Exam Three Practice Test Answers.pdf

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CH203 Fall 2014 Exam Three Practice TestAnswers

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1. Which of the following compounds is the strongest acid?

a. CH3CH2CH2COOHb. CH3CH2CHClCOOHc. CH3CHClCH2COOH

d. ClCH2CH2CH2COOH

ANS: B

2. Which of the following is the strongest base?

a. iodide anion, I!

b. fluoride anion, F!

c. bromide anion, Br!

d. chloride anion, Cl!

ANS: B

3. Which of the following compounds has the highest pKa?

a. NH3b. H2O

c. HCld. CH4

ANS: D

4. Which of the following compounds has the lowest pKa?

a. H2Ob. HBr

c. NH3d. CH4

ANS: B

5. Which of the following compounds has the lowest pKa?

a. H2O

b. H2Sc. H2Sed. H2Te

ANS: D


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6. Which of the following is present in the highest concentration upon dissolution of H2SO4inwater?

a. H2SO4b. H

+

c. H3O+

d. HO!

ANS: C

7. Which of the following is present in the highest concentration upon dissolution of acetic acid in

water?

a. OH!

b. H3O+

c. CH3COOH

d. CH3COOH+

ANS: C

8. Which of the following terms describes the reactivity of boron tribromide, BBr3?a. Brnsted-Lowry acid and Lewis acid

b. Brnsted-Lowry base and Lewis basec. Lewis acid and nota Brnsted-Lowry acid

d. Lewis base and nota Brnsted-Lowry base

ANS: C

9. Which sets of curved arrows accounts for the protonation of propene with HI?

a. 1

b. 2

c.3d. 4

ANS: D


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a. 1b. 2

c. 3d. 4

ANS: D

14. Which of the following is a definition of the rate-determining step of a reaction mechanism?a. the first step

b. the last stepc. the step that crosses the highest energy barrier

d. the most exothermic step

ANS: C

15. Which of the following is a definition of the activation energy of a reaction?

a. the difference in Gibbs free energy between the reactants and the transition stateb. the difference in Gibbs free energy between the reactants and the intermediatec. the difference in Gibbs free energy between the reactants and the product

d. the difference in Gibbs free energy between the transition state and the product

ANS: A

16. Which of the following energy diagrams best represents the changes in energy during addition of

HBr to an alkene?

a. 1b. 2

c. 3d. 4

ANS: A


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17. Use curved arrows to show the movement of pairs of electrons in the following acid-base

reaction and show the structures of the conjugate acid and conjugate base.

ANS:

18. Use curved arrows to show the movement of pairs of electrons in the following reaction betweena Lewis acid and a Lewis base, and show the structure of the product.

ANS:

19. What is the major organic product obtained from the following reaction?

a. 1

b. 2c. 3

d. 4

ANS: C


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a. 1

b. 2c. 3

d. 4

ANS: C


a. 1

b. 2c. 3

d. 4

ANS: C


a. 1b. 2

c. 3


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d. 4

ANS: B

23. What is (are) the major organic product(s) obtained from the following reaction?

1. (2R,3R)-dibromobutane

2. (2S,3S)-dibromobutane3. meso-2,3-dibromobutane

a. only 1b. only 2

c. only 3d. only 1and 2

ANS: C


1. (2R,3R)-dibromobutane2. (2S,3S)-dibromobutane

3. meso-2,3-dibromobutane

a. only 1b. only 2


ANS: D



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a. 1

b. 2c. 3

d. 4

ANS: A


a. 1b. 2

c. 3d. 4

ANS: D


1. (2R,3R)-butanediol

2. (2S,3S)-butanediol3. meso-2,3-butanediol

a. only 1

b. only 2


ANS: D


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1. (2R,3R)-butanediol

2. (2S,3S)-butanediol

3. meso-2,3-butanediol

a. only 1

b. only 2c. only 3

d. only 1and 2

ANS: C

29. What is the best choice of reagent to perform the following transformation?

a. Br2b. HBr

c. Br2, H2Od. N-bromosuccinimide

ANS: C

30. What type of reactive intermediate is formed in the reaction of an alkene with Br2and water to

give a bromohydrin?a. carbocation

b. carbanion

c. radicald. cyclic bromonium ion

ANS: D


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31. What type of reactive intermediate is formed in the reaction of an alkene with aqueous acid to

give an alcohol?a. carbocation

b. carbanion

c. radicald. carbene

ANS: A

32. Which of the following reactions of alkenes takes place with anti stereospecificity?

a. bishydroxylation (treatment with OsO4followed by NaHSO3)b. hydrogenation (treatment with H2/Pt)

c. addition of HBr (treatment with HBr)d. bromohydrin formation (treatment with Br2, H2O)

ANS: D

33. Which of the following reactions of alkenes takes place with syn stereospecificity?

a. addition of bromine (treatment with Br2)b. hydrogenation (treatment with H2/Pt)

c. addition of HBr (treatment with HBr)d. acid-catalyzed hydration (treatment with aqueous H2SO4)

ANS: B

34. What is the IUPAC name of the following compound?

a. (R)-4-methyl-2-hexyne

b. (S)-4-methyl-2-hexynec. (R)-3-methyl-4-hexyne

d. (S)-3-methyl-4-hexyne

ANS: B



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a. (E) 2-buteneb. (Z) 2-butene

c. 2-butyned. 1-butyne

ANS: C


a. 2-methyl-3-hexeneb. 2-methyl-3-heptyne

c. 2-bromo-3-methylbutane

d. 2-methyl-2-butene

ANS: B


a. 3,4-dibromohexane

b. 3,3-dibromohexanec. (Z) 3,4-dibromohexened. 3,3,4,4-tetrabromohexane

ANS: D


a. 2-hexanoneb. hexanalc. 2-hexanol

d. cis-2-hexene

ANS: B


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a. 1

b. 2c. 3

d. 4

ANS: D


a. 1b. 2

c. 3d. 4

ANS: D


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a. 1

b. 2c. 3d. 4

ANS: A

42. What is the best choice of reagent(s) to perform the following transformation?

a. 1 mol of Br2b. 2 mol of Br2

c. 1 mol of HBrd. 2 mol of HBr

ANS: D

43. What is the best choice of reagent(s) to perform the following transformation?

a. H2/Ptb. H2/Lindlar catalyst


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c. Na/NH3d. BH3; followed by H2O2, NaOH

ANS: C

44. What is the major organic product obtained from the following series of reactions?

a. 1

b. 2c. 3

d. 4

ANS: A

45. What is the major organic product obtained from the following series of reactions?

a. (Z)-2-hepteneb. (E)-2-heptene

c. 1-heptened. heptane

ANS: B


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46. Outline how one might achieve the following transformation, showing reagents and the isolated

intermediates in the synthetic scheme.

ANS:

47. Outline how one might achieve the following transformation, showing reagents and the isolated

intermediates in the synthetic scheme.

ANS:


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48. Predict the products:

Answer:

49. Predict the products:

Answer:

HCl (1.0 equiv.)

OMe

Br2

Cl

HCl (1.0 equiv.)

OMeOMe

Br2

Cl

OMe

Br Br

Br

OMe

Cl Br

Na or Li,NH3(liquid)

Pd, H2,

H2, Lindlar Cat

Me

Me

Me

Me


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The first product is the major product formed due to the greater stability of the secondarycarbocation formed next to the oxygen. The oxygen atom resonance stabilizes the cation with its

lone pairs:

Methanol adds to that carbocation and is deprotonated by solvent to give the product.

54. In the following reaction, only one product is recovered. Which product is it, and why?

Answer:

Cl is more electronegative than I, so in ICl the iodine has a slight positive character and isattacked by the alkene Lewis base to give a cyclic iodonium ion. The free chloride then adds anti

coplanar to the iodonium ion at the carbon which is more able to bear the positive character thesecondary benzylic carbon. This gives the product on the right.

O

H

O

H

I Cl

!+ !"

I

Cl

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Exam Three Practice Test Answers.pdf