Impact Factor:7.5

DOI number:10.1039/c7sc02964k

Journal:CHEMICAL SCIENCE

Abstract:Mechanistic studies of the catalyst [Pd2(dba)3/1,1′-bis(tert-butyl(pyridin-2-yl)phosphanyl)ferrocene, L2] for olefin alkoxycarbonylation reactions are described. X-ray crystallography reveals the coordination of the pyridyl nitrogen atom in L2 to the palladium center of the catalytic intermediates. DFT calculations on the elementary steps of the industrially relevant carbonylation of ethylene (the Lucite α-process) indicate that the protonated pyridyl moiety is formed immediately, which facilitates the formation of the active palladium hydride complex. The insertion of ethylene and CO into this intermediate leads to the corresponding palladium acyl species, which is kinetically reversible. Notably, this key species is stabilized by the hemilabile coordination of the pyridyl nitrogen atom in L2. The rate-determining alcoholysis of the acyl palladium complex is substantially facilitated by metal–ligand cooperation. Specifically, the deprotonation of the alcohol by the built-in base of the ligand allows a facile intramolecular nucleophilic attack on the acyl palladium species concertedly. Kinetic measurements support this mechanistic proposal and show that the rate of the carbonylation step is zero-order dependent on ethylene and CO. Comparing CH3OD and CH3OH as nucleophiles suggests the involvement of (de)protonation in the rate-determining step.

Co-author:Zhihong Wei；Jie Liu；Ricarda Dühren；Anke Spannenberg；Haijun Jiao；Helfried Neumann；Ralf Jackstell；Robert Franke；Matthias Beller*；

First Author:Kaiwu Dong；Rui Sang

Indexed by:Journal paper

Correspondence Author:Matthias Beller*；

Document Type:J

Volume:9

Issue:9

Page Number:2510-2516

Translation or Not:no

Date of Publication:2018-03-07

Included Journals:SCI

Links to published journals:https://pubs.rsc.org/en/content/articlelanding/2018/sc/c7sc02964k