56 results about "Diethyl malonate" patented technology

The invention belongs to the technical field of separation of drug intermediates, and particularly relates to a control method for a process impurity 2-ethyl valeric acid (EP-B) in preparation of valproic acid or sodium valproate by a diethyl malonate method. According to the method disclosed by the invention, the content of 2-ethyl-2-propylmalonic acid process impurities in dipropylmalonic acid is controlled, so that the content of 2-ethylvaleric acid (EP-B) which is a process impurity in valproic acid or sodium valproate is accurately controlled; adding a polar solvent into the dipropylmalonic acid crude product, heating, pulping for a certain time, cooling, filtering and drying to obtain a high-purity dipropylmalonic acid refined product; high-purity valproic acid (RRT is equal to 1.00) is prepared through decarboxylation of the dipropyl malonic acid fine product, and the purity is 99.779%; 0.020% of 2-ethyl valeric acid (RRT is equal to 0.90); and valeric acid (RRT = 0.77), 0.039%. The valproic acid product quality meets the requirements of European Pharmacopoeia. According to the method, the problems of quality control and process evaluation of valproic acid or sodium valproate prepared by a diethyl malonate method are solved.

The invention discloses a low-temperature cured polyurethane varnish resin for automobiles and a preparation method thereof, and belongs to the technical field of chemical product processing, the low-temperature cured polyurethane varnish resin comprises a resin matrix and a curing agent, the resin matrix comprises a component A and a component B. The component A comprises a crosslinking system A1, a crosslinking system A2 and an auxiliary agent, the component B is a curing activity regulator of a double-crosslinking system of the crosslinking system A1 and the crosslinking system A2; the curing agent is diethyl malonate blocked isocyanate; the cross-linking system A1 is mainly composed of hydroxy acrylic resin containing beta-diketone metal ligand and a bismuth neodecanoate catalyst; the bismuth neodecanoate catalyst and a beta-diketone metal ligand form a bismuth complex; the cross-linking system A2 is mainly composed of hydroxyl acrylic resin containing alkoxy silane groups; the component B is prepared from poly (decane-4, 6-diyne diacid) modified nano porous fibers and a silane coupling agent. The service life of the varnish is prolonged on the basis of ensuring low-temperature rapid curing.

The present invention relates to a method of adding an isocitrate lyase specific inhibitor to a lactic acid fermentation process to block the production of succinic acid as a byproduct of fermentation. The specific inhibitor includes a combination of one or more of glycolic acid methyl ester, malonic acid dimethyl ester, hydroxymalonic acid diethyl ester, 3-nitropropionic acid ethyl ester, mercuric chloride, or 5,5'-dithiobis(2-nitrobenzoic acid) to effectively reduce the amount of succinic acid in the lactic acid.

The invention discloses a positive pole piece and a preparation method thereof, a diaphragm-free battery and a battery. The positive pole piece comprises a positive pole current collector and a positive pole active material layer arranged on at least one side of the positive pole current collector, the positive pole active material layer comprises a polymer, and the polymer is formed by polymerizing at least one of small molecules of the following raw material components: vinylethylene carbonate, vinylene carbonate, 2, 3, 4-trimethyl-1, 3-pentanedione, 2, 3, 4-trimethyl-1, 3-pentanedione and 2, 3, 4-trimethyl-1, 3-pentanedione. The adhesive is prepared from 2, 4-hexadienoic acid, allyl trifluoroacetate, diethyl allylmalonate, allyl methacrylate, allyl chloroformate, allyl phenylacetate, allyl acetate, allyl 4-hydroxybenzoate and allyl phenoxyacetate. The adhesive is prepared from the following raw materials: 1, 4-hexadienoic acid, allyl trifluoroacetate, diethyl allylmalonate, allyl methacrylate, allyl chloroformate, allyl phenylacetate, allyl acetate, allyl 4-hydroxybenzoate and allyl phenoxyacetate. The positive pole piece provided by the invention comprises the polymer, so that the interface impedance can be reduced, and the rate capability of the battery can be improved.

