315results about How to "Gentle operation" patented technology

The present invention is process of preparing 3-hydroxy propionate and 1, 3-propylene glycol with epoxide as material. The present invention prepares 3-hydroxy propionate with epoxide, CO and alcohol under the action of cobalt catalyst and co-catalyst, and prepares 1, 3-propylene glycol under the action of 3-hydroxy propionate hydrogenating catalyst. The present invention has the advantages of simple reaction apparatus, simple operation, mild reaction condition, high catalyst activity, no environmental pollution, low production cost, etc.

The invention provides a tulathromycin intermediate, a preparation method of the tulathromycin intermediate, and a preparation method of the tulathromycin. The preparation method of the tulathromycin has the advantages of mild condition, convenience for operation, and low cost. The preparation method of the tulathromycin comprises the following steps of: using azithromycin A as a raw material; protecting 2'-hydroxy and 6'-amino in the azithromycin A through di-tert-butyl dicarbonate so as to obtain double-protective azithromycin A; carrying out Swern oxidation to 4''-hydroxy to the double-protective azithromycin A; salifying along with trifluoroacetic acid; and synchronously removing boc t-butyloxycarbonyl to obtain the azithromycin A bitrifluoroacetic acid salt of 4''-carbonyl; and then reacting with trimethylsulfonium bromide to obtain 4''-epoxy compound; and finally carrying out nucleophilic addition on the 4''-epoxy compound by n-propylamine so as to obtain the phosphate of tulathromycin; and further neutralizing via alkaline to obtain the target compound tulathromycin; and synchronously obtaining the tulathromycin intermediate of azithromycin A bitrifluoroacetic acid salt of 4''-carbonyl.

The invention discloses a preparation method of metformin hydrochloride. The preparation method is characterized by using dicyandiamide and dimethylamine hydrochloride as raw materials, feeding the materials in a mole ratio of (1:1)-(1:1.2), using N,N-dimethylacetamide or dimethyl sulfoxide 2-4 times dicyandiamide by weight as a solvent, and reacting for 4-8 hours at 140+ / -5 DEG C to prepare a crude metformin hydrochloride product; recrystallizing the crude product with ethanol, regulating the pH value to be 5-6, decoloring the crystal, cooling the crystal to minus 10-0 DEG C while stirring, precipitating the crystal, obtaining a refined metformin hydrochloride product through filtering and drying, and recovering the solvent from filtrate. The qualified product has yield of 80-85% and high purity. The preparation method has the advantages that as the selected reaction solvent has a relatively high boiling point, the recovery rate of the solvent is high; the phenomenon of material surging can be effectively avoided, so that the preparation method has the advantages of mild reaction conditions, simplicity in operation and high safety.

The invention discloses a method for preparing a compound shown as the formula (I), which is characterized by comprising the following steps of: (1) carrying out hydroxyl protection on a compound shown as the formula (II) by using a first hydroxyl protecting group, and then, reacting with hydride to generate a compound shown as the formula (III); (2) carrying out hydroxyl protection on the compound shown as the formula (III) by using a second hydroxyl protecting group, and then, removing the first hydroxyl protecting group to obtain a compound shown as the formula (IV); (3) enabling the compound shown as the formula (IV) to carry out non-corresponding selective epoxidation reaction to generate a compound shown as the formula (V); (4) reacting the compound shown as the formula (V) with thecompound shown as the formula (VI) in a polar aprotic solvent to obtain a compound shown as the formula (VII); and (5) carrying out condensation, desilylation and oxidization on the compound shown asthe formula (VII) to generate the compound shown as the formula (I). In the general formulas of the compounds in each step, R1 is selected from naphthyl or any substituted naphthyl; R2 is selected from alkyl or benzyl of C1-C4; P is selected from hydroxyl protecting groups, such as 2-methoxyl propyl or p-methoxyl benzyl and the like; P' is a hydroxyl protecting group capable of resisting and removing P, such as benzyl; and X is selected from Cl, Br, I or benzyloxyl.

The invention relates to a method for catalysis-synthesizing 2,5-dicarbaldehyde by carbohydrate; carbohydrate is used as raw material, N,N-dimethylacetylamide is used as reaction medium, sodium bromide is used as additive, 5-hydroxymethylfurfural is dehydrated under acid catalysis, vandic salt is added as the catalyst, and air flows in under normal pressure to carry out oxidizing reaction, so as to synthesize 2,5-dicarbaldehyde; in the method, the reaction condition is mild, the raw materials and the catalyst are obtained easily, the method has high 2,5-dicarbaldehyde yield and the reaction process is easily operated.

