8. Elimination Reactions

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)

For each pair, choose the more reactive nucleophile.

(a)

In contrast to the results of Assessment 13.18, when a secondary haloalkane is treated with sodium ethanethiolate, we predict formation of a thioether. How is this rationalized?

Between pyrrole and pyrrolidine, which nitrogen would be most nucleophilic? Why?

The zwitterionic form of carbonyls is often used to explain their electrophilicity. Draw the zwitterionic structure of NO⁺₂. Why is this such a great electrophile at the central nitrogen?

Would you expect the following bases to favor E1 or E2 elimination?

(c)

For each pair, choose the more reactive nucleophile.

(b)