The invention discloses a method for preparing a fluorinated ethylene-propylene emulsion, and relates to a polymer emulsion polymerization technology. Comprising the following steps: adding water into a reaction kettle, heating, and replacing with nitrogen to control oxygen; adding perfluoropolyether ammonium carboxylate, heating, adding an initial TFE / HFP mixed monomer, stirring, and adding a potassium persulfate solution to initiate polymerization; supplementing the mixed monomer in the reaction to maintain the pressure, and adding diethyl malonate and a copolymerization composition regulator at the same time; and stopping the reaction after the designed feeding amount is reached. According to the invention, the proportion of copolymerization units can be optimized, high monomer conversion is realized, and the emulsion with high solid content and uniform particle size is obtained.

The application discloses a preparation method of ammonium glufosinate, which comprises the following steps: adding diethyl malonate and liquid bromine into a first solvent to react to obtain intermediate I; adding the intermediate I, potassium phthalimide and a quaternary ammonium salt catalyst into toluene to react to obtain intermediate II; adding the intermediate II, potassium carbonate, 1,2-dibromoethane and a phase transfer catalyst into a second solvent to react to obtain intermediate III; adding the intermediate III and diethyl methyl phosphonite into toluene to react under argon to obtain intermediate IV; adding the intermediate IV into hydrochloric acid to react under reflux; cooling, precipitation, drying to obtain intermediate V; mixing the intermediate V with water, passing in ammonia and adjusting pH value; adding methanol and stirring to react; cooling, filtering and drying to obtain ammonium glufosinate. The method can avoid using sodium cyanide or hydrocyanic acid, and no large amount of difficult-to-separate ammonium chloride is generated, the content of the obtained ammonium glufosinate is 90% to 98%, and the total yield is greater than 68%.

The application relates to a preparation method of 4-chloropyrrolopyrimidine, in particular to a four-step high-yield synthesis of 4-chloropyrrolopyrimidine by taking diethyl malonate and bromoacetaldehyde diethyl acetal as raw materials, through substitution reaction, then ring closure reaction with formamidine acetate, ring closure reaction under acidic conditions, and then chlorination reaction with phosphorus oxychloride; the preparation method of 4-chloropyrrolopyrimidine provided by the synthesis route is a preparation method with high yield, low cost, easy operation and suitability for industrialization.

To provide a collagen-containing composition and a method for producing the same, a collagen-containing composition for addition to foods and drinks, and a collagen odor masking agent and a masking method that enable effective masking of collagen odor.SOLUTION: A collagen-containing composition contains collagen, a steviol glycoside, α-glucosyl rutin, and diethyl succinate and / or diethyl malonate.SELECTED DRAWING: None

The invention relates to the technical field of cables, and provides an extruded insulation low-voltage power cable which sequentially comprises a conductor, an insulation layer, an armor layer and a sheath layer from inside to outside. The sheath layer is prepared from the following raw material components in parts by weight: 80 to 100 parts of polyvinyl chloride, 10 to 20 parts of ethylene propylene diene monomer, 15 to 25 parts of ethylene vinyl acetate copolymer, 20 to 30 parts of filler, 25 to 35 parts of flame retardant, 3 to 5 parts of plasticizer, 1 to 3 parts of antioxidant and 3 to 5 parts of compatilizer; the filler is obtained by modifying potassium titanate whiskers with a titanate coupling agent and diethyl aminovinylmalonate, and the insulating layer is obtained by extruding an insulating layer material on the outer side of the conductor. According to the technical scheme, the problem of insufficient tensile strength of the sheath layer in the prior art is solved.

A biphenylthiourea carboxylic acid metal organic framework crystal material and a preparation method and application thereof.The material has the following chemical formula: {[Zn4O(L)3]·DMF·H2O} n , wherein L is a 6-thio-6,7-dihydro-5H-dibenzo[d,f][1,3]diazepine-3,9-dicarboxylate divalent anion, and n is a degree of polymerization.The metal organic framework crystal material of the present application is synthesized by a solvothermal method, is simple to operate, has low cost, high yield, and is easy to mass industrial production.The prepared metal organic framework crystal material has a high specific surface area (a BET specific surface area of 594 m 2 / g), and an adsorption amount of CO2 of 46.0 cm 3 / g at 1 atm and 273 K.The biphenylthiourea carboxylic acid metal organic framework crystal material of the present application can efficiently catalyze a Friedel-Crafts alkylation reaction of substituted indole and substituted trans-nitrostyrene to generate an indole 3-substituted derivative, and can also efficiently catalyze a Michael addition reaction of diethyl malonate and substituted trans-nitrostyrene, both of which have mild conditions, and the catalyst can be recycled with almost no activity loss, and are good heterogeneous catalysts.

