52 results about "Potassium borohydride" patented technology

The invention provides a synthesis method and application of a sulfuration modified palladium-iron bimetallic material. The method comprises the steps that potassium borohydride and sodium sulfide nonahydrate are dissolved in a solvent, sodium hydroxide is added into a sulfuration solution, the pH of the sulfuration solution is adjusted to be alkaline, and an alkaline solution is obtained. The method comprises the following steps: dropwise adding an alkaline solution into a mixed aqueous solution of FeSO4. 7H2O and sodium tetrachloropalladate at a speed of 10mL / min in a nitrogen atmosphere; and separating the precipitate from the mixed aqueous solution in a magnetic separation manner, and washing the precipitate for three times by using oxygen-free water and absolute ethyl alcohol to obtain the palladium iron sulfide bimetallic particles. Through a one-step reduction method of vulcanization and palladium doping, vulcanization modification and bimetal modification are combined to act on zero-valent iron, the stability of the zero-valent iron is enhanced through vulcanization, meanwhile, the reactivity of the zero-valent iron is improved through addition of bimetal, especially the selectivity to pollutants such as chlorinated paraffin and the reactivity after surface passivation are improved, and the stability of the zero-valent iron is improved. And the reliability and efficiency of the zero-valent iron in organic pollution remediation are greatly improved.

The invention relates to the technical field of perfume production, in particular to a composite catalyst, a preparation method thereof and a synthesis method of ambergris. The composite catalyst disclosed by the invention is obtained by quaternizing porous silicon dioxide and then loading aluminum trichloride; when the composite catalyst is applied to synthesis of ambergris, the composite catalyst can be matched with potassium borohydride, so that sclareolide can be subjected to a one-step reduction reaction to generate ambergris, the reaction condition is mild, the method is stable, generation of sclareolide ring-opening byproducts is reduced, the product yield is increased, and the yield can reach 95% or above.

The invention discloses a preparation method of 3-quinuclidinone hydrochloride, which comprises the following steps: carrying out temperature control reaction on 4-picolinic acid and chloroacetic acid under alkaline water conditions to obtain an aqueous solution of a compound a, and directly entering the next reaction without post-treatment after the reaction is finished; adding a reducing agent alkaline water system into the aqueous solution of the compound a, controlling the temperature to react, controlling the temperature to adjust the pH value to 5-5.5 after the reaction is finished, extracting with n-butyl alcohol, and drying to obtain an n-butyl alcohol solution of a compound b, and directly entering the next reaction step; wherein the reducing agent is one of sodium borohydride and potassium borohydride; dropwise adding thionyl chloride into an n-butyl alcohol solution of the compound b, controlling the temperature to react after dropwise adding is ended, and concentrating to remove the solvent and unreacted thionyl chloride after the reaction is ended, so as to obtain a compound c; carrying out Dieckmann condensation reaction on the compound c at controlled temperature under the condition of organic alkali by using toluene as a solvent, carrying out hydrochloric acid quenching reaction after the reaction is finished, and directly carrying out next-step reaction after extracting and removing impurities from a water phase containing a hydrochloride solution of a compound d by using toluene; and carrying out a decarboxylation reaction on the compound d in a hydrochloric acid aqueous solution at controlled temperature, after the reaction is finished, adjusting the pH value to 10-13, extracting, and salifying to obtain a target compound TM, namely 3-quinuclidinone hydrochloride. The preparation method of 3-quinuclidinone hydrochloride provided by the invention has the advantages of economical and easily available raw materials, mild reaction conditions, efficient reaction, simple operation and low cost, and is suitable for industrial application.

The invention discloses a preparation method of a cyanoethoxy alkyl derivative, which comprises the following steps: 1, mixing polyose and deionized water, heating to 50-70 DEG C, adding a boron reducing agent in batches, cooling to room temperature, adding a catalytic amount of inorganic base into the reaction liquid according to the molar ratio of the polyose to the inorganic base being (1: 0.01)-(1: 0.1), stirring and dissolving, and reacting at 30-45 DEG C for 2-3 hours to obtain the cyanoethoxy alkyl derivative; the preparation method comprises the following steps: adding polyose into a reaction kettle, dropwise adding acrylonitrile, and after dropwise adding, carrying out heat-preservation reaction according to a feeding molar ratio of the polyose to acrylonitrile of 1: 5-1: 9; the boron reducing agent is selected from one of sodium borohydride, potassium borohydride and sodium cyanoborohydride; and 2, after the reaction is finished, firstly adding a benign organic solvent into the reaction liquid for extraction, then adding an inert organic solvent into the organic phase, stirring for crystallization, and carrying out vacuum drying on the precipitated solid to obtain the product. The method has the advantages of few side reactions, simple post-treatment, high product yield and high purity, and is suitable for industrial production.

The application belongs to the technical field of catalysts, and provides a titanium nickel nitride-based palladium catalyst, a preparation method and application thereof. The method comprises the following steps: mixing titanium tetrachloride, nickel acetate tetrahydrate and ethanol under an ammonia atmosphere, and performing a reaction to obtain a complex powder; performing a nitriding reaction on the complex powder under an ammonia atmosphere to obtain titanium nickel nitride nanoparticles; mixing the titanium nickel nitride nanoparticles, a chloropalladic acid solution, water and a potassium borohydride solution, and performing a reaction to obtain the titanium nickel nitride-based palladium catalyst. The catalyst prepared by the application has a high specific surface area and is composed of two parts, namely a titanium nickel nitride nanoparticle carrier and a supported Pd nanocluster. Among them, nickel atoms are doped between the titanium nitride crystal lattices. The Pd nanocluster is supported on the surface of the TiNiN carrier, and by adjusting the loading amount of Pd atoms, efficient and high-selectivity catalysis of various environmental hydrogenation catalytic processes can be realized.

The present invention discloses an octahedral BIF-29 catalytic material and a continuous preparation method and application thereof, which belong to the field of electrochemical catalysis. The octahedral BIF-29 catalytic material includes a metal copper salt and an organic ligand, wherein the organic ligand is tri(1H-imidazolyl) potassium borohydride; the metal copper salt is copper nitrate. The octahedral BIF-29 catalytic material is an M6L8 structure, that is, six metal copper sites are connected to eight organic ligands to form a cage structure, with six exposed mononuclear copper centers, which are connected to the ligands through copper-nitrogen bonds inside, and the micromorphology presents an octahedral morphology. The octahedral BIF-29 