The invention discloses a preparation method of polyene ether compounds. The method includes: organic small-molecule 4-dimethylamino pyridine (DMAP) is used as the catalyst, binary alkynyl compounds and binary hydroxy compounds are mixed with organic solvent, and the polyene ether compounds are obtained by using the click polymerization reaction of alkynyl-hydroxy. The polyene ether compounds comprise an inner unit indicated by formula (I). The polymerization step is showed in the formula (V), wherein n is larger than 1, and R1 and R2 are selected from organic groups. The method has the advantages that water and oxygen do not need to be removed during reaction, polymerization temperature is low, polymerization efficiency is high, and no metal residues exist in products; the prepared polyene ether compounds are high in steric regularity, good in machinability, and high in heat stability, degradability and aggregation-induced emission performance.

The invention relates to a hydrangea flower-cluster-shaped bismuth tungstate / biocarbon composite photocatalytic material, a preparation method and an application thereof. The preparation method comprises the following steps: firstly adding biocarbon, Bi(NO3)3.5H2O and Na2WO4.2H2O into water, mixing uniformly, then adding a surface active agent to mix uniformly, and thus obtaining reaction precursor solution, wherein the proportion among Bi(NO3)3.5H2O, Na2WO4.2H2O, biocarbon and the surface active agent is (3-5)mmol:(1-3)mmol:(0.1-0.3)g:(1.2-1.8)mmol; adjusting the pH value of the reaction precursor solution to 1-3; carrying out hydrothermal reaction on the reaction precursor solution with adjusted pH value; and after the hydrothermal reaction is finished, taking out products, washing, drying and grinding to obtain the hydrangea flower-cluster-shaped bismuth tungstate / biocarbon composite photocatalytic material. The hydrangea flower-cluster-shaped bismuth tungstate / biocarbon composite photocatalytic material, the preparation method and the application have the advantages that by introduction of the biocarbon, not only can the cost be reduced and the process be simplified, but also the photocatalytic activity of the material can be improved and the degrading effect for organic pollutants is good.

The invention provides a method for preparing soluble silicate with high modulus by gasified slag. The method comprises the following steps of (1) leaching the gasified slag by acid, and separating solid and liquid, so as to obtain the activated gasified slag and liquid phase; (2) performing desilicication reaction on the activated gasified slag and an alkaline solution of which the concentrationof hydroxyl ions is 1 to 5 mol / L at the temperature of 85 to 105 DEG C, and separating solid and liquid, so as to obtain the desilicication liquid and solid phase; (3) post-treating the desilicicationliquid, so as to obtain the soluble silicate with high modulus. Compared with the prior art, the method has the advantages that any silicon source does not need to be added, the sources of the raw materials are broad, the reaction conditions are mild, the process is simple, and the operation is easy; the quality of the prepared silicate is higher, the modulus is 1.5 to 2.5, the production cost islower, and the secondary solid and liquid pollutants are not produced; the reduction and recycling type efficient utilization of the gasified slag can be realized, and the economic benefit and environment benefit are obvious.

The invention discloses a preparation method for edaravone. The preparation method comprises a step of subjecting hydrazinobenzene and ethyl acetoacetate to a cyclization reaction under a solvent-free condition and action of an acid so as to prepare edaravone, wherein the usage amount of the acid is 0.02 to 10 equivalent of the molar weight of hydrazinobenzene. The preparation method provided by the invention has the advantages of mild conditions, fast reaction, safety, reliability, easy and convenient operation, low cost, almost quantitative completion of the reaction, capacity of obtaining a high purity (greater than 98%) crude product which accords with medicinal standards after simple recrystallization, and suitability for industrial production.

The invention relates to a high-temperature endurable active toughener powder used for epoxy resin, which comprises a general molecular structural formula as right, wherein -R1- is the diatomic linking group of aromatic series binary primary amine containing phenolic hydroxyl groups and -R2- is the diatomic linking group of aromatic series binary estolide molecule. The preparation method thereof comprises the steps of mixing the aromatic series binary primary amine, 2,2-Bis[4-(4-aminophenoxy)phenyl]propane and the aromatic series binary estolide with the mol ratio ranging from 1:1-5:2-6 in phenol solvent to react with each other at a temperature ranging from 100 to 150 DEG C for 5 hours and then pouring the obtained products into a precipitator stirred at a high speed to precipitate solid powder which is then filtered, washed, marinated, filtered and dried for preparing the high-temperature endurable active toughener powder for epoxy resin. The preparation method has the advantages of simple process and low cost, is environmental friendly, can finish the preparation process in universal equipment, and is applicable to industrial production.

