Method for preparing diol and derivatives thereof through photocatalytic decarboxylation

Abstract

The invention relates to a method for preparing diol and derivatives thereof through photocatalytic decarboxylation. The method comprises the following steps: taking a carboxylic acid compound with hydroxyl and a derivative thereof as raw materials, carrying out decarboxylation reaction on a photocatalyst under an illumination condition to generate a carbon free radical intermediate, and then carrying out coupling reaction to generate diol and a derivative thereof. According to the method, the low-carbon carboxylic acid compound obtained by biomass fermentation can be used as a reaction raw material, the reaction condition is mild, an expensive and toxic additive is not needed, the product yield is relatively high, and the catalyst can be recycled after being filtered after the reaction and can be recycled for multiple times after being cleaned and dried. # imgabs0 #

Description

Technical Field

[0001] The invention relates to a method for preparing diol and its derivatives, and in particular to a method for preparing diol and its derivatives by photocatalytic decarboxylation. Technical Background

[0002] Diols and their derivatives are important organic and chemical raw materials, and are widely used in the fields of medicine, textiles, automobiles and daily chemicals. The domestic demand is growing. For example, 1,4-butanediol and 1,6-hexanediol are monomers for the synthesis of high-performance polyesters and polyurethanes. They are also used as plasticizers, curing agents, additives for medicines and cosmetics, etc. Taking the production of 1,4-butanediol as an example, its current main production processes include: (1) the Peppe method using acetylene and formaldehyde as raw materials, in which acetylene and formaldehyde are synthesized into butynediol under the action of copper catalyst, and then hydrogenated to produce 1,4-butanediol. This process was first industrialized by BASF in Germany; (2) the Davy-Mckee method using maleic anhydride and methanol as raw materials, in which maleic anhydride and methanol undergo esterification to produce maleic acid diesters, which are then hydrogenated to produce 1,4-butanediol; (3) the Mitsubishi method using butadiene and acetic acid as raw materials. Chemical method, butadiene undergoes acetyl oxidation reaction under the action of palladium catalyst to produce 1,4-diacetoxy-2-butene, which is then hydrogenated and hydrolyzed to produce 1,4-butanediol; (4) Lyondell method using propylene oxide as raw material, propylene oxide is first isomerized to allyl alcohol at high temperature, and then undergoes hydroformylation reaction in the presence of rhodium catalyst, and then purified and hydrogenated to produce 1,4-butanediol. 1.6-Hexanediol is mainly prepared by hydrogenation reduction of dimethyl adipate, which is mainly prepared by cyclohexane oxidation ring opening. In summary, the current production of diols mainly relies on petroleum or coal-based raw materials, and the process often involves high temperature and high pressure hydrogenation process.

[0003] It is particularly important to develop green and environmentally friendly production processes and renewable clean energy. A large amount of biomass resources are available in nature, which can be converted into various useful chemicals through appropriate treatment and catalytic reactions, while reducing our dependence on non-renewable fossil resources. For example, carbohydrates such as glucose can be converted into γ-hydroxycarboxylic acid compounds of different chain lengths through a biological fermentation process. On the other hand, photocatalysis can use light as a driving force to achieve various chemical conversions under very mild conditions, and is considered to be a green and low-carbon conversion method. Therefore, the use of photocatalytic methods to achieve the conversion of biomass resources under mild conditions and prepare high-value-added chemicals, such as the above-mentioned diols and their derivatives, has important scientific research significance and industrial application value. Summary of the invention

[0004] The significance of the present invention is that diols and their derivatives can be prepared under mild conditions (normal temperature and pressure) by using a photocatalytic method, and the product yield can reach up to 78%, and the method can use carboxylic acid compounds with hydroxyl functional groups obtained by biomass fermentation as raw materials. The catalyst can be recycled for multiple times after simple separation and cleaning after the reaction.