The application discloses a synthesis method of pimobendan, which comprises the following steps: a Friedel-Crafts acylation reaction: compound I and compound A are subjected to a Friedel-Crafts acylation reaction in aprotic solvent under the action of a Lewis acid to generate compound II; a substitution and hydrolysis reaction: under alkaline conditions, compound II and dimethyl malonate or diethyl malonate are subjected to a substitution reaction in an ether solvent, and the generated compound is subjected to a hydrolysis reaction in an alkaline aqueous solution to generate compound III; a decarboxylation and ring-closing reaction: compound III is heated under the condition of hydrazine hydrate and acid to generate compound IV; a substitution reaction: compound IV and an amine are subjected to a substitution reaction in a polar solvent to generate compound V; a reduction reaction: compound V is subjected to a reaction in an acidic aqueous solution of a protic solvent under the condition of palladium-carbon and hydrogen to generate compound VI; and a ring-closing reaction, so that the pimobendan is obtained. The method has high safety, short line steps and simple operation.

The invention belongs to the technical field of medicine detection, and particularly relates to a high performance liquid chromatography detection method for dipropylmalonic acid and impurities thereof. The method comprises the following steps: preparing a to-be-detected sample into a test solution; the to-be-detected sample is dipropyl malonic acid prepared by adopting a diethyl malonate method and impurities of the dipropyl malonic acid; and detecting the test solution by adopting a high performance liquid chromatography method to obtain a detection result of dipropylmalonic acid and impurities thereof in the sample to be detected. According to the detection method provided by the invention, the detection of dipropylmalonic acid prepared by adopting a diethyl malonate method and impurities thereof is realized through high performance liquid chromatography (HPLC) for the first time, and the problems of quality control and process evaluation of the dipropylmalonic acid prepared by adopting the diethyl malonate method, which is an intermediate of a sodium valproate raw material medicine, are solved; therefore, detection and control of impurities (including 2-ethyl valeric acid) in the sodium valproate raw material medicine are realized.

The present application relates to phenylethyl malonic acid diethyl ester heating technical field, specifically, it is a kind of phenylethyl malonic acid diethyl ester reaction heating device capable of uniform heating.It includes heating tank, feeding opening, discharge port and heater, heating tank is fixedly provided with sleeve inside, the sleeve is used to separate the inner wall of heating tank and sleeve into liquid storage cavity and shunt cavity, liquid storage cavity is located above shunt cavity, auxiliary liquid mixing stirring mechanism is arranged in the inner ring of sleeve, reciprocating mechanism is arranged at the top end of sleeve inside and the end of stirring mechanism.Liquid inside the sleeve is guided into the liquid storage cavity, then steam in the heater flows outward through shunt ring and steam pipe, the flowing steam can continuously conduct heat to the shunt ring, the shunt ring conducts heat to the sprayed liquid, and the sprayed liquid is divided into two streams under the action of shunt ring, so that the contact area of liquid and shunt ring is increased, thereby improving the efficiency of heat transfer and enhancing the uniformity of heat conduction.

A preparation process of 2-[2-(2, 4-difluorophenyl)-2-propylene-1-yl]-1, 3-propylene glycol belongs to the field of medical intermediates, and comprises the following steps: step 1, adding 1-[1-(bromomethyl) vinyl]-2, 4-difluoro-benzene and diethyl malonate into N, N-dimethylformamide, and then adding potassium carbonate for reaction; 2, after the reaction in the step 1 is completed, filtering to remove potassium carbonate, and then carrying out acid pickling, toluene extraction, saturated saline solution washing, concentration and rectification to obtain an oily substance; and step 3, adding the oily substance obtained in the step 2 into methanol, mixing, then adding sodium borohydride for reaction, and after the reaction is completed, concentrating, crystallizing and filtering to obtain the 2-[2-(2, 4-difluorophenyl)-2-propylene-1-yl]-1, 3-propylene glycol. According to the method, the cost is effectively reduced, so that the reaction period can be shortened, meanwhile, the reaction yield can be increased, and industrial production is facilitated.

