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Gas-phase models for the nickel- and palladium-catalyzed deoxygenation of fatty acids


Parker, K and Weragoda, GK and Pho, V and Canty, AJ and Polyzos, A and O'Hair, RAJ and Ryzhov, V, Gas-phase models for the nickel- and palladium-catalyzed deoxygenation of fatty acids, ChemCatChem, 12, (21) pp. 5476-5485. ISSN 1867-3880 (2020) [Refereed Article]

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Copyright 2020 Wiley-VCH GmbH

DOI: doi:10.1002/cctc.202000908


Using fatty acids as renewable sources of biofuels requires deoxygenation. While a number of promising catalysts have been developed to achieve this, their operating mechanisms are poorly understood. Here, model molecular systems are studied in the gas phase using mass spectrometry experiments and DFT calculations. The coordinated metal complexes [(phen)M(O2CR)]+ (where phen=1,10‐phenanthroline; M=Ni or Pd; R=CnH2n+1, n≥2) are formed via electrospray ionization. Their collision‐induced dissociation (CID) initiates deoxygenation via loss of CO2 and [C,H2,O2]. The CID spectrum of the stearate complexes (R=C17H35) also shows a series of cations [(phen)M(Rí)]+ (where Rí < C17) separated by 14 Da (CH2) corresponding to losses of C2H4‐C16H32 (cracking products). Sequential CID of [(phen)M(Rí)]+ ultimately leads to [(phen)M(H)]+ and [(phen)M(CH3)]+, both of which react with volatile carboxylic acids, RCO2H, (acetic, propionic, and butyric) to reform the coordinated carboxylate complexes [(phen)M(O2CR)]+. In contrast, cracking products with longer carbon chains, [(phen)M(R)]+ (R>C2), were unreactive towards these carboxylic acids. DFT calculations are consistent with these results and reveal that the approach of the carboxylic acid to the "free" coordination site is blocked by agostic interactions for R > CH3.

Item Details

Item Type:Refereed Article
Keywords:fatty acids, deoxygenation, computation, organopalladium, DFT, mass spectrometry
Research Division:Chemical Sciences
Research Group:Inorganic chemistry
Research Field:Transition metal chemistry
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the chemical sciences
UTAS Author:Canty, AJ (Professor Allan Canty)
ID Code:141761
Year Published:2020
Web of Science® Times Cited:2
Deposited By:Chemistry
Deposited On:2020-11-17
Last Modified:2020-12-03

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