Preparation of functionalized lignin fragments

Abstract

The present invention relates to a method for producing fragments of lignin having functional groups.

Description

[Technical Field]

[0001] The present invention relates to a method for producing fragments of lignin having functional groups. [Background technology]

[0002] BACKGROUND OF THE INVENTION Lignin is reported to be the second most abundant natural polymer on Earth after cellulose, accounting for 15–30% by weight of lignocellulosic biomass and approximately 30% of the organic carbon present in the biosphere. Unlike cellulose and hemicellulose, the other two major components of lignocellulosic biomass, lignin is not a polysaccharide, a polymer of sugars. Rather, lignin is a complex polymer of several different aromatic subunits. This structure gives lignin a 30% greater energy density than cellulosic polymers, making it one of the few natural sources of aromatic molecules. Due to these properties, lignin monomers are increasingly recognized as essential precursors for the production of renewable aromatic chemicals and drop-in fuels.

[0003] WO 2017 / 178513 addresses the lack of a practical, high-yield lignin depolymerization method that can be integrated with a process for improving the quality of the polysaccharide fraction of the parent biomass. In particular, the document describes a process that includes heating a lignocellulose-containing composition under acidic conditions, in particular with an aldehyde, such as formaldehyde, separating the resulting lignin fragments from the resulting mixture, and reducing the fragments to convert them into monomers.

[0004] U.S. Patent No. 2,760,861 discloses a process for producing cellulose fibers and lignin, during which acidic decomposition products are neutralized with organic compounds.

[0005] Furthermore, the Luterbacher group reported a strategy to condense benzyl alcohols from lignin structures with adjacent aromatic lignin subunits during the lignin extraction process, thus enabling the fractionation of lignocellulosic biomass into its three constituent biopolymers (Luterbacher et al. “Formaldehyde Stabilization Facilitates Lignin Monomer Production during Biomass Depolymerization”, Science 80, 2016, 354 (6310), pages 329-333). The aldehyde stabilizes lignin through the formation of acetals with the free diols in the lignin side chains, preventing the benzyl alcohol from eliminating as water and forming benzyl cations or alkenes.

[0006] An unexpected consequence of using formaldehyde to form acetals during lignin extraction is that it also hydroxymethylates electron-rich aryl species in lignin, fundamentally altering its structure and doubling the number of monomers that can be predicted by hydrogenolysis.

[0007] Furthermore, the above processes are reported to produce a large amount of undesirable by-products, reducing the efficiency and yield of the process.

[0008] Apart from the indicated reduction with hydrogen to produce monomers, the fragments of lignin obtained by the process are unlikely to be used in further chemical reactions, and therefore these fragments of lignin are mostly only depolymerized to give the corresponding monomers, preventing other possible applications of these valuable compounds.

[0009] Therefore, there is a need for methods to produce fragments of lignin that are readily accessible and can be subjected to simple chemical transformations to interconvert available functionality, alter solubility, or introduce specific structural motifs. With all prior art lignins, such transformations have been impractical or impossible. Summary of the Invention [Problem to be solved by the invention]

[0010] Therefore, the object of the present invention was to overcome the drawbacks of the above process.

[0011] In particular, it was an object of the present invention to provide a method for producing fragments of lignin which, according to the desired use / application, already carry active chemical groups (functional groups) or which can be further derivatized for the desired purpose.

[0012] Furthermore, a method must be provided that avoids harsh reaction conditions, is compatible with common biorefining processes, provides high yields of lignin fragments, and reduces or completely eliminates the production of undesirable by-products.

[0013] According to the present invention, the above objectives are achieved by the particular method described herein for producing fragments of lignin. [Means for solving the problem]

[0014] (summary) The present invention unexpectedly solves this object by providing a new method for producing lignin fragments. In particular, a method is provided that unexpectedly involves the addition of specific aldehydes that result in functionalized lignin compounds and a reduction in undesirable by-products, allowing for high yields of these compounds.

[0015] The subject of the present invention is thus a method for producing monomers from lignin by depolymerization, comprising the following steps: a) providing a lignocellulose-containing composition; b) reacting the composition of step a) under acidic conditions with an aldehyde of formula 1

[0016] [ka]

[0017] wherein L is absent or a linking group, and where R is a functional group and x is 1 to 5. heating with; c) separating lignin fragments having one or more functional groups from the mixture of step b; and d) Optionally, further reacting one or more functional groups of the product of step c) to obtain fragments of lignin having one or more functional groups R'.

[0018] A further subject of the present invention are fragments of lignin carrying one or more functional groups R or R' obtainable by the method of the invention.

[0019] Another aspect of the invention is a composition comprising fragments of the lignin described above, the fragments preferably being represented by one or more of formulas 2-4:

[0020] [ka]

[0021] [ka]

[0022] [ka]

[0023] Finally, further subject matter of the present invention are resins, adhesives, polymers, carbon fibers, concrete additives, thermal insulation agents, electrical insulation agents, paints, surfactants, photoresists, photographic films, antibacterial films, antifungal films, anticorrosion coatings, waterproofing agents, lubricants, UV absorbing additives for polymers, activated carbon, pigments, dyes, anticorrosion additives, flame retardants, catalysts, battery anodes, battery cathodes, ionomers, ion exchange resins, ion exchange membranes, superabsorbent polymers, gas permeable membranes, UV absorbing creams (sunblocks or sunscreens), drug delivery substrates, fragrance delivery substrates, flavor delivery substrates, food additives (antioxidants), food supplements (antioxidants), cosmetic additives, fuel for concrete kilns, fuel for power generation, fuel for steel mills, explosives, solid rocket fuels, gunpowder, smokeless powder, fireworks, ablative armour, reactive armour Use of the lignin fragments of the invention or the composition of the invention for the manufacture of an antifungal, antiviral, sun cream, and / or antibiotic. [Brief explanation of the drawings]

[0024] [Figure 1] HSQC-NMR of lignin stabilized with chloroacetaldehyde (E.1) and p-chlorobenzaldehyde (E.2) in DMSO-d6 [Figure 2] HSQC-NMR of lignin stabilized with glyoxylic acid (E.3) and p-formylbenzoic acid (E.4) in DMSO-d6 [Figure 3] HSQC-NMR of lignin stabilized with 4-hydroxybenzaldehyde (E.5) and 3-hydroxybenzaldehyde (E.6) in DMSO-d6 [Figure 4] HSQC-NMR of lignin stabilized with 2-hydroxybenzaldehyde (E.7) and vanillin (E.8) in DMSO-d6 [Figure 5] HSQC-NMR of lignin stabilized with glycoaldehyde (E.9) in DMSO-d6 DETAILED DESCRIPTION OF THE INVENTION

[0025] Detailed Description of the Invention In a preferred embodiment of the present invention, the method comprises the steps of: a) providing a lignocellulose-containing composition: b) reacting the composition of step a) with an aldehyde of formula 1

[0026] [ka]

[0027] wherein L is absent or a linking group, and R is a functional group and x is 1 to 5, provided that R is not hydrogen or a linear, branched, or cyclic organic residue having 1 to 20 carbon atoms. heating under acidic conditions with c) separating lignin fragments having one or more functional groups from the mixture of step b; and d) Optionally, further reacting one or more functional groups of the product of step c) to obtain fragments of lignin having one or more functional groups R'.

[0028] Step a) of the method of the present invention is the provision of a lignocellulose-containing composition.

[0029] Lignocellulose (biomass) is considered one of the most abundantly available renewable raw materials on Earth. Lignocellulosic biomass can be classified as virgin biomass, waste biomass, and energy crops. Virgin lignocellulosic biomass includes all terrestrial plants found in nature, such as trees, shrubs, and grasses. Waste lignocellulosic biomass is produced as a low-value by-product of various industrial sectors, such as agriculture (corn stover, sugarcane bagasse, straw, etc.) and forestry (sawmill and paper mill waste).

[0030] Lignocellulose includes hemicellulose, cellulose, and lignin. Both hemicellulose and cellulose can be considered carbohydrate polymers. Carbohydrate polymers contain five- and six-carbon sugar monomers, which are linked to lignin.

[0031] Lignin can be considered an aromatic polymer, which contains phenol-propane subunits, such as p-hydroxyphenyl, guaiacyl, and syringyl subunits.

[0032] Xylan is a polysaccharide belonging to the hemicellulose family, and its main monomer unit is D-xylose. Cellulose can be considered a polysaccharide, and its main monomer unit is D-glucose linked via β-1-4 bonds.

[0033] In a preferred embodiment of the present invention, the lignocellulose-containing composition is lignocellulosic biomass, preferably virgin lignocellulosic biomass, such as trees or grasses. The lignocellulosic biomass is preferably derived from trees, such as birch, beech, poplar, cedar, Douglas fir, cypress, fir, juniper, kauri, larch, pine, hemlock, redwood, spruce, and yew. Most preferred is debarked hardwood or softwood, such as birch and / or beech (hardwood) or pine and / or spruce (softwood) as the lignocellulose-containing composition.

