209results about How to "High product yield" patented technology

A radiation detection apparatus including a sensor panel, having a photoreceiving unit constituted of plural photoelectric converting elements two-dimensionally arranged on a substrate and electrical connecting portions provided in an external portion of the photoreceiving unit and electrically connected to the photoelectric converting elements of respective rows or columns of the photoreceiving unit, a phosphor layer provided at least on the photoreceiving unit for converting a radiation into a light detectable by the photoelectric converting element, and a phosphor protective member covering the phosphor layer and in contact with the sensor panel, characterized in that the phosphor protective member includes a frame member provided between the phosphor layer and the electric connecting portion on the sensor panel, and a phosphor protective layer covering an upper surface of the phosphor layer and provided in close contact with an upper surface of the frame member. This configuration allows to prevent a discharge of an electrostatic charge accumulated on the sensor panel, thereby providing a stable radiation detection apparatus with a high production yield.

The invention relates to a method for extracting soybean dietary fibre and soybean protein from soybean residue, solving the problem of comprehensive use of the side product of soybean residue in soybean. The method comprises the following steps: drying, crashing and sieving fresh soybean to obtain soybean powder, adding extracting solution containing cellulase into the soybean powder for synchronous ultrasound extraction to obtain extracting solution; centrifuging the extracting solution to obtain supernatant A and sediment B; depositing, drying and crashing the supernatant A to obtain soluble dietary fibre; dissolving the sediment B by weak base to obtain supernatant C and sediment D; depositing, drying and crashing the supernatant C by food acid to obtain soybean protein; washing, decolouring, drying and crashing the sediment D to obtain insoluble dietary fibre. The invention utilizes ultrasonic and enzymolysis synergy food acid to obtain soybean soluble dietary fibre, soybean insoluble dietary fibre and soybean protein, and has the advantages of short extraction time, high product yield, simple technical process, easy operation control and convenience for large-scale industrial production.

The invention relates to a polyformaldehyde dimethyl ether synthesis method which mainly solves the problems of difficult catalyst separation, low raw material conversion rate and poor product selectivity in the prior art. The technical scheme of the polyformaldehyde dimethyl ether synthesis method comprises the following steps: by taking methanol, methylal and polyformaldehyde as raw materials, under the conditions that the reaction temperature is 70-200 DEG C and the reaction pressure is 0.2-6 MPa, enabling the raw materials to be in contact with a catalyst, and reacting to generate polyformaldehyde dimethyl ether, wherein the weight ratio of the methanol, the methylal and the polyformaldehyde is (0-10):(0-10):1, and the amounts of the methanol and the methylal can not be 0 at the same time; the amount of the catalyst accounts for 0.1-5.0% of the weight of the raw materials; and the used catalyst comprises the following components in parts by weight: a) 30-80 parts of carrier, which is at least one selected from SBA-15, MCM-41 or MCM-22 molecular sieve, and b) 20-70 parts of solid super-strong acid carried thereon, which is at least one selected from SO4<2->/ZrO2, SO4<2->/Fe2O3, Cl<->/TiO2 or Cl<->/Fe2O3. Thus, the problems are well solved; and the polyformaldehyde dimethyl ether synthesis method can be used for industrial production of polyformaldehyde dimethyl ether.

The invention in particular relates to a new method to prepare budesonide, belonging to medicinal synthesis. The method simplifies production process through repeated tests and experiments, greatly improves yield, reduces prodiction cost and works out the optimum temperature, time and solvent for the reaction; the conditions during the reaction are easy to realize; therefore the method is applicable to large-scale industrial production to produce budesonide.

The invention discloses a biological preparation method for natural safe starch nano particles. The natural safe starch nano particles are prepared by gelatinization and recrystallization by using natural starch as a raw material, and the method belongs to the technical field of nano structure materials. The method comprises the following steps of: mixing the natural starch with water in a certain proportion to form starch milk; and performing gelatinization, debranching, low-speed centrifugation, recrystallization, differential speed centrifugation and vacuum freezing and drying to prepare the nanoscale starch crystalline. Toxic and harmful organic solvents and inorganic metal ions are not added during the preparation of the starch nano particles, and the starch nano particles are wide in sources of raw materials, biodegradable, good in biocompatibility, low in cost, and simple in production process, and industrial scale production of starch nano particles can be realized easily. The method has a special function in the fields of biological membrane preparation, medicine carriers, high-molecular polymer and the like.