The invention provides a preparation method of diethyl malonate and a preparation method of valproic acid, and belongs to the technical field of organic synthesis. According to the method, diethyl carbonate and ethyl acetate are taken as initial raw materials, the ethyl acetate has three alpha-H and loses one alpha-H under the attack of strong base, so that ethyl acetate enol negative ions are formed, and ethyl acetate carbon negative ions are obtained through rearrangement; carrying out nucleophilic addition on carbonyl of diethyl carbonate by using the ethyl acetate carbon negative ions to obtain an addition intermediate, and then removing ethanol negative ions from the addition intermediate to obtain diethyl malonate; by controlling the reaction temperature, ethanol generated in the reaction process is continuously distilled out, so that the reaction is carried out in the forward direction, and side reactions are reduced to the greatest extent; as the condensation catalyst used in the invention has strong nucleophilicity and alkalinity, the use of the aprotic solvent can avoid the consumption of the condensation catalyst by the solvent.

To provide an oral composition that contains an azulene compound while effectively inhibiting color change of the composition itself.SOLUTION: An oral composition comprising the following components (A) and (B): (A) one or two or more azulene compounds selected from azulene, azulene sulfonic acid and a salt thereof, and guaiazulene; and (B) one or two or more fragrance components selected from thymol, terpinolene, β-ionone, nerol, carvone, anisaldehyde, vanillin, cis-3-hexenone, menthyl lactate, benzyl alcohol, diethyl malonate, isopulegol, triethyl citrate, and citronellol.SELECTED DRAWING: None

This invention discloses a method for synthesizing 3-oxa[3.1.1]spiropropane, belonging to the fields of organic synthetic chemistry and medicinal chemistry. This method is the first to introduce oxygen atoms into the high-strength skeleton of [3.1.1]spiropropane, successfully synthesizing the 3-oxa[3.1.1]spiropropane molecule. The specific synthetic route is as follows: starting with 3,3-bis(bromomethyl)oxacyclobutane, the 3-oxabicyclo[3.1.1]heptane diol skeleton is constructed sequentially via nucleophilic substitution with diethyl malonate, reduction, and intramolecular cyclization. Then, oxidation and Barton decarboxylation iodination are performed to obtain the key intermediate 1,3-diiodo-3-oxabicyclo[3.1.1]heptane, which is finally reacted with an organolithium reagent to obtain the target product. This invention fills a technological gap in the synthesis of heteroatom-substituted spiroalkyl, providing a key precursor for the subsequent development of its free radical bifunctionalization reaction and the construction of structurally diverse 3-oxabicyclic [3.1.1]heptane dominant skeletons. It has important application prospects in drug design, especially as a bio-electroisoster of meta-substituted aromatics.

The invention belongs to the technical field of medicine synthesis, and particularly relates to a preparation method of a milobalin intermediate. The preparation method comprises the following steps: carrying out hydrogenation reaction on [(1RS, 5SR, 6RS)-6-cyano-3-ethyl bicyclo [3.2. 0] hept-3-ene-6-yl] diethyl malonate serving as a raw material under the action of palladium on carbon or raney nickel to obtain a compound III, and carrying out acid hydrolysis on the compound III to obtain [6-aminomethyl-3-ethyl bicyclo [3.2. 0] hept-3-ene-6-yl] acetic acid (racemization), namely a compound I. The preparation method comprises the following steps: carrying out a reaction on the raw material and the compound I, the method is novel in route, raw materials are easy to obtain, and compared with the prior art, the method has higher yield and is suitable for industrial production.

The invention relates to a cuprous salt antioxidant containing a phosphite structure and a preparation method and application thereof.The preparation method comprises the steps that firstly, diethyl malonate reacts in the presence of ammonia gas to obtain an intermediate A, then the intermediate A and 3-amino-2, 5-di-tert-butylphenol are subjected to condensation cyclization to obtain an intermediate B, finally, after the intermediate B and a phosphite derivative react, the cuprous salt antioxidant containing the phosphite structure is obtained, and the cuprous salt antioxidant containing the phosphite structure is obtained. And coordinating with cuprous salt to obtain a final product. The invention also provides a nylon composition containing the antioxidant. The antioxidant disclosed by the invention has the characteristics of high-efficiency oxidation resistance, hydrolysis resistance and good compatibility with nylon through the synergistic effect of a plurality of intramolecular stable mechanisms, and can be used for remarkably improving the thermal oxidation stability of a nylon material, inhibiting degradation in the processing and using processes and effectively keeping the mechanical properties, appearance and color of the material.