[0034] In an alternative preferred embodiment of the present invention, the lignocellulose-containing composition is derived from energy crops. Energy crops are crops that have a high yield of lignocellulosic biomass. Furthermore, because energy crops grow rapidly, lignocellulosic biomass is readily available within a short period of time, e.g., several months. Examples of energy crops include giant reed, big bluestem, Chinese tallow tree, cabbage, duckweed, Taiwan jasmine, black jasmine, switchgrass, and elephant grass.

[0035] Preferably, the lignocellulose-containing composition is solid at a temperature of 23° C. In a preferred embodiment, the lignocellulose-containing composition is air-dried at a temperature below 100° C., preferably below 65° C. For example, the lignocellulose-containing composition is air-dried at ambient temperature for storage to remove excess water. The air-dried lignocellulose-containing composition preferably contains less than 50% by weight of water, more preferably less than 30% by weight, especially 0-20% by weight.

[0036] Furthermore, the lignocellulose-containing composition preferably has 1 wt% to 50 wt%, more preferably 10 wt% to 40 wt%, even more preferably 13 wt% to 35 wt%, and particularly preferably 15 wt% to 30 wt% of a lignin-containing composition, based on the total weight of the lignocellulose-containing composition, wherein the lignin is measured as Klason lignin.

[0037] The Klason lignin test was used to measure Klason lignin. In this test, wood particles (0.25–0.50 g) were placed in a 50 mL beaker and 7.5 mL of 72 wt% H2SO4 solution was added. The mixture was left at room temperature for 2 hours and stirred every 10 minutes with a glass rod. The slurry was then transferred to a round-bottom flask and 290 mL of water was added to bring the H2SO4 concentration to 3 wt%. The glass bottle was sealed with a screw cap and sterilized in an autoclave at 120 °C for 1 hour. The resulting solution was filtered, and the precipitate was washed with water, dried at 105 °C, and weighed to determine the Klason lignin content.

[0038] The content of Klason lignin can be calculated using the following formula: Klason lignin content [%] = (KL × 100) / LCC, where KL is Klason lignin [g]; LCC is lignocellulose-containing composition [g].

[0039] Furthermore, step a) preferably comprises providing the lignocellulose-containing composition in the form of particles such as chips, flakes, pellets, beads, splints, granules, shivers, dust, and fragments, for example, wood can be cut and milled to obtain these particles.

[0040] In a preferred embodiment, step a) comprises suspending the lignocellulose-containing composition in an organic solvent.

[0041] An organic solvent may be considered a carbon-based compound that is preferably in a liquid state at 23° C. The organic solvent may comprise a single organic solvent or a mixture of organic solvents.

[0042] More preferably, the organic solvent has a boiling point of 60°C to 250°C, preferably at 1013 mbar. Furthermore, for example, when a mixture of organic solvents is used, the boiling point may refer to a temperature interval rather than to a single temperature. The boiling point is preferably determined according to Pharm. Eur. 6.0, Chapter 2.2.12.

[0043] In a preferred embodiment, the water solubility of the organic solvent is greater than 50% by weight, preferably greater than 70% by weight, especially greater than 90% by weight at 25° C. The upper limit of water solubility can be 90% by weight or preferably 100% by weight. Water solubility can be measured by visual inspection, i.e., the ratio of organic solvent to water is measured until precipitation or until suspension or phase separation between water and organic solvent appears.

[0044] In a preferred embodiment of the present invention, the log K ow The value is from −3.0 to 0.8, preferably from −2.5 to 0.7, more preferably from −1.8 to 0.6, and particularly preferably from −1.2 to 0.5.

[0045] K ow The K value (also called the P value) is the distribution coefficient, which indicates the ratio of the concentrations of a compound in the two phases of an octanol / water (hydrophobic / hydrophilic) mixture. ow The value is determined according to the following formula:

[0046]

number

[0047] where

number

number

[0048] K ow The value (P value) is usually expressed as logK ow Logarithm of 10 as (logP)

number

[0049] Examples of organic solvents are alcohols having 1 to 6 carbon atoms, such as methanol, ethanol, propanol, isopropanol, butanol, and polyethylene glycol; ethers, such as dimethyl ether, diethyl ether, and methyl tert-butyl ether; cyclic ethers, such as tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, and dioxane; nitriles, such as acetonitrile; carboxylic acids, such as formic acid, lactic acid, pyruvic acid, propionic acid, and acetic acid; carboxamides, such as dimethylformamide and dimethylacetamide; lactones, such as γ-valerolactone; lactams, such as N-methyl-2-pyrrolidone; sulfoxides, such as dimethyl sulfoxide; and sulfones, such as sulfolane.

[0050] The above logK owAprotic solvents with a .DELTA. value of -3.0 to 0.8, preferably -2.5 to 0.7, more preferably -1.8 to 0.6, and particularly preferably -1.2 to 0.5, are preferred. Examples include ethers such as dimethyl ether, diethyl ether, and methyl tert-butyl ether; cyclic ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, and dioxane; nitriles such as acetonitrile; carboxamides such as dimethylformamide and dimethylacetamide; lactones such as γ-valerolactone; lactams such as N-methyl-2-pyrrolidone; sulfoxides such as dimethyl sulfoxide; and sulfones such as sulfolane. Particularly preferred are ethers and cyclic ethers, especially cyclic ethers such as dioxane, 3-methyltetrahydrofuran, 2-methyltetrahydrofuran, and tetrahydrofuran, especially dioxane (1,4-dioxane).

[0051] In a preferred embodiment, the organic solvent can contain water, preferably less than 50 volume percent water, more preferably less than 30 volume percent water, and especially 0 to 10 volume percent water.

[0052] In a preferred embodiment, step a) comprises subjecting the lignocellulose-containing suspension to a process according to the log K ow a value of from -3.0 to 0.8, wherein the aprotic organic solvent contains less than 50 volume percent water, preferably less than 30 volume percent water, especially 0 to 10 volume percent water.

[0053] The suspension may preferably contain 2 to 15 ml, preferably 3 to 10 ml, and particularly preferably 4 to 6 ml of organic solvent per gram of the lignocellulose-containing composition.

[0054] Step b) of the method of the present invention comprises treating the composition of step a) under acidic conditions with a compound of formula 1:

[0055] [ka]

[0056] wherein L is absent or a linking group, and where R is a functional group and x is an integer from 1 to 5. This involves heating with an aldehyde of

[0057] Heating the composition from step a) is considered to be the application of heat to the composition provided in step a) to raise the temperature of the composition provided in step a) from an initial temperature to a higher final temperature. In a preferred embodiment of the present invention, the composition of step a) is provided at a temperature of 15°C to 25°C, which is considered to be the initial temperature. In a preferred embodiment, a temperature of 35 to 140°C, preferably 40 to 130°C, and especially 50 to 120°C, which is considered to be the final temperature, can be applied in step b). In particular, it is particularly preferred to apply a temperature of 60 to 100°C, especially about 85°C.

[0058] In a preferred embodiment, step b) can be carried out for 0.1 to 72 hours, preferably 0.5 to 12 hours, more preferably 0.75 to 10 hours, even more preferably 1 to 8 hours, and especially 1.5 to 5.5 hours.

[0059] In a preferred embodiment, a temperature of 50 to 120° C. is applied in step b) for 0.1 to 72 hours.

[0060] Furthermore, in step b), the reaction mixture may preferably be subjected to mechanical movement, such as stirring.

[0061] To achieve acidic conditions, one or more acidic compounds are added to the composition of step a). An acidic compound can be considered a compound that, when added to water, results in a pH value of less than 7. Examples of acidic compounds include organic carboxylic acids such as acetic acid, sulfonic acids such as methanesulfonic acid, and mineral acids, with mineral acids being preferred. Mineral acids are considered to be acids that do not contain carbon atoms. Examples of mineral acids include hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, phosphoric acid, boric acid, and silicic acid. Preferred are hydrochloric acid, methanesulfonic acid, sulfuric acid, and phosphoric acid, and more preferred are hydrochloric acid, methanesulfonic acid, and sulfuric acid, especially hydrochloric acid.

[0062] In a preferred embodiment, the acidic conditions can be achieved using 0.5 to 20 mmol, preferably 1 to 9 mmol, and especially 1.5 to 3 mmol of acidic compound per gram of lignocellulose-containing composition.

[0063] Further, in step b), the aldehyde of formula 1 is heated together with the lignocellulose-containing composition under acidic conditions, preferably at a temperature of 60°C to 100°C.

[0064] The aldehyde of formula 1 has the following chemical structure:

[0065] [ka]

[0066] wherein L is absent or a linking group, and where R is a functional group and x is an integer from 1 to 5. It is an organic compound represented by the formula:

[0067] The left side of the above compound of Formula 1 is an aldehyde group, characterized by a carbon atom attached to an oxygen through a hydrogen and a double bond.

[0068] A functional group can be considered a characteristic group of one or more atoms in a compound, which contributes to the properties and reaction behavior of said compound. Functional groups can be classified according to the one or more atoms of the characteristic group.