The present invention is room temperature cross-linking process of preparing silane cross-linked polyethylene, and the silane cross-linked polyethylene is prepared with grafting material and catalytic material in the weight ratio of 5-20 to 1 and through room temperature cross-linking. The grafting material consists of polyethylene resin 100 weight portions, alkenyl alkoxy silane 0.5-5 weight portions, alkyl trimethoxy silane 0.5-3 weight portions, titanium-alkoxide chelate 0.5-3 weight portions and free radical initiator 0.01-2 weight portions. The catalytic material consists of polyethylene resin 100 weight portions, water generating agent 0.5-30 weight portions, cross-linking catalyst 1-5 weight portions. Compared with available technology, the present invention has the features of advanced technological process, high product yield, low power consumption, excellent product performance, etc.

The invention relates to a fluorine-silicon three-block copolymer and a process for preparation, which relates to the synthesis of fluorine low-surface three-block copolymer. The invention provides a fluorine-silicon three-block copolymer and a process for preparation, whose reaction condition is moderate, the structure of the reaction products is accurate, the original skeleton construction of each block is kept, the production has micro-phase separation structure, and the operation is simple and convenient. The invention is named as dimethyl silicone polymer-b-polymethyl methacryate-b-poly seven-fluorine butyl methacrylate ester, the process for preparation comprises first, preparing dimethyl silicone polymer macromolecule initiator of the sealing end of bromine atom, second, preparing two-block copolymer macromolecule initiator of the dimethyl silicone polymer-b-polymethyl methacryate, finally, preparing the fluorine-silicon three-block copolymer of the dimethyl silicone polymer-b-polymethyl methacryate-b-poly seven-fluorine butyl methacrylate ester.

The invention discloses a crude benzene hydrofining method, and belongs to the application field of crude benzene deep processing. The method sequentially comprises the following steps of: A, crude benzene pretreatment; B, crude benzene hydrogenation; C, pre-rectification; and D, rectification for obtaining pure benzene. The pure benzene obtained in the step D can be used for preparing cyclohexane by hydrogenation, and the cyclohexane is prepared into crude alcoholic ketone by oxidization and decomposition reaction. The method optimizes the crude benzene refining flow and the hydrogenation process parameters; the method is particularly suitable for the condition that the product obtained after the crude benzene hydrofining is used as a raw material for producing the cyclohexane; by implementing the method, the yield of the crude benzene hydrofining product is improved by over 4 percent, and the energy is saved by over 32 percent; and the pure benzene produced by crude benzene hydrogenation fully meet the preparation requirement of cyclohexanone.

The invention relates to a preparation method of an ortho/para-substituted phenylformic acid compound with a general formula (I), wherein R1 and R2 are respectively or simultaneously C1-C3 sulfenyl, nitryl, CF3, C2F5 or C3F7 and other groups. The compound is obtained by conducting hydrolysis on a compound with a corresponding general formula (II) in an alkaline condition at the temperature controlled within a range of 80-180 DEG C for 1-6 h. The preparation method has the advantages of simple process, short reaction time, high reaction conversion rate and selectivity, high product purity and the like, and is suitable for large-scale industrial production.

The present invention relates to chemical preparation process, and is especially preparation process of 5-sodium sulfo isophthalate. The preparation process includes the following steps: the first sulfonation reaction between isophthalic acid and fuming sulfuric acid; the subsequent neutralization of the reaction product with alkali; and refining the product through centrifugation, hot dissolving and drying. The present invention features the sulfonating agent of fuming sulfuric acid in certain concentration and the closed loop circulation of the mother liquid after refining product, and has no environmental pollution, high product yield up to 80 %, low material consumption and high product quality.

The invention relates to a production method of dalteparin sodium. The production method comprises the following steps: adding methylic organic solvent into heparin sodium solution; under specific temperature and acidic conditions, reacting with nitrous acid to cause deamination on N-sulfuric-base aminoglucose residues, so that rearrangement reaction occurs, thereby causing glycosidic bond rupture between aminoglucose and uronic acid and forming 2,5-dehydrated mannitose terminal residue; carrying out further treatment to obtain stable 2,5-dehydrated mannitol terminal, thereby obtaining the crude product of dalteparin sodium of which the molecular weight is 5600-6400 Daltons; and decoloring the crude product of dalteparin sodium by oxidizing and hydroxylating, settling with ethanol, and freeze drying or vacuum drying to obtain the finished product of dalteparin sodium. The invention overcomes the defects of disqualified product structure and poor product stability in the traditional production technique; the product of the invention has the uniform structure and properties as the European standard sample structure; and the invention has the advantages of simple operation, high stability and high product yield, and can realize industrial production.