The application discloses a cis-trans cyclopropane diacid diethyl ester nondestructive detection method based on feature screening, relates to the technical field of testing or analyzing materials by means of determining the chemical or physical properties of the materials, and comprises the following steps: taking a plurality of mixtures formed by cis isomers and trans isomers of cyclopropane diacid diethyl ester respectively at a plurality of mass ratios, and taking Raman characteristic peak parameters of the plurality of mixtures; based on the Raman characteristic peak parameters of the plurality of mixtures, a plurality of Raman characteristic peak proportional type variables between cis-trans isomers are constructed; a prediction model is constructed; and based on the prediction model, the mass ratio of the cis-trans isomers of cyclopropane diacid diethyl ester is predicted; the method has the advantages of rapidness, nondestructiveness, non-separation, high recognition precision and the like, and is suitable for the fields of isomer component analysis, structure identification and precise quantitative detection.

The invention relates to the technical field of organic synthesis, and discloses a preparation method of 2-oxoglutaric acid, which comprises the following steps: by taking diethyl 2-oxosuccinate and diethyl 2-bromomalonate as raw materials, carrying out condensation reaction in an absolute ethyl alcohol solvent under the catalytic action of sodium ethoxide; adjusting the pH value of the obtained condensation product, performing intermediate purification, transferring into a mixed system of sulfuric acid and ethanol, performing hydrolysis and decarboxylation reaction, and finally crystallizing and refining to obtain a target product. The invention provides a brand new synthesis route, the reaction conditions are mild, the use of raw materials with higher toxicity and the reaction conditions with great danger are avoided, and the safety of the production process is high. And by setting a key intermediate product purification step, the purity of the final product is effectively ensured, and the product quality is high. Meanwhile, raw materials used in the method are commercially available conventional chemicals, operation is easy and convenient, cost is controllable, and the method is suitable for industrial production.

A method for synthesizing a trifluoromethyl-containing nitrogen-containing heterocycle by metal catalysis is implemented by using a reinforced heating jacket to prepare 2-trifluoromethyl-4-hydroxy-5-nitropyridine from 2-trifluoromethyl-4-chloro-5-nitropyridine; then prepare 2-(5-nitro-2-(trifluoromethyl)pyridin-4-yl) diethyl malonate; further obtain 2-trifluoromethyl-4-methyl-5-nitropyridine; and finally obtain 2-trifluoromethyl-4-methyl-5-aminopyridine.

The application relates to a high-flame-retardant electronic connecting wire and a preparation method thereof, and belongs to the technical field of high polymer materials. The electronic connecting wire is composed of a wire and a surface flame-retardant protective layer, wherein the components of the flame-retardant protective layer are as follows: modified phosphorus-silicon flame retardant 7.5-10 wt%, plasticizer 14-18 wt%, heat stabilizer 1.7-2.2 wt%, antioxidant 0.12-0.16 wt% and lubricant 0.9-1.3 wt%, and the rest is PVC resin; the modified phosphorus-silicon flame retardant is synthesized by synthesizing a phosphorus oxychloride intermediate 1 with a double spiro ring structure from pentaerythritol and phosphorus oxychloride, carrying out amine-ester exchange between terminal amino polydimethylsiloxane and ketone-based diethyl malonate to prepare an intermediate 2 containing terminal amino groups, and then reacting the intermediate 2 with active phosphorus oxychloride of the intermediate 1 to form a chain-shaped macromolecular phosphorus amide compound, so that in-situ toughening, migration inhibition and carbon net flame retardation are simultaneously realized in the PVC matrix.

The invention relates to the field of chemical synthesis, in particular to a synthesis method of 6-bromoindole-2-carboxylic acid. Comprising the following steps: preparing 4-bromo-2-aminotoluene; preparation of 6-bromoindole-2-carboxylic acid ethyl ester; and preparing the 6-bromoindole-2-carboxylic acid. According to the present invention, the reduction cyclization and hydrolysis process is improved, the diethyl malonate is adopted as the mild reducing agent, and the step-by-step temperature control technology is combined so as to significantly improve the yield and the purity; the invention discloses a three-step synthesis process of a bromo-indole carboxylic acid derivative. The method comprises the following steps: 1, in an improved mixed solvent system, carrying out a reduction reaction of reducing nitryl into amino; in the second step, a controllable reduction cyclization technology is adopted, and nitro amination is achieved; in the third step, the ester bond breaking efficiency is improved through the synergistic effect of alkaline hydrolysis and a solvent.

