- Method for inhibiting condensation of lignin aryl ether dimer and/or lignin aryl ether dimer depolymerization product
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The invention provides a method for inhibiting condensation of a lignin aryl ether dimer and/or a lignin aryl ether dimer depolymerization product, and belongs to the technical field of lignin depolymerization. The method for inhibiting condensation of the lignin aryl ether dimer and/or the lignin aryl ether dimer depolymerization product comprises the following steps: mixing the lignin aryl etherdimer with a eutectic solvent, and carrying out a reaction on the obtained mixed material under a heating condition, wherein the eutectic solvent is a mixture of choline chloride, diol and oxalic acid. The mixture of choline chloride, diol and oxalic acid is used as a eutectic solvent, and intramolecular/intermolecular condensation of the lignin aryl ether dimer and aldehyde condensation of a lignin aryl ether dimer depolymerization product can be inhibited under the condition that no catalyst is added; and the eutectic solvent is green, non-toxic, recyclable and degradable. The method provided by the invention is simple in process and remarkable in condensation inhibition effect.
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Paragraph 0043-0048
(2020/05/05)
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- Metal Triflates for the Production of Aromatics from Lignin
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The depolymerization of lignin into valuable aromatic chemicals is one of the key goals towards establishing economically viable biorefineries. In this contribution we present a simple approach for converting lignin to aromatic monomers in high yields under mild reaction conditions. The methodology relies on the use of catalytic amounts of easy-to-handle metal triflates (M(OTf)x). Initially, we evaluated the reactivity of a broad range of metal triflates using simple lignin model compounds. More advanced lignin model compounds were also used to study the reactivity of different lignin linkages. The product aromatic monomers were either phenolic C2-acetals obtained by stabilization of the aldehyde cleavage products by reaction with ethylene glycol or methyl aromatics obtained by catalytic decarbonylation. Notably, when the method was ultimately tested on lignin, especially Fe(OTf)3 proved very effective and the phenolic C2-acetal products were obtained in an excellent, 19.3±3.2 wt % yield.
- Deuss, Peter J.,Lahive, Ciaran W.,Lancefield, Christopher S.,Westwood, Nicholas J.,Kamer, Paul C. J.,Barta, Katalin,de Vries, Johannes G.
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p. 2974 - 2981
(2016/11/02)
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- Combination of NH2OH·HCl and NaIO4: an effective reagent for molecular iodine-free regioselective 1,2-difunctionalization of olefins and easy access of terminal acetals
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We have demonstrated a new application of our oxidizing reagent, a combination of NH2OH·HCl and NaIO4, in the first generalized regioselective 1,2-difunctionalization of olefins. It is a general method for the preparation of β-iodo-β′-hydroxy ethers, β-iodo ethers, β-iodohydrin, and β-iodo acetoxy compounds using different reaction media. The reactions are highly regioselective, always affording Markovnikov's type addition products. The methodology is also applicable for the easy access of terminal acetals. Molecular iodine-free synthesis, room temperature reaction conditions, high yields, use of less expensive reagents, mild reaction conditions, broad applicability of nucleophiles, and applicability for gram-scale synthesis are the notable advantages of this present protocol.
- Chakraborty, Nirnita,Santra, Sougata,Kundu, Shrishnu Kumar,Hajra, Alakananda,Zyryanov, Grigory V.,Majee, Adinath
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p. 56780 - 56788
(2015/07/15)
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- Aromatic Monomers by in Situ Conversion of Reactive Intermediates in the Acid-Catalyzed Depolymerization of Lignin
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Conversion of lignin into well-defined aromatic chemicals is a highly attractive goal but is often hampered by recondensation of the formed fragments, especially in acidolysis. Here, we describe new strategies that markedly suppress such undesired pathways to result in diverse aromatic compounds previously not systematically targeted from lignin. Model studies established that a catalytic amount of triflic acid is very effective in cleaving the β-O-4 linkage, most abundant in lignin. An aldehyde product was identified as the main cause of side reactions under cleavage conditions. Capturing this unstable compound by reaction with diols and by in situ catalytic hydrogenation or decarbonylation lead to three distinct groups of aromatic compounds in high yields acetals, ethanol and ethyl aromatics, and methyl aromatics. Notably, the same product groups were obtained when these approaches were successfully extended to lignin. In addition, the formation of higher molecular weight side products was markedly suppressed, indicating that the aldehyde intermediates play a significant role in these processes. The described strategy has the potential to be generally applicable for the production of interesting aromatic compounds from lignin.
- Deuss, Peter J.,Scott, Martin,Tran, Fanny,Westwood, Nicholas J.,De Vries, Johannes G.,Barta, Katalin
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supporting information
p. 7456 - 7467
(2015/06/30)
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- Nickel-mediated inter- and intramolecular reductive cross-coupling of unactivated alkyl bromides and aryl iodides at room temperature
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A nickel-mediated intermolecular reductive cross-coupling reaction of unactivated alkyl bromides and aryl iodides at room temperature has been developed and successfully extended to less explored intramolecular versions and tandem cyclization-intermolecular cross-coupling. Highly stereoselective (or stereospecific) synthesis of linear-fused perhydrofuro[2,3-b]furan (pyran) and spiroketal skeletons allows rapid access to these useful building blocks, which would be potentially valuable in the synthesis of relevant natural products. A rational explanation for the formation of contiguous stereogenic centers is given. Copyright
- Yan, Chang-Song,Peng, Yu,Xu, Xiao-Bo,Wang, Ya-Wen
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supporting information; experimental part
p. 6039 - 6048
(2012/06/18)
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