Under certain conditions, the reaction of 0.5 M 1-bromobutane with 1.0 M sodium methoxide forms 1-methoxybutane at a rate of 0.05 mol/L per second. What would be the rate if 0.1 M 1-bromobutane and 2.0 M NaOCH₃ were used?

Consider the reaction of 1-bromobutane with a large excess of ammonia (NH₃). Draw the reactants, the transition state, and the products. Note that the initial product is the salt of an amine (RNH₃⁺Br⁻), which is deprotonated by the excess ammonia to give the amine.

Under certain conditions, the reaction of 0.5 M 1-bromobutane with 1.0 M sodium methoxide forms 1-methoxybutane at a rate of 0.05 mol/L per second.

c. Show another S_N2 reaction using a different combination of an alkoxide and an alkyl bromide that also produces 1-methoxybutane.

Predict the major products of the following substitutions.

a.

Predict the major products of the following substitutions.

b.

Predict the major products of the following substitutions.

d. CH₃CH₂CH₂I + NaCN →

Predict the major products of the following substitutions.

e. 1-chloropentane + NaI →

Predict the major products of the following substitutions.

f.

When methylenecyclohexane is treated with a low concentration of bromine under irradiation by a sunlamp, two substitution products are formed.

a. Propose structures for these two products. (b) Propose a mechanism to account for their formation.

Show how you might use S_N2 reactions to convert 1-chlorobutane into the following compounds.

c. 1-iodobutane

d. CH₃—(CH₂)₃—CN

Show how you might use SN2 reactions to convert 1-chlorobutane into the following compounds.

e. CH₃—(CH₂)₃—C≡CH

f. CH₃CH₂—O—(CH₂)₃—CH₃

g. CH₃—(CH₂)₃—NH₂

For each pair, predict the stronger nucleophile in the SN2 reaction (using an alcohol as the solvent). Explain your prediction.

a. (CH₃CH₂)₃N or (CH₃CH₂)₂NH

b. (CH₃)₂O or (CH₃)₂S

For each pair, predict the stronger nucleophile in the SN2 reaction (using an alcohol as the solvent). Explain your prediction.

c. NH₃ or PH₃

d. CH₃S^– or H₂S

For each pair, predict the stronger nucleophile in the SN2 reaction (using an alcohol as the solvent). Explain your prediction.

e. (CH₃)₃N or (CH₃)₂O

f. CH₃COO^– or CF₃COO^–

For each pair, predict the stronger nucleophile in the SN2 reaction (using an alcohol as the solvent). Explain your prediction.

g. (CH₃)₂CHO^– or CH₃CH₂CH₂O^–

h. I^– or Cl^–

When diethyl ether (CH₃CH₂OCH₂CH₃) is treated with concentrated HBr, the initial products are CH₃CH₂Br and CH₃CH₂OH. Propose a mechanism to account for this reaction.

Rank the following compounds in decreasing order of their reactivity toward the S_N2 reaction with sodium ethoxide (Na^{+ –}OCH₂CH₃) in ethanol.

methyl chloride

tert-butyl iodide 

neopentyl bromide

isopropyl bromide

methyl iodide

ethyl chloride

For each pair of compounds, state which compound is the better S_N2 substrate.

a. 2-methyl-1-iodopropane or tert-butyl iodide.

b. cyclohexyl bromide or 1-bromo-1-methylcyclohexane

For each pair of compounds, state which compound is the better S_N2 substrate.

c. 2-bromobutane or isopropyl bromide

d. 1-chloro-2,2-dimethylbutane or 2-chlorobutane

e. 1-iodobutane or 2-iodopropane

Draw a perspective structure or a Fischer projection for the products of the following S_N2 reactions.

(a) trans-1-bromo-3-methylcyclopentane + KOH

(b) (R)-2-bromopentane + KCN

Draw a perspective structure or a Fischer projection for the products of the following S_N2 reactions.

(c)

(d)

Draw a perspective structure or a Fischer projection for the products of the following S_N2 reactions.

(e)

Draw a perspective structure or a Fischer projection for the products of the following S_N2 reactions.

(f)

Propose an S_N1 mechanism for the solvolysis of 3-bromo-2,3-dimethylpentane in ethanol.

Choose the member of each pair that will react faster by the S_N1 mechanism.

a. 1-bromopropane or 2-bromopropane

b. 2-bromo-2-methylbutane or 2-bromo-3-methylbutane

Choose the member of each pair that will react faster by the SN1 mechanism.

c. n-propyl bromide or allyl bromide

d. 1-bromo-2,2-dimethylpropane or 2-bromopropane

Choose the member of each pair that will react faster by the SN1 mechanism.

e. 2-iodo-2-methylbutane or tert-butyl chloride

f. 2-bromo-2-methylbutane or ethyl iodide

3-Bromocyclohexene is a secondary halide. It undergoes S_N1 substitution about as fast as most tertiary halides. Use resonance structures to explain this enhanced reactivity.

Benzyl bromide is a primary halide. It undergoes S_N1 substitution about as fast as most tertiary halides. Use resonance structures to explain this enhanced reactivity.

Give the S_N1 mechanism for the formation of 2-ethoxy-3-methylbutane, the unrearranged product in this reaction.