[0005] The photocatalytic decarboxylation to prepare diols and their derivatives involved in the present invention can be achieved by the following scheme. After mixing the carboxylic acid raw material, photocatalyst and solvent, put them into a quartz reactor, replace the atmosphere in the reactor with a specific atmosphere, stir, and irradiate with an external light source for a period of time at a certain temperature to cause a decarboxylation reaction to generate the target product, and use chromatography to detect the product. The carboxylic acid raw material is one or more of 3-hydroxypropionic acid, 4-hydroxybutyric acid, 3-hydroxybutyric acid, 3-methoxypropionic acid, 3-ethoxypropionic acid, 3-phenoxypropionic acid, 3-acetoxypropionic acid, 4-methoxybutyric acid and 3-methoxybutyric acid; the initial reaction concentration of the carboxylic acid raw material is 0.02-0.5 mol / L; the photocatalyst is a metal-modified titanium dioxide catalyst; wherein the titanium dioxide is one or more of TiO2-A (anatase phase TiO2), TiO2-R (rutile phase TiO2), P25 (mixed phase TiO2 of anatase phase and rutile phase); the metal The metal in the surface-modified titanium dioxide is one or more of Pt, Pd, Ru, Rh, Au, Ag, and Ni; the loading amount of the metal is 0.1-10.0wt% (based on the mass of the titanium dioxide carrier); the solvent is one or more of acetonitrile, 1,2-dichloroethane, dichloromethane, ethyl acetate, trifluorotoluene, and n-hexane; the reaction atmosphere is nitrogen or argon, and the reaction pressure is 0.1-0.5MPa; the external light source is one or more of LED (central wavelength 365nm), xenon lamp (300W) and high-pressure mercury lamp; and the reaction temperature is 15-60°C.

[0006] Preferably: the carboxylic acid raw material is preferably one or more of 4-hydroxybutyric acid, 3-methoxypropionic acid, 3-ethoxypropionic acid, 3-phenoxypropionic acid, 3-acetoxypropionic acid, 4-methoxybutyric acid and 3-methoxybutyric acid; the initial reaction concentration of the carboxylic acid raw material is preferably 0.05-0.3 mol / L; the photocatalyst is a metal-modified titanium dioxide catalyst; wherein the titanium dioxide is preferably one or two of TiO2-A (anatase phase TiO2) and P25 (mixed phase of anatase phase and rutile phase TiO2); the metal The metal in the surface-modified titanium dioxide is preferably one or more of Pt, Pd, Ru, and Rh; the metal loading is preferably 0.1-5.0wt% (based on the mass of the titanium dioxide carrier); the solvent is preferably one or more of acetonitrile, trifluorotoluene, and n-hexane; the reaction atmosphere is nitrogen or argon, and the reaction pressure is preferably 0.1-0.3MPa; the external light source is preferably one or both of LED (central wavelength 365nm) and xenon lamp (300W); and the reaction temperature is preferably 15-40°C.

[0007] The best is: the best carboxylic acid raw material is one or more of 3-methoxypropionic acid, 3-ethoxypropionic acid, 3-phenoxypropionic acid and 4-methoxybutyric acid; the best initial reaction concentration of the carboxylic acid raw material is 0.05-0.15 mol / L; the photocatalyst is a metal-modified titanium dioxide catalyst; the best titanium dioxide is P25 (TiO2 mixed with anatase phase and rutile phase); the best metal in the titanium dioxide modified with metal surface is one or two of Pt and Ru; the best metal loading is 0.5-2.0wt% (based on the mass of the titanium dioxide carrier); the best solvent is one or two of acetonitrile and n-hexane; the reaction atmosphere is nitrogen or argon, and the best reaction pressure is 0.1-0.15MPa; the best external light source is LED (central wavelength 365nm); the best reaction temperature is 20-30℃.