The invention provides an adsorbent for removing PFOS and PFOA in water and a preparation method thereof. The adsorbent comprises cotton as a parent material, and quaternary ammonium salt is formed on the surface on the adsorbent. The use of the adsorbent can effectively remove PFOS and PFOA in water.

The invention discloses an extracting process for a club fungi polysaccharide. The extracting process comprises the following steps: carrying out the pretreatment of raw materials, carrying out the hot water leaching, ultrasonic extraction or microwave extraction, and storing the extract after concentration, alcohol deposition, centrifugation and drying, wherein the hot water leaching method has moderate conditions and simple operation; and the ultrasonic extraction method and the microwave extraction method can save time and improve the extraction efficiency. The extracted club fungi polysaccharide has an inhibition rate of 70 percent for little white rat S-180 and Ehrlich carcinoma, and has the functions of improving the immunity, diminishing inflammation, easing pain, and the like.

The present invention discloses a method to remove bitterness of the orange juice using a compound enzyme preparation, which comprises the following steps. Step a is that the orange juice is obtained by crude filtration after juice pressing. Step b comprises obtaining a compound enzyme preparation from a dictamnolactone enzyme and a naringinase with the weight ratio between five to 1 and one to five. Step b comprises adjusting pH value of the orange juice, adding the compound enzyme preparation with the addition quantity of 1g per kilogram to 3g per kilogram, heating the juice till 30 DEG C to 75 DEG C, keeping the constant temperature for 20 minutes to 90 minutes. Step d comprises obtaining the orange juice after minutes, enzyme denaturing and sterilization through instantaneous heating by super high temperature. Characteristics of the invention method comprises little nutrient loss and little loss in orange juice flavor, good debittering effect, stable product quality, high degree safety in the product, high production efficiency, simple operation and convenient application.

The invention discloses to a method used for simultaneous preparation of phospholipid microtubule and vesicle using point-plane electrode electric field. The method is used for solving a problem that existing method is not capable of realizing simultaneous preparation of phospholipid microtubule and vesicle. The method comprises following steps: step 1, electrode cleaning; step 2, preparation of phospholipid dry membrane; step 3, assembling of a sealed preparation apparatus; and step 4, preparation of the phospholipid microtubule and vesicle, and obtaining of the phospholipid microtubule and vesicle. Advantages of the method are that: firstly, the method is capable of realizing simultaneous preparation of the phospholipid microtubule and vesicle using point-plane electrode electric field in a same system, form of the obtained phospholipid microtubule is good, yield is high, and phospholipid microtubule size is relatively large and uniform; and secondly, the length of the obtained phospholipid microtubule ranges from 200 to 1300 mum, and diameter ranges from 1 to 2 mum; and diameter of the obtained phospholipid vesicle ranges from 15 to 120 mum. The method is used for simultaneous preparation of the phospholipid microtubule and vesicle using point-plane electrode electric field.

The invention discloses a graphene-supported palladium catalyst, which includes following raw materials, by volume, 2-10 parts of a material A, 30-50 parts of ethylene glycol, 100-150 parts of graphene and 5-20 parts of a KTiNbO5 nano sheet solution, wherein the material A includes the raw materials of PdCl2 and hydrochloric acid being 30-37% in concentration, wherein the weight / volume ratio of the PdCl2 to the hydrochloric acid is (0.01-0.1) g : (10-40) ml. The invention also provides the preparation method and an application of the graphene-supported palladium catalyst. In the invention, a conventional method of the graphene-supported palladium catalyst is replaced by the preparation method, which is free of surfactants, is small in particle size, is simple in operation, can be used in synthesis of cinnamic acid, is high in yield of cinnamic acid, is simple in separation and after-treatment, is mild in reaction conditions and is green and economical.

