A method for preparing chiral D- / L-glyceric acid by catalytic conversion of D- / L-xylose, D- / L-arabinose and D- / L-ribose

Abstract

A method for preparing chiral D- / L-glyceric acid by catalytic conversion of D- / L-xylose, D- / L-arabinose, and D- / L-ribose. First, an Ag / Al2O3 catalyst was designed and prepared using a sedimentation precipitation method. D- / L-xylose, D- / L-arabinose, and D- / L-ribose were used as raw materials, and water was used as the reaction solvent. Chiral D- / L-glyceric acid was prepared in an autoclave under an oxygen atmosphere. Ag / Al2O3 efficiently catalyzes the conversion of D- / L-xylose, D- / L-arabinose, and D- / L-ribose to chiral D- / L-glyceric acid. Under optimal conditions, the molar yield of chiral D-glyceric acid obtained using D-xylose as the raw material reached 86.8%, with an ee value of >99%.

Description

Technical Field

[0001] The present invention relates to the preparation of a catalyst for efficiently catalyzing the conversion of D- / L-xylose, D- / L-arabinose and D- / L-ribose to prepare chiral D- / L-glyceric acid, and a method for catalyzing the conversion of D- / L-xylose, D- / L-arabinose and D- / L-ribose to prepare chiral D- / L-glyceric acid. Background Art

[0002] Glyceric acid contains both hydroxyl and carboxyl functional groups, allowing it to undergo a variety of chemical reactions, including esterification, acetalization, and dehydration. It is an important chemical intermediate and raw material for organic synthesis, widely used in chemical synthesis, cosmetics, and pharmaceutical synthesis. Glyceric acid and its derivatives also have important biological applications. Glyceric acid has two enantiomers: D-glyceric acid and L-glyceric acid, with significantly different chemical properties. Therefore, D-glyceric acid and L-glyceric acid have different applications. For example, in the pharmaceutical field, D-glyceric acid can enhance the vitality of human gastric cells after stimulation by ethanol, thereby promoting the metabolism of ethanol and acetaldehyde, thus having the effect of detoxifying alcohol and protecting the liver. Therefore, it can be used as an ingredient in alcohol detoxification drugs. D-glyceric acid also stimulates liver regeneration and reduces sterol levels. L-glyceric acid can be used as a primary raw material for additional chemicals such as phosphatidylcholine analogs and optically pure L-hexose. Research has shown that other enantiomerically pure substances synthesized from L-glyceric acid play an important role in many chemical, pharmacological, and biological applications.

[0003] The production methods of glyceric acid are mainly divided into microbial methods and chemical synthesis methods. The microbial method uses biomass or other biomass-derived small molecule compounds (such as glycerol) as a carbon source and produces glyceric acid through enzymatic catalysis. The microbial method can produce high-purity D-glyceric acid solutions. However, the microbial method is inefficient, has a long production cycle, is costly, and is difficult to scale up. The chemical synthesis method mainly uses glycerol as the raw material and produces the glyceric acid product by catalyzing the selective oxidation of glycerol with a designed efficient catalyst. Currently, there are many reports on the chemical method for preparing glyceric acid from glycerol. For example, using glycerol as a raw material, Au / TiO2 as a catalyst, and a trickle bed as a continuous reactor, glyceric acid can be obtained by catalytic oxidation of glycerol with a selectivity of 53% (Topics in Catalysis, 2009, 52(3): 269-277); using Pt-CeO2 / CNT catalyst, glycerol can be catalytically oxidized to obtain glyceric acid with a selectivity of 78% (ACS Catal. 2020, 10, 3832-3837); by regulating the Co / Si ratio in the Pt-Co / MCM-41 bimetallic catalyst, under optimal conditions, the selectivity of glyceric acid can reach 85.2% (Catal. Sci. Technol., 2019, 9, 4909). However, since the glycerol molecule does not have a chiral carbon atom, the glyceric acid obtained using glycerol as a raw material is almost a racemic mixture with low optical purity.