[0008] Taking the conversion of 3-hydroxypropionic acid as an example, the conversion process is shown in Formula 1. Under the irradiation of light, the semiconductor TiO2 is excited to produce photogenerated electrons and holes. 3-Hydroxypropionic acid undergoes dissociative adsorption on the TiO2 surface, and then is oxidized by holes to undergo decarboxylation to generate carbon free radicals, which then undergo dimerization to generate 1,4-butanediol. The photogenerated electrons will migrate to the loaded metal, reduce protons, and release hydrogen as a by-product. The rapid precipitation of hydrogen is conducive to inhibiting the formation of by-products.

[0009]

[0010] Formula 1 is the reaction process of photocatalytic decarboxylation of 3-hydroxypropionic acid to produce 1,4-butanediol.

[0011] The photogenerated holes on the photocatalyst have strong oxidizing properties. In addition to initiating decarboxylation reactions, they also deoxidize the hydroxyl groups in the substrate and product to generate corresponding aldehydes, resulting in reduced product selectivity. For example, 3-hydroxypropionic acid will be oxidized to 3-oxypropionic acid, and the resulting product 1,4-butanediol will be oxidized to 1,4-butanedialdehyde, etc. If the hydroxyl groups in the substrate are etherified, the side reaction of hydroxyl oxidation can be avoided. However, the product obtained by the decarboxylation dimerization reaction is a diether. For example, 3-methoxypropionic acid, a derivative of 3-hydroxypropionic acid, is converted into 1,4-dimethoxybutane. These diethers are also very important chemicals and can be used as solvents, fuel additives, etc. After a simple hydrolysis reaction, the diether can be converted into the corresponding diol product.

[0012] The method of the present invention uses carboxylic acid compounds and derivatives thereof with hydroxyl groups as raw materials, and a decarboxylation reaction occurs on a photocatalyst under light conditions to produce a carbon free radical intermediate, and then a coupling reaction occurs to produce diols and derivatives thereof. The present invention can use low-carbon carboxylic acid compounds obtained by biomass fermentation as reaction raw materials, the reaction conditions are mild, no expensive and toxic additives are required, and the product yield is high. After the reaction, the catalyst can be filtered to recover the catalyst, and can be recycled for multiple times after cleaning and drying.

[0013]

[0014] Compared with the existing preparation methods of diols and their derivatives, the present invention has the following advantages:

[0015] 1. The reaction conditions are mild, avoiding harsh reaction conditions such as high temperature and high pressure, and can be efficiently converted at room temperature (15-40°C) and normal pressure (≤0.2MPa);

[0016] 2. The reaction raw materials do not rely on fossil resources. The reaction substrate hydroxycarboxylic acid can be directly produced from biomass such as glucose by biological fermentation;

[0017] 3. The substrate has a wide range of applications and can be used to prepare diols and their derivatives with different structures;

[0018] 4. In addition to the target product, the process will co-produce a large amount of H2, which can be used as green fuel; DETAILED DESCRIPTION

[0019] In order to further explain the present invention in detail, several specific embodiments are given below, but the present invention is not limited to these embodiments.

[0020] Example 1

[0021] The catalyst Pt / P25 was prepared by an impregnation calcination method, that is, the carrier titanium dioxide P25 was dispersed in a 0.0013 mol / L chloroplatinic acid aqueous solution, the solvent was evaporated, and the obtained powder solid was calcined in an air atmosphere at 400°C for 2 hours and in a hydrogen atmosphere at 350°C for 4 hours.

[0022] 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-hydroxypropionic acid and 5 mg of catalyst Pt / P25 (Pt content in the catalyst is 1 wt%) were added to a transparent quartz reaction tube, and the internal atmosphere was replaced with argon (0.1 MPa). The quartz reaction tube was sealed and stirred. The reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm) irradiation, the product was detected by chromatography. The raw material conversion rate was 81%, and the yield of the product 1,4-butanediol was 36%.

[0023] Example 2

[0024] The catalyst was prepared by the preparation method of the catalyst Pt / P25 in Example 1.

[0025] 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-hydroxybutyric acid and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the internal atmosphere was replaced with argon (0.1 MPa). The tube was sealed and stirred. The reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm) irradiation, the product was detected by chromatography. The raw material conversion rate was 78%, and the yield of the product 2,5-hexanediol was 39%.