The invention discloses a soybean protein and a preparation method of the soybean protein. The preparation method comprises the following steps of: (1) diluting soy protein isolate to be 1 percent by using deionized water, putting the soy protein in a water bath at the temperature of 90 DEG C for 30 minutes, cooling to room temperature, and regulating the pH to be 3.5-4.5; (2) adding mucor miehei according to 0.2-1 percent of the mass of the protein, performing enzymolysis at the temperature of 50 DEG C, performing enzymolysis for 15-60 minutes when the pH is 3.5, wherein the pH is more than 3.5 and is less than or equal to 4.5, and performing enzymolysis for 30-60 minutes; and (3) immediately performing enzyme deactivation treatment, cooling to room temperature, regulating the pH to be 5.0-7.0, and finally, performing freeze drying to prepare the soybean protein. According to the soybean protein prepared through enzymatic modification, compared with the foaming capacity and foam stability of the soy protein isolate which is not treated, the foaming capacity is improved by 48.4-58.2 percent, the foam stability is improved by 265.9-284.1 percent, and the application range of the soybean protein which serves as an ingredient in food industry is widened.

The invention discloses a preparation method and an intermediate of ramelteon. The preparation method comprises the following steps: 1. deprotecting a compound (5) in an organic solvent to obtain a compound (6); 2. after condensing the compound (6) and a chiral resolution reagent, crystallizing to obtain an S type condensate crystal, and hydrolyzing under alkaline conditions to obtain an S type optical isomer compound (7) of the compound (6); and 3. reacting the compound (7) with propionyl chloride under alkaline conditions to generate the ramelteon (8).

The invention relates to the field of river surge treatment, in particular to a method for preparing a dominant microbial solid bacterial agent for river water pollution control, which includes acclimating microorganisms, preparing a composite bacterial liquid, selecting a carrier and preparing a solid bacterial agent. On the one hand, before the preparation of the solid bacterial agent, the microorganisms were domesticated, and the obtained microbial mixture had an absolute advantage in enriching and cultivating the target bacteria, and the concentration was high. The microorganisms in the solid microbial agent could well colonize in the water body. It is conducive to improving the quality and efficiency of subsequent water pollution treatment; secondly, the solid bacterial agent is prepared by adsorption or embedding, the environmental requirements are not harsh, the reaction conditions are mild, and the operation is simple. The microorganisms in the composite bacterial liquid can be combined with the carrier The combination is tight, and the concentration of microorganisms in the prepared solid bacterial agent is high; in the third aspect, the carrier has a particle size of 1-3mm and a density of 1.1-1.5g / cm 3 The special ceramsite or molecular sieve carrier for porous organisms is non-toxic and has good biocompatibility, which is conducive to material transmission and exchange.

The invention provides a method for preparing a beta-amino-carbonyl compound. Aldehydes, ketones and amines are directly mixed under the condition of synergetic catalysis of titanocene dichloride and a ligand, and react at room temperature to obtain the beta-amino-carbonyl compound, wherein the ligand is salicylic acid or salicylic acid derivatives or structural analogues thereof. According to the method, the catalyst used in the method is low in cost, nontoxic and stable and effective to air and water, the reaction condition is mild, a solvent is not needed, the operation is simple, and the atom economy is high.

The invention provides a method for processing fresh castanea mollissima packaged products. The method comprises the following steps: taking fresh deburred castanea mollissima, shearing notches on castanea mollissima shells by using scissors, drying the castanea mollissima through hot air for 30-60 minutes at temperature of 40-50 DEG C, shelling and peeling manually, soaking the castanea mollissima in 1-3ppm ozone water for 30-45 minutes; then blanching the castanea mollissima in a freshness retaining and color protecting liquid for 5-10 seconds at temperature of 80-90 DEG C, then instantly putting the castanea mollissima into the freshness retaining and color protecting liquid at temperature of 5-10 DEG C for carrying out ultrasonic treatment for 30-45 minutes, then refrigerating the castanea mollissima for 10-16 hours at temperature of 2-8 DEG C, then pre-freezing the castanea mollissima for 10-16 hours at temperature of -18 DEG C to -48 DEG C, and finally, drying the castanea mollissima for 48-72 hours till the content of water is 10-18%, and packing in vacuum under a clean environment and thus obtaining the fresh castanea mollissima packaged products. The products have good color, fragrance, taste and shape, can be stored and transported for 2 months at room temperature and sold by bulks in common farmers markets; the products are applicable to cooking and preparation in houses and commercial catering and secondary processing and sales of castanea mollissima food factories; by trial marketing, the fresh castanea mollissima packaged products are deeply favored by all consumers.

