Question 1

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

Accepted Answer

Tertiary carbocations are stabilized by hyperconjugation and alkyl group electron donation, which disperses the positive charge.

Question 2

A reaction is performed with a secondary alkyl halide and sodium ethoxide ($\mathrm{NaOEt}$) in ethanol. Which mechanism is most likely to occur, and what is the major product?

Accepted Answer

E2 mechanism; the major product is the more substituted alkene (Zaitsev product).

Question 3

Which of the following solvents would most favor an SN2 reaction with a small nucleophile?

Accepted Answer

Acetone ($\mathrm{CH_3COCH_3}$)

Question 4

Which of the following is TRUE regarding the anti-Markovnikov addition of HBr to an alkene in the presence of peroxides ($\mathrm{ROOR}$)?

Accepted Answer

The bromine atom adds to the less substituted carbon of the double bond.

Question 5

A cyclohexane derivative undergoes E2 elimination. Which geometric requirement must be met for the reaction to proceed efficiently?

Accepted Answer

The leaving group and the hydrogen must be anti-periplanar (trans-diaxial) in the chair conformation.

Question 6

Which of the following best describes the stereochemical outcome of an SN2 reaction at a chiral center?

Accepted Answer

The configuration at the chiral center is inverted.

Question 7

What is the degree of unsaturation for a molecule with the formula $\mathrm{C_6H_{10}Br_2}$?

Accepted Answer

2

Question 8

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

Accepted Answer

When adding HX to an alkene, the hydrogen adds to the carbon with more hydrogens, and the halide adds to the more substituted carbon.

Question 9

Which of the following is a common carbocation rearrangement that increases stability?

Accepted Answer

Hydride shift

Question 10

A reaction of 2-bromobutane with sodium hydroxide ($\mathrm{NaOH}$) in water produces 2-butene as the major product. Which mechanism is most likely responsible?

Accepted Answer

E2 elimination

Question 11

Which of the following is the best leaving group for substitution and elimination reactions?

Accepted Answer

Iodide ($\mathrm{I^-}$)

Question 12

Which of the following statements about SN1 reactions is FALSE?

Accepted Answer

SN1 reactions require polar aprotic solvents.

Question 13

In an E2 elimination, what is the effect of using a bulky base such as tert-butoxide ($\mathrm{tBuO^-}$)?

Accepted Answer

It favors formation of the less substituted alkene (Hofmann product).

Question 14

Which of the following is TRUE about the transition state of an SN2 reaction?

Accepted Answer

It is trigonal planar with partial bonds to both the nucleophile and the leaving group.

Question 15

Which of the following best describes the role of a base in an elimination reaction?

Accepted Answer

The base removes a proton from the beta carbon, facilitating the formation of a double bond.

Question 16

Which of the following statements about nucleophile strength is correct?

Accepted Answer

Nucleophile strength increases as electronegativity decreases and atomic size increases.

Question 17

Which of the following is NOT a requirement for an E2 elimination to occur?

Accepted Answer

Formation of a carbocation intermediate

Question 18

Which of the following best describes the product of syn addition of $\mathrm{H_2}$ to an alkene using a metal catalyst?

Accepted Answer

Both hydrogen atoms add to the same side of the double bond, resulting in syn stereochemistry.

Question 19

Which of the following statements about the use of halides in organic reactions is correct?

Accepted Answer

If a halide is used as a reagent, the reaction is a substitution, not an elimination.

Organic Chemistry Study Notes: Substitution, Elimination, and Addition Reactions (Chapters 6–8)

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