91Ó°ÊÓ

Classify each reaction as a substitution, an elimination, or neither. Identify the leaving group in each reaction, and the nucleophile in substitutions.

Question: Which is the better leaving group in each pair?

a.${\mathrm{Cl}}^{-},{\mathrm{I}}^{-}$

b. ${\mathrm{NH}}_3,{\mathrm{NH}}_2$

c. ${\mathrm{H}}_2\mathrm{O},{\mathrm{H}}_2\mathrm{S}$

Question: Which molecules contain good leaving groups?

a.

b.

c.

d.

CH_3$-$CH₃

Question: Does the equilibrium favor the reactants or products in each substitution reaction?

a.

b.

Question: Identify the stronger nucleophile in each pair

a.NH₃ NH₂ ${\mathrm{NH}}_3,{\mathrm{NH}}_2$

b.CH₃ NH₂ ,CH₃ OH ${\mathrm{CH}}_3{\mathrm{NH}}_2,{\mathrm{CH}}_3\mathrm{OH}$

c.CH₃CO₂^- ,CH₃CH₂O^- ${\mathrm{CH}}_3{{\mathrm{CO}}_2}^{-},{\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{O}}^{-}$

Question: Classify each solvent as protic or aprotic

a.

b.

c.

Question: Identify the stronger nucleophile in each pair of anions.

a. Br^- or Cl^- in a polar protic solvent.

b. OH^-or Cl^- in a polar aprotic solvent.

c. HS^- or F^- in a polar protic solvent.

Question: Rank the nucleophiles in each group in order of increasing nucleophilicity.

a. OH^-,NH₂^- , H₂O

b. OH^- ,Br^- , F^-(polar aprotic solvent)

c. H₂O, OH^-,CH₃CO₂^-

Question: What nucleophile is needed to convert to each product?

a.

b.

c.

d.

Question: What happens to the rate of an S_N2 reaction under each of the following conditions?

a. [RX] is tripled, and$\left[:{\mathrm{Nu}}^{-}\right]$ stays the same.

b. Both [RX] and role="math" localid="1648206216789" $\left[:{\mathrm{Nu}}^{-}\right]$are tripled.

c. [RX] is halved, androle="math" localid="1648206048742" $\left[:{\mathrm{Nu}}^{-}\right]$stays the same.

d. [RX] is halved, and role="math" localid="1648206067374" $\left[:{\mathrm{Nu}}^{-}\right]$is doubled.