This invention relates to the field of pharmaceutical intermediate synthesis, specifically to a method for synthesizing 3,4-difluoro-2-methoxyphenylacetic acid. The method includes the following steps: Compound III reacts with diethyl malonate in the presence of a copper catalyst, a nitrogen-containing ligand, and base I; then, an inorganic strong base II is directly added for hydrolysis, followed by acidification to obtain compound IV; compound IV undergoes decarboxylation in an acidic solution to yield 3,4-difluoro-2-methoxyphenylacetic acid (compound I) with a purity of up to 99.3% and an overall yield of up to 74.04%. This invention features a simple route, mild reaction conditions, low cost, environmental friendliness, stable yields at each step, and simple post-processing, making it suitable for industrial production.

The invention relates to the technical field of synthesis of 4, 6-dihydroxypyrimidine, in particular to a synthesis method of 4, 6-dihydroxypyrimidine. The synthesis method of the 4, 6-dihydroxypyrimidine comprises the following steps: S1, adding formamide, a composite catalyst system, a phase transfer catalyst and a solvent into a container, and uniformly stirring and mixing to obtain a mixed solution; s2, adding the mixed solution obtained in the step S1 and diethyl malonate into a reactor, heating to 110-120 DEG C, carrying out condensation cyclization reaction for 0.5-5 hours, and filtering to remove the catalyst while hot after the reaction to obtain a reaction solution; s3, cooling the reaction liquid obtained in the step S2 to-5 to 0 DEG C, and filtering to obtain a solid; and S4, recrystallizing the solid obtained in the step S3 to obtain the product. The synthesis method is simple in preparation process, stable in reaction process, simple in purification method, high in product purity, easy for industrial production and capable of being quickly popularized and applied.

The present application relates to ethyl malonate mixing technical field, specifically, it relates to a kind of condensation device for reducing mixing time of diethyl phenylethyl malonate production.The condensation device includes mixing bin, condensation kettle, stirring device and storage bin fixedly arranged at the top of mixing bin, the bottom of mixing bin is communicated with condensation kettle with communicating pipe, storage bin is formed with liquid storage cavity and nitrogen cavity for storing raw materials and nitrogen respectively in the inside, and isolating mechanism for separating first mixed liquid and secondary mixed liquid is movably arranged in the inside of mixing bin.The gravity of secondary mixed liquid on the floating plate is used to pressurize first mixed liquid in discharge cavity, at the same time, the gravity of secondary mixed liquid is used to hit reciprocating plate, so that nitrogen in nitrogen cavity is transported into discharge cavity, the pressure in discharge cavity is increased, the speed of liquid discharge is improved, and in the process of first mixed liquid discharge, stirring device can also stir first mixed liquid and secondary mixed liquid simultaneously, so as to shorten mixing time.

The application belongs to the technical field of solar cells, and discloses a perovskite solar cell, a preparation method and application thereof. The perovskite solar cell comprises, from bottom to top, a flexible conductive substrate, a hole transport layer, a perovskite active layer, a passivation layer, an electron transport layer and a metal electrode layer. The perovskite active layer comprises APbX3. A comprises at least one of formamidinium ion, methylamine ion, cesium ion and potassium ion. X comprises at least one of chloride ion, bromide ion and iodide ion. The passivation layer comprises 2-ethyl-2-phenyl malonic acid diethyl ester. The solar cell has excellent photoelectric conversion efficiency and long-term stability, and can be used to prepare photovoltaic modules and electronic devices. In addition, the preparation method is simple and easy to implement, does not require complex equipment and processes, can effectively control the thickness of each layer, is used to prepare large-area high-performance perovskite solar cells, and meets the needs of industrial production.

This invention provides a method for preparing (E)-octyl-4-en-1,8-diic acid, comprising the steps of reacting diethyl malonate and allyl chloride as raw materials first in the presence of an organic base, then in the presence of a catalyst, and finally obtaining (E)-octyl-4-en-1,8-diic acid through hydrolysis and decarboxylation. The starting materials of this invention are inexpensive and readily available, the reaction operation is simple, the conditions are mild, the safety is good, and the product yield and purity are high, making it of great value for widespread application.