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

CH 318 N EXAM #2 UTEID

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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)

CH 318 N EXAM #2 UTEID

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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