8. Elimination Reactions

Predict the product(s) that would result when the following molecules are allowed to react under the following conditions: (v) H₂O; (vi) NaOH, H₂O. If there is no reaction, write 'no reaction.'

(f)

Pure (S)-2-bromo-2-fluorobutane reacts with methoxide ion in methanol to give a mixture of (S)-2-fluoro-2-methoxybutane and three fluoroalkenes.

a. Use mechanisms to show which three fluoroalkenes are formed.

a. Draw the structures of the products obtained from the reaction of each enantiomer of cis-1-chloro-2-isopropylcyclopentane with sodium methoxide in methanol.

b. Are all the products optically active?

For each pair, choose the haloalkane that would react most quickly in an Sₙ1 or E1 reaction.

(c)

Predict the products and mechanisms of the following reactions. When more than one product or mechanism is possible, explain which are most likely.

g. 1−bromo−1−methylcyclopentane + NaOEt in ethanol

Predict the products and mechanisms of the following reactions. When more than one product or mechanism is possible, explain which are most likely.

a. 1−bromohexane + sodium ethoxide in ethanol

Suggest an appropriate base to synthesize the alkene as the major product from the starting haloalkane.

(b)

Draw the products of each of the following S_N2/E2 reactions. If the products can exist as stereoisomers, show which stereoisomers are formed.

b. (3R,4R)-3-bromo-4-methylhexane + CH₃O⁻

When (1-bromoethyl)cyclohexane is heated in methanol for an extended period of time, five products result: two ethers and three alkenes. Predict the products of this reaction, and propose mechanisms for their formation.

Would you expect the following bases to favor E1 or E2 elimination?

(c)

If 2-fluoropentane could undergo an E1 reaction, would you expect the major product to be the more stable alkene or the less stable alkene? Explain your answer.

What products are formed from the following reactions?

a.

What product is formed when 1-bromopropane reacts with each of the following nucleophiles?

c. CH₃S⁻

Show a mechanism for the following elimination reactions. Label the mechanism as E1 or E2.

(a)

Silver-assisted solvolysis of bromomethylcyclopentane in methanol gives a complex product mixture of the following five compounds. Propose mechanisms to account for these products.

(d)