[0026] Example 3

[0027] The catalyst was prepared by the preparation method of the catalyst Pt / P25 in Example 1.

[0028] 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 4-hydroxybutyric acid and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the internal atmosphere was replaced with argon (0.1 MPa). The tube was sealed and stirred. The reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm) irradiation, the product was detected by chromatography. The raw material conversion rate was 94%, and the yield of the product 1,6-hexanediol was 45%.

[0029] Example 4

[0030] The catalyst was prepared by the preparation method of the catalyst Pt / P25 in Example 1.

[0031] 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-acetoxypropionic acid and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the internal atmosphere was replaced with argon (0.1 MPa). The tube was sealed and stirred. The reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm), the product was detected by chromatography. The raw material conversion rate was 80%, and the yield of the product 1.4-butanediol diacetate was 52%.

[0032] Example 5

[0033] The catalyst was prepared by the preparation method of the catalyst Pt / P25 in Example 1.

[0034] 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxybutyric acid and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the internal atmosphere was replaced with argon (0.1 MPa). The tube was sealed and stirred. The reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm) irradiation, the product was detected by chromatography. The raw material conversion rate was 82%, and the yield of the product 2,5-dimethoxyhexane was 55%.

[0035] Example 6

[0036] The catalyst was prepared by the preparation method of the catalyst Pt / P25 in Example 1.

[0037] 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-phenoxypropionic acid and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the internal atmosphere was replaced with argon (0.1 MPa). The tube was sealed and stirred. The reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm) irradiation, the product was detected by chromatography. The raw material conversion rate was 96%, and the yield of the product 1,4-diphenoxybutane was 65%.

[0038] Example 7

[0039] The catalyst was prepared by the preparation method of the catalyst Pt / P25 in Example 1.

[0040] 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the internal atmosphere was replaced with argon (0.1 MPa). The tube was sealed and stirred. The reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm) irradiation, the product was detected by chromatography. The raw material conversion rate was 94%, and the yield of the product 1,4-dimethoxybutane was 72%.

[0041] Example 8

[0042] The catalyst was prepared by the preparation method of the catalyst Pt / P25 in Example 1.

[0043] 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 4-methoxybutyric acid and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the internal atmosphere was replaced with argon (0.1 MPa). The tube was sealed and stirred. The reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm) irradiation, the product was detected by chromatography. The raw material conversion rate was 95%, and the yield of the product 1,6-dimethoxyhexane was 78%.

[0044] Example 9

[0045] The catalyst was prepared by the preparation method of the catalyst Pt / P25 in Example 1.

[0046] 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-ethoxypropionic acid and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the internal atmosphere was replaced with argon (0.1 MPa), sealed and stirred, and the reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm) irradiation, the product was detected by chromatography. The raw material conversion rate was 97%, and the yield of the product 1,4-diethoxybutane was 70%.

[0047] Example 10

[0048] The catalyst was prepared by the preparation method of the catalyst Pt / P25 in Example 1.

[0049] 1.2 mL of acetonitrile, 0.60 mmol (concentration of 0.5 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the internal atmosphere was replaced with argon (0.1 MPa). The tube was sealed and stirred. The reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm) irradiation, the product was detected by chromatography. The raw material conversion rate was 82%, and the yield of the product 1,4-dimethoxybutane was 42%.

[0050] Embodiment 11

[0051] The catalyst was prepared by the preparation method of the catalyst Pt / P25 in Example 1.

[0052] 1.2 mL of acetonitrile, 0.024 mmol (concentration of 0.02 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the internal atmosphere was replaced with argon (0.1 MPa). The tube was sealed and stirred. The reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm) irradiation, the product was detected by chromatography. The raw material conversion rate was 74%, and the yield of the product 1,4-dimethoxybutane was 46%.

[0053] Example 12

[0054] The catalyst was prepared by the preparation method of the catalyst Pt / P25 in Example 1.