The invention discloses a method for synthesizing gamma lactone. The method comprises the following steps of: putting acrylic acid or acrylic ester as well as alcohol and a ditertiary butyl peroxide or benzoyl peroxide into a stirring pot by a molar ratio of 1:(3-30); uniformly mixing at -20-30 DEG C; adding accessories to a kettle type reactor from a fractionating column which is filled with a cy700 stainless steel ripple filler and has 5-30 theoretical plates; controlling the flow rate to 50-200g/hour and the reaction temperature between 165 DEG C and 280 DEG C and pressurizing nitrogen to 0.05-1.25MPa; after 5 hours, fractionating out tertiary butanol and low-carbon ester which are byproducts under normal pressure through the fractionating column, and recovering unacted alcohol; after 10 hours, under vacuum pressure of 133-1,000Pa, extracting a crude reaction product from the reactor; and fractionating the crude product in a rectifying column to obtain a product. The method effectively improves the product yield, and the product quality conforms to the requirement on food blending.

The invention relates to a method of synthetizing small molecule hydroxyl silicone oil through using a continuation method. The method comprises the steps as follows: adding the1,000 g of hexamethyl cyclotrisiloxane, 1,400 g of acetone and 120 g of water into a 3,000 ml four-mouth bottle with the stirring function, heating and keeping the temperature to 40 DEG C to 60 DEG C, melting and mixing uniformly; adopting a peristaltic pump to continuously pass through two fixed beds added with 100 g of strongly acidic styrene cation exchange resin, wherein the strongly acidic styrene cation exchange resin comprises a macroporous type and a gel type, and has the following grades: 732, D001, KY-2 and KY-23; obtaining a small molecule hydroxyl silicone oil crude product after the each fixed bed reaction temperature is 40 DEG C to 60 DEG C and the retention time is controlled to 30-70 seconds; and obtaining small molecule hydroxyl silicone oil after the crude product is subject to normal pressure desolvation, decompression and removal of low component. The method has the advantages of continuation production, high reproducibility and high product yield; and moreover, the product is colorless transparent liquid from the appearance, the viscosity is 15-30 mm2/s, and the hydroxyl content is in the range of 6-10%.

This invention provides a solanesol refining method, including pre-treatment of solanesol crude cream with zymolysis and alkali saponification, and making eater key formed from solanesol and organic acid break off. Its characteristics also include: supercritical extraction purifying, decompressing separation purifying, modified extraction purifying. This invention greatly simplifies the refining procedure and improves the yield of products in order to lower the cost and overcomes many weak points of present techniques, and greatly decreases the exhaustion of industrial residues to aim the low cost, high efficiency, scalization and environmental protection. It is a method with high industrial value.

The invention relates to a synthesis method for cefuroxime acid, which includes the following steps: (1) N-acylation reaction is first carried out by using 7-ACA and methoxy imino furan ammonium acetate as materials; then, the 3 bit acetyl of the reaction product is hydrolyzed; finally MDCC is crystallized out by using hydrochloride in water phase; (2) the MDCC and a strong carbamoyl agent P-isocyanate are done with nucleophilic addition in an organic solvent to obtain chlorosulfonation cefuroxime; cefuroxime acid is obtained after the hydrolyzation; then a product is crystallized. The main technical features of the method are as follows: the adoption of a strong alkaline environment is avoided during the period of the hydrolysis of the step (1); while the mild-conditioned enzymatic hydrolysis is adopted to cause the yield of the product to be improved by more than 8 percent and reach 93 percent, and the stability of the product can be improved at the same time. The cefuroxime acid of the step (2) crystallizing in the water phase environment facilitates the removing of impurities and acid media, improves the stability of products and lowers the production cost simultaneously.

