8. Elimination Reactions

Which is a better nucleophile?

c. CH₃O⁻ or CH₃OH in H₂O

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^–

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

[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).

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?

Which is a better nucleophile?

e. HO⁻ or ^-NH₂ in NH₃

f. HO⁻ or ^-NH₂ in DMSO

Which member of each pair is a better nucleophile in methanol?

e. I⁻ or Br⁻

f. Cl⁻ or Br⁻

Rank the following species in each set from best nucleophile to poorest nucleophile.

c. H₂O and NH₃ in methanol

d. Br⁻, Cl⁻, I⁻ in methanol

How does the ratio of substitution product to elimination product formed from the reaction of propyl ­bromide with CH₃O⁻ in methanol change if the nucleophile is changed to CH₃S⁻?

Which is a better nucleophile?

d. CH₃O⁻ or CH₃OH in DMSO

Rank the following species in each set from best nucleophile to poorest nucleophile.

a.

Rank the following species in each set from best nucleophile to poorest nucleophile.

b.

Rank the reactivity of the following anions with a general electrophile from least to most reactive.

Which nucleophile would be more reactive in the solvent given?

(a)

Which nucleophile would be more reactive in the solvent given?

(b)