[0069] The functional group can preferably be considered as a saturated or unsaturated, linear or branched, cyclic or aromatic hydrocarbon group, in which at least one hydrogen atom is replaced by a substituent and / or which contains one or more heteroatoms such as N, O, S in its carbon skeleton, and / or the hydrocarbon group contains at least one double or triple bond. Preferred substituents include F, Cl, Br, I, CF, OH, OR, SH, SR, NH, NHR, NR, SiR, CN, =0, or =S. Alkenes, alkynes, and aromatic systems are also included in the above definition, even if they are unsubstituted and do not contain heteroatoms.

[0070] The functional group R, or if multiple functional groups R are present, each functional group can be selected independently.

[0071] In a preferred embodiment, each R is selected from an alkene, alkyne, aldehyde, carboxylic acid, carboxylic acid ester, carboxylic acid amide, amino acid, ketene, ketone, diazoketone, imine, oxime, amine, acetal, ketal, hemiacetal, hemiketal, fulminate, cyanate, isocyanate, isothiocyanate, nitrile, ether, thioether, hydroxyl, thiol, nitro, fluoride, chloride, bromide, iodide, azide, triflate, boronic acid, boronic acid ester, borate, borate salt, borane, silane, silyl ether, siloxane, silanol, sulfonamide, sulfonic acid, sulfonate, sulfoxide, sulfone, dithiane, phosphate, phosphate ester, phosphonate, phosphonic acid, phosphonate ester, phosphonium salt, phosphine, phosphite, phosphite ester, and phosphite salt; or Aziridine, 2H-azirine, oxirane, thiirane, azetidine, 2,3-dihydroazeto, azeto, 1,3-diazetidine, oxetane, 2H-oxete, thietane, 2H-thiete, azetidin-2-one, pyrrolidine, 3-pyrroline, 2-pyrroline, 2H-pyrrole, 1H-pyrrole, pyrazolidine, imidazolidine, 2-pyrazoline, 2-imidazoline, pyrazole, imidazole, 1,2,4-triazole, 1,2,3-triazole, tetrazole, tetrahydrofuran, furan, 1,3- Diazolane, tetrahydrothiophene, thiophene, oxazole, isoxazole, isothiazole, thiazole, 1,2-oxathiolane, 1,3-oxathiolane, 1,2,5-oxadiazole, 1,2,3-oxadiazole, 1,3,4-thiadiazole, 1,2,5-thiadiazole, sulfolane, 2,4-thiazolidinedione, succinimide, 2-oxazolidone, hydantoin, piperidine, pyridine, piperazine, pyridazine, pyrimidine, pyrazine, 1,2,4-triazine, 1,3,5-triazine, tetrahydrothiophene ... Dropyran, 2H-pyran, 4H-pyran, pyrylium, 1,4-dioxane, 1,4-dioxine, thiane, 2H-thiopyran, 4H-thiopyran, 1,3-dithiane, 1,4-dithiane, 1,3,5-trithiane, morpholine, 2H-1,2-oxazine, 4H-1,2-oxazine, 6H-1,2-oxazine, 2H-1,3-oxazine, 4H-1,3-oxazine, 6H-1,3-oxazine, 4H-1,4-oxazine, 2H-1,4-oxazine, thiomorpholine, 4H-1,4-thiazine, 2H-1,2-thiazine, 6H -1,2-Thiazine, 2H-1,4-Thiazine, cytosine, thymine, uracil, thiomorpholine dioxide, hexahydro-1H-pyrrolidine, 1,4,5,6-tetrahydrocyclopental[b]pyrrole, 1,3a,4,6a-tetrahydropyrrolo[3,2-b]pyrrole, 1,4-dihydropyrrolo[3,2-b]pyrrole, 1,6-dihydropyrrolo[2,3-b]pyrrole, 6H-furo[2,3-b]pyrrole, 4H-furo[3,2-b]pyrrole, 4H-thieno[3,2-b]pyrrole, 6H-thieno[2,3-b]pyrrole, 2,3-Dihydro-1H-indene, indene, indoline, 3H-indole, 1H-indole, 2H-isoindole, indolizine, 1H-indazole, benzimidazole, 4-azaindole, 5-azaindole, 6-azaindole, 7-azaindole, 7-azaindazole, pyrazolo[1,5-a]pyrimidine, purine, benzofuran, isobenzofuran, benzo[c]thiophene, benzo[b]thiophene, 1,2-benzisoxazole, 2,1-benzisoxazole ... benzisothiazole, 2,1-benzisothiazole, benzoxazole, benzthiazole, benzo[c][1,2,5]thiadiazole, 1,2-benzisothiazol-3(2H)-one, adenine, guanine, decahydroisoquinoline, decahydroquinoline, tetrahydroquinoline, 1,2-hydroquinoline, 1,2-dihydroisoquinoline, quinoline, isoquinoline, 4H-quinolizine, quinoxaline, phthalazine, quinazoline, cinnoline, 1,8-naphthyridine, pyrido[3,2-d]pyrimidine , pyrido[4,3-d]pyrimidine, pyrido[3,4-d]pyrazine, pyrido[2,3-b]pyrazine, pteridine, 2H-chromene, 1H-isochromene, 3H-isochromene, 2H-chromen-2-one, 2H-benzo[e][1,2]oxazine, 2H-benzo[e][1,3]oxazine, 2H-benzo[b][1,4]oxazine, quinolin-2(1H)-one, isoquinolin-1(2H)-one, isoquinolin-1(2H)-one, fluorene, carbazole, dibenzofuran, acridine, phenazine and the functional groups are independently selected from heterocycles selected from azine, phenoxazine, phenothiazine, phenoxathiin, quinuclidine, 1-azaadamantane, 2-azaadamantane, 2,3-dihydroazepine, 2,5-dihydroazepine, 4,5-dihydroazepine, azepine, 2H-azepine, 3H-azepine, 4H-azepine, 1,2-diazepine, 1,3-diazepine, 1,4-diazepine, oxepane, thiepine, 1,4-thiazepine, azocane, azocine, thiocane, azonane, and azecine.

[0072] In a more preferred embodiment, each R is an alkene, alkyne, aldehyde, carboxylic acid, carboxylic acid ester, carboxylic acid amide, amino acid, ketone, diazoketone, imine, oxime, amine, acetal, ketal, hemiacetal, hemiketal, nitrile, ether, thioether, hydroxyl, thiol, nitro, fluoride, chloride, bromide, iodide, azide, triflate, boronic acid, boronic acid ester, borate, borate salt, borane, silane, silyl ether, siloxane, silanol, sulfonamide, sulfonic acid, sulfonate, sulfoxide, sulfone, dithiane, phosphite, or the like. More preferably, each R is a functional group independently selected from alkene, alkyne, aldehyde, carboxylic acid, carboxylic acid amide, amino acid, ketone, acetal, ketal, nitrile, ether, thioether, hydroxyl, thiol, nitro, fluoride, chloride, bromide, iodide, azide, triflate, boronic acid, boronic ester, silane, silyl ether, siloxane, silanol, sulfonic acid, sulfoxide, sulfone, and phosphonic acid.

[0073] In a more preferred embodiment, each R is a functional group independently selected from aldehyde, anhydride, acyl chloride, carboxylic acid ester, carboxylic acid amide, isocyanate, ether, alkyne, alkene, amine, carboxylic acid, nitrile, ether, thioether, hydroxyl, thiol, nitro, chloride, bromide, iodide, azide, and triflate.

[0074] In a more preferred embodiment, each R is a functional group independently selected from carboxylic acid, anhydride, acyl chloride, carboxylic acid ester, carboxylic acid amide, isocyanate, ether, alkyne, alkene, aldehyde, chloride, bromide, iodide, triflate, hydroxyl, thiol, amine, and azide.

[0075] In a more preferred embodiment, each R is a functional group independently selected from carboxylic acid, carboxylic acid amide, ether, alkyne, alkene, aldehyde, chloride, hydroxyl, and azide.

[0076] In an even more preferred embodiment, each R is a functional group independently selected from carboxylic acid, carboxylic acid amide, ether, aldehyde, chloride, and hydroxyl.

[0077] In particularly preferred embodiments, each R is a functional group independently selected from aldehyde, carboxylic acid, nitrile, ether, thioether, hydroxyl, thiol, nitro, chloride, bromide, iodide, azide, and triflate.

[0078] In the aldehyde of formula 1, L can be absent or a linking group.

[0079] In one embodiment, L may be absent. When L is absent, the functional group is directly attached to the carbon atom of the aldehyde group. Aldehydes of Formula 1 in which L is absent are, for example, ethanedial (also known as glyoxal or oxalaldehyde) and oxoethanoic acid (also known as 2-oxoacetic acid or glyoxylic acid), as well as esters and amides of oxoethanoic acid.

[0080] In another embodiment, L is a linking group, preferably an organic residue having, for example, 1 to 15 carbon atoms.

[0081] The term "organic residue" generally refers to residues known in organic chemistry. Preferably, the backbone of the organic residue contains primarily carbon atoms, nitrogen atoms, and / or oxygen atoms, more preferably only carbon atoms.