The invention relates to a method for breaking walls of Haematococcus pluvialis and extracting astaxanthin. The method comprises the following steps: (S1) uniformly mixing Haematococcus pluvialis powder with a concentrated sulfuric acid-alcohol system, stirring at 30-70 DEG C, and carrying out wall breaking for a preset time, so as to obtain an alcohol solution containing wall-broken Haematococcus pluvialis; and (S2) adding an extraction solvent into the alcohol solution containing the wall-broken Haematococcus pluvialis obtained in the step (S1), carrying out stirring extraction at 30-70 DEG C, layering, and concentrating supernate, so as to obtain an extract containing the astaxanthin. The method has the beneficial effects that the wall-breaking temperature and the extraction temperature are relatively low, reaction conditions are mild, the loss of astaxanthin is reduced, and the content of the astaxanthin in a crude extract can reach up to about 10%, so that the subsequent purification level of difficulty can be lowered, and the commercialization of the astaxanthin is promoted. Compared with existing methods, the method has the advantages that the operation steps are relatively simplified and the type and use amount of reagents are less, so that the energy consumption can be reduced, and the comprehensive cost can be lowered.

The invention discloses a method for digesting spent rhodium catalyst in carbonyl group synthetic reaction, which is characterized by adding concentrated sulfuric acid into the spent rhodium catalyst in carbonyl group synthetic reaction for carbonization; and then adding alkali metal nitrate solid for digestion until solution of a system is clear and transparent; at this moment, organic matters are digested and removed in a format of carbon dioxide, and rhodium exists in acidic solution in a format of soluble salt. The method disclosed by the invention is high in recovery rate of rhodium, environment-friendly, moderate in operating condition, and high in efficiency.

The invention provides a synthesis method of 1,4-butanediamine, which comprises the steps of: (a) dissolving the 1,4-dibromobutyl amine represented by formula (1) in a solvent A, adding the phthalimide potassium represented by formula (2), reacting while stirring at a reflux temperature, filtering reaction liquid, washing by using distilled water to obtain the 1,4-diphthalimide butane representedby formula (3); (b) adding the 1,4-diphthalimide butane obtained in the step (1) and 40% methylamine water solution to a solvent B, heating until solids are dissolved completely, stirring and reacting for 0.5-4 hours at the reflux temperature to obtain reaction products; and (c) filtering the reaction products, post-treating filtrate, distilling the filtrate under normal pressure, and collecting the fractions between 158 DEG C and 160 DEG C to obtain the 1,4-butanediamine. The invention has simple and convenient technological conditions, cheap raw materials, mild reaction conditions, easy control and convenient industrial production.

The invention discloses a synthetic method for adenine. Malononitrile and thiourea are employed as raw materials. The raw materials are subjected to a cyclization reaction under action of sodium alkoxide, and 4,6-diamino-2-sulfydryl pyrimidine. Then through three reaction routes, adenine is obtained. Though the method has many reaction steps, no refining or drying are needed for the product of each reaction step, the product can be used in the next reaction step, and the operation is simple. The raw materials are easily available, the prices are relatively low, the reaction conditions are mild, the operation is simple, the reaction steps are decreased, the reaction time is shortened, the overall reaction yield is high, and the synthetic method is suitable for industrial production.

The invention discloses an automatic histocyte separator which is used for separating tissues into single cells. The separator comprises a separation tube and a motor, wherein the separation tube comprises a tube wall and a tube core in the tube wall; the top part of the tube wall is blocked; a tube cover covers the bottom part of the tube wall; the tube core comprises a stator sleeve and a rotor in the sleeve; a rotor joint is arranged on the tube cover; the rotor is connected with the rotor joint; the motor is located outside the separation tube, and is used for providing rotary power for the rotor through the rotor joint; and the inside of the tube core is sequentially divided into an archimedes spiral pipe area, a cell separation area and a negative pressure rotary cutting area from top to bottom. An automatic system with a special tube core is utilized; a microprocessor is used for defining special application program to optimize operation regulations; a specimen can be conveniently treated; the cell separation and preparation processes are standardized and programmed; and the effects on human factors are reduced.

The invention discloses a preparation method for 3-substituted trifluoromethyl indole. Various substituted acetanilides are taken as a reaction substrate with a medium to excellent reaction yield, excellent reaction chemical selectivity, and high area selectivity; another isomer (2-substituted trifluoromethyl indole) is monitored to be not detected in detection; the conditions are gentle; the substrate is wide in scope of application (wherein R is H or various electron-donating groups such as CH3, OCH3, SCH3 and the like, as well as various electron withdrawing groups such as NO2, Cl and the like, and Ar is various substituted benzene rings); the preparation method is simple and convenient in operation, relatively low in cost, less in side reaction, high in product purity, convenient in separation and purification, and suitable for large-scale preparation; and a product prepared by the preparation method has a very good application prospect in the biomedicine field.

