Question 1

For an E2 elimination reaction to occur, what is the required orientation of the beta-hydrogen atom relative to the leaving group?

Accepted Answer

It must be anti-periplanar to the leaving group.

Question 2

Which of the following is considered a good leaving group in nucleophilic substitution reactions?

Accepted Answer

Tosylate ion ($$\mathrm{TsO^-})$$

Question 3

Which of the following is a tertiary alkyl halide?

Accepted Answer

tert-butyl bromide

Question 4

Rank the following compounds in order of increasing acidity: $$\mathrm{CH_3CH_2OH}$$, $$\mathrm{CH_3COOH}$$, $$\mathrm{H_2O}$$, $$\mathrm{NH_3$}.$$

Accepted Answer

IV (NH$$_3$$), I (EtOH), III (H$$_2O$$), II (AcOH)

Question 5

What is the stereochemical implication when an $$\mathrm{S_N1}$$ reaction occurs at a chiral center?

Accepted Answer

Formation of a racemic mixture

Question 6

Which of the following solvents is considered polar aprotic?

Accepted Answer

Dimethyl sulfoxide (DMSO)

Question 7

What happens to the rate of the reaction between methyl iodide and sodium hydroxide when the concentration of sodium hydroxide is doubled?

Accepted Answer

The rate doubles.

Question 8

Which reagent is necessary to convert an alkene to a vicinal diol via syn addition?

Accepted Answer

OsO$$_4$$ followed by NaHSO$$_3$$

Question 9

In the addition of HBr to an alkene, which rule predicts the major product?

Accepted Answer

Markovnikov's rule

Question 10

Which of the following statements about $$\mathrm{S_N2}$$ reactions is FALSE?

Accepted Answer

The reaction rate increases with increasing steric hindrance.

Question 11

Which of the following compounds is most reactive towards an $$\mathrm{S_N1}$$ reaction?

Accepted Answer

tert-butyl chloride

Question 12

What is the major product when 2-bromopropane reacts with sodium ethoxide in ethanol?

Accepted Answer

propene

Question 13

Which statement best explains why $$\mathrm{S_N2}$$ reactions are faster in polar aprotic solvents?

Accepted Answer

Polar aprotic solvents do not solvate anions well, making nucleophiles more reactive.

Question 14

Which of the following is NOT a possible product of an E1 elimination reaction?

Accepted Answer

A primary alkene from a tertiary substrate

Question 15

Which of the following statements about carbocation stability is correct?

Accepted Answer

Allylic carbocations are stabilized by resonance.

Question 16

Which of the following is the correct IUPAC name for the molecule shown below?

$$\mathrm{CH_3CH_2CH(CH_3$)CH_2CH_3}$$

Accepted Answer

2-methylpentane

Question 17

Which of the following transformations requires a carbocation intermediate?

Accepted Answer

Hydrohalogenation of an alkene

Question 18

Which of the following statements about the $$\mathrm{S_N1}$$ mechanism is TRUE?

Accepted Answer

The rate-determining step is the formation of the carbocation.

Question 19

Which of the following is the best description of Markovnikov's rule?

Accepted Answer

The electrophile adds to the more substituted carbon of the alkene.

Question 20

Which of the following statements about elimination reactions is correct?

Accepted Answer

E2 reactions require a strong base and a good leaving group.

Practice Exam #3 Study Guide: Substitution, Elimination, and Related Organic Chemistry Concepts

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