7. Substitution Reactions

Formation of the carbocation should be fastest for which leaving group?

(a)

Which of the following correctly ranks the leaving groups from worst to best?

Given the reactants shown, what type of elimination would you expect to occur?

(c)

Which of the following is a good nucleophile and a strong base?

Which of the following is the better leaving group in a polar aprotic solvent?

(c) Br ⁻ vs. I ⁻

Which is a better leaving group, HO⁻ or H₂O? Explain your answer.

Which of the following molecules contains a good leaving group?

Explain why the rate of the reaction of 1-bromo-2-butene with ethanol is increased if silver nitrate is added to the reaction mixture.

A trifluoromethanesulfonate (triflate) can be used in a manner similar to tosylates. Which would you expect to be a better leaving group? Why?

Formation of the carbocation should be fastest for which leaving group?

(b)

Which substitution reaction takes place more rapidly?

d. CH₃CH₂Cl + I⁻ or CH₃CH₂Br + I⁻

Which member in each pair in [PROBLEM 9-68] is a better leaving group?

a. H₂O or HO⁻

b. NH₃ or H₂O

Formation of the carbocation should be fastest for which leaving group?

(c)

Which of the following is the best leaving group in a nucleophilic substitution reaction?

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?