[0004] Based on the above research, it is shown that it is of great significance to develop a high-performance, low-cost chemical synthesis method for chiral D-glyceric acid. Sugars are widely present in biomass and are one of the important platform chemicals obtained after biomass hydrolysis. For example, wood cellulosic biomass contains a large amount of hemicellulose components, of which D-xylose is its main structural unit. D-xylose is also the second most abundant monosaccharide in nature after glucose and is an economical chemical renewable resource. Biomass-based sugars have rich and diverse structures, especially containing multiple chiral centers. By making full use of the natural chiral structure of D-xylose, it is expected to obtain chiral glyceric acid by regulating the selective cleavage of the CC bond during the conversion of xylose without adding additional chiral catalysts.

[0005] In light of this, the present invention uses inexpensive D-xylose as the reaction raw material, designs a γ-alumina-supported silver-based catalyst (Ag / Al2O3), uses water as the solvent, and uses Na2CO3 as a reaction aid. Under relatively mild reaction conditions, chiral D- / L-glyceric acid is obtained with high yield and selectivity. The solid catalyst can be directly separated from the reaction solution by vacuum filtration, facilitating product purification and catalyst reuse. Summary of the Invention

[0006] The present invention designs and prepares a highly efficient Ag / Al2O3 catalyst for catalyzing the conversion of D- / L-xylose, D- / L-arabinose, and D- / L-ribose to produce chiral D- / L-glyceric acid. The catalyst is simple, easy to prepare, and low-cost; it also has high catalytic efficiency, and the resulting D-glyceric acid product has high yield and enantioselectivity. Furthermore, after the reaction, the catalyst can be recovered by simple filtration, resulting in a high reusability. This method overcomes the shortcomings of traditional chemical synthesis methods, which typically produce racemic mixtures using glycerol as a raw material, and also overcomes the shortcomings of microbial methods, which have low production efficiency and high costs. This method does not require the addition of complex chiral catalysts used in traditional asymmetric synthesis, and is highly economical.

[0007] Key points of the invention: γ-alumina solid is added to 40 mL of water, along with the surfactant polyvinylpyrrolidone K30. Aqueous solutions of silver nitrate and sodium carbonate are slowly added dropwise while stirring, and the mixture is stirred for three hours. The solid separated by filtration is placed in an oven and dried at 80°C for 10 hours. The dried solid is ground and calcined in a muffle furnace at 450°C for 2 hours (heating rate 5°C / min) to produce an Ag / Al2O3 catalyst.

[0008] 100 mg of D-xylose, Na2CO3, and the Ag / Al2O3 catalyst prepared according to the above method were added to 50 mL of water and heated in a sealed autoclave under an initial oxygen atmosphere of 0.1-3.0 MPa. The catalyst loading was 1-20 wt%, the catalyst calcination temperature was 50-600°C, the reaction temperature was 50-200°C, the reaction time was 1-300 min, the catalyst dosage was 10-200 mg, and the Na2CO3 dosage was 0.1-8 mmol. After the reaction, the autoclave was cooled to room temperature and filtered under reduced pressure to obtain a solid catalyst. The solid catalyst was dried in an oven at 80°C for 10 h and then calcined in a muffle furnace at 450°C for 2 h before being used in the next catalytic reaction. The small molecule products in the filtered reaction solution were detected by HPLC.

[0009] In the present invention, the reaction temperature is selected to be 50-200°C. At lower reaction temperatures, the xylose conversion rate, glyceric acid yield, and ee value of D-glyceric acid are all low; while at reaction temperatures exceeding 200°C, the xylose conversion rate, glyceric acid yield, and ee value of D-glyceric acid all decrease as the temperature rises.

[0010] In the present invention, the amount of Na2CO3 used is 0.1 to 8 mmol. When the amount of Na2CO3 added is less than 0.1 mol, the xylose conversion rate, glyceric acid yield, and ee value of D-glyceric acid are all low; when the amount of Na2CO3 used exceeds 8 mmol, the glyceric acid yield is significantly reduced.