The invention discloses a preparation method of shape memory polyurethane based on lactide and 1, 4-p-dioxanone. The preparation method comprises the following steps of: firstly carrying out vacuum melting reaction on the 1, 4-p-dioxanone, stannous octoate and small molecule diol to generate hydroxyl-terminated polybutadiene (1, 4-p-dioxanone), carrying out vacuum melting reaction on the hydroxyl-terminated polybutadiene and the lactide as well as the stannous octoate to prepare the hydroxyl-terminated polybutadiene (lactide-co-1, 4-p-dioxanone), then reacting the hydroxyl-terminated polybutadiene with diisocyanate as well as the stannous octoate in a benzene solvent to generate prepolymer, and then reacting the prepolymer with an isopropyl alcohol solution of chain extender small molecule diol or small molecule diamine to prepare shape memory polyurethane. The invention adopts a tow-step method to prepare hydroxyl-terminated polybutadiene (lactide-co-1, 4-p-dioxanone), takes the benzene solvent as a pre-polymerization reaction solvent, introduces isopropanol as a cosolvent in the chain extension reaction, and can enhance reaction controllability, reduce by-product production, enhance product yield and obtain high molecular weight chain-shaped shape memory polyurethane with excellent shape memory performance.

The invention relates to a preparation method of cefminox sodium, which comprises the following steps of: (1) dispersing a compound with a structure shown in formula (V) in specific organic solvent, and then adding sodium methoxide; (2) replacing the solvent in ethyl acetate I containing a compound with a structure shown in formula (III) with specific organic solvent by a reduced-pressure concentration manner; (3) mixing a solution or suspension containing the compound with the structure shown in formula (IV) with a solution containing the compound with the structure shown in the formula (III), carrying out condensation reaction and separating to obtain anhydrous cefminox sodium with the structure shown in formula (II); and (4) transforming anhydrous cefminox sodium into cefminox sodium heptahydrate crystal in the presence of water. Compared with the traditional condensation reaction in an aqueous solution, the method is more favorable to reducing specific impurity in the product and improving product purity and yield.

The invention relates to a method for synthesizing polyformaldehyde dimethyl ether from methanol, methylal and paraformaldehyde, and is mainly used for solving the problems that the catalyst in the prior art is low in percent conversion, unstable in reaction, complicated in preparation technology, and not easy to control. The problems are well solved by adopting the technical scheme that methanol, methylal and paraformaldehyde are adopted as raw materials, and the raw materials contact the catalyst and react to generate polyformaldehyde dimethyl ether under the conditions that the reaction temperature is 70-200 DEG C and the reaction pressure is 0.2-6MPa, wherein the mass ratio of methanol to methylal to paraformaldehyde is (0-10):(0-10):1, and the dosages of methanol and methylal cannot be 0 at the same time; the used catalyst is acidic ion exchange resin; the dosage of the catalyst is 0.05-10% of the weight of the raw materials. The method can be applied to industrial production of polyformaldehyde dimethyl ether.

The invention relates to a preparation method of a bisphenol monocarboxylic ester compound antioxidant product which mainly used for synthesizing high molecular materials of rubber, polyolefine plastics, engineering plastics and the like. The invention adopts bisphenol compound and fatty acyl chloride as raw materials, triethylamine as acid absorbent, and the aliphatic hydrocarbon as solvent to generate the bisphenol monocarboxylic ester compound antioxidant product by esterification reaction. Suitable process conditions for synthesizing the bisphenol monocarboxylic ester compound are as follows: the mol ratio of the bisphenol compound to the fatty acyl chloride is 1.1-1.3; the mol ratio of the bisphenol compound to the triethylamine is 1:1.3-1.5; the reaction temperature is 60-85 DEG C; and the reaction time is 120-240 minutes. The bisphenol monocarboxylic ester compound antioxidant product is obtained by filtering, separating, crystallizing and refining after the reaction. The invention has the characteristics of simple production process, high product yield, high quality and convenient industrialized production. The obtained white crystallized bisphenol monocarboxylic ester antioxidant product can be used for high molecular materials having high requirements for color.

This invention relates to a preparation method for 4-amido-phenyl butyrate including: mixing benzene formate and methyl alcohol with nitromethane to be reacted at heat preservation, cooled and crystallized, separated for solid and liquid to be dried to get nitrobenzene ethane, which is put into a methanol solution together with diethyl malonate to be reacted to generate alpha-carbomethoxy-beta-phenyl-gamma-nitryl methyl butyrate, then Ni and H2 are added into a methanol solution to carry out hydrogenation reaction to get alpha-carbomethoxy-beta-phenyl-gamma tetrahydroketopyrrolidine, which is added with HCl to be hydrolyzed dried to get a product of 4-amido-phenyl butyrate.

