7. Substitution Reactions

Optically active butan-2-ol racemizes in dilute acid. Propose a mechanism for this racemization.

Draw the stereoisomers that are formed from the following S_N1 reactions:

a. 3-bromo-3-methylpentane and methanol

b. 3-chloro-3-methylhexane and methanol

Rank the following from most reactive to least reactive in an S_N1 reaction:

The bromoalkanes shown below participate in S_N1 reactions with the relative rates shown. Explain this trend. relative rate:

Practice your electron-pushing skills by drawing a mechanism for the following S_N1 reactions.

(c)

Provide a mechanism for the following S_N1 reactions that feature a rearrangement.

(a)

Which of the following S_N1 reactions should proceed at a faster rate? Justify your answer on a reaction coordinate diagram.

Practice your electron-pushing skills by drawing a mechanism for the following S_N1 reactions.

(a)

The allylic bromide below gives two S_N1 products. Justify the formation of each.

Rank the ability of the following compounds to undergo an S_N1 reaction ( 1 = fastest, 5 = slowest ).

Propose a mechanism for each reaction, showing explicitly how the observed mixtures of products are formed.

(b) 2-methylbut-3-en-2-ol + HBr → 1-bromo-3-methylbut-2-ene + 3-bromo-3-methylbut-1-ene

Treatment of an alkyl halide with AgNO₃ in alcohol often promotes ionization.

Ag⁺ + R–Cl → AgCl + R⁺

When 4-chloro-2-methylhex-2-ene reacts with AgNO₃ in ethanol, two isomeric ethers are formed. Suggest structures, and propose a mechanism for their formation

When 3-bromo-1-methylcyclohexene undergoes solvolysis in hot ethanol, two products are formed. Propose a mechanism that accounts for both of these products.

Which haloalkane would you expect to undergo the fastest S_N1 reaction? Why?

Provide a mechanism for the following S_N1 reaction. What roles (acid/base/nucleophile/electrophile) does ethanol play in the reaction? What functional group is made in this reaction?