The invention discloses a full-spectrum selective reflection and photoluminescence Janus oligomer and a preparation method thereof, wherein the full-spectrum selective reflection and photoluminescenceJanus oligomer is constructed by graft copolymerization of a chiral liquid crystal monomer, a nematic liquid crystal monomer, fluorescent molecules and polymethyl hydrogen-containing siloxane, and the structure is shown as a formula I in the specification. According to the invention, the Janus oligomer can realize full-spectrum selective reflection in heating and cooling processes, and has high reversibility and accuracy; under the excitation of ultraviolet light, the Janus oligomer can emit fluorescence, wherein when the temperature rises to the thermal decomposition temperature of the Janusoligomer from the room temperature, the fluorescence intensity is monotonically reduced, and the fluorescence intensity still has high reversibility along with the change of the temperature; and theJanus oligomer prepared by the method has dual characteristics of dynamic reversible full-spectrum selective reflection and photoluminescence, has a wide application prospect in the anti-counterfeiting field, and is short in preparation route, safe and simple to operate and mild in reaction condition.

The invention relates to a method for preparing a spherical carbon heavy metal adsorbent. The method is characterized by taking pentosan extracted by a bleached hardwood pulp alkaline method as a raw material and pure water as a solvent, and comprising the steps of after treatment at high temperature and high pressure under a hydrothermal condition, centrifugally separating so as to obtain a dark brown solid product, namely carbon spheres rich in acid oxygen-containing functional groups, washing the dark brown solid product for many times by distilled water and absolute ethyl alcohol till filtrate is clear, and drying in vacuum so as to obtain the spherical carbon heavy metal adsorbent. The method has the main characteristics that the pentosan extracted from a byproduct of pulping and papermaking is taken as the raw material and is environmentally friendly, cheap and easily available, water is taken as the solvent, the reaction needs no modifier and further oxidation, the adsorbent containing a large quantity of hydroxyl and carboxyl oxygen-containing functional groups is formed through dehydration, condensation, aromatization and carbonization, the adsorbent and metal ions can have chelation, and the adsorbent can be used as high performance adsorbent for adsorbing heavy metal ions like Pb(II) and Cd(II).The hydrothermal reaction adopted in the method has a simple operation process and the adsorbent is low in cost and has an excellent adsorbing effect.

The invention belongs to the technical field of the catalytic synthesis, and particularly discloses a CO (carbon monoxide)-promoted method for directly oxygenizing a hydroxylated aromatic compound by molecular oxygen. The method provided by the invention uses an aromatic compound as a substrate, uses a combined catalyst consisting of a supported precious metal catalyst and a heteroatom zeolite containing Ti, V, Cu or Fe or a polyoxometalate, and uses the mixed liquid of water and an organic solvent as a solvent; the CO (carbon monoxide) and O2 (oxygen) are put into the reaction system; and, under the promotion of the CO (carbon monoxide), the molecular oxygen directly oxygenizes the hydroxylated aromatic compound to prepare a corresponding phenol compound. The equipment and the process used by the method provided by the invention are simple; the separation of the target product is relatively easy; the reaction conditions are moderate; the system is environment-friendly; and thus the method is a green process route.

The invention relates to a preparation method of N-protected (2S, 3S)-3-amino-1-chloro-4-phenyl-2-butanol. The preparation method comprises the following steps: by taking N-protected (S)-3-amino-1-chloro-4-phenyl-2-butanone as a substrate, performing a reducing reaction on the substrate to generate the N-protected (2S, 3S)-3-amino-1-chloro-4-phenyl-2-butanol, wherein the reducing reaction is performed in the presence of a ketoreductase, a cofactor and a hydrogen donor, in an aqueous phase having the pH of 8-10 and at a temperature ranging from 30 to 50 DEG C; and the DNA sequence of the ketoreductase is as shown in any one of SEQ ID No. 1-20. According to the preparation method, as the specific ketoreductase is used for catalyzing the reduction reaction, the preparation method has the advantages of small enzyme dosage, mild reaction condition, simplicity in operation, short reaction time, high yield, and environmental protection. Compared with the chemical methods in the prior art, the preparation method is high in economic efficiency and low in pollution, and has an important application value.