9. Alkenes and Alkynes

Propose a mechanism for each reaction.

(a)

Dehydration synthesis always results in the formation of which of the following?

Which mechanism best describes the formation of the major product(s) in the dehydration of $2_{-\mathrm{butanol}}$ under acidic conditions?

What product is obtained when the following vicinal diol is heated in an acidic solution?

What occurs during a dehydration synthesis reaction?

A vicinal diol has OH groups on adjacent carbons. The dehydration of a vicinal diol is accompanied by a rearrangement called the pinacol rearrangement. Propose a mechanism for this reaction.

When HCl was used for the attempted dehydration reaction shown, a reaction occurred, but none of the desired product was formed. Suggest the identity of the actual product obtained.

Which of the following alcohols dehydrates the fastest when heated with acid?

Write a balanced equation for each reaction, showing the major product you expect.

(a)

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

(a)

Which of the following reactions is a dehydration reaction?

Show the product(s) you expect from dehydration of the following alcohols when they are heated in sulfuric or phosphoric acid. In each case, use a mechanism to show how the products are formed.

(c)

Propose a mechanism for each of the following reactions:

a.

Predict the major products of acid-catalyzed dehydration of the following alcohols.

(c)

(d)

A dehydration synthesis reaction results in which of the following?