Jump to Main Content
Tandem Isomerization-Decarboxylation for Convertiing Alkenoic Fatty Acids into Alkenes
- Rex E. Murray, Erin L. Walter, Kenneth M. Doll
- ACS Catalysis 2014 v.4 no.10 pp. 3517-3520
- alkenes, catalysts, catalytic activity, cinnamic acid, decarboxylation, isomerization, isomers, oleic acid, stearic acid, structure-activity relationships
- We report a facile Ru-catalyzed route to alkenes from alkenoic fatty acids via a readily accessible pre-catalyst [Ru(CO)2RCO2]n. The catalyst apparently functions in a tandem mode by dynamically isomerizing the positions of double bonds in an aliphatic chain and, subsequently, decarboxylating specific isomers with lower activation barriers. Substrates capable of tandem isomerization-decarboxylation processes (oleic acid, undecylenic acid) are readily converted to mixtures of alkenes. A catalytic cycle is proposed that relies on isomerization positioning double bonds proximate to the acid function to enable facile decarboxylation. To elucidate the proposed mechanistic pathway, substrates capable of only isomerization (methyl oleate) or decarboxylation (cinnamic acid), but not both, were shown to be operational under these catalytic reaction conditions. Another illustrative comparison shows that the saturated octadecanoic acid is 28 times less reactive than the unsaturated counterpart when reacted using this precatalyst.