[0055] 1.2 mL of acetonitrile, 0.36 mmol (concentration of 0.3 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the internal atmosphere was replaced with argon (0.1 MPa). The tube was sealed and stirred. The reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm) irradiation, the product was detected by chromatography. The raw material conversion rate was 92%, and the yield of the product 1,4-dimethoxybutane was 60%.

[0056] Example 13

[0057] The catalyst was prepared by the preparation method of the catalyst Pt / P25 in Example 1.

[0058] 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Pt / TiO2-R (1 wt%) were added to a quartz reaction tube, and the internal atmosphere was replaced with argon (0.1 MPa), sealed and stirred, and the reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm) irradiation, the product was detected by chromatography, the raw material conversion rate was 66%, and the yield of the product 1,4-dimethoxybutane was 32%.

[0059] Embodiment 14

[0060] The catalyst was prepared by the preparation method of the catalyst Pt / P25 in Example 1.

[0061] 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Pt / TiO2-A (1 wt%) were added to a quartz reaction tube, and the internal atmosphere was replaced with argon (0.1 MPa), sealed and stirred, and the reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm), the product was detected by chromatography. The raw material conversion rate was 90%, and the yield of the product 1,4-dimethoxybutane was 65%.

[0062] Embodiment 15

[0063] The preparation process and conditions of the catalyst are the same as those of the preparation of the catalyst Pt / P25 in Example 1, except that the metal precursor used is chloroauric acid (instead of chloroplatinic acid).

[0064] 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Au / P25 (1 wt%) were added to a quartz reaction tube, and the internal atmosphere was replaced with argon (0.1 MPa). The tube was sealed and stirred. The reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm) irradiation, the product was detected by chromatography. The raw material conversion rate was 51%, and the yield of the product 1,4-dimethoxybutane was 36%.

[0065] Example 16

[0066] The preparation process and conditions of the catalyst are the same as those of the preparation method of the catalyst Pt / P25 in Example 1, except that the metal precursor used is silver nitrate (instead of chloroplatinic acid). 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of the catalyst Ag / P25 (1 wt%) are added to a quartz reaction tube, and the inner atmosphere is replaced with argon (0.1 MPa), sealed, stirred, and the reaction temperature is 25°C. After reacting for 12 hours under LED (central wavelength 365 nm) irradiation, the product is detected by chromatography, and the raw material conversion rate is 81%, and the yield of the product 1,4-dimethoxybutane is 45%.

[0067] Embodiment 17

[0068] The preparation process and conditions of the catalyst are the same as those of the preparation method of the catalyst Pt / P25 in Example 1, except that the metal precursor used is nickel chloride (instead of chloroplatinic acid). 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Ni / P25 (1 wt%) are added to a quartz reaction tube, and the inner atmosphere is replaced with argon (0.1 MPa), sealed, stirred, and the reaction temperature is 25°C. After reacting for 12 hours under LED (central wavelength 365 nm) irradiation, the product is detected by chromatography, the raw material conversion rate is 53%, and the yield of the product 1,4-dimethoxybutane is 25%.

[0069] Embodiment 18

[0070] The preparation process and conditions of the catalyst are the same as those of the preparation method of the catalyst Pt / P25 in Example 1, except that the metal precursor used is palladium chloride (instead of chloroplatinic acid). 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Pd / P25 (1 wt%) are added to a quartz reaction tube, and the inner atmosphere is replaced with argon (0.1 MPa), sealed, stirred, and the reaction temperature is 25°C. After reacting for 12 hours under LED (central wavelength 365 nm) irradiation, the product is detected by chromatography, the raw material conversion rate is 87%, and the yield of the product 1,4-dimethoxybutane is 51%.

