New method for preparing glycerol and pyruvic acid via coal chemical glycolic acid raw material

Abstract

This invention relates to the field of new materials and fine chemicals, and particularly to a novel manufacturing process technology for glycerol and pyruvate series products based on the coal chemical glycolate raw material route, including glycerol, glyceric acid, glycerate esters, pyruvate, and pyruvate esters. The process is characterized by the use of abundant coal-derived carbon monoxide (syngas), methanol, or formaldehyde, among other readily available C1 raw materials, to produce a simple and efficient series of C3-based products. This technology achieves significant cost reduction and efficiency improvement, and is conducive to the large-scale production of high-value chemicals based on my country's abundant coal resources.

Description

[Technical Field]

[0001] This invention relates to the field of new materials and fine chemicals, and particularly to a novel manufacturing process technology for glycerol and pyruvate series products based on the coal chemical glycolate raw material route, including glycerol, glyceric acid, glycerate esters, pyruvate, and pyruvate esters. The process is characterized by the use of abundant coal-derived carbon monoxide (syngas), methanol, or formaldehyde, among other readily available C1 raw materials, to produce a simple and efficient series of C3-based products. This technology achieves significant cost reduction and efficiency improvement, and is conducive to the large-scale production of high-value chemicals based on my country's abundant coal resources. [Background Technology]

[0002] Glycerin and glyceric acids and esters are a large class of basic chemicals. They are excellent hygroscopic agents, antifreeze agents, lubricants, plasticizers, food additives, and raw materials for chemical production. They are widely used in the food industry, pharmaceutical industry, defense industry, daily chemical industry, and textile printing and dyeing industry.

[0003] Glycerin is usually extracted from natural animal and plant oils or synthesized from propylene, a petrochemical raw material.

[0004] Pyruvic acid, also known as acetylated carboxylic acid, is one of the most important organic acids. It is widely used in pharmaceuticals, food, chemicals, and agrochemicals, and plays a crucial role in biological metabolism.

[0005] The main industrial production methods for pyruvic acid include lactic acid oxidation, tartaric acid oxidation, enzymatic conversion, and microbial fermentation. The main problems are high environmental pollution risk and high production cost.

[0006] This application has now discovered for the first time that, through ingenious reaction principle design and practical exploration, it is possible to use C1 type raw materials, which are abundant and industrially inexpensive and readily available in my country's coal chemical industry, especially representative bulk industrial products such as carbon monoxide, carbon monoxide / hydrogen (syngas), methanol, or formaldehyde, to achieve a brand-new intelligent manufacturing of glycerol series products through an extremely simple process flow.

[0007] Furthermore, it was discovered that the intermediates involved can be directly used to efficiently prepare pyruvate-like substances through a simple dehydration process.

[0008] This newly disclosed technology boasts outstanding process safety, environmental friendliness, and overall cost competitiveness. Furthermore, this technological breakthrough unexpectedly enables the large-scale, low-cost production of two major C3-based products—glycerol and pyruvate—from coal chemical resources for the first time. Leveraging my country's abundant coal resources, this alternative technology holds immense strategic significance for energy security and industrial upgrading. [Summary of the Invention]

[0009] This application has now unexpectedly discovered that, as shown in reaction (I), the glycolate type substance represented by structural formula A reacts with formaldehyde under reaction conditions to obtain the hydroxymethylated intermediate glyceric acid (ester) represented by structural formula B; subsequently, B and the reducing agent [H] undergo a reduction reaction under reaction conditions to obtain the glycerol series products represented by structural formula C.

[0010] The above steps A to B and B to C can be performed separately or in stages; or preferably, the above two steps can be performed continuously in a "one-step" or "one-pot" manner without separating and purifying intermediate B. Compared with conventional natural animal and vegetable oil extraction or propylene oxidation routes, the product obtained by the technology disclosed in this invention is easier to obtain and purify. It should also be noted that this technology can be used to produce glyceryl ester B or glycerol C alone, or for the co-production of B and C.

[0011]

[0012] R1 or R2 is independent of each other and is hydrogen or an aliphatic or aromatic hydrocarbon group containing 1-24 carbon atoms; preferably, R1 or R2 is hydrogen, methyl, ethyl, propyl, butyl, or a long-chain aliphatic hydrocarbon group containing 6-24 carbon atoms.

[0013]

H

[0014] "conditions" refers to at least one of the following: additives, light, heat, microwave, ultrasound, vacuum or pressure, solvents, etc.

[0015] The additive is a catalyst or accelerator; based on raw material A, the amount of the additive used is a catalytic amount, an equivalent amount, or an excess amount (0.001-100 equivalents). Preferably, the catalyst or accelerator is a Lewis acid or Lewis base compound; the amount of catalyst or accelerator added is 0.1-1000% of the reactant; preferably 1-1000%, more preferably 1-200%, and even more preferably 1-120%.

[0016] Light refers to the reaction system under light irradiation conditions, with the wavelength range of light being 200-780 nanometers.

[0017] Heat refers to the reaction system being carried out under heating conditions, with a reaction temperature of -25 to 450 degrees Celsius, preferably -20 to 150 degrees Celsius; more preferably -20 to 100 degrees Celsius.

[0018] Microwave or ultrasonic means using a microwave or ultrasonic generator to radiate the reaction system. Pressure refers to the pressure or vacuum conditions under which the reaction system is carried out. The pressure of the reaction process can be 0.001-200 atmospheres, preferably 0.01-100 atmospheres.

[0019] The solvent is selected from at least one of substituted or unsubstituted aromatic hydrocarbons, straight-chain or branched aliphatic hydrocarbons, (sulfoxides), amides, ethers, alcohols, esters, ketones, nitriles, carboxylic acids, water, amines, carbonates, ionic liquids, and supercritical carbon dioxide containing 1 to 24 carbons; or the liquid substrate itself acts as a solvent medium.

[0020] In some preferred embodiments of the present invention, the solvent is selected from water, dioxane, acetonitrile, ethanol, butanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, dimethyl sulfone, benzyl sulfoxide, benzyl sulfone, cyclobutane sulfoxide, sulfolane, trichlorosilane, dichloromethane, dichloroethane, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, chloroform, carbon tetrachloride, benzene, toluene, xylene, trimethylbenzene, tetramethylbenzene, acetonitrile, ethylbenzene, diethylbenzene, chlorobenzene, dichlorosilane, etc. At least one of benzene, anisole, nitrobenzene, heptane, hexane, petroleum ether, tetrahydrofuran, methyltetrahydrofuran, methyl tert-butyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, propylene glycol methyl ether acetate, triethylamine, tributylamine, dimethylisopropylamine, pyridine, N,N-tetramethylethylenediamine, N-alkylmorpholine, N-alkylpyrrole, N,N-dimethylformamide, formylmorpholine, N,N-diethylformamide, and N-methylpyrrolidone.

[0021] The use of solvents is preferred but not essential. Under certain conditions, solvents can be omitted, i.e., using the dissolved or melted form of the reactants, or directly mixing the reactants and then reacting under heating, grinding, or gas-phase conditions; and using supercritical carbon dioxide as the reaction medium. The advantages of using supercritical carbon dioxide as the reaction medium are that it is environmentally friendly and facilitates the occurrence of the reaction and the separation of products, advantages well known to professionals in this field.

[0022] We further discovered that the key intermediate B readily undergoes a dehydration reaction, directly generating D-pyruvate or an ester after enol isomerization. Therefore, we claim rights to reaction formula (II).

[0023]

[0024] The above steps A to B and B to D can be performed separately or in stages; or preferably, the above two steps can be performed continuously in a "one-step" or "one-pot" manner without separating and purifying intermediate B.

[0025] It should also be noted that this technology can be used to produce glyceryl ester B or pyruvate D separately, or for the co-production of B and D.

[0026] The following synthetic routes show that methyl glycolate type feedstock A can be conveniently prepared by selective hydrogenation reduction via the so-called coal-to-syngas-oxalate DMO route, or by carbonylation of methyl acetal obtained from methanol-formaldehyde. These are both known and mature technologies, and both directly use the cheapest and most readily available C1 type feedstock.

[0027]

[0028] Utilizing abundant C1 feedstocks from coal chemical production, particularly carbon monoxide (syngas), methanol, and formaldehyde—materials with the lowest cost advantage—to produce typical downstream products that previously relied on bio-based or petrochemical refining chains not only achieves cost reduction and efficiency improvement but also makes a positive contribution to national energy security and industrial transformation and upgrading. Furthermore, my country's vast coal-producing regions possess extremely rich coal-to-methanol / formaldehyde, as well as coal-to-oxalate, ethylene glycol, and methyl glycolate production capacity, which has a strong industrial empowerment characteristic for revitalizing existing assets and converting them to produce high-value-added glycerol or pyruvate series products.

[0029] An exemplary, and not limiting, example of a glyceric acid or ester compound B that can be synthesized via the techniques disclosed in this invention is the following structure:

[0030]

[0031] An exemplary, and not limiting, example of a glycerol compound C that can be synthesized via the techniques disclosed in this invention is the following structure:

[0032]

[0033] A preferred example of pyruvate D that can be synthesized via the techniques disclosed in this invention is methyl pyruvate.

[0034] Preferably, one implementation of the general formula (I) is (IA), which involves using methyl glycolate as a raw material and undergoing a hydroxymethylation reaction to obtain methyl glycerate, which is then subjected to a hydrogenation reduction reaction to obtain the glycerol product.

[0035]

[0036] Preferably, another implementation of the general formula (I) is (IB), which involves using methyl methyl glycolate as a raw material, undergoing a hydroxymethylation reaction to obtain methyl methylglycerate, which is then subjected to a hydrogenation reduction reaction to obtain the methyl glycerol product.

[0037]

[0038] Preferably, one embodiment of reaction formula (II) is (IIA), which involves using methyl glycolate as a raw material and undergoing a hydroxymethylation reaction to obtain methyl glycerate, which is then subjected to a dehydration isomerization reaction to obtain methyl pyruvate (preferably R2 is hydrogen or methyl):

[0039]

[0040] Preferably, one embodiment of reaction formula (II) is (IIB), which involves the co-production of methyl glycolate and methyl pyruvate from methyl glycolate via hydroxymethylation and dehydration isomerization (preferably R2 is hydrogen or methyl):

[0041]

[0042] The hydrolysis of pyruvate esters can prepare pyruvate or its corresponding metal salts, such as sodium, potassium, and calcium salts, as is well known to those skilled in the art.

[0043] The core of this application discloses a universal coal chemical route for the preparation of glycerol, glyceric acid and esters, and pyruvate and esters. Practitioners can use the process disclosed in this invention to manufacture any one of the following substances: glyceric acid (ester) B, glycerol C, or pyruvate (ester) D, or co-produce any two of them.

[0044] A series of so-called triglyceride products can be prepared by esterification of glycerol, and a series of esters can also be prepared by esterification or transesterification of pyruvate or methyl ester, the techniques involved being conventional. In view of this, this application also claims rights to downstream applications of compounds prepared via the disclosed routes.

[0045] We will explain further in the embodiments.

Detailed Implementation Methods

[0046] The essence of the invention is further illustrated below with reference to specific embodiments:

[0047] Example:

[0048]

[0049] Under nitrogen protection at room temperature, 2.8 g of Hunig base and 5.6 g of solid formaldehyde were placed in 50 mL of dry DMF. 9.8 g of methyl glycolate was added dropwise to the system with rapid mechanical stirring overnight. The reaction mixture was adjusted to neutral with sulfuric acid, the solvent was removed by vacuum distillation, and the solution was diluted with 30 mL of ice-cold ethyl acetate. The solution was rapidly filtered through diatomaceous earth, and the supernatant was concentrated and eluted with hexane-ethyl acetate on silica gel column chromatography to obtain 11.9 g of methyl glycerate.

[0050] Copper nitrate and chromium nitrate were mixed in a 7:3 ratio, with solid ammonium bicarbonate as a precipitant. The resulting copper-chromium gel was calcined and pressed into tablets to prepare a 20-40 mesh hydrogenation catalyst. This Cu-Cr hydrogenation catalyst was loaded into a fixed-bed reactor, activated with hydrogen, and then subjected to hydrogenation at 210°C, 3.5 MPa, and 0.4 h. -1 Hydrogenation reduction was carried out at a space velocity of 1 and a hydrogen-methyl glycerate molar ratio of 36 / 1. The resulting mixture after cooling / gas-liquid separation / hydrogen venting was quantitatively analyzed by gas chromatography. Methyl glycerate was converted to glycerol with a conversion rate of 96% and a selectivity of 91%.

[0051] Example:

[0052]

[0053] Under nitrogen protection at room temperature, 8.2 g of sodium methoxide and 6.0 g of solid formaldehyde were placed in 50 mL of dry DMF. The mixture was heated to 40–50 °C with rapid mechanical stirring. 11.6 g of methyl glycolate was added dropwise to the system and stirred overnight. The solvent was removed from the reaction solution under reduced pressure, and the solution was diluted with 30 mL of ice-cold ethyl acetate. The solution was rapidly filtered through diatomaceous earth, and the supernatant was concentrated and eluted with hexane-ethyl acetate on silica gel column chromatography to obtain 13.0 g of methyl methyl glycolate.

[0054] Referring to the hydrogenation reduction conditions of Example 1, methyl methylglycerate was converted to 2-methylglycerol with a conversion rate of 92% and a selectivity of 86%.

[0055] Example:

[0056]

[0057] Under nitrogen protection at room temperature, 14.6 g of sodium methoxide and 8.1 g of solid formaldehyde were placed in 80 mL of dry methanol. 16.2 g of methyl glycolate was added dropwise to the system under rapid mechanical stirring and reflux, and the reaction was stirred for 5 hours. After cooling the mixture to room temperature, 30% hydrochloric acid solution was added to adjust the pH to 2-3, and the reaction was continued overnight with stirring. The system was concentrated, and 100 mL of ethyl acetate was added under rapid stirring. The mixture was filtered through diatomaceous earth to remove salts. The supernatant was concentrated and eluted with hexane-ethyl acetate on silica gel column chromatography to obtain 15.3 g of methyl pyruvate.

[0058] Example:

[0059]

[0060] Under nitrogen protection at room temperature, 12.0 g of sodium methoxide and 6.7 g of solid formaldehyde were placed in 80 mL of dry methanol. 13.5 g of methyl glycolate was added dropwise to the system under rapid mechanical stirring and reflux, and the reaction was stirred for 6 hours. After cooling the mixture to room temperature, 30% hydrochloric acid solution was added to adjust the pH to 2-3, and the reaction was continued under reflux and stirring for 3 hours. The system was concentrated, and 100 mL of ethyl acetate was added under rapid stirring. The mixture was filtered through diatomaceous earth to remove salts. The supernatant was concentrated and eluted with hexane-ethyl acetate on silica gel column chromatography to obtain 10.3 g of methyl pyruvate and 4.5 g of methyl glycerate.

[0061] Example:

[0062]

[0063] Under nitrogen protection at room temperature, 14.8 g of sodium methoxide and 8.1 g of solid formaldehyde were placed in 80 mL of dry methanol. 20.0 g of methyl glycolate was added dropwise to the system under rapid mechanical stirring and reflux, and the reaction was stirred for 6 hours. After cooling the mixture to room temperature, 30% hydrochloric acid solution was added to adjust the pH to 2-3, and the reaction was continued under reflux and stirring overnight. The system was concentrated, and 100 mL of ethyl acetate was added under rapid stirring. The mixture was filtered through diatomaceous earth to remove salts. The supernatant was concentrated and eluted with hexane-ethyl acetate on silica gel column chromatography to give 11.8 g of methyl pyruvate and 8.1 g of methyl methylglycerate.

[0064] It should be emphasized that the above embodiments are merely exemplary and not limiting. Based on the disclosure of this application, any adjustments or changes to the reaction conditions or parameters that a person skilled in the art might normally adopt will not deviate from the spirit of the invention. The scope of protection of this patent shall be determined by the relevant claims.

Claims

1. A novel process for preparing glyceric acid (ester) and glycerol. As shown in reaction formula (I), the glycolate type substance represented by structural formula A reacts with formaldehyde under reaction conditions to obtain glyceric acid (ester) represented by structural formula B; subsequently, B and reducing agent [H] undergo a reduction reaction under reaction conditions to obtain a series of glycerol products represented by structural formula C: R1 or R2 are independent of each other and are either hydrogen or aliphatic or aromatic hydrocarbon groups containing 1-24 carbon atoms; [H] is any reducing agent that can reduce a carbonyl group (C=O) to the corresponding methylene group (CH2); conditions refer to at least one of the following: additives, light, heat, microwave, ultrasound, vacuum or pressure, solvent, etc.

2. A novel process for preparing pyruvate (ester). As shown in reaction formula (II), the glycolate type substance represented by structural formula A reacts with formaldehyde under reaction conditions to obtain the glyceric acid (ester) represented by structural formula B; subsequently, B undergoes dehydration isomerization to generate pyruvate D or its ester.

3. According to claims (1-2), the additive is a catalyst or accelerator; based on raw material A, the amount of the additive used is a catalytic amount, an equivalent amount, or an excess amount (0.001-100 equivalents). Preferably, the catalyst or accelerator is a Lewis acid or Lewis base compound; light refers to the reaction system being carried out under light irradiation conditions, with a wavelength range of 200-780 nm; heat refers to the reaction system being carried out under heating conditions, with a reaction temperature of -25-450 degrees Celsius; microwave or ultrasound refers to the use of a microwave or ultrasound generator to irradiate the reaction system; pressure refers to the reaction system being carried out under pressure or a certain vacuum condition, with the reaction process pressure being 0.001-200 atmospheres; the solvent is selected from at least one of substituted or non-substituted aromatic hydrocarbons, straight-chain or branched aliphatic hydrocarbons, (sulfoxide) sulfones, amides, ethers, alcohols, esters, ketones, nitriles, carboxylic acids, water, amines, carbonates, ionic liquids, and supercritical carbon dioxide containing 1-24 carbon atoms; or the liquid substrate itself simultaneously acts as a solvent medium.

4. According to claim (1), an exemplary, and not limiting, example of a glyceric acid or ester compound B that can be synthesized via the technique disclosed in this invention is the following structure:

5. According to claim (1), an exemplary, and not limiting, example of a glycerol compound C that can be synthesized via the technique disclosed in this invention has the following structure:

6. According to claim (2), a preferred example of pyruvate (ester) D that can be synthesized via the technology disclosed in this invention is pyruvate or methyl pyruvate.

7. According to claim (1), a preferred embodiment of the general reaction formula (I) is (IA), namely, methyl glycolate is used as a raw material and undergoes a hydroxymethylation reaction to obtain methyl glycerate, which is then subjected to a hydrogenation reduction reaction to obtain a glycerol product:

8. According to claim (1), another preferred embodiment of the general reaction formula (I) is (IB), that is, using methyl methyl glycolate as a raw material, it undergoes a hydroxymethylation reaction to obtain methyl methyl glycerate, which is then subjected to a hydrogenation reduction reaction to obtain methyl glycerol product:

9. According to claim (2), a preferred embodiment of the general reaction formula (II) is (IIA), namely, methyl glycolate is used as a raw material and undergoes a hydroxymethylation reaction to obtain methyl glycerate, which is then subjected to elimination and isomerization reactions to obtain methyl pyruvate (preferably R2 is hydrogen or methyl):

10. According to claim (2), another preferred embodiment of the general reaction formula (II) is (IIB), which involves using methyl glycolate A as a raw material and undergoing hydroxymethylation and dehydration isomerization to co-produce methyl glycerate B and methyl pyruvate D (preferably R2 is hydrogen or methyl):

11. The use of compounds glyceric acid (ester) B, glycerol C, and pyruvate (ester) D obtained by the process technology disclosed in this invention as organic synthesis raw materials or synthesizers according to claims (1-2).

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