7. Substitution Reactions

Predict the major products of the following reactions.

(a) ethyl tosylate + potassium tert-butoxide

(b) isobutyl tosylate + NaI

(c) (R)-2-hexyl tosylate + NaCN

Practice your electron-pushing skills by drawing a mechanism for the following S_N2 reactions.

(a)

Practice your electron-pushing skills by drawing a mechanism for the following S_N2 reactions.

(b)

Which S_N2 reaction would you expect to be faster? Explain your answer.

For each pair, choose the haloalkane that would react most quickly in an S_N2 reaction.

(b)

For each pair, choose the haloalkane that would react most quickly in an S_N2 reaction.

(d)

The following reaction, though run under standard solvolysis conditions, occurs via an S_N2 reaction. Why?

Crown ethers are able to solvate cations based on their size. Specifically, 15-crown-5 forms stable complexes with sodium. How would the addition of a crown ether change the rate of an S_N2 reaction?

Cardura, a drug used to treat hypertension, is synthesized as shown here.

b. Show the mechanism for conversion of A to B. Which is formed more rapidly, A or B?

Propose a mechanism for the following reaction that explains why the configuration of the asymmetric center in the reactant is retained in the product:

The S_N2 reaction is the concerted, backside displacement of a good leaving group by a nucleophile. Why do nucleophiles attack from the back in S_N2 reactions?

For each pair, choose the haloalkane that would react most quickly in an S_N2 reaction.

(a)

Predict the product(s) that would result when molecules (a)–(p) are allowed to react under the following conditions: (iii) SOCl₂ , NEt₃ (iv) 1. TsCl, Et₃N 2. NaCN; If no reaction occurs, write 'no reaction.'

(f)

Practice your electron-pushing skills by drawing a mechanism for the following S_N2 reactions.

(c)

For each pair, choose the nucleophile that would react most quickly in an S_N2 reaction (assume H₂O is the solvent).

(c)