Q: Which of the following statements about the rate law for the E2 mechanism is correct?

The rate is second-order overall: $$\text{rate} = k[\mathrm{R-X}][\mathrm{B}]$$

Question 1

Which of the following statements best describes the difference between a nucleophile and a base in organic reactions?

Accepted Answer

A nucleophile attacks electron-deficient carbon atoms, while a base attacks protons.

Question 2

In an E2 elimination reaction, which of the following is true regarding the transition state?

Accepted Answer

The transition state requires the leaving group and the hydrogen to be anti-periplanar.

Question 3

Which of the following bases would most likely favor an E2 elimination over an E1 elimination?

Accepted Answer

Potassium tert-butoxide ($$\mathrm{KO^+ tBu^-})$$

Question 4

Which of the following statements about the rate law for the E2 mechanism is correct?

Accepted Answer

The rate is second-order overall: $$	ext{rate} = k[\mathrm{R-X}][\mathrm{B}]$$

Question 5

Which of the following alkyl halides would react fastest in an E1 elimination reaction?

Accepted Answer

3° alkyl halide

Question 6

Why are trans (E) alkenes generally more stable than cis (Z) alkenes?

Accepted Answer

Trans alkenes have less steric repulsion between substituents.

Question 7

Which of the following statements about alkene stereoisomers is correct?

Accepted Answer

Cis and trans alkenes are diastereomers.

Question 8

A student performs an elimination reaction on 2-bromobutane using sodium amide ($$\mathrm{$$NaNH_2$$}) as $$the base. Which product is favored and why?

Accepted Answer

The more substituted alkene, due to increased stability from hyperconjugation.

Question 9

Which of the following best explains why increasing the number of alkyl substituents on an alkene increases its stability?

Accepted Answer

Alkyl groups donate electrons by induction and hyperconjugation, stabilizing the double bond.

Question 10

Which of the following solvents would most likely favor an E1 elimination mechanism?

Accepted Answer

Polar protic solvent such as water ($$\mathrm{H_2O})$$

Question 11

Which of the following is the correct order of leaving group ability for halides in elimination reactions?

Accepted Answer

$$\mathrm{F^-} \u003c \mathrm{Cl^-} \u003c \mathrm{Br^-} \u003c \mathrm{I^-}$$

Question 12

Which of the following best describes the stereoselectivity of E2 elimination reactions?

Accepted Answer

E2 reactions favor formation of the alkene with the leaving group and hydrogen in an anti-periplanar arrangement.

Question 13

Which of the following statements about the E1 mechanism is correct?

Accepted Answer

The rate-determining step is the formation of a carbocation by loss of the leaving group.

Question 14

Which of the following is true regarding the rotation of bonds in alkenes?

Accepted Answer

C=C double bonds have restricted rotation, so cis and trans forms are distinct molecules.

Question 15

Which of the following is the correct rate law for the E1 elimination mechanism?

Accepted Answer

$$	ext{rate} = k[\mathrm{R-X}]$$

Question 16

A chemist wants to maximize the formation of the most substituted alkene in an elimination reaction. Which combination of substrate and base should they choose?

Accepted Answer

A 3° alkyl halide and a strong base such as $$\mathrm{KO^+ tBu^-}$$

Question 17

Which of the following statements about the competition between substitution and elimination is correct?

Accepted Answer

Strong bases that are also good nucleophiles can promote both substitution and elimination.

Question 18

Which of the following is a real-world application of E2 elimination reactions?

Accepted Answer

Synthesis of alkenes for use in polymer production, such as polyethylene.

Alkyl Halides & Elimination Reactions: Mechanisms, Products, and Selectivity

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