[0071] Embodiment 19

[0072] The preparation process and conditions of the catalyst are the same as those of the preparation method of the catalyst Pt / P25 in Example 1, except that the metal precursor used is rhodium chloride (instead of chloroplatinic acid). 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Rh / P25 (1 wt%) are added to a quartz reaction tube, and the inner atmosphere is replaced with argon (0.1 MPa), sealed, stirred, and the reaction temperature is 25 ° C. After reacting for 12 hours under LED (central wavelength 365 nm) irradiation, the product is detected by chromatography, the raw material conversion rate is 90%, and the yield of the product 1,4-dimethoxybutane is 54%.

[0073] Embodiment 20

[0074] The catalyst was prepared by the preparation method of catalyst Pt / P25 in Example 1. 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Pt / P25 (10 wt%) were added to a quartz reaction tube, and the inner atmosphere was replaced with argon (0.1 MPa), sealed, stirred, and the reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm), the product was detected by chromatography, the raw material conversion rate was 54%, and the yield of the product 1,4-dimethoxybutane was 34%.

[0075] Embodiment 21

[0076] The catalyst was prepared by the preparation method of catalyst Pt / P25 in Example 1. 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Pt / P25 (5 wt%) were added to a quartz reaction tube, and the inner atmosphere was replaced with argon (0.1 MPa), sealed, stirred, and the reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm), the product was detected by chromatography, the raw material conversion rate was 72%, and the yield of the product 1,4-dimethoxybutane was 42%.

[0077] Embodiment 22

[0078] The catalyst was prepared by the preparation method of catalyst Pt / P25 in Example 1. 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Pt / P25 (0.5 wt%) were added to a quartz reaction tube, and the inner atmosphere was replaced with argon (0.1 MPa), sealed, stirred, and the reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm), the product was detected by chromatography, the raw material conversion rate was 87%, and the yield of the product 1,4-dimethoxybutane was 61%.

[0079] Embodiment 23

[0080] The catalyst was prepared by the preparation method of catalyst Pt / P25 in Example 1. 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Pt / P25 (2 wt%) were added to a quartz reaction tube, and the inner atmosphere was replaced with argon (0.1 MPa), sealed, stirred, and the reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm), the product was detected by chromatography, the raw material conversion rate was 92%, and the yield of the product 1,4-dimethoxybutane was 70%.

[0081] Embodiment 24

[0082] The catalyst was prepared by the preparation method of catalyst Pt / P25 in Example 1. 1.2 mL of 1,2-dichloroethane, 0.12 mmol of 3-methoxypropionic acid (concentration of 0.1 mol / L) and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the inner atmosphere was replaced with argon (0.1 MPa), sealed, stirred, and the reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm), the product was detected by chromatography, the raw material conversion rate was 72%, and the yield of the product 1,4-dimethoxybutane was 38%.

[0083] Embodiment 25

[0084] The catalyst was prepared by the preparation method of catalyst Pt / P25 in Example 1. 1.2 mL of dichloromethane, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the inner atmosphere was replaced with argon (0.1 MPa), sealed, stirred, and the reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm), the product was detected by chromatography, the raw material conversion rate was 69%, and the yield of the product 1,4-dimethoxybutane was 34%.

[0085] Embodiment 26

[0086] The catalyst was prepared by the preparation method of catalyst Pt / P25 in Example 1. 1.2 mL of ethyl acetate, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the internal atmosphere was replaced with argon (0.1 MPa), sealed, stirred, and the reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm), the product was detected by chromatography, the raw material conversion rate was 80%, and the yield of the product 1,4-dimethoxybutane was 42%.

[0087] Embodiment 27

[0088] The catalyst was prepared by the preparation method of catalyst Pt / P25 in Example 1. 1.2 mL of trifluorotoluene, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the internal atmosphere was replaced with argon (0.1 MPa), sealed, stirred, and the reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm), the product was detected by chromatography, the raw material conversion rate was 84%, and the yield of the product 1,4-dimethoxybutane was 52%.

[0089] Embodiment 28

[0090] The catalyst was prepared by the preparation method of catalyst Pt / P25 in Example 1. 1.2 mL of n-hexane, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the inner atmosphere was replaced with argon (0.1 MPa), sealed, stirred, and the reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm), the product was detected by chromatography, the raw material conversion rate was 90%, and the yield of the product 1,4-dimethoxybutane was 63%.