[0082] In a preferred embodiment of the present invention, L can be an aromatic or an aliphatic residue.

[0083] Aromatic residues contain at least one ring system containing mainly carbon, nitrogen, sulfur, or oxygen atoms, which, according to Hückel's rule, contain conjugated double bonds, free electron pairs, or some 4n+2 (n=0, 1, 2,...) delocalized electrons in unoccupied p orbitals.

[0084] In a preferred embodiment, an aromatic residue refers to a residue having an aromatic backbone structure, wherein the ring atoms of the aromatic backbone structure are carbon atoms. The aromatic residue can be bonded to one or more functional groups, as described above.

[0085] Suitable functional groups attached to the aromatic residue may be independently selected from one or more functional groups, preferably selected from aldehyde, carboxylic acid, nitrile, ether, thioether, hydroxyl, thiol, nitro, chloride, bromide, iodide, azide, and triflate, particularly carboxylic acid, hydroxy, nitro, chloride, bromide, and iodide.

[0086] Aliphatic residues are non-aromatic hydrocarbon compounds containing primarily carbon and hydrogen atoms, where some of the carbon atoms may also be replaced by, for example, oxygen, sulfur, and nitrogen atoms. The aliphatic residues may be bonded to one or more functional groups, as described above.

[0087] Suitable functional groups attached to the aliphatic residue may be independently selected from one or more functional groups, preferably selected from aldehyde, carboxylic acid, nitrile, hydroxy, nitro, chloride, bromide, iodide, azide, and triflate, particularly aldehyde, carboxylic acid, hydroxy, chloride, bromide, and iodide.

[0088] In a preferred embodiment of the present invention, L is an aliphatic linking group having 1 to 6 carbon atoms or an aromatic linking group having 4 to 15 carbon atoms.

[0089] Examples of aliphatic linking groups having 1 to 6 carbon atoms are -CH-, -CH(CH)-, -C(CH)-, CH(CHCH)-, -C(CH)(CH)-, -C(CH)(CH)-, 1,1-cyclopropylene, 1,1-cyclobutylene, and 1,1-cyclohexylene. Methylene is preferred.

[0090] Examples of aromatic linking groups having 4 to 15 carbon atoms include phenylene, 2-methylphenylene, 4-methylphenylene, 2-methoxyphenylene, 3-methoxyphenylene, 4-methoxyphenylene, 3,5-dimethoxyphenylene, and naphthylene. Preferred are phenylene, 2-methylphenylene, 4-methylphenylene, 3-methoxyphenylene, and 3,5-dimethoxyphenylene, and more preferred are 3-methoxyphenylene and 3,5-dimethoxyphenylene, especially phenylene.

[0091] In a preferred embodiment of the present invention, the aldehyde of formula 1 is 2-hydroxyacetaldehyde, 2-chloroacetaldehyde, 2-bromoacetaldehyde, 2-iodoacetaldehyde, ethanedial (also known as glyoxal or oxalaldehyde), oxoethanoic acid, (also known as 2-oxo-acetic acid or glyoxylic acid), 2,2,2-trichloroacetaldehyde, 4-hydroxy-3,4-dimethoxybenzaldehyde (syringaldehyde), 4-hydroxy-3-methoxybenzaldehyde (vanillin), 2-hydroxybenzaldehyde (salicylaldehyde), 2-chlorobenzaldehyde, 2-bromobenzaldehyde benzaldehyde, 2-iodobenzaldehyde, 3-hydroxybenzaldehyde, 3-chlorobenzaldehyde, 3-bromobenzaldehyde, 3-iodobenzaldehyde, 4-hydroxybenzaldehyde, 4-chlorobenzaldehyde, 4-bromobenzaldehyde, 4-iodobenzaldehyde, 2,4-dichlorobenzaldehyde, 2,4-dibromobenzaldehyde, 2,4-diiodobenzaldehyde, 2-nitrobenzaldehyde, 4-nitrobenzaldehyde, 2,4-dinitrobenzaldehyde, 2,4,6-trinitrobenzaldehyde, 2-formylbenzoic acid, 4-formylbenzoic acid, and terephthalaldehyde.

[0092] In a preferred embodiment of the invention, the lignocellulose-containing composition and the aldehyde of formula 1 are present in a weight ratio of from 25:1 to 1:1, preferably from 20:1 to 1.25:1, more preferably from 15:1 to 1.5:1, especially from 10:1 to 2:1, wherein the weight of the aldehyde of formula 1 is based on the weight of formaldehyde.

[0093] "Based on the weight of formaldehyde" means the following: The molecular weight of formaldehyde is 30 g / mol. The molecular weight of an aldehyde other than formaldehyde is x g / mol. For example, the molecular weight of oxoethanoic acid (also known as 2-oxoacetic acid or glyoxylic acid) is 74 g / mol. Therefore, to contain the same amount of reactive aldehyde groups, the aldehyde of Formula 1 other than formaldehyde must be present in a weight amount that is x / 30 times the weight of formaldehyde.

[0094] For example, if 25 g of lignocellulose-containing composition and 1 g of formaldehyde are provided, the lignocellulose-containing composition and formaldehyde are present in a weight ratio of 25:1.

[0095] If the aldehyde is oxoethanoic acid, then if 25 g of a lignocellulose-containing composition and 2.47 g of oxoethanoic acid are provided, the lignocellulose-containing composition and the oxoethanoic acid, which has a molecular weight of 74 g / mol, are present in a weight ratio of 25:1, where 2.47 corresponds to the ratio of the molecular weight of acetaldehyde to the molecular weight of formaldehyde.

[0096] Thus, if the lignocellulose-containing composition and acetaldehyde are present in a weight ratio of 12.5:1 (corresponding to 25:2), 25 g of lignocellulose-containing composition and 4.94 g of oxoethanoic acid are provided.

[0097] In another preferred embodiment, 1 to 100 mmol, preferably 1.5 to 70 mmol, more preferably 2 to 50 mmol, particularly 2.5 to 20 mmol of aldehyde can be used per gram of the lignocellulose-containing composition.

[0098] By applying step b), bonds between the lignin fraction and the cellulose or hemicellulose fraction in the lignocellulose-containing composition are cleaved. Furthermore, bonds within the lignin are also cleaved to obtain "lignin fragments", which can alternatively be considered as so-called "lignin oligomers".

[0099] In a preferred embodiment, in step b) the lignocellulose-containing composition and the aldehyde of formula 1 are reacted to form a lignocellulose-containing compound of formula RL-CH(OR 2 )(OR 3 ), where R is defined as above and R 2 and R 3 is a continuous portion of the lignin polymer contained in the lignocellulose-containing composition. Such continuous portions of lignin polymer are known to those skilled in the art. In a preferred embodiment, R 2 and R 3 are different successive parts of the lignin polymer. 2 and R 3 may be the same part of the lignin polymer.

[0100] In a preferred embodiment, in step b) the lignocellulose-containing composition is reacted with an aldehyde of formula 1 to produce one or more acetals, preferably of formulas 2-4:

[0101] [ka]

[0102] [ka]

[0103] [ka]

[0104] In step c) of the method of the present invention, the resulting lignin fragments carrying one or more functional groups are separated from the remaining mixture of step b).

[0105] Step c) may preferably comprise the following substeps:

[0106] c1) separating the lignin fragment-containing phase and the residue; c2) removing the solvent from the lignin fragment-containing phase; c3) treating the product of step c2) with a solvent; and c4) Separating lignin fragments having one or more functional groups.

[0107] Step c1) may preferably comprise cooling the reaction mixture from step b). Cooling the composition from step b) may be considered as lowering the temperature from the starting temperature to a lower limit temperature. In a preferred embodiment of the present invention, the reaction mixture from step b) is cooled to a temperature of 0 to 35°C, preferably 10 to 30°C, in particular about 23°C.

[0108] Step c1) may preferably include filtering the mixture. The mixture may be filtered, preferably by applying a vacuum to the filtrate side. Furthermore, the filter cake may preferably be washed. Suitable washing liquids may be, for example, tetrahydrofuran, ethyl acetate, or dioxane, preferably dioxane. Generally, the filter cake may contain cellulose or hemicellulose, as well as insoluble materials contained in the lignocellulose-containing composition. The filtrate is considered to be a phase containing lignin fragments.

[0109] Alternatively, step c1) may preferably comprise centrifuging the mixture of step b) and decanting the lignin fragment-containing phase from the residue.

[0110] Step c2) may preferably comprise neutralizing the lignin fragment-containing phase (filtrate) from step c1) by adding an alkaline compound, preferably an alkaline inorganic compound. The alkaline inorganic compound may be, for example, hydroxides, carbonates, hydrogencarbonates, phosphates, hydrogenphosphates, and sulfates of alkali metals and alkaline earth metals. In a preferred embodiment, calcium hydroxide and / or calcium carbonate is used as the alkaline inorganic compound. More preferred are carbonates of alkali metals, such as sodium carbonate or potassium carbonate, in particular sodium carbonate. After neutralization, the solvent may be removed from the resulting lignin fragment-containing phase.

