8. Elimination Reactions

Which nucleophile would be more reactive in the solvent given?

(a)

For each pair, predict the stronger nucleophile in the SN2 reaction (using an alcohol as the solvent). Explain your prediction.

a. (CH₃CH₂)₃N or (CH₃CH₂)₂NH

b. (CH₃)₂O or (CH₃)₂S

Which of the following charged nucleophiles is most reactive in $\mathrm{DMSO}$ solvent?

Which of the following molecules is a negatively charged nucleophile?

Indicate which species in each pair gives a higher substitution-product-to-elimination-product ratio when it reacts with isopropyl bromide:

a. ethoxide ion or tert-butoxide ion

In aqueous solution, rank the following species in order of increasing nucleophilicity: $F_{-}$, ${\mathrm{Cl}}_{-}$, ${\mathrm{Br}}_{-}$, $I_{-}$.

[FIGURE: KEY MECHANISM 7-1]

Show what happens in step 2 of the example if the solvent acts as a nucleophile (forming a bond to carbon) rather than as a base (removing a proton).

Which of the following correctly ranks the nucleophilicity of the species $F_{-}$, ${\mathrm{Cl}}_{-}$, ${\mathrm{Br}}_{-}$, and $I_{-}$ in water from greatest to least?

Which of the following species is most likely to react as a nucleophile rather than as a base?

Which of the following reagents is the best choice to convert an alkyl bromide to an alcohol via an S$N_2$ mechanism?

For each pair, choose the more reactive nucleophile.

(b)

a. Which is a stronger base: RO⁻ or RS⁻?

b. Which is a better nucleophile in an aqueous solution?

c. Which is a better nucleophile in DMSO?

For each pair, predict the stronger nucleophile in the SN2 reaction (using an alcohol as the solvent). Explain your prediction.

c. NH₃ or PH₃

d. CH₃S^– or H₂S

For each pair, predict the stronger nucleophile in the SN2 reaction (using an alcohol as the solvent). Explain your prediction.

e. (CH₃)₃N or (CH₃)₂O

f. CH₃COO^– or CF₃COO^–

Which nucleophile would be more reactive in the solvent given

(c)