[0091] Embodiment 29

[0092] The catalyst was prepared by the preparation method of catalyst Pt / P25 in Example 1. 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the inner atmosphere was replaced with argon (0.5 MPa), sealed, stirred, and the reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm), the product was detected by chromatography, the raw material conversion rate was 89%, and the yield of the product 1,4-dimethoxybutane was 55%.

[0093] Embodiment 30

[0094] The catalyst was prepared by the preparation method of catalyst Pt / P25 in Example 1. 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the inner atmosphere was replaced with argon (0.3 MPa), sealed, stirred, and the reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm), the product was detected by chromatography, the raw material conversion rate was 91%, and the yield of the product 1,4-dimethoxybutane was 60%.

[0095] Embodiment 31

[0096] The catalyst was prepared by the preparation method of catalyst Pt / P25 in Example 1. 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the internal atmosphere was replaced with nitrogen (0.1 MPa), sealed, stirred, and the reaction temperature was 25°C. After reacting for 12 hours under LED (central wavelength 365 nm), the product was detected by chromatography, the raw material conversion rate was 93%, and the yield of the product 1,4-dimethoxybutane was 68%.

[0097] Embodiment 32

[0098] The catalyst was prepared by the preparation method of catalyst Pt / P25 in Example 1. 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the inner atmosphere was replaced with argon (0.1 MPa), sealed, stirred, and the reaction temperature was 25°C. After reacting for 12 hours under high-pressure mercury lamp irradiation, the product was detected by chromatography, the raw material conversion rate was 78%, and the yield of the product 1,4-dimethoxybutane was 42%.

[0099] Embodiment 33

[0100] The catalyst was prepared by the preparation method of catalyst Pt / P25 in Example 1. 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the inner atmosphere was replaced with argon (0.1 MPa), sealed, stirred, and the reaction temperature was 25°C. After reacting for 12 hours under the irradiation of a xenon lamp (300 W), the product was detected by chromatography, the raw material conversion rate was 82%, and the yield of the product 1,4-dimethoxybutane was 57%.

[0101] Embodiment 34

[0102] The catalyst was prepared by the preparation method of catalyst Pt / P25 in Example 1. 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the inner atmosphere was replaced with argon (0.1 MPa), sealed, stirred, and the reaction temperature was 60°C. After reacting for 12 hours under LED (central wavelength 365 nm), the product was detected by chromatography, the raw material conversion rate was 78%, and the yield of the product 1,4-dimethoxybutane was 48%.

[0103] Embodiment 35

[0104] The catalyst was prepared by the preparation method of catalyst Pt / P25 in Example 1. 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the inner atmosphere was replaced with argon (0.1 MPa), sealed, stirred, and the reaction temperature was 40°C. After reacting for 12 hours under LED (central wavelength 365 nm), the product was detected by chromatography, the raw material conversion rate was 90%, and the yield of the product 1,4-dimethoxybutane was 62%.

[0105] Embodiment 35

[0106] The catalyst was prepared by the preparation method of catalyst Pt / P25 in Example 1. 1.2 mL of acetonitrile, 0.12 mmol (concentration of 0.1 mol / L) of 3-methoxypropionic acid and 5 mg of catalyst Pt / P25 (1 wt%) were added to a quartz reaction tube, and the inner atmosphere was replaced with argon (0.1 MPa), sealed, stirred, and the reaction temperature was 15°C. After reacting for 12 hours under LED (central wavelength 365 nm), the product was detected by chromatography, the raw material conversion rate was 80%, and the yield of the product 1,4-dimethoxybutane was 59%.

Claims

1. A method for preparing diols and their derivatives by photocatalytic decarboxylation, characterized in that: The method comprises the following steps: mixing a carboxylic acid raw material, a photocatalyst and a solvent, placing the mixture in a reactor, replacing the atmosphere in the reactor with an inert atmosphere gas, stirring the mixture, and irradiating the mixture with an external light source to cause a decarboxylation reaction to generate a target product.

