2785-87-7Relevant articles and documents
Lignin depolymerization to monophenolic compounds in a flow-through system
Kumaniaev, Ivan,Subbotina, Elena,S?vmarker, Jonas,Larhed, Mats,Galkin, Maxim V.,Samec, Joseph S.M.
, p. 5767 - 5771 (2017)
A reductive lignocellulose fractionation in a flow-through system in which pulping and transfer hydrogenolysis steps were separated in time and space has been developed. Without the hydrogenolysis step or addition of trapping agents to the pulping, it is possible to obtain partially depolymerized lignin (21 wt% monophenolic compounds) that is prone to further processing. By applying a transfer hydrogenolysis step 37 wt% yield of lignin derived monophenolic compounds was obtained. Pulp generated in the process was enzymatically hydrolyzed to glucose in 87 wt% yield without prior purification.
Antioxidant activity of eugenol and related monomeric and dimeric compounds
Ogata, Masahiro,Hoshi, Midori,Urano, Shiro,Endo, Toyoshige
, p. 1467 - 1469 (2000)
Since the inhibitory effect of eugenol (a), which was isolated as an antioxidative component from plant, Caryopylli flos, on lipid peroxidation was less than that of α-tocopherol, we synthesized, the eugenol-related compounds dieugenol (b), tetrahydrodieugenol (c), and dihydroeugenol (d), to find new strong antioxidants and assessed them for their inhibitory effect on lipid peroxidation and scavenging ability for superoxide and hydroxyl radicals. The antioxidative activities were in the order: (b)>(c)>(d)>(a) for the thiobarbituric acid reactive substance (TBARS) formation. These results suggest that the dimerized compounds have higher antioxidant activities than that of the monomers. Electron spin resonance (ESR) spin trapping experiments revealed that eugenol and its dimer, having allyl groups in the structure, scavenged superoxide, and that only eugenol trapped hydroxyl radicals under the conditions used. These finding suggest that eugenol and dieugenol have a different mechanism of antioxidation, i.e. eugenol may inhibit lipid peroxidation at the level of initiation, however, the related dimeric compounds may inhibit lipid peroxidation at the level of propagation of free radical chain reaction like α-tocopherol.
Phillips
, p. 568 (1931)
Catalytic Activation of Unstrained C(Aryl)-C(Alkyl) Bonds in 2,2′-Methylenediphenols
Dong, Guangbin,Ratchford, Benjamin L.,Xue, Yibin,Zhang, Rui,Zhu, Jun
supporting information, p. 3242 - 3249 (2022/02/23)
Catalytic activation of unstrained and nonpolar C-C bonds remains a largely unmet challenge. Here, we describe our detailed efforts in developing a rhodium-catalyzed hydrogenolysis of unstrained C(aryl)-C(alkyl) bonds in 2,2′-methylenediphenols aided by removable directing groups. Good yields of the monophenol products are obtained with tolerating a wide range of functional groups. In addition, the reaction is scalable, and the catalyst loading can be reduced to as low as 0.5 mol %. Moreover, this method proves to be effective to cleave C(aryl)-C(alkyl) linkages in both models of phenolic resins and commercial novolacs resins. Finally, detailed experimental and computational mechanistic studies show that with C-H activation being a competitive but reversible off-cycle reaction, this transformation goes through a directed C(aryl)-C(alkyl) oxidative addition pathway.
Highly selective reductive catalytic fractionation at atmospheric pressure without hydrogen
Ren, Tianyu,You, Shengping,Zhang, Zhaofeng,Wang, Yuefei,Qi, Wei,Su, Rongxin,He, Zhimin
supporting information, p. 1648 - 1657 (2021/03/09)
Reductive catalytic fractionation (RCF) is an efficient and selective way to produce phenolic monomers from lignin. However, this strategy is difficult to scale up due to its high operating pressure. In this work, we investigated RCF reaction at or near atmospheric pressure and without the use of hydrogen. The atmospheric RCF (ARCF) was conducted in acidified ethylene glycol in glass vessels at 185-195 °C catalyzed by 5% Ru/C. The products mainly include propylguaiacol and propylsyringyl (up to 95.6% among the lignin monomers) and do not contain propanolguaiacol, propanolsyringyl, or H monomers. Although the total yield of lignin monomers in ARCF is about one-quarter less than that of RCF, the operation of ARCF is much easier, milder, safer, and cheaper due to the atmospheric condition and the feasibility of the semi-continuous operation.
Efficient demethylation of aromatic methyl ethers with HCl in water
Bomon, Jeroen,Bal, Mathias,Achar, Tapas Kumar,Sergeyev, Sergey,Wu, Xian,Wambacq, Ben,Lemière, Filip,Sels, Bert F.,Maes, Bert U. W.
supporting information, p. 1995 - 2009 (2021/03/26)
A green, efficient and cheap demethylation reaction of aromatic methyl ethers with mineral acid (HCl or H2SO4) as a catalyst in high temperature pressurized water provided the corresponding aromatic alcohols (phenols, catechols, pyrogallols) in high yield. 4-Propylguaiacol was chosen as a model, given the various applications of the 4-propylcatechol reaction product. This demethylation reaction could be easily scaled and biorenewable 4-propylguaiacol from wood and clove oil could also be applied as a feedstock. Greenness of the developed methodversusstate-of-the-art demethylation reactions was assessed by performing a quantitative and qualitative Green Metrics analysis. Versatility of the method was shown on a variety of aromatic methyl ethers containing (biorenewable) substrates, yielding up to 99% of the corresponding aromatic alcohols, in most cases just requiring simple extraction as work-up.