[0111] Alternatively, the solvent can be removed from the lignin fragment-containing phase from step c1) without neutralization.

[0112] In line with step c2) of the present application, the removal of the solvent can be considered as the removal of the majority of the solvent, i.e., even after the removal of the solvent, the obtained product may still contain up to 15% by weight of residual solvent.

[0113] In a preferred embodiment, the removal of the solvent can be carried out at elevated temperature, preferably 35-60° C., in particular about 45° C., and / or under reduced pressure, for example 1-100 mbar, preferably about 50 mbar.

[0114] In step c3), the product from step c2) can be treated with a solvent, which may depend on one or more functional groups R. Examples of suitable solvents include water, methanol, tetrahydrofuran, and ethyl acetate. Treating the product from step c2) with a solvent can be preferably carried out under mechanical motion, such as stirring. Furthermore, treating with a solvent can be preferably carried out at a temperature of 20°C to 25°C.

[0115] In one embodiment, the treatment of the product from step c2) with a solvent may result in the formation of a precipitate. The treatment of the product from step c2) with a solvent may preferably be carried out under stirring.

[0116] In one embodiment, when the product from step c2) is treated with a solvent, the product from step c2) can be dissolved in the solvent, preferably completely dissolved in the solvent. If the product from step c2) can be dissolved in a solvent, the corresponding solution can be added to a second solvent, preferably so that a precipitate is formed. The addition of the solution to the second solvent can be preferably carried out under stirring. Examples of suitable second solvents are diethyl ether, dibutyl ether, tert-butyl methyl ether, cyclopentane, hexane, heptane, benzene, and toluene, or a mixture thereof.

[0117] Step c4) may preferably comprise filtering the mixture of c3), i.e., filtering the precipitate from the supernatant solution. The mixture may be filtered, preferably by applying a vacuum to the filtrate side, to obtain lignin fragments having one or more functional groups. The product may be dried, preferably at elevated temperature, preferably between 40°C and 60°C, and / or under reduced pressure, e.g., between 0.01 and 50 mbar, preferably about 0.05 mbar. The filtrate may contain some by-products and may be discarded.

[0118] Alternatively, step c4) may preferably comprise centrifuging the mixture of step c3) and decanting the supernatant solution from the lignin fragments having one or more functional groups. The product may preferably be dried at elevated temperature, preferably 40-60°C, and / or under reduced pressure, for example 0.01-50 mbar, preferably about 0.05 mbar.

[0119] In a preferred embodiment, the method can include bleaching the product obtained from step c) (step c5). If the product of step c4) exhibits an undesirable color, a bleaching step can be applied. The bleaching step preferably comprises contacting the product obtained from step c) with a mixture of an oxidizing agent and an alkaline compound, preferably an inorganic alkaline compound, in a solvent, preferably at 40 to 80°C for 10 to 180 minutes. The oxidizing agent is known in the art, and hydrogen peroxide is preferred. The same applies as above with respect to the alkaline compound, preferably the inorganic alkaline compound. Sodium hydroxide is preferred. Suitable solvents are, for example, water, benzene, toluene, and ethyl acetate, especially ethyl acetate. Further, the step can include washing the organic phase with water or brine, drying the organic phase, separating the drying agent from the organic phase, and removing the solvent to obtain a less colored, preferably off-white, product.

[0120] In a further embodiment, the method of the present invention comprises a step d) of optionally further reacting one or more functional groups of the product of step c) to obtain fragments of lignin having one or more functional groups R'.

[0121] In a preferred embodiment, R' is an alkene, alkyne, aldehyde, anhydride, carboxylic acid, carboxylic acid ester, acyl chloride, acyl bromide, acyl iodide, acyl fluoride, sulfonyl chloride, sulfonyl iodide, sulfonyl bromide, sulfonyl fluoride, ketene, hydroxy, ketone, acetal, ketal, hemiacetal, hemiketal, ether, carboxylic acid amide, diazoketone, imine, oxime, amine, fulminate, cyanate, azide, nitro, nitrile, isocyanate, amino acid, boronic acid, boronic acid ester, borate, borate salt, borane, organosilane, silyl ether, or the like. a functional group selected from ether, siloxane, silanol, isothiocyanate, thiol, sulfonamide, sulfonate, sulfonic acid, sulfate, sulfone, persulfate, peroxide, sulfoxide, thioether, dithiane, phosphate, phosphate ester, phosphonate, phosphonic acid, phosphonate ester, phosphonium salt, phosphine, phosphite, phosphite ester, phosphite salt, fluoride, chloride, bromide, iodide, triflate, organomagnesium (Grignard), organolithium, dialkyllithium cuprate, organozinc, and acetylide; or Aziridine, 2H-azirine, oxirane, thiirane, azetidine, 2,3-dihydroazeto, azeto, 1,3-diazetidine, oxetane, 2H-oxete, thietane, 2H-thieto, azetidin-2-one, pyrrolidine, 3-pyrroline, 2-pyrroline, 2H-pyrrole, 1H-pyrrole, pyrazolidine, imidazolidine, 2-pyrazoline, 2-imidazoline, pyrazole, imidazole, 1,2,4-triazole, 1,2,3-triazole, tetrazole, tetrahydrofuran, furan, 1,3-diazolane, tetrahydrofuran Thiophene, thiophene, oxazole, isoxazole, isothiazole, thiazole, 1,2-oxathiolane, 1,3-oxathiolane, 1,2,5-oxadiazole, 1,2,3-oxadiazole, 1,3,4-thiadiazole, 1,2,5-thiadiazole, sulfolane, 2,4-thiazolidinedione, succinimide, 2-oxazolidone, hydantoin, piperidine, pyridine, piperazine, pyridazine, pyrimidine, pyrazine, 1,2,4-triazine, 1,3,5-triazine, tetrahydropyran, 2 H-pyran, 4H-pyran, pyrylium, 1,4-dioxane, 1,4-dioxine, thiane, 2H-thiopyran, 4H-thiopyran, 1,3-dithiane, 1,4-dithiane, 1,3,5-trithiane, morpholine, 2H-1,2-oxazine, 4H-1,2-oxazine, 6H-1,2-oxazine, 2H-1,3-oxazine, 4H-1,3-oxazine, 6H-1,3-oxazine, 4H-1,4-oxazine, 2H-1,4-oxazine, thiomorpholine, 4H-1,4-thiazine, 2H-1,2-thiazine, 6H-1, 2-Thiazine, 2H-1,4-thiazine, cytosine, thymine, uracil, thiomorpholine dioxide, hexahydro-1H-pyrrolidine, 1,4,5,6-tetrahydrocyclopental[b]pyrrole, 1,3a,4,6a-tetrahydropyrrolo[3,2-b]pyrrole, 1,4-dihydropyrrolo[3,2-b]pyrrole, 1,6-dihydropyrrolo[2,3-b]pyrrole, 6H-furo[2,3-b]pyrrole, 4H-furo[3,2-b]pyrrole, 4H-thieno[3,2-b]pyrrole, 6H-thieno[2,3-b]pyrrole, 2,3-Dihydro-1H-indene, indene, indoline, 3H-indole, 1H-indole, 2H-isoindole, indolizine, 1H-indazole, benzimidazole, 4-azaindole, 5-azaindole, 6-azaindole, 7-azaindole, 7-azaindazole, pyrazolo[1,5-a]pyrimidine, purine, benzofuran, isobenzofuran, benzo[c]thiophene, benzo[b]thiophene, 1,2-benzisoxazole, 2,1-benzisoxazole, 1, 2-Benzisothiazole, 2,1-benzisothiazole, benzoxazole, benzthiazole, benzo[c][1,2,5]thiadiazole, 1,2-benzisothiazol-3(2H)-one, adenine, guanine, decahydroisoquinoline, decahydroquinoline, tetrahydroquinoline, 1,2-hydroquinoline, 1,2-dihydroisoquinoline, quinoline, isoquinoline, 4H-quinolizine, quinoxaline, phthalazine, quinazoline, cinnoline, 1,8-naphthyridine, pyrido[3,2- d]pyrimidine, pyrido[4,3-d]pyrimidine, pyrido[3,4-d]pyrazine, pyrido[2,3-b]pyrazine, pteridine, 2H-chromene, 1H-isochromene, 3H-isochromene, 2H-chromen-2-one, 2H-benzo[e][1,2]oxazine, 2H-benzo[e][1,3]oxazine, 2H-benzo[b][1,4]oxazine, quinolin-2(1H)-one, isoquinolin-1(2H)-one, isoquinolin-1(2H)-one, fluorene, carbazole, dibenzofuran and a heterocycle selected from the group consisting of benzophenone, acridine, phenazine, phenoxazine, phenothiazine, phenoxathiin, quinuclidine, 1-azaadamantane, 2-azaadamantane, 2,3-dihydroazepine, 2,5-dihydroazepine, 4,5-dihydroazepine, azepine, 2H-azepine, 3H-azepine, 4H-azepine, 1,2-diazepine, 1,3-diazepine, 1,4-diazepine, oxepane, thiepine, 1,4-thiazepine, azocane, azocine, thiocane, azonane, and azecine.

