92409-44-4

Upstream product

• 50-00-0 formaldehyd 
• 1434536-61-4 2-(2-methoxyphenoxy)-1-(3,4,5-trimethoxyphenyl)ethan-1-one 
• 86-81-7 3,4,5-trimethoxy-benzaldehyde 
• 13078-21-2 ethyl 2-(2-methoxyphenoxy)acetate 
• 90-05-1 2-methoxy-phenol 

Downstream Products

• 14385-48-9 2-(2-methoxyphenoxy)-acetophenone 
• 19513-80-5 2-(2-methoxyphenoxy)-1-(4-methoxyphenyl)ethan-1-one 
• 22675-96-3 2-methoxyphenoxy-3',4'-dimethoxyacetophenone 
• 51-17-2 benzoimidazole 
• 175714-45-1 2-(3,4,5-trimethoxyphenyl)-1H-benzo[d]imidazole 
• 90-05-1 2-methoxy-phenol 
• 150433-18-4 3-(3,4,5-trimethoxyphenyl)-1H-pyrazole 
• 91766-31-3 1-(3,4,5-trimethoxyphenyl)-1,3-propanediol 

Relevant academic research and scientific papers

One-Pot Transformation of Lignin and Lignin Model Compounds into Benzimidazoles

It is a challenging task to simultaneously achieve selective depolymerization and valorization of lignin due to their complex structure and relatively stable bonds. We herein report an efficient depolymerization strategy that employs 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as oxidant/catalyst to selectively convert different oxidized lignin models to a wide variety of 2-phenylbenzimidazole-based compounds in up to 94 % yields, by reacting with o-phenylenediamines with varied substituents. This method could take full advantage of both Cβ and/or Cγ atom in lignin structure to furnish the desirable products instead of forming byproducts, thus exhibiting high atom economy. Furthermore, this strategy can effectively transform both the oxidized hardwood (birch) and softwood (pine) lignin into the corresponding degradation products in up to 45 wt% and 30 wt%, respectively. Through a “one-pot” process, we have successfully realized the oxidation/depolymerization/valorization of natural birch lignin at the same time and produced the benzimidazole derivatives in up to 67 wt% total yields.

Sequential Cleavage of Lignin Systems by Nitrogen Monoxide and Hydrazine

The cleavage of representative lignin systems has been achieved in a metal-free two-step sequence first employing nitrogen monoxide for oxidation followed by hydrazine for reductive C?O bond scission. In combining nitrogen monoxide and lignin, the newly developed valorization strategy shows the particular feature of starting from two waste materials, and it further exploits the attractive conditions of a Wolff-Kishner reduction for C?O bond cleavage for the first time. (Figure presented.).

Highly Selective Oxidation and Depolymerization of α,γ-Diol-Protected Lignin

Lignin oxidation offers a potential sustainable pathway to oxygenated aromatic molecules. However, current methods that use real lignin tend to have low selectivity and a yield that is limited by lignin degradation during its extraction. We developed stoichiometric and catalytic oxidation methods using 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as oxidant/catalyst to selectively deprotect the acetal and oxidize the α-OH into a ketone. The oxidized lignin was then depolymerized using a formic acid/sodium formate system to produce aromatic monomers with a 36 mol % (in the case of stoichiometric oxidation) and 31 mol % (in the case of catalytic oxidation) yield (based on the original Klason lignin). The selectivity to a single product reached 80 % (syringyl propane dione, and 10–13 % to guaiacyl propane dione). These high yields of monomers and unprecedented selectivity are attributed to the preservation of the lignin structure by the acetal.

Selective C-O Bond Cleavage of Lignin Systems and Polymers Enabled by Sequential Palladium-Catalyzed Aerobic Oxidation and Visible-Light Photoredox Catalysis

Lignin, which is a highly cross-linked and irregular biopolymer, is nature's most abundant source of aromatic compounds and constitutes an attractive renewable resource for the production of aromatic commodity chemicals. Herein, we demonstrate a practical and operationally simple two-step degradation approach involving Pd-catalyzed aerobic oxidation and visible-light photoredox-catalyzed reductive fragmentation for the chemoselective cleavage of the β-O-4 linkage - the predominant linkage in lignin - for the generation of lower-molecular-weight aromatic building blocks. The developed strategy affords the β-O-4 bond cleaved products with high chemoselectivity and in high yields, is amenable to continuous flow processing, operates at ambient temperature and pressure, and is moisture- and oxygen-tolerant.

METHOD OF SELECTIVELY OXIDIZING LIGNIN

A method of selectively reacting lignin or a lignin-derived reactant to yield an aromatic product. The method includes the step of reacting lignin or a lignin-derived reactant with a molybdenum-containing catalyst, in a solvent, and optionally in the presence of an oxidant, for a time and a temperature wherein at least a portion of the lignin or lignin-derived reactant is selectively converted into an aromatic product, preferably coniferaldehyde and/or sinapaldehyde.

Selective oxidation of lignin model compounds

Lignin, the planet’s most abundant renewable source of aromatic compounds, is difficult to degrade efficiently to well-defined aromatics. We developed a microwave-assisted catalytic Swern oxidation system using an easily prepared catalyst, MoO2Cl2(DMSO)2, and DMSO as the solvent and oxidant. It demonstrated high efficiency in transforming lignin model compounds containing the units and functional groups found in native lignins. The aromatic ring substituents strongly influenced the selectivity of β-ether phenolic dimer cleavage to generate sinapaldehyde and coniferaldehyde, monomers not usually produced by oxidative methods. Time-course studies on two key intermediates provided insight into the reaction pathway. Owing to the broad scope of this oxidation system and the insight gleaned with regard to its mechanism, this strategy could be adapted and applied in a general sense to the production of useful aromatic chemicals from phenolics and lignin.

Photocatalytic Oxidation of Lignin Model Systems by Merging Visible-Light Photoredox and Palladium Catalysis

Lignin valorization has long been recognized as a sustainable solution for the renewable production of aromatic compounds. Two-step oxidation/reduction strategies, whereby the first oxidation step is required to "activate" lignin systems for controlled fragmentation reactions, have recently emerged as viable routes toward this goal. Herein we describe a catalytic protocol for oxidation of lignin model systems by combining photoredox and Pd catalysis. The developed dual catalytic protocol allowed the efficient oxidation of lignin model substrates at room temperature to afford the oxidized products in good to excellent yields.

DEPOLYMERISATION OF OXIDISED LIGNIN

A method of depolymerising a lignin includes oxidising the lignin to provide an oxidised lignin wherein benzylic –OH of β-O-4 linkages have been converted to carbonyl. The oxidised lignin is depolymerised with a metal selected from the group consisting of zinc, magnesium, aluminium and titanium or mixtures thereof, in the presence of an ammonium salt or carbon dioxide. Also described are methods for manufacturing phenolic products from lignin and a method for the cleavage of a β-O-4 linkage in a substrate.

Isolation of functionalized phenolic monomers through selective oxidation and CO bond cleavage of the β-O-4 linkages in Lignin

Functionalized phenolic monomers have been generated and isolated from an organosolv lignin through a two-step depolymerization process. Chemoselective catalytic oxidation of β-O-4 linkages promoted by the DDQ/tBuONO/ O2 system was achieved in model compounds, including polymeric models and in real lignin. The oxidized β-O-4 linkages were then cleaved on reaction with zinc. Compared to many existing methods, this protocol, which can be achieved in one pot, is highly selective, giving rise to a simple mixture of products that can be readily purified to give pure compounds. The functionality present in these products makes them potentially valuable building blocks.

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.