9. Alkenes and Alkynes

Ethinylestradiol is a synthetic hormone mimic used as a contraceptive for its ability to prevent ovulation. Suggest a mechanism for the synthesis using sodium acetylide and estrone, followed by quenching with acid.

Predict the product of the following acetylide alkylations.

(a)

Predict the product of the following acetylide alkylations.

(c)

Suggest reagents you might use to generate the product from the given reactant.

(a)

Suggest reagents you might use to generate the product from the given reactant.

(c)

A student provided the product of the following reactions, but made a mistake. Identify the mistake, correct the mistake, and suggest a way for the student to avoid that mistake in the future.

(b)

A student provided the product of the following reactions, but made a mistake. Identify the mistake, correct the mistake, and suggest a way for the student to avoid that mistake in the future.

(a)

In Chapter 10, you learned how to make an alkyne by acetylide alkylation with a 1° haloalkane. Suggest a mechanism by which this reaction occurs.

What is the product of the reaction of an ester with excess acetylide ion followed by the addition of pyridinium chloride?

Explain why ethyne should be alkylated before, rather than after, nucleophilic addition.

Suggest an acetylide ion and a carbonyl that might be used to make the following products.

(a) oct-4-yn-3-ol

Suggest an acetylide ion and a carbonyl that might be used to make the following products.

(b) 2,6-dimethylhept-3-yn-2-ol

Suggest an acetylide ion and a carbonyl that might be used to make the following products.

(c) 5-phenylhex-2-yn-1-ol

Show the products of the following acetylide alkylation reactions. [Make sure your product has the correct number of carbons.]

(d)

The introduction of elimination reactions provides a second way to synthesize alkynes in a two-step process starting with an alkene. Suggest a mechanism for both steps of this process.