-CH3
OH
CH3
O
CH3
N
CH3
CH3HN
CH3
CH3
H2 Pd
5) Mechanism: Provide a mechanism for the following transformation. Show all important flows of electrons, charges and intermediates. For this reaction, you must indicate the correct stereochemistry of the transition state. (9 pts)
O
OHPh
O
CH3Ph
O
O
OPh
OH
O
C
OCH2Ph
OH
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KEY 6) Transformations: Provide the products for each of the reactions below. If stereochemistry is involved (cis, trans, racemate, etc.), then predict the major product. (12 pts)
H
O
1) LiAlH42) H
3O +
H2CrO4
H2NNHPh
HOCH2CH2OH
cat H+NH2NH2KOH;
1) CH3NH2
2) H2/Pt
CHH
OHOH
O
Ph H
NNH
CH3
Ph
Ph HPh H
HNOO
CH3
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KEY 7) The Wittig reagents are used to prepare alkenes from ketones or aldehydes. The Wadsworth-Horner-Emmons reagents were developed to ensure that specific geometric isomers would be produced when used in these types of reactions. For the example below, provide the mechanism for the reaction and use Newman projections to explain how the stereochemistry is controlled. The problem has been broken into separate parts to facilitate your discussion.
Part 1: Draw the critical C-C bond forming reaction to give the betaine: (5 pts)
Part 2: Using Newman projections, show how the substitutents are aligned: (5 pts)
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KEY Part 3: Draw the oxaphosphetane and its subsequent collapse to provide the final product, with the correct stereochemistry: (5 pts)
END OF EXAM SECTION