Isoprene alkenylation reaction

It was long believed that the isobutylalane does not give the growth reaction at all 299). This, however, was due to the fact that the reaction vessels employed always contained traces of a transition metal that catalyzed the displacement. With isoprene, isobutene is split off and polymeric alkyl aluminum compounds are formed which still contain some alkenyl groups. These are said to be less sensitive to air and moisture than the trialkyl alanes. The replacement is hastened by Ni as catalyst 61). 

As exemplified by the stmctural formulas of a-pinene, P-pinene, A -carene, isoprene, and limonene, shown in Figure 16.1, terpenes contain alkenyl (olefinic) bonds, in some cases two or more per molecule. Because of these and other structural features, terpenes are among the most reactive compounds in the atmosphere. The reaction of terpenes with hydroxyl radical is very rapid, and terpenes also react with other oxidizing agents in the atmosphere, particularly ozone, O3. Turpentine, a mixture of terpenes, has been widely used in paint because it reacts with atmospheric oxygen to form a peroxide, then a hard resin. It is likely that compounds such as a-pinene and isoprene undergo similar reactions in the atmos-... 

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