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Hydrogenolysis and configurational isomerization of stereoisomeric 1-methyl-3-ethylcyclobutanes on Pt, Pd, and Rh catalysts

Research paper by O. V. Bragin, E. G. Khelkovskaya-Sergeeva, A. V. Preobrazhenskii, A. L. Liberman

Indexed on: 01 Sep '75Published on: 01 Sep '75Published in: Russian Chemical Bulletin



Abstract

The transformations of the stereoisomeric 1-methyl-3-ethylcyclobutanes were studied in the range 150–320° on the catalysts: Pt/C, Pd/C, Rh/C, and Ir/C. On all of the catalysts the hydrogenolysis proceeds at both of the ring bonds with the predominant formation of 2-methylhexane. The difference in the relative hydrogenolysis rates at bonds a1 (formation of 2-methylhexane) and a2 (formation of 3-methyl-hexane) is manifested more strongly at low temperatures. The different reactivity of thea1 anda2 bonds was explained from the standpoint of the planar mechanism of hydrogenolysis with the inclusion of conformational concepts.The configurational isomerization of the stereoisomeric dialkylcyclobutanes occurs on the employed catalysts; hydrogen is necessary for this reaction. The conditions were found for the “pure” progress of configurational isomerization on the catalysts Pt/C, Pd/C, and Ir/C. This reaction was detected for the first time on the Rh and Ir catalysts.