[0122] In a more preferred embodiment, R' is an alkene, alkyne, aldehyde, anhydride, carboxylic acid, carboxylic acid ester, acyl chloride, sulfonyl chloride, hydroxy, ketone, acetal, ketal, ether, carboxylic acid amide, diazoketone, imine, oxime, amine, azide, nitro, nitrile, isocyanate, boronic acid, boronic acid ester, borate, borate salt, borane, organosilane, silyl ether, siloxane, silanol, thiol, sulfonamide, sulfonate, sulfonic acid, thioether, phosphate ester, phosphonate, phosphonate ester, phosphonium salt, fluoride, chloride, bromide, iodide, triflate, organomagnesium (Grignard), A functional group selected from organolithium, dialkyllithium cuprate, organozinc, and acetylide, and even more preferably R' is a functional group selected from alkene, alkyne, aldehyde, anhydride, carboxylic acid, carboxylic ester, acyl chloride, sulfonyl chloride, hydroxy, ketone, ether, carboxylic acid amide, diazoketone, amine, azide, nitro, nitrile, isocyanate, boronic acid, boronic ester, borate, borate salt, organosilane, thiol, sulfonamide, sulfonate, sulfonic acid, phosphonium salt, fluoride, chloride, bromide, iodide, triflate, organomagnesium (Grignard), organolithium, organozinc, and acetylide.

[0123] In particularly preferred embodiments, R' is a functional group selected from carboxylic acid, anhydride, acyl chloride, carboxylic acid ester, carboxylic acid amide, isocyanate, ether, alkyne, alkene, aldehyde, chloride, bromide, iodide, triflate, hydroxy, thiol, amine, and azide.

[0124] Reaction of one or more functional groups of the product of step c) to obtain lignin fragments having one or more functional groups R' can be carried out by reactions known in the art, such as nucleophilic substitution, oxidation, and Grignard reaction.

[0125] A further subject of the present invention are lignin fragments having one or more functional groups R and / or R' obtainable by the method of the present invention. These lignin fragments can be considered as compounds with functional groups prepared for a corresponding application or use.

[0126] Another subject of the present invention is a composition comprising fragments of lignin according to the invention. In a preferred embodiment, the fragments are represented by one or more of formulas 2 to 4:

[0127] [ka]

[0128] [ka]

[0129] [ka]

[0130] In a preferred embodiment, the composition may further comprise one or more additives selected from pharmaceutical excipients, solvents, dyes, colorants, strengthening agents, surfactants, dispersants, acids, bases, pesticides, polymers, resins, conductive metals, catalytic metals, reactive metals, catalysts, cellulose fibers, glass fibers, sugars, humins, bitumen, concrete, superabsorbent polymers, formaldehyde, glyoxylic acid, activated carbon, proteins, amino acids, cosmetic additives, vitamins, antioxidants, vitamins, resins, silicones, desiccants, antifungals, antibacterial agents, exfoliants, caffeine, clays, essential oils, fatty acids, mineral oils, metal oxides, detergents, drying agents, and crosslinking agents.

[0131] Further subject matter of the present invention are resins, adhesives, polymers, carbon fibers, concrete additives, thermal insulation materials, electrical insulation materials, paints, surfactants, photoresists, photographic films, antibacterial films, antifungal films, anticorrosion coatings, waterproofing materials, lubricants, UV absorbing additives for polymers, activated carbon, pigments, dyes, anticorrosion additives, flame retardants, catalysts, battery anodes, battery cathodes, ionomers, ion exchange resins, ion exchange membranes, superabsorbent polymers, gas permeable membranes, UV absorbing creams (sunblocks), ck or sunscreen, drug delivery substrate, fragrance delivery substrate, flavor delivery substrate, food additive (antioxidant), food supplement (antioxidant), cosmetic additive, fuel for concrete kilns, fuel for power generation, fuel for steel mills, explosives, solid rocket fuel, gunpowder, smokeless powder, fireworks, ablative armor, reactive armor, insecticide, bactericide, antifungal agent, antiviral agent, suntan cream, and / or antibiotic.

[0132] The present invention will now be described with reference to the following examples.

[0133] Experimental Section:

[0134] I. Materials

[0135] I.1 Biological materials Birch wood was sourced from Dr. Michael Studer at the Bern University of Applied Sciences. Birch trees (Betula pendula, approximately 40 years old) were harvested in Solothurn, Switzerland, in May 2018. The bark was removed, and the stems were converted into wood chips, which were air-dried at 40°C for 24 hours. The wood chips were then collected and transported to EPFL, where they were sieved and sorted to remove any remaining bark or leaves. The wood chips were then crushed using a 6 mm screen and then mechanically sieved through a 0.45 mm mesh to remove fines.

[0136] I.2 Chemicals All chemicals were commercially available and used without further purification. 1,4-Dioxane (synthetic grade ≥99.5%), 2-hydroxybenzaldehyde (salicylaldehyde; synthetic grade ≥99%), 3-hydroxybenzaldehyde (synthetic grade ≥99%), 4-hydroxybenzaldehyde (synthetic grade ≥99%), and vanillin (biochemical grade 99%) were purchased from Carl Roth AG. Ethyl acetate, hexane, methanol, and toluene were purchased from Thommen-Fürler AG. Chloroacetaldehyde (50 wt% in HO), glycoaldehyde dimer (mixture of stereoisomers), and 4-chlorobenzaldehyde were purchased from Sigma-Aldrich. Hydrogen peroxide (30 wt / wt%) and sodium hydroxide (tablets) were purchased from Reacto Lab SA. Diethyl ether (≥99.5%, stabilized with BHT) was purchased from Carlo Erba Reagents. Di-n-butyl ether (99%) was purchased from ABCR. Glyoxylic acid monohydrate (97%) and 4-formylbenzoic acid (99%) were purchased from Fluorochem. Hydrochloric acid (analytical grade 37% w / w, fuming) was purchased from Merck, and dimethyl sulfoxide-d6 (99.9 d-atom%) was purchased from Cambridge Isotope Laboratories.

[0137] II. Working Examples

[0138] II.1 Preparation of lignin fragments with one or more functional groups Typical biomass extraction procedures Biomass (5.0000 g) was collected in a 100 mL reagent bottle. Next, 1,4-dioxane (25 mL), the corresponding aldehyde (66 mmol, 6.6 equiv.), hydrochloric acid (37% w / w, 0.83 mL, 10 mmol, 1.0 equiv.), and a PTFE-coated stir bar were added to the bottle. The bottle was then sealed with a GL45 cap and heated to 85 °C with stirring. After 3 h (5 h if the aldehyde was chloroacetaldehyde), the reaction mixture was cooled to room temperature (approximately 25 °C) and filtered through a glass filter funnel (porosity grade 3), washing with dioxane (25 mL) to remove the cellulose-rich solids. The filtrate was then transferred to a 29 / 32, 250 mL round-bottom flask and concentrated on a rotary evaporator at a bath temperature of 45 °C and an ultimate pressure of 10 mbar. Lignin was then precipitated according to the corresponding aldehyde used in the reaction (see below).

[0139] E.1 Chloroacetaldehyde as an aldehyde The concentrated crude reaction mixture obtained from the general biomass extraction procedure described above was diluted with dioxane (50 mL) and then added dropwise using a glass pipette to a 500 mL round-bottom flask containing di-n-butyl ether (250 mL) stirred at 500 RPM with an oval PTFE-coated stir bar. The crude lignin was collected by filtration and placed in a Soxhlet extraction apparatus sock consisting of a 100 mL Soxhlet extractor, a 500 mL round-bottom flask, a PTFE-coated stir bar, a 45 / 50 male to 29 / 32 female adapter, a reflux condenser, and an oil bubbler. The 500 mL round-bottom flask was charged with 250 mL of diethyl ether, and the apparatus was then heated to 90 °C overnight to wash the lignin. The next day, the lignin was transferred to a tared 100 mL round-bottom flask and vacuum-dried to yield the product as a pink powder (1.0170 g, 20.2% w / w).

[0140] E.2 p-Chlorobenzaldehyde as an aldehyde The concentrated crude reaction mixture obtained from the general biomass extraction procedure described above was diluted with dioxane (10 mL) and then added dropwise using a glass pipette to a 500 mL round-bottom flask containing di-n-butyl ether (250 mL) stirred at 500 RPM with an oval PTFE-coated stir bar. The crude lignin was collected by filtration and placed in a Soxhlet extraction apparatus sock consisting of a 100 mL Soxhlet extractor, a 500 mL round-bottom flask, a PTFE-coated stir bar, a 45 / 50 male to 29 / 32 female adapter, a reflux condenser, and an oil bubbler. The 500 mL round-bottom flask was charged with 250 mL of diethyl ether, and the apparatus was then heated to 90 °C overnight to wash the lignin. The next day, the lignin was transferred to a tared 100 mL round-bottom flask and vacuum-dried to yield the product as a pink powder (0.7515 g, 14.8 wt / wt%).

