71367-49-2

Upstream product

• 93-16-3 Methylisoeugenol 
• 10548-77-3 1-(3,4-dimethoxyphenyl)-3-hydroxy-2-(2-methoxyphenoxy)propan-1-one 
• 776-99-8 3,4-dimethoxyphenylacetone 
• 25083-95-8 1-bromo-1-(3',4'-methoxyphenyl)propan-2-one 
• 64-18-6 formic acid 
• 10535-17-8 1-(3,4-dimethoxyphenyl)-2-(methoxyphenoxy)propane-1,3-diol 
• 13419-49-3 1-(3,4-dimethoxyphenyl)-1-hydroxy-propan-2-one 
• 1835-02-5 2-Bromo-1-(3,4-dimethoxyphenyl)ethanone 
• 29389-04-6 2-(2,6-dimethoxyphenoxy)-1-(3,4-dimethoxyphenyl)ethan-1-one 
• 22675-96-3 2-methoxyphenoxy-3',4'-dimethoxyacetophenone 
• 18133-46-5 α-(3,4-dimethoxyphenyl)acetoacetonitrile 
• 1346260-38-5 (E)-1-(3,4-dimethoxyphenyl)-2-(methoxyimino)propan-1-one 
• 33251-02-4 1-chloro-3-(3,4-dimethoxy-phenyl)-acetone 
• 408525-15-5 2-bromo-1-(3,4-dimethoxy-phenyl)-propenone 

Relevant academic research and scientific papers

Cleavage of lignin model compounds and ligninox using aqueous oxalic acid

Aqueous oxalic acid cleaves oxidised β-O-4 lignin model compounds by two distinct mechanisms that are dependent on the presence of the hydroxymethyl substituent. Various β-O-4 phenoxyacetophenones that do not contain the hydroxymethyl substituent undergo oxidative cleavage upon exposure to aqueous oxalic acid in the presence of air, likely through concerted ring opening of a dioxetane intermediate to give the corresponding benzoic acid and phenyl formate. Importantly, detrimental side reactions arising from singlet oxygen and hydroperoxy radicals (from both O2 and oxalic acid) are minimal when the cleavage is run under air compared to neat oxygen. When oxidised β-O-4 lignin model compounds bearing the hydroxymethyl group are cleaved by aqueous oxalic acid, the resulting diketone and phenol products arise from a redox neutral cleavage that is analogous to the formic acid-sodium formate mediated lignin cleavage process reported by Stahl. Aqueous oxalic acid also cleaves lignin itself, with oxidised milled wood lignin (MWLox) from Pinus radiata giving a 14% yield of ethyl acetate soluble aromatics with good selectivity for vanillin. Aqueous oxalic acid appears to be a promising lignin cleavage system given the benign, bio-based reagents, absence of metals and organic solvents and a simple extraction procedure that enables oxalic acid recycling.

PPh3·HBr-DMSO: A Reagent System for Diverse Chemoselective Transformations

The broad applicability of the hitherto unexplored reagent combination PPh3·HBr-DMSO is exemplified with multiple highly diverse one-step transformations to synthetically useful building blocks, such as flavones, 4H-thiochromen-4-ones, α-hydroxy ketones, 1,4-naphthoquinones (including vitamin K3), 2-bromo-3-substituted-1H-1-indenones, 2-methylthio-1H-1-indenones, 3-butyne-1,2-dione, and 4-pentene-2,3-diones. The simple and mild reaction conditions make the reagent superior in terms of yield and substrate scope in comparison with the existing alternatives.

Iron-catalysed oxidative cleavage of lignin and β-O-4 lignin model compounds with peroxides in DMSO

Simple FeCl3-derived iron catalysts are used for the cleavage of β-O-4 linkages in lignin and lignin model compounds. The degradation of the β-O-4 linkages and the resinol structures in both organosolv and kraft lignin was proven by 2D-NMR (HSQC) experiments, and the oxidative depolymerisation of these lignin sources was confirmed by GPC. Key reactive species facilitating this cleavage are methyl radicals generated from H2O2 and DMSO.

SELECTIVE C-O BOND CLEAVAGE OF OXIDIZED LIGNIN AND LIGNIN-TYPE MATERIALS INTO SIMPLE AROMATIC COMPOUNDS

A method to cleave C-C and C-0 bonds in β-Ο-4 linkages in lignin or lignin sub-units is described. The method includes oxidizing at least a portion of secondary benzylic alcohol groups in β-Ο-4 linkages in the lignin or lignin sub-unit to corresponding ketones and then leaving C-0 or C-C bonds in the oxidized lignin or lignin sub-unit by reacting it with an organic carboxylic acid, a salt of an organic carboxylic acids, and/or an ester of an organic carboxylic acids. The method may utilize a metal or metal-containing reagent or proceed without the metal or metal-containing reagent.

Formic-acid-induced depolymerization of oxidized lignin to aromatics

Lignin is a heterogeneous aromatic biopolymer that accounts for nearly 30% of the organic carbon on Earth and is one of the few renewable sources of aromatic chemicals. As the most recalcitrant of the three components of lignocellulosic biomass (cellulose, hemicellulose and lignin), lignin has been treated as a waste product in the pulp and paper industry, where it is burned to supply energy and recover pulping chemicals in the operation of paper mills. Extraction of higher value from lignin is increasingly recognized as being crucial to the economic viability of integrated biorefineries. Depolymerization is an important starting point for many lignin valorization strategies, because it could generate valuable aromatic chemicals and/or provide a source of low-molecular-mass feedstocks suitable for downstream processing. Commercial precedents show that certain types of lignin (lignosulphonates) may be converted into vanillin and other marketable products, but new technologies are needed to enhance the lignin value chain. The complex, irregular structure of lignin complicates chemical conversion efforts, and known depolymerization methods typically afford ill-defined products in low yields (that is, less than 10-20wt%). Here we describe a method for the depolymerization of oxidized lignin under mild conditions in aqueous formic acid that results in more than 60wt% yield of low-molecular-mass aromatics. We present the discovery of this facile C-O cleavage method, its application to aspen lignin depolymerization, and mechanistic insights into the reaction. The broader implications of these results for lignin conversion and biomass refining are also considered.

Synthesis of 1,2-diketones from β-keto nitriles via a protection-oxidative-decyanation-deprotection protocol

A variety of 1,2-diketones were prepared from -keto nitriles via a three-step protocol including the protection of the ketones with methoxyamine, oxidative decyanation, and microwave-assisted deprotection in the final step. This approach provides a novel and efficient access to a wide scope of symmetric and unsymmetric 1,2-diketones using molecular oxygen as the oxidant in the decyanation process. Georg Thieme Verlag Stuttgart - New York.