9. Alkenes and Alkynes

Suggest an alkene that, in two steps, could be converted into each of the following ketones. Each sequence should involve a pinacol rearrangement.

(c)

Indicate which alcohol in each pair undergoes an elimination reaction more rapidly when heated with H₂SO₄.

d.

Produce a mechanism for the following transformation.

Identify the alcohol(s) that would produce the following alkenes under the given conditions.

(b)

Predict the products of the following reactions. When more than one product is expected, predict which will be the major product.

What stereoisomers are formed in the following reactions? Which stereoisomer is the major product?

a. the acid-catalyzed dehydration of 1-pentanol to 2-pentene

Propose a mechanism for each of the following reactions:

a.

Treatment of the following alcohol was expected to give alkene A. Instead, B was produced as the major product. Suggest a mechanism by which B formed.

Explain why the following alcohols, when heated with acid, form the same alkene.

Predict the product of the following pinacol rearrangements.

(c)

Indicate which alcohol in each pair undergoes an elimination reaction more rapidly when heated with H₂SO₄.

a.

b.

Propose a mechanism for the following reaction:

During the acid-catalyzed dehydration of $2_{\text{-}}\text{butanol}$, which alkene is the major product?

Predict the major product of the following elimination reactions.

(b)

Propose mechanisms for the following reactions. Additional products may be formed, but your mechanism only needs to explain the products shown.

(b)