[0141] E.3 Glyoxylic acid monohydrate as the aldehyde To the concentrated lignin solution obtained from the general biomass extraction procedure described above, deionized water (100 mL) was added, followed by the addition of an oval PTFE-coated stir bar. The mixture was stirred at 500 RPM for 30 minutes to break up large agglomerates. The stir bar was then removed. Filtration and drying yielded a beige powder (1.0731 g, 21.3 wt%).

[0142] E.4 4-Formylbenzoic acid as an aldehyde The concentrated crude reaction mixture obtained from the general biomass extraction procedure described above was diluted with dioxane (10 mL) and then added dropwise using a glass pipette to a 500 mL round-bottom flask containing di-n-butyl ether (250 mL) stirred at 500 RPM with an oval PTFE-coated stir bar. The crude lignin was collected by filtration and placed in a Soxhlet extraction apparatus sock consisting of a 100 mL Soxhlet extractor, a 500 mL round-bottom flask, a PTFE-coated stir bar, a 45 / 50 male to 29 / 32 female adapter, a reflux condenser, and an oil bubbler. The 500 mL round-bottom flask was charged with 250 mL of diethyl ether, and the apparatus was then heated to 90 °C overnight to wash the lignin. The next day, the lignin was transferred to a tared 100 mL round-bottom flask and vacuum-dried to yield the product as a purple-brown powder (0.7924 g, 15.6 wt / wt%).

[0143] E.5 4-Hydroxybenzaldehyde as an aldehyde The concentrated crude reaction mixture obtained from the general biomass extraction procedure described above was diluted with dioxane (10 mL) and then added dropwise using a glass pipette to a 500 mL round-bottom flask containing di-n-butyl ether (250 mL) stirred at 500 RPM with an oval PTFE-coated stir bar. The crude lignin was collected by filtration and placed in a Soxhlet extraction apparatus sock, consisting of a 100 mL Soxhlet extractor, a 500 mL round-bottom flask, a PTFE-coated stir bar, a 45 / 50 male to 29 / 32 female adapter, a reflux condenser, and an oil bubbler. The 500 mL round-bottom flask was charged with 250 mL of diethyl ether, and the apparatus was then heated to 90 °C overnight to wash the lignin. The next day, the lignin was transferred to a tared 100 mL round-bottom flask and vacuum-dried to yield the product as a dark brown powder (0.9851 g, 19.5 wt / wt%).

[0144] E.6 3-Hydroxybenzaldehyde as an aldehyde The concentrated crude reaction mixture obtained from the general biomass extraction procedure described above was diluted with dioxane (10 mL) and then added dropwise using a glass pipette to a 500 mL round-bottom flask containing di-n-butyl ether (250 mL) stirred at 500 RPM with an oval PTFE-coated stir bar. The crude lignin was collected by filtration and placed in a Soxhlet extraction apparatus sock, consisting of a 100 mL Soxhlet extractor, a 500 mL round-bottom flask, a PTFE-coated stir bar, a 45 / 50 male to 29 / 32 female adapter, a reflux condenser, and an oil bubbler. The 500 mL round-bottom flask was charged with 250 mL of diethyl ether, and the apparatus was then heated to 90 °C overnight to wash the lignin. The next day, the lignin was transferred to a tared 100 mL round-bottom flask and vacuum-dried to yield the product as a dark brown powder (0.9765 g, 19.5 wt / wt%).

[0145] E.7 2-Hydroxybenzaldehyde (Salicylaldehyde) as an Aldehyde The concentrated crude reaction mixture obtained from the general biomass extraction procedure described above was diluted with dioxane (10 mL) and then added dropwise using a glass pipette to a 500 mL round-bottom flask containing di-n-butyl ether (250 mL) stirred at 500 RPM with an oval PTFE-coated stir bar. The crude lignin was collected by filtration and placed in a Soxhlet extraction apparatus sock, consisting of a 100 mL Soxhlet extractor, a 500 mL round-bottom flask, a PTFE-coated stir bar, a 45 / 50 male to 29 / 32 female adapter, a reflux condenser, and an oil bubbler. The 500 mL round-bottom flask was charged with 250 mL of diethyl ether, and the apparatus was then heated to 90 °C overnight to wash the lignin. The next day, the lignin was transferred to a tared 100 mL round-bottom flask and vacuum-dried to yield the product as a dark brown powder (0.8169 g, 16.2 wt / w%).

[0146] E.8 4-Hydroxy-3-methoxybenzaldehyde (vanillin) as an aldehyde The concentrated crude reaction mixture obtained from the general biomass extraction procedure described above was diluted with dioxane (10 mL) and then added dropwise using a glass pipette to a 500 mL round-bottom flask containing di-n-butyl ether (250 mL) stirred at 500 RPM with an oval PTFE-coated stir bar. The crude lignin was collected by filtration and placed in a Soxhlet extraction apparatus sock, consisting of a 100 mL Soxhlet extractor, a 500 mL round-bottom flask, a PTFE-coated stir bar, a 45 / 50 male to 29 / 32 female adapter, a reflux condenser, and an oil bubbler. The 500 mL round-bottom flask was charged with 250 mL of diethyl ether, and the apparatus was then heated to 90 °C overnight to wash the lignin. The next day, the lignin was transferred to a tared 100 mL round-bottom flask and vacuum-dried to yield the product as a dark brown powder (1.0694 g, 21.2 wt / wt%).

[0147] E.9 2-Hydroxyaldehyde (Glycolaldehyde) as Aldehyde The concentrated crude reaction mixture obtained from the general biomass extraction procedure described above was diluted with dioxane (10 mL) and then added dropwise using a glass pipette to a 500 mL round-bottom flask containing di-n-butyl ether (250 mL) stirred at 500 RPM with an oval PTFE-coated stir bar. The crude lignin was collected by filtration and placed in a Soxhlet extraction apparatus sock, consisting of a 100 mL Soxhlet extractor, a 500 mL round-bottom flask, a PTFE-coated stir bar, a 45 / 50 male to 29 / 32 female adapter, a reflux condenser, and an oil bubbler. The 500 mL round-bottom flask was charged with 250 mL of diethyl ether, and the apparatus was then heated to 90 °C overnight to wash the lignin. The next day, the lignin was transferred to a tared 100 mL round-bottom flask and vacuum-dried to yield the product as a brown powder (1.5464 g, 30.9 wt / wt%).

[0148] The products obtained in E.1 to E.9 can be considered as fragments of lignin carrying one or more functional groups.

[0149] II.2 Bleaching of lignin fragments with one or more functional groups

[0150] General bleaching instructions: Lignin fragments (1 g) bearing one or more functional groups were collected in a 29 / 32, 50 mL round-bottom flask. To the flask was added a PTFE-coated stir bar, ethyl acetate (10 mL), 2 M sodium hydroxide (5 mL, 10 mmol, 1.0 equiv.), and hydrogen peroxide (30 wt.%, 1.4 mL, 13.7 mmol, 13.7 equiv.). The flask was then uncapped and heated to 60 °C with stirring for 30 minutes or until all bubbling had ceased. The reaction mixture was then cooled to room temperature (approximately 23-30 °C) and quantitatively transferred to a 100 mL separatory funnel using ethyl acetate. Saturated sodium chloride solution (15 mL) and ethyl acetate (10 mL) were added. The separatory funnel was swirled but not shaken (to prevent emulsion formation) and the layers were separated. The organic layer was quantitatively transferred back to the separatory funnel using ethyl acetate, followed by the addition of more saturated sodium chloride solution (15 mL). The separatory funnel was again spun to separate the layers. This washing cycle was repeated once more. Next, anhydrous magnesium sulfate (approximately 1-2 g) and a PTFE-coated stir bar were added to the organic layer. The solution was stirred for 30 minutes, then filtered through a glass filter funnel (porosity grade 3) and quantitatively transferred with ethyl acetate. The filtrate was then transferred to a 250 mL round-bottom flask and concentrated under vacuum on a rotary evaporator. The resulting oily solid was transferred to a tared 100 mL round-bottom flask, concentrated again, diluted with hexane (20 mL), and finally concentrated once more to yield oxidized lignin fragments bearing one or more functional groups as an off-white powder.