The invention discloses a method for preparing 4,4'-dihydroxydiphenylmethane (BPF), which comprises the following steps of: diazotizing 4,4'-diaminodiphenyl-methane (MDA) and sodium nitrite serving as raw materials, hydrolyzing, refining and the like to synthesize the 4,4'-dihydroxydiphenylmethane with the purity of over 98.5 percent. The raw materials are low-cost, the operation process is simple, and industrial production is easy to realize; and a mixture of three isomers of dihydroxydiphenylmethane does not exist in the product, the product is easy to purify, and cost for complicated separation and purification is reduced.

The invention discloses a powdered epoxy resin toughener and a preparation method thereof, which belong to the technical field of tougheners. The method takes n-butyl acrylate and glycidyl methacrylate as raw materials to prepare an active toughener in solution through a copolymerization reaction. The toughener is blended, cross-linked and cured with a powdered epoxy resin and then can form a cross-linking network with the epoxy resin. A structure of the toughener contains a flexible segment and an active epoxy group, so the toughener has excellent toughening effect on the powdered epoxy resin. When the mass ratio of a polymer to the epoxy resin is 5 to 100, the measured impact resistance is improved to 209.2 percent of a pure epoxy resin. The synthesis of the toughener is only a one-step reaction without side reactions, and has high product yield. The method has the advantages of cheap raw materials, simple reaction, mild conditions, easy control, and convenient industrialization.

The invention belongs to the field of processes for extracting plant effective components and discloses a method for extracting and separating ceramide in konjac flying powder. According to the invention, an ultrasonic technology is utilized to carry out primary processing, so as to separate the ceramide from raw material cells in short time, extraction time is short, damage to effective ingredients, which is caused by high temperature heating, is avoided, and an extraction rate is improved for extraction and separation in the next step; then the characteristic of selective dissolving capacity of carbon dioxide in a super-critical state is utilized to carry out secondary extraction, refining and separation on different polar materials. The method has the advantages of low operating temperature, good selectivity, no damage to effective ingredient structures, capability of perfectly storing active ingredients of natural plants and the like, and enables the ceramide in the konjac flying powder to be efficiently extracted and separated out; compared with the prior art, content of the ceramide is higher and the konjac flying powder is more pure.

The invention relates to a block copolymer and its hydrogel as well as application. The block copolymer of the invention is a temperature-sensitive block copolymer with a solution-gel transition characteristic. Specifically, the block copolymer of the invention is a BAB or ABA-type triblock copolymer composed of a poly(2-alkyl-2-oxazoline) (PAOz) block B and a polyester (PE) block A, or a copolymer containing the triblock copolymers. The aqueous solution of the block copolymer undergoes solution-gel phase transition along with temperature rise, and the phase transition temperature is 20-80DEG C. The block copolymer has good biocompatibility and biodegradability. The copolymer provided in the invention can provide a suitable drug delivery system for controlled release of stereotactic injection preparations and drugs, and also can provide a gel matrix and an effective means for enzyme immobilization, cell culture, tissue engineering, and vascular thrombosis, etc., as well as provides an appropriate material and technique for gelation of various aqueous solutions or aqueous humor systems in food, health care products and other fields. The method involved in the invention has the advantages of simple operation, high product yield, high purity, controllable property, and suitability for large-scale production application.

The invention discloses a preparation method of a hydroformylation homogeneous complex catalyst and aims at directly preparing hydridocarbonyl tri(triphenylphosphine) rhodium by taking hydroformylation catalyst waste liquid containing a phosphine rhodium complex as an initial raw material. The preparation method comprises the following steps of: taking the hydroformylation catalyst waste liquid containing the phosphine rhodium complex as the initial raw material, when the concentration of rhodium in the waste liquid is 1000-2,0000ppm, firstly, carrying out oxidation treatment on the catalyst waste liquid under the acid condition to break through a rhodium cluster; secondly, synthesizing the hydridocarbonyl tri(triphenylphosphine) rhodium in the atmosphere of synthetic gas; and thirdly, filtering an ethanol solution as a precipitation prepared in the second step when the precipitation is hot and washing and drying the obtained precipitation to obtain a product of the hydridocarbonyl tri(triphenylphosphine) rhodium. The preparation method has the advantages of high yield, simple process flow and mild conditions.

