7. Substitution Reactions

Predict the products of the following S_N2 reactions.

(e)

(f)

Predict the products of the following S_N2 reactions.

(a)

(b)

Predict the compound in each pair that will undergo the S_N2 reaction faster.

(a)

(b)

Draw the substitution product formed by each of the following S_N2 reactions:

a. trans-1-iodo-4-ethylcyclohexane and methoxide ion

b. cis-1-chloro-3-methylcyclobutane and ethoxide ion

Draw the products obtained from the S_N2 reaction of:

c. (S)-3-chlorohexane and hydroxide ion.

d. 3-iodopentane and hydroxide ion.

Which alkyl halide is more reactive in an S_N2 reaction with a given nucleophile?

c.

d.

Rank the following alkyl bromides from most reactive to least reactive in an S_N2 reaction:

1-bromo-2-methylbutane, 1-bromo-3-methylbutane, 2-bromo-2-methylbutane, and 1-bromopentane.

Which alkyl halide is more reactive in an S_N2 reaction with a given nucleophile?

a.

b.

Does increasing the energy barrier for an S_N2 reaction increase or decrease the magnitude of the rate constant for the reaction?

The rate of the reaction of methyl iodide with quinuclidine was measured in nitrobenzene, and then the rate of the reaction of methyl iodide with ­triethylamine was measured in the same solvent. The concentration of the reagents was the same in both experiments.

a.Which reaction had the larger rate constant?

Draw a transition state for the following substitution reaction.

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.