Learning Objectives: You should be able to apply the electrophilic addition and reduction reactions of alkenes to the alkyne system. The mechanisms and reactivity - in terms of regioselectivity and stereoselectivity - are very similar. Understand that alkynes are less reactive than alkenes toward electrophilic addition since the intermediate vinyl cation is less stable than simple secondary carbocations. Therefore, whenever an alkene and an alkyne are present in the same molecule, the alkene will usually react first toward electrophilic addition.

Synthesis problems become very important from here on in. These problems are easiest when you have committed all the reagents in a chapter to memory. It may be helpful to have the summary page of reactions open when you do these problems. Working synthesis problems well takes a lot of practice.

Nomenclature

Predict the product of reactions with alkynes

Predict the starting material needed to provide a given product

Deduce the structure of an unknown

8.8, 8.19, 8.24,8.27, 8.38, 8.39, 8.41

Hybridization and acidity

8.9, 8.23, 8.35

Synthesis problems

8.12, 8.13, 8.26, 8.30, 8.32, 8.33, 8.34