1835-09-2Relevant academic research and scientific papers
Ruthenium-Catalyzed C-C bond cleavage in lignin model substrates
Vom Stein, Thorsten,Den Hartog, Tim,Buendia, Julien,Stoychev, Spas,Mottweiler, Jakob,Bolm, Carsten,Klankermayer, Jürgen,Leitner, Walter
, p. 5859 - 5863 (2015)
Ruthenium-triphos complexes exhibited unprecedented catalytic activity and selectivity in the redox-neutral C-C bond cleavage of the β-O-4 lignin linkage of 1,3-dilignol model compounds. A mechanistic pathway involving a dehydrogenation-initiated retro-aldol reaction for the C-C bond cleavage was proposed in line with experimental data and DFT calculations.
Rhodium-terpyridine catalyzed redox-neutral depolymerization of lignin in water
Liu, Yuxuan,Li, Changzhi,Miao, Wang,Tang, Weijun,Xue, Dong,Xiao, Jianliang,Zhang, Tao,Wang, Chao
supporting information, p. 33 - 38 (2020/01/13)
Simple rhodium terpyridine complexes were found to be suitable catalysts for the redox neutral cleavage of lignin in water. Apart from cleaving lignin model compounds into ketones and phenols, the catalytic system could also be applied to depolymerize dioxasolv lignin and lignocellulose, affording aromatic ketones as the major monomer products. The (hemi)cellulose components in the lignocellulose sample remain almost intact during lignin depolymerization, providing an example of a "lignin-first" process under mild conditions. Mechanistic studies suggest that the reaction proceeds via a rhodium catalyzed hydrogen autotransfer process.
Electroorganic Reactions. 38. Mechanism of Electrooxidative Cleavage of Lignin Model Dimers
Pardini, Vera L.,Smith, Carmen Z.,Utley, James H. P.,Vargas, Reinaldo R.,Viertler, Hans
, p. 7305 - 7313 (2007/10/02)
The mechanisms for oxidative cleavage of several phenolic ethers, models for lignins, have been investigated by a detailed comparison of the results of anodic oxidation at nickel anodes in alkaline electrolyte with that of oxidation in acetonitrile in the presence of a triarylamine redox catalyst.The latter reaction is unambiguously initiated by single-electron transfer (SET), and in this case the major product of cleavage is aldehyde (vanillin or syringaldehyde derivatives).At nickel anodes polymerization is predominant although the aldehydes are formed together with larger amounts of the corresponding carboxylic acids.Combinations of 4-hydroxyl, α-keto, β-O-aryl, and β-hydroxymethyl functionality are shown to be crucial for the oxidation at nickel; the carboxylic acid formation probably involves a route with initial hydrogen atom abstraction at the surface.Important chemical conversions precede and accompany oxidation in alkaline media, and these are associated with the propensity for polymerization.