2. The method according to claim 1, characterized in that: The carboxylic acid raw material is one or more of 3-hydroxypropionic acid, 4-hydroxybutyric acid, 3-hydroxybutyric acid, 3-methoxypropionic acid, 3-ethoxypropionic acid, 3-phenoxypropionic acid, 3-acetoxypropionic acid, 4-methoxybutyric acid and 3-methoxybutyric acid; The initial reaction concentration of the carboxylic acid raw material is 0.02-0.5 mol / L; The photocatalyst is a metal-modified titanium dioxide catalyst; wherein the titanium dioxide is one or more of TiO2-A (anatase phase TiO2), TiO2-R (rutile phase TiO2), P25 (mixed phase TiO2 of anatase phase and rutile phase); the metal in the titanium dioxide with metal surface modification is one or more of Pt, Pd, Ru, Rh, Au, Ag, Ni; the metal loading is 0.1-10.0wt% (based on the mass of the titanium dioxide carrier); The solvent is one or more of acetonitrile, 1,2-dichloroethane, dichloromethane, ethyl acetate, trifluorotoluene, and n-hexane; The reaction atmosphere is one or both of nitrogen and argon, and the reaction pressure is 0.1-0.5 MPa; The external light source is one or more of LED (central wavelength 365nm), xenon lamp (300W) and high-pressure mercury lamp; the reactor is a reactor with a light-transmitting window or a transparent quartz reactor; The reaction temperature is 15-60°C.

3. The method according to claim 1 or 2, characterized in that: The carboxylic acid raw material is preferably one or more of 4-hydroxybutyric acid, 3-methoxypropionic acid, 3-ethoxypropionic acid, 3-phenoxypropionic acid, 3-acetoxypropionic acid, 4-methoxybutyric acid and 3-methoxybutyric acid; The initial reaction concentration of the carboxylic acid raw material is preferably 0.05-0.3 mol / L; The photocatalyst is preferably a metal-modified titanium dioxide catalyst; wherein the titanium dioxide is one or two of TiO2-A (anatase phase TiO2) and P25 (mixed phase of anatase phase and rutile phase TiO2); the metal in the metal surface-modified titanium dioxide is preferably one or more of Pt, Pd, Ru, and Rh; the metal loading is preferably 0.1-5.0wt% (based on the mass of the titanium dioxide carrier); The solvent is preferably one or more of acetonitrile, trifluorotoluene, and n-hexane; The inert atmosphere gas is one or both of nitrogen and argon, and the reaction pressure is preferably 0.1-0.3 MPa; The external light source is preferably one or both of LED (central wavelength 365nm) and xenon lamp (300W); The reaction temperature is preferably 15-40°C.

4. The method according to claim 1 or 2, characterized in that: The carboxylic acid raw material is preferably one or more of 3-methoxypropionic acid, 3-ethoxypropionic acid, 3-phenoxypropionic acid and 4-methoxybutyric acid; The optimal initial reaction concentration of the carboxylic acid raw material is 0.05-0.15 mol / L; The photocatalyst is preferably a metal-modified titanium dioxide catalyst; wherein the best titanium dioxide is P25 (TiO2 mixed with anatase phase and rutile phase); the best metal in the metal surface-modified titanium dioxide is one or two of Pt and Ru; the best loading amount of the metal is 0.5-2.0wt% (based on the mass of the titanium dioxide carrier); The best solvent is one or two of acetonitrile and n-hexane; The reaction atmosphere is one or both of nitrogen and argon, and the optimal reaction pressure is 0.1-0.15MPa; The best external light source is preferably LED (central wavelength 365nm); The optimal reaction temperature is 20-30°C.

5. The method according to claim 1 or 2, characterized in that: The reaction time is 6-48 hours, preferably 12 hours.

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