Question 1

Which of the following statements best describes the difference between an electrophilic site and a nucleophilic site in organic molecules?

Accepted Answer

An electrophilic site is electron-poor and accepts electrons, while a nucleophilic site is electron-rich and donates electrons.

Question 2

Which of the following is the best leaving group in a nucleophilic substitution reaction?

Accepted Answer

$$\mathrm{Cl^-}$$

Question 3

Consider the following reaction: $$\mathrm{CH_3CH_2Br}$$ reacts with $$\mathrm{OH^-} in $$water. Which mechanism is most likely to occur?

Accepted Answer

SN2 substitution

Question 4

Which of the following conditions would favor an E2 elimination over an SN2 substitution?

Accepted Answer

A strong base and a tertiary alkyl halide

Question 5

Which of the following is the correct order of leaving group ability (best to worst) for the following groups: $$\mathrm{I^-}$$, $$\mathrm{Br^-}$$, $$\mathrm{Cl^-}$$, $$\mathrm{F^-}$$?

Accepted Answer

$$\mathrm{I^-} \u003e \mathrm{Br^-} \u003e \mathrm{Cl^-} \u003e \mathrm{F^-}$$

Question 6

A student is asked to predict the major product of the following reaction: $$\mathrm{CH_3CH_2CH_2Br}$$ with $$\mathrm{NaOEt} in $$ethanol. Which product will be favored?

Accepted Answer

Propene via E2 elimination

Question 7

Which of the following statements about Markovnikov's rule in addition reactions is correct?

Accepted Answer

The hydrogen atom adds to the carbon with the most hydrogens already attached.

Question 8

Which reagent would you use to convert an alkene to a vicinal diol via syn addition?

Accepted Answer

$$\mathrm{$$OsO_4$$} ($$osmium tetroxide)

Question 9

Which of the following best explains why tertiary carbocations are more stable than secondary or primary carbocations?

Accepted Answer

Tertiary carbocations are stabilized by hyperconjugation and inductive effects from three alkyl groups.

Question 10

Which of the following mechanisms is responsible for the acid-catalyzed hydration of alkenes?

Accepted Answer

Electrophilic addition via carbocation intermediate

Question 11

A student is asked to predict the product of the following reaction: $$\mathrm{CH_2$=CH_2$}$$ reacts with $$\mathrm{Br_2$} in$$ $$\mathrm{$$CCl_4$$}. $$What is the major product?

Accepted Answer

1,2-dibromoethane

Question 12

Which of the following statements about anti-Markovnikov addition is correct?

Accepted Answer

It occurs when $$\mathrm{HBr} is $$added to an alkene in the presence of peroxides.

Question 13

Which of the following is a key difference between SN1 and SN2 mechanisms?

Accepted Answer

SN1 involves a carbocation intermediate, while SN2 is concerted and does not.

Question 14

Which of the following best describes the product of ozonolysis of 1-butene ($$\mathrm{CH_2$=CHCH_2CH_3}) $$followed by reductive workup?

Accepted Answer

Acetaldehyde and propanal

Question 15

Which of the following reagents would you use for the halogenation of an alkene to form a vicinal dihalide?

Accepted Answer

$$\mathrm{Br_2$} in$$ $$\mathrm{$$CCl_4$$}$$

Question 16

Which of the following statements about the thermodynamic nature of addition reactions to alkenes is correct?

Accepted Answer

Addition reactions to alkenes are generally exothermic because stronger sigma bonds are formed.

Question 17

Which of the following is the correct mechanism for the acid-catalyzed hydration of ethene ($$\mathrm{CH_2$=CH_2$}$$)?

Accepted Answer

Protonation of the alkene to form a carbocation, followed by nucleophilic attack by water, and deprotonation to yield ethanol.

Question 18

Which of the following best describes the role of peroxides in the addition of $$\mathrm{HBr} to $$alkenes?

Accepted Answer

Peroxides initiate a radical mechanism that leads to anti-Markovnikov addition.

Question 19

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

Accepted Answer

E2 eliminations require the leaving group and the hydrogen to be anti-coplanar.

Organic Chemistry: Substitution, Elimination, and Electrophilic Addition Reactions (Ch. 7 & 8)

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