The invention discloses a method for preparing VI-type slowly-digested starch through ultrasonically-assisted acid-base sedimentation. The method comprises the steps of dispersing common corn starch into a 0.01ml/L KOH solution to prepare a suspension, carrying out ultrasonic treatment at 30 DEG C and 200W for 10min to uniformly disperse the starch to further accelerate to gelatinization and improve the capacity of the starch including fatty acid; gelatinizing the suspension in a boiling water bath for 10 minutes, and cooling to 60 DEG C; dissolving the fatty acid into the 60-DEG C KOH solution, mixing the fatty acid and starch paste, regulating the pH value to 4.7 by using 1.5mol/L tartaric acid, and preserving the heat for a period of time to sufficiently combine the starch and fatty acid; and centrifuging the mixture, washing and settling for 3 times, and carrying out freeze drying to obtain the VI-type slowly-digested starch. A common corn starch-conjugated linoleic acid inclusion complex product is measured to contain 40.62% of slowly-digested starch, and the slowly-digested starch product has a relatively-high nutrient value. X-ray diffraction results show that the slowly-digested starch product prepared by using the method is a VI-type starch complex.

4-diaminobezene sulfonic acid and salt thereof The invention relates to a production method of a dye intermediate 2,4-diaminobezene sulfonic acid. The method is characterized by using m-phenylenediamine as a main raw material and comprising operations of sulfonation, hydrolysis and refining to prepare the 2,4-diaminobezene sulfonic acid. The invention also provides a preparation method of 2,4-diaminobezene sulfonic acid ammonium salt or sodium salt by using the 2,4-diaminobezene sulfonic acid prepared by the above method, so as to solve problems of low reaction efficiency, high sulfonation temperature, secondary pollution caused by usage of organic solvent and acid-containing processing in the production process. The method of the invention employs addition of fusing m-phenylenediamine to increase solubility of the m-phenylenediamine in the sulfuric acid and reduce generation of side reaction; m-phenylenediamine and sulfuric acid are added respectively to control the acidity of the reaction system at a required acidity, control generation of side reaction and increase product quality and product yield; grading control of acidity and temperature maintains stable proceeding of reaction; and addition of hydrolysis increases yield of the product, improves product quality and reduces production cost.

The invention discloses a method for preparing 3-deacetyl-7-aminocephalosporanic acid, which comprises the following steps: catalyzing extract of cephalosporin C serving as a raw material by D-amino-acid oxidase to prepare solution of glutaryl-7-ACA; catalyzing the solution of glutaryl-7-ACA by glutaryl-7-ACA acylase and cephalosporin esterase to prepare solution of 3- deacetyl-7-aminocephalosporanic acid; and performing acidification crystallization, washing and drying to obtain solid 3-deacetyl-7-aminocephalosporanic acid. The method for preparing the3-deacetyl-7-aminocephalosporanic acid only needs two steps of normal temperature reaction and one-time crystallization process and has short process route; solvents are not used basically; the molar yield from the extract of the cephalosporin C to the 3-deacetyl-7-aminocephalosporanic acid can reach 71.5 percent; and the yield of the product is high. In addition, compared with the prior art, the method has much lower energy consumption, power cost, labor cost and environmental cost.

The invention discloses a method for preparing sulfoxide and sulfone through water phase oxidation of thioether. According to the method, H2O2 and a supported metal oxide catalyst are added to a thioether aqueous solution, and a reaction is performed to obtain sulfoxide and sulfone. According to the present invention, the reaction for preparing sulfoxide or sulfone is performed in the water phaseby using H2O2 as the oxidant without the organic solvent, wherein the product yield is high, the reaction conditions are mild, the reaction process is environmentally friendly, and the production costis low.

The invention discloses a method for preparing chiral 2-chloro-3,4-difluorophenethyl alcohol. According to the method, 2-chloro-3,4-difluoroacetophenone is used as a substrate, and ketoreductase is used for catalytic reduction of the substrate so as to generate the chiral 2-chloro-3,4-difluorophenethyl alcohol. Amino acid sequence of the ketoreductase is as shown in the SEQ ID NO.1-21. 2-chloro-3,4-difluoroacetophenone which is cheap and easily available is used as the substrate, and the biocatalyst ketoreductase is adopted so as to carry out an asymmetric reduction reaction to obtain 2-chloro-3,4-difluorophenethyl alcohol with high chiral purity. The method has advantages of high yield, mild reaction condition and simple operation. Problems of a chemical reduction method, such as strict reaction condition, complex preparation of a catalyst, high cost, inflammable property and low chiral purity of the product, are avoided. The method has good practical industrial application value.