54083-20-4Relevant academic research and scientific papers
Toward the oxidative deconstruction of lignin: Oxidation of β-1 and β-5 linkages
Fang, Zhen,Meier, Mark S.
, p. 2330 - 2341 (2018/04/05)
There have been numerous reports on methods for the oxidative cleavage of β-O-4 linkages in lignin model compounds, but relatively few reports of how those methods affect other linkages that are present in lignin. We have investigated the effect of several of these oxidation methods on the β-1 and the β-5 lignin linkages, using four β-1 and β-5 model compounds. We observed that direct oxidative cleavage of C-C bonds occurs in metal-catalyzed TEMPO oxidation systems and with iron porphyrin oxidations, neither of which had we observed in similar oxidations on β-O-4 models. The β-5 linkage proved to be largely resistant to all of these oxidative systems, but the dihydrofuran ring in the β-5 model 3 was opened when treated with KMnO4 at elevated temperature. Most promising was the oxidation of 2 with DDQ, which produced the benzylic ketone in high yield (84%), as it does in reactions with β-O-4 models. This reaction exhibits selectivity for the benzylic position as well as compatibility with phenols, characteristics that are highly desirable for a two-step, benzylic oxidation/Baeyer-Villiger route for cleavage of lignin.
Flash-metathesis for the coupling of sustainable (poly)hydroxyl β-methylstyrenes from essential oils
Hitce,Crutizat,Bourdon,Vivès,Marat,Dalko-Csiba
supporting information, p. 3756 - 3761 (2015/07/15)
A cross-metathesis procedure was developed to synthetize symmetrical and non symmetrical stilbenes from sustainable resources. The reaction proceeds under solvent-free conditions and at low catalyst loading (down to 0.01 mol%) within a couple of minutes only (TOF up to 6.9 s-1), on multi-gram scale. The highly reactive β-methylstyrene substrates were homo-coupled not only as pure synthons but also as components of essential oils that were reacted directly in order to eliminate prior substrate isolation from the overall process.
Reactive Structures in Wood and High-yield Pulps. IV. Daylight-induced Oxidation of Stilbene Structures in the Solid State
Zhang, Liming,Gellerstedt, Goeran
, p. 490 - 497 (2007/10/02)
In order to mimic the light-induced yellowing of stilbene structures present in hydrogen peroxide bleached high-yield pulps, two monohydroxy stilbenes have been synthesized and irradiated with daylight in the solid state on filter paper.The key step in the reaction sequence seems to be an electron transfer-proton transfer process leading to the formation of a stilbene phenoxyl radical.Subsequent oxidation gives rise to a cation which can add water and after loss of methanol is converted into an ortho-quinone.By hydrogen donation and subsequent addition to the stilbene double bond, thiol groups like that in mercaptoacetic acid could be used to capture all radical species formed, and thus prevent the formation of coloured products.Other major reaction pathways leading to the formation of non-coloured products were also identified.