[0151] E.9 Bleaching of products of E.3 The general bleaching procedure described above was applied, except that more sodium hydroxide was used (6 mL, 12 mmol, 1.0 equiv.) and no ethyl acetate was used. To work up the reaction, it was first cooled to room temperature (approximately 23-30 °C) and then acidified with hydrochloric acid (37 wt%, 1.1 mL, 13.2 mmol, 1.1 equiv.). The resulting off-white precipitate was collected by filtration and dried to yield bleached glyoxylic acid-stabilized lignin as an off-white powder (0.7216 g, 70%). Examples of embodiments of the present invention are listed in the following items [Aspect 1] to [Aspect 15]. [Aspect 1] A method for producing fragments of lignin having one or more functional groups, comprising the steps of: a) providing a lignocellulose-containing composition: b) reacting the composition of step a) with an aldehyde of formula 1 [ka] wherein L is absent or a linking group, and R is a functional group, and x is an integer from 1 to 5. heating under acidic conditions with c) separating lignin fragments having one or more functional groups from the mixture of step b; and d) Optionally, further reacting one or more functional groups of the product of step c) to obtain fragments of lignin having one or more functional groups R'. [Aspect 2] 2. The method of embodiment 1, wherein the lignocellulose-containing composition has a lignin content of 1 to 50 wt.%. [Aspect 3] 3. The method of any one of the preceding claims, wherein step a) comprises suspending the lignocellulose-containing composition in an organic solvent, wherein the organic solvent is preferably a polar aprotic solvent containing less than 50% v / v water. [Aspect 4] 4. The method according to any one of aspects 1 to 3, wherein in step b) a temperature of 50 to 120° C. is applied for 0.1 to 72 hours. [Aspect 5] 5. The method of any one of aspects 1 to 4, wherein the acidic addition is achieved by adding 0.5 to 20 mmol of acidic compound per gram of lignocellulose-containing composition. [Aspect 6] A method according to any one of aspects 1 to 5, wherein each R is a functional group independently selected from aldehyde, anhydride, acyl chloride, carboxylic acid ester, carboxylic acid amide, isocyanate, ether, alkyne, alkene, amine, carboxylic acid, nitrile, ether, thioether, hydroxyl, thiol, nitro, chloride, bromide, iodide, azide, and triflate; Preferably, in the formula, each R is a functional group independently selected from carboxylic acid, anhydride, acyl chloride, carboxylic acid ester, carboxylic acid amide, isocyanate, ether, alkyne, alkene, aldehyde, chloride, bromide, iodide, triflate, hydroxyl, thiol, amine, and azide; More preferably, wherein each R is a functional group independently selected from carboxylic acid, carboxylic acid amide, ether, alkyne, alkene, aldehyde, chloride, hydroxyl, and azide; and Most preferably, R is a functional group independently selected from carboxylic acid, carboxylic acid amide, ether, aldehyde, chloride, and hydroxyl. [Aspect 7] The method of any one of aspects 1 to 6, wherein L is an aliphatic linking group having 1 to 6 carbon atoms or an aromatic linking group having 4 to 15 carbon atoms. [Aspect 8] A method according to any one of aspects 1 to 7, wherein the aldehyde of formula (1) is 2-hydroxyacetaldehyde, 2-bromoacetaldehyde, 2-iodoacetaldehyde, 2-hydroxyacetaldehyde, ethanedial (also known as glyoxal or oxalaldehyde), oxoethanoic acid (also known as 2-oxoacetic acid or glyoxylic acid), 2,2,2-trichloroacetaldehyde, 4-hydroxy-3,4-dimethoxybenzaldehyde (syringaldehyde), 4-hydroxy-3-methoxybenzaldehyde (vanillin), 2-hydroxybenzaldehyde (salicylaldehyde), 2-chlorobenzaldehyde, 2-bromobenz ...isopropylbenzaldehyde, 2-isopropylbenzaldehyde, 2-isopropylbenzaldehyde, 2-isopropylbenzaldehyde, 2-isopropylbenzaldehyde, 2-isopropylbenzaldehyde, 2-isopropylbenzaldehyde, 2-isopropylbenzaldehyde, 2-isopropylbenzaldehyde, 2-isopropylbenzaldehyde, 2-isopropylbenzaldehyde, 2-isopropylbenzaldehyde, 2-isopropylbenzaldehyde, 2-isopropylbenzaldehyde, 2-isopropylbenzaldehyde, 2-isopropylbenzaldehyde, 2-isopropylbenzaldehyde, 2-isopropylbenzaldehyde, 2-isopropylbenzaldehyde, 2-isopropylbenzaldehyde, 2-isopropylbenzaldehyde, 2-isopropylbenzaldehyde, 2,4-Dinitrobenzaldehyde, 2-formylbenzoic acid, 4-formylbenzoic acid, and terephthalaldehyde. [Aspect 9] 9. The method of any one of aspects 1 to 8, wherein the lignocellulose-containing composition and the aldehyde of Formula 1 are present in a weight ratio of from 25:1 to 1:1, wherein the aldehyde is based on the weight of formaldehyde. [Aspect 10] The method of any one of aspects 1 to 9, wherein in step b) the lignocellulose-containing composition is reacted with an aldehyde of formula 1 to form a lignocellulose-containing compound of formula RL-CH(OR 2 )(OR 3 ) acetal is produced, where R 2 and R 3 is a continuous portion of a lignin polymer contained in a lignocellulose-containing composition, and the lignocellulose-containing composition is reacted with an aldehyde of Formula 1 to preferably produce one or more acetals of Formulas 2 to 4,

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Claims

1. A method for producing fragments of lignin having one or more functional groups, comprising the steps of: a) providing a lignocellulose-containing composition; b) reacting the composition of step a) with an aldehyde of formula 1 【Chemical 1】 wherein L is absent or a linking group; and each R is a functional group independently selected from aldehyde, anhydride, acyl chloride, carboxylic acid ester, carboxylic acid amide, isocyanate, ether, alkyne, alkene, amine, carboxylic acid, nitrile, thioether, hydroxyl, thiol, nitro, chloride, bromide, iodide, azide, and triflate; and x is an integer from 1 to 5. heating under acidic conditions with c) separating lignin fragments having one or more functional groups from the mixture of step b; wherein in step b) the lignocellulose-containing composition reacts with an aldehyde of formula 1 to produce an acetal of formula R-L-CH(OR 2 )(OR 3 ), where R 2 and R 3 are consecutive portions of a lignin polymer contained in the lignocellulose-containing composition, and the lignocellulose-containing composition reacts with the aldehyde of formula 1 to produce one or more acetals of formulas 2-4. 【Chemistry 2】 【Chemistry 3】 【Chemistry 4】

2. The method of claim 1, wherein the lignocellulose-containing composition has a lignin content of 1 to 50% by weight.

3. 3. The method of claim 1 or 2, wherein step a) comprises suspending the lignocellulose-containing composition in an organic solvent, wherein the organic solvent is a polar aprotic solvent containing less than 50% v / v water.

4. 4. The method according to any one of claims 1 to 3, wherein in step b) a temperature of 50 to 120°C is applied for a time of 0.1 to 72 hours.

5. The method of any one of claims 1 to 4, wherein the acidic addition is achieved by adding 0.5 to 20 mmol of acidic compound per gram of the lignocellulose-containing composition.

6. The method of any one of claims 1 to 5, wherein L is an aliphatic linking group having 1 to 6 carbon atoms or an aromatic linking group having 4 to 15 carbon atoms.

7. The method according to any one of claims 1 to 6, wherein the aldehyde of formula (1) is 2-hydroxyacetaldehyde, 2-bromoacetaldehyde, 2-iodoacetaldehyde, 2-hydroxyacetaldehyde, ethanedial (also known as glyoxal or oxalaldehyde), oxoethanoic acid (also known as 2-oxoacetic acid or glyoxylic acid), 2,2,2-trichloroacetaldehyde, 4-hydroxy-3,4-dimethoxybenzaldehyde (syringaldehyde), 4-hydroxy-3-methoxybenzaldehyde (vanillin), 2-hydroxybenzaldehyde (salicylaldehyde), 2-chlorobenzaldehyde, 2-bromobenzaldehyde, 2-isopropyl ... 2,4-Dinitrobenzaldehyde, 2-formylbenzoic acid, 4-formylbenzoic acid, and terephthalaldehyde.

8. 8. The method of any one of claims 1 to 7, wherein the lignocellulose-containing composition and the aldehyde of Formula 1 are present in a weight ratio of from 25:1 to 1:1, wherein the aldehyde is based on the weight of formaldehyde.

9. The method according to any one of claims 1 to 8, wherein step c) comprises the following substeps: c1) separating the lignin fragment-containing phase and the residue; c2) removing the solvent from the lignin fragment-containing phase; c3) treating the residue of step c2) with a solvent; c4) Separating lignin fragments.

10. 10. The method of any one of claims 1 to 9, wherein R' is a functional group selected from alkene, alkyne, aldehyde, anhydride, carboxylic acid, carboxylic acid ester, acyl chloride, sulfonyl chloride, hydroxy, ketone, ether, carboxylic acid amide, diazoketone, amine, azide, nitro, nitrile, isocyanate, boronic acid, boronic acid ester, borate, borate salt, organosilane, thiol, sulfonamide, sulfonate, sulfonic acid, phosphonium salt, fluoride, chloride, bromide, iodide, triflate, organomagnesium (Grignard), organolithium, organozinc, and acetylide.

11. The method of claim 1, wherein the product obtained from step c) is contacted with a mixture of an oxidizing agent and an alkaline compound in a solvent.

12. The method of claim 11, wherein the oxidizing agent is sodium hydroxide.

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