Stagewise character of the hydrogenation of the double bonds of cyclopentadiene over raney nickel

Summary

• 1. An investigation was made into the kinetics of the hydrogenation of cyclopentadiene in presence of Raney nickel at 25° and normal pressure in alcoholic and hydrocarbon solutions.

• 2. It was shown that cyclopentadiene is rapidly hydrogenated to cyclopentane in methyl, ethyl, and isobutyl alcohols.

• 3. In aromatic, hydroaromatic,aliphatic hydrocarbon solutions, cyclopentadiene is rapidly hydrogenated only as far as cyclopentene, and the second molecular proportion of hydrogen adds very slowly.

• 4. In all solvents examined, the conjugated double bands of cyclopentadiene are hydrogenated successively. In hydrocarbon solvents the two-stage character of the process can be demonstrated also by kinetic methods.

• 5. Both in alcohol and in hydrocarbon solvents cyclopentene can be obtained from cyclopentadiene if the hydrogenation is arrested after the Addition of one molecular proportion of hydrogen.