[0011] In the present invention, the reaction time is selected to be 1 to 300 minutes. If the reaction temperature is stopped within 1 minute of reaching the target temperature, the xylose conversion is incomplete and the glyceric acid yield is low. When the reaction time exceeds 300 minutes, the xylose conversion rate and the glyceric acid yield remain essentially unchanged.

[0012] In the present invention, the catalyst loading is selected to be 1 to 20 wt%. When the silver loading is less than 1 wt%, the xylose conversion rate, glyceric acid yield, and ee value of D-glyceric acid are all low; while when the catalyst loading exceeds 20 wt%, the xylose conversion rate and glyceric acid yield decrease as the loading increases.

[0013] In the present invention, the catalyst calcination temperature is selected to be 50-600°C. When the catalyst calcination temperature is lower than 50°C, the xylose conversion rate, glyceric acid yield, and ee value of D-glyceric acid increase with increasing catalyst calcination temperature; however, when the catalyst calcination temperature exceeds 600°C, the xylose conversion rate and glyceric acid yield decrease.

[0014] In the present invention, the catalyst dosage is selected to be 10 to 200 mg. When the catalyst dosage is less than 10 mg, the xylose conversion rate and glyceric acid yield are both low; when the catalyst dosage exceeds 200 mg, the xylose conversion rate and glyceric acid yield decrease as the catalyst dosage increases.

[0015] In the present invention, the initial oxygen pressure is selected to be 0.1-3 MPa. When the oxygen pressure is lower than 0.1 MPa, the xylose conversion rate and glyceric acid yield are low; when the oxygen partial pressure is greater than 3 MPa, the xylose conversion rate and glyceric acid yield decrease instead.

[0016] The catalytic system of the present invention is also applicable to L-xylose, D- / L-arabinose and D- / L-ribose, and the optimal conditions for catalytic conversion of D-xylose to prepare chiral D-glyceric acid are also applicable to catalytic conversion of L-xylose, D- / L-arabinose and D- / L-ribose to prepare D- / L-glyceric acid. DETAILED DESCRIPTION

[0017] Example 1:

[0018] 1) In a 100 mL autoclave, 100 mg of D-xylose, 100 mg of Ag / Al2O3 catalyst (catalyst Ag loading of 8 wt%, catalyst calcination temperature of 450°C), and 2 mmol of Na2CO3 were added, followed by 50 mL of deionized water. The autoclave was sealed, and oxygen was introduced to maintain a pressure of 1.0 MPa. The temperature was raised to 80°C with stirring, and the reaction was continued for 120 minutes. The autoclave was then removed from the heating device and naturally cooled to room temperature. The autoclave was opened, and the solid-liquid mixture in the autoclave was separated by vacuum filtration to obtain a solid residue and a product mixture.

[0019] 2) The collected solid residue was washed three times with deionized water, placed in an oven, dried, and then calcined in a muffle furnace at 450°C for 2 hours for use in the next catalytic reaction. The small molecule product in the reaction solution was analyzed by HPLC, and the results are shown in Table 1 (yields in the table are molar yields, product yield = amount of product obtained / amount of raw material added × 100%).

[0020] Table 1

[0021] Implementation Cases Conversion rate Glyceric acid glycolic acid Formic acid oxalic acid ee value 1 81.1％ 76.9％ 19.5％ 41.9％ 56.3％ 95.0％

[0022] Example 2-5:

[0023] The experimental steps are the same as those in Example 1, except that the reaction temperature is different. Other conditions remain unchanged. The specific results are listed in Table 2 (the yield in the table is molar yield).

[0024] Table 2

[0025] Implementation Cases Reaction temperature Conversion rate Glyceric acid glycolic acid Formic acid oxalic acid ee value 2 70℃ 73.8％ 72.7％ 18.8％ 45.6％ 46.4％ 94.4％ 3 90℃ 92.3％ 80.1％ 24.5％ 43.1％ 64.0％ 96.2％ 4 100℃ 96.3％ 78.5％ 28.8％ 49.2％ 67.6％ >99％ 5 110℃ 99.2％ 71.5％ 33.1％ 60.0％ 71.6％ >99％

[0026] Examples 6-9:

[0027] The experimental steps are the same as those in Example 3, except that the amount of Na2CO3 used is different. Other conditions remain unchanged. The specific results are listed in Table 3 (the yield in the table is molar yield).

