Question 1

Which of the following carbocations is the most stable due to hyperconjugation and resonance effects?

A. $$CH_3$$^+$$

B. $$($$CH_3)_3C$$^+$$

C. C_6H_5CH_2$$^+$$

D. CH_2$=CH-CH_2$^+$$

Accepted Answer

$$C_6H_5CH_2^+$$

Question 2

Rank the following nucleophiles in order of increasing reactivity towards $$CH_3Br in a $$polar aprotic solvent:

A. $$CH_3O^-

B$$. $$Br^-

C$$. $$CH_3OH

D$$. $$Cl^-$$

Accepted Answer

$$CH_3OH \u003c Br^- \u003c Cl^- \u003c CH_3O^-$$

Question 3

Which of the following alkyl halides will undergo a hydride shift during an $$S_N1$$ reaction?

A. $$1-$$bromo-$$2-$$methylpropane

B. $$2-$$bromo-$$2-$$methylpropane

C. $$3-$$bromo-$$3-$$methylpentane

D. $$1-$$bromo-$$3-$$methylbutane

Accepted Answer

$$3-$$bromo-$$3-$$methylpentane

Question 4

A reaction of $$2-$$bromopropane with $$NaOH in $$ethanol produces which major product?

A. $$2-$$propanol

B. $$propene

C$$. $$1-$$propanol

D. $$2-$$bromopropane$

Accepted Answer

$$propene$$

Question 5

Which of the following statements best explains why $$S_N2$$ reactions are faster in polar aprotic solvents than in polar protic solvents?

A. Polar aprotic solvents stabilize the nucleophile, making it less reactive.

B. Polar aprotic solvents do not solvate anions well, increasing nucleophilicity.

C. Polar aprotic solvents increase the electrophilicity of the substrate.

D. Polar aprotic solvents favor carbocation formation.

Accepted Answer

Polar aprotic solvents do not solvate anions well, increasing nucleophilicity.

Question 6

Which of the following pairs of molecules are enantiomers?

A. $$CH_3CH(OH)CH_3$ and CH_3CH(OH$$)$$CH_3

B$$. $$(R)-2-$$butanol and $$(S)-2-$$butanol

C. $$cis-1$$,2-dichloroethene and $$trans-1$$,2-dichloroethene

D. $$meso-$$tartaric acid and $$D-$$tartaric acid

Accepted Answer

$$(R)-2-$$butanol and $$(S)-2-$$butanol

Question 7

Which of the following reactions is most likely to proceed via an $$E2$$ mechanism?

A. $$2-$$bromopropane + $$NaOH ($$ethanol, heat)

B. $$1-$$bromopropane + $$NaOH ($$water, room temp)

C. $$2-$$bromopropane + $$CH_3OH ($$room temp)

D. $$2-$$bromopropane + $$NaOCH_3 ($$methanol, heat)

Accepted Answer

$$2-$$bromopropane + $$NaOCH_3 ($$methanol, heat)

Question 8

Which of the following compounds is optically inactive?

A. $$meso-2$$,3-butanediol

B. $$(R)-2-$$butanol

C. $$(S)-2-$$butanol

D. $$D-$$glucose

Accepted Answer

$$meso-2$$,3-butanediol

Question 9

Which of the following Fischer projections correctly represents the same stereochemistry as the given compound X?

A. $$\displaystyle \begin{array}{c} H \quad | \quad OH \ | \quad | \ CH_3$ \quad | \quad CH_2OH \end{array}

B$$. $$\displaystyle \begin{array}{c} CH_2OH \quad | \quad OH \ | \quad | \ CH_3$ \quad | \quad H \end{array}

C$$. $$\displaystyle \begin{array}{c} CH_3$ \quad | \quad OH \ | \quad | \ CH_2OH \quad | \quad H \end{array}

D$$. $$\displaystyle \begin{array}{c} OH \quad | \quad CH_3$ \ | \quad | \ H \quad | \quad CH_2OH \end{array}$$

Accepted Answer

C

Question 10

Which of the following best describes the relationship between the following two molecules?

A. Identical

B. Enantiomers

C. Diastereomers

D. Constitutional isomers

Accepted Answer

Enantiomers

Question 11

A student mixes $$2-$$bromobutane with $$NaOEt in $$ethanol and heats the mixture. Which is the major product?

A. $$2-$$butanol

B. $$1-$$butene

C. $$2-$$butene

D. $$2-$$bromobutane

Accepted Answer

$$2-$$butene

Question 12

Which of the following statements about $$S_N1$$ reactions is correct?

A. The rate depends only on the concentration of the nucleophile.

B. The rate depends only on the concentration of the substrate.

C. The rate depends on both the substrate and nucleophile concentrations.

D. The rate is independent of both substrate and nucleophile concentrations.

Accepted Answer

The rate depends only on the concentration of the substrate.

Question 13

Which of the following is the correct order of leaving group ability in $$S_N1$$ reactions?

A. $$I^- \u003e Br^- \u003e Cl^- \u003e F^-

B$$. $$F^- \u003e Cl^- \u003e Br^- \u003e I^-

C$$. $$Cl^- \u003e Br^- \u003e I^- \u003e F^-

D$$. $$Br^- \u003e I^- \u003e Cl^- \u003e F^-$$

Accepted Answer

$$I^- \u003e Br^- \u003e Cl^- \u003e F^-$$

Question 14

Which of the following best explains why tertiary alkyl halides favor $$S_N1$$ and $$E1$$ mechanisms?

A. Tertiary alkyl halides are less sterically hindered.

B. Tertiary carbocations are more stable due to hyperconjugation and inductive effects.

C. Tertiary alkyl halides have poor leaving groups.

D. Tertiary alkyl halides are more nucleophilic.

Accepted Answer

Tertiary carbocations are more stable due to hyperconjugation and inductive effects.

Question 15

Which of the following is a correct statement about the stereochemistry of $$E2$$ eliminations?

A. The leaving group and the hydrogen must be syn-periplanar.

B. The leaving group and the hydrogen must be anti-periplanar.

C. The reaction always produces a racemic mixture.

D. The reaction only occurs with primary alkyl halides.

Accepted Answer

The leaving group and the hydrogen must be anti-periplanar.

Question 16

A mixture of $$2-$$bromobutane and $$MeOH$$ gives a racemic mixture of products. Which mechanism is most likely?

A. $$S_N2

B$$. $$E2

C$$. $$S_N1

D$$. $$E1$$

Accepted Answer

$$S_N1$$

Question 17

Which of the following is the correct configuration (R or S) for the chiral center in $$CH_3CH(OH)CH_2CH_3 if $$the priorities are: $$OH \u003e CH_2CH_3 \u003e CH_3$ \u003e H$$ and the lowest priority is in the back?

A. $$R

B$$. $$S

C. $$Cannot be determined

D. Both R and S

Accepted Answer

$$R$$

Question 18

Which of the following reactions would proceed faster via an $$S_N2$$ mechanism?

A. $$CH_3Br$$ + $$NaI in $$DMSO

B. $$CH_3Br$$ + $$NaI in$$ $$CH_3OH

C$$. $$CH_3Br$$ + $$NaI in$$ $$H_2O

D$$. $$CH_3Br$$ + $$NaI in$$ $$CCl_4$$

Accepted Answer

$$CH_3Br$$ + $$NaI in $$DMSO

Question 19

Which of the following is a correct statement about meso compounds?

A. Meso compounds are optically active.

B. Meso compounds have chiral centers but are achiral overall.

C. Meso compounds are always enantiomers.

D. Meso compounds have no chiral centers.

Accepted Answer

Meso compounds have chiral centers but are achiral overall.

Organic Chemistry II: Substitution, Elimination, and Stereochemistry Study Guide

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