[0028] Table 3

[0029] Implementation Cases <![CDATA[Dosage of Na2CO3]]> Conversion rate Glyceric acid glycolic acid Formic acid oxalic acid ee value 6 1mmol 68.0％ 66.1％ 17.9％ 45.6％ 40.1％ 91.1％ 7 1.5mmol 86.3％ 76.7％ 22.0％ 46.5％ 52.5％ 94.3％ 8 2.5mmol 94.8％ 81.1％ 26.9％ 42.1％ 70.0％ >99％ 9 3mmol 95.2％ 77.6％ 27.0％ 33.8％ 73.4％ >99％

[0030] Examples 10-16:

[0031] The experimental steps are the same as those in Example 8, except that the reaction time is different. Other conditions remain unchanged. The specific results are listed in Table 4 (the yield in the table is molar yield).

[0032] Table 4

[0033] Implementation Cases Reaction time Conversion rate Glyceric acid glycolic acid Formic acid oxalic acid ee value 10 1min 34.4％ 30.6％ 9.5％ 14.7％ 15.7％ >99％ 11 10min 57.3％ 57.7％ 11.8％ 19.7％ 35.2％ >99％ 12 20min 74.0％ 69.9％ 15.6％ 26.2％ 46.4％ >99％ 13 30min 86.7％ 72.8％ 20.1％ 38.0％ 69.1％ >99％ 14 60min 93.1％ 78.3％ 23.3％ 41.4％ 64.8％ >99％ 15 90 minutes 92.7％ 82.6％ 24.8％ 38.8％ 69.3％ >99％ 16 150min 95.9％ 81.4％ 29.2％ 45.0％ 72.6％ >99％

[0034] Examples 17-21:

[0035] The experimental steps are the same as those in Example 15, except that the catalyst loading is different. Other conditions remain unchanged. The specific results are listed in Table 5 (the yield in the table is molar yield).

[0036] Table 5

[0037] Implementation Cases Catalyst loading Conversion rate Glyceric acid glycolic acid Formic acid oxalic acid ee value 17 1wt% 69.9％ 26.0％ 49.6％ 36.3％ 46.4％ 89.6％ 18 3wt% 86.8％ 65.0％ 29.3％ 47.5％ 55.5％ 94.1％ 19 5wt% 94.5％ 73.5％ 23.7％ 38.3％ 65.3％ >99％ 20 12wt% 94.2％ 73.6％ 20.6％ 33.5％ 64.1％ >99％ 21 15wt% 97.3％ 67.5％ 23.4％ 36.4％ 60.2％ 98.1％

[0038] Examples 22-26:

[0039] The experimental procedure is the same as that of Example 15, except that the catalyst calcination temperature is different. Other conditions remain unchanged. The specific results are listed in Table 6 (the yield in the table is molar yield).

[0040] Table 6

[0041] Implementation Cases Catalyst calcination temperature Conversion rate Glyceric acid glycolic acid Formic acid oxalic acid ee value 22 100℃ 89.2％ 66.7％ 29.8％ 37.8％ 55.0％ 56.1％ 23 200℃ 90.5％ 68.6％ 30.6％ 35.1％ 52.5％ 56.1％ 24 300℃ 98.9％ 77.3％ 28.9％ 38.4％ 69.1％ 84.7％ 25 400℃ 100％ 82.7％ 30.2％ 41.0％ 75.6％ >99％ 26 500℃ 100％ 83.9％ 29.0％ 38.1％ 74.0％ >99％

[0042] Examples 27-30:

[0043] The experimental procedure is the same as that of Example 15, except that the amount of catalyst used is different. Other conditions remain unchanged. The specific results are listed in Table 7 (the yield in the table is molar yield).

[0044] Table 7

[0045] Implementation Cases Catalyst dosage Conversion rate Glyceric acid glycolic acid Formic acid oxalic acid ee value 27 40mg 82.2％ 55.5％ 27.1％ 34.2％ 41.7％ >99％ 28 60mg 91.5％ 75.1％ 27.3％ 32.5％ 62.3％ >99％ 29 80mg 100.0％ 86.8％ 26.2％ 34.7％ 74.8％ >99％ 30 120mg 97.7％ 81.6％ 29.4％ 39.3％ 71.1％ >99％

[0046] Examples 31-34:

[0047] The experimental procedure is the same as that of Example 29, except that the catalyst is reused a different number of times. Other conditions remain unchanged. The specific results are listed in Table 8 (the yield in the table is molar yield).

[0048] Table 8

[0049] Implementation Cases Initial oxygen pressure Conversion rate Glyceric acid glycolic acid Formic acid oxalic acid ee value 31 0.4MPa 72.2％ 44.2％ 20.1％ 11.6％ 36.6％ >99％ 32 0.6MPa 63.3％ 54.7％ 11.9％ 12.2％ 38.9％ >99％ 33 0.8MPa 94.4％ 79.2％ 28.2％ 36.1％ 72.2％ >99％ 34 1.2MPa 100％ 78.1％ 27.6％ 36.7％ 70.1％ >99％

[0050] Examples 35-37:

[0051] The experimental procedure is the same as that of Example 29, except that the catalyst is reused a different number of times. Other conditions remain unchanged. The specific results are listed in Table 9 (the yield in the table is molar yield).

[0052] Table 9

[0053] Implementation Cases Number of cycles Conversion rate Glyceric acid glycolic acid Formic acid oxalic acid ee value 35 1 98.6％ 86.2％ 26.4％ 35.9％ 80.0％ >99％ 36 2 92.3％ 83.7％ 30.9％ 40.9％ 79.1％ >99％ 37 3 93.2％ 84.3％ 29.2％ 38.7％ 78.9％ >99％

[0054] Examples 38-42:

[0055] The experimental procedure is the same as that of Example 29, except that different reaction substrates are used. Other conditions remain unchanged. The specific results are listed in Tables 10 and 11 (the yields in the tables are molar yields).

[0056] Table 10

[0057] Implementation Cases Reaction substrate Conversion rate Glyceric acid glycolic acid Formic acid oxalic acid D-glyceric acid ee value 38 D-arabinose 88.2％ 47.2％ 38.8％ 55.0％ 66.6％ >99％ 39 D-ribose 70.4％ 38.1％ 34.9％ 52.9％ 50.4％ >99％

[0058] Table 11

[0059] Implementation Cases Reaction substrate Conversion rate Glyceric acid glycolic acid Formic acid oxalic acid L-glyceric acid ee value 40 L-Xylose 91.3％ 75.1％ 31.2％ 44.6％ 67.0％ >99％ 41 L-arabinose 94.7％ 48.0％ 43.2％ 54.9％ 75.3％ >99％ 42 L-ribose 85.3％ 31.6％ 40.4％ 60.0％ 72.9％ >99％

Claims

1. A method for preparing chiral D- / L-glyceric acid by catalytic conversion of D- / L-xylose, D- / L-arabinose, and D- / L-ribose, characterized in that A Ag / Al2O3 catalyst was designed and prepared by a deposition precipitation method for subsequent catalytic reactions. Chiral D- / L-glyceric acid was prepared in a closed autoclave under an oxygen atmosphere using D- / L-xylose, D- / L-arabinose, and D- / L-ribose as raw materials and water as solvent. The amount of substrate was 100 mg, the silver loading in the catalyst was 1-20 wt%, the amount of catalyst was 10-200 mg, the amount of Na2CO3 was 0.1-8 mmol, the reaction time was 1-300 min, the reaction temperature was 50-200°C, the catalyst was calcined at 50-600°C, and the initial oxygen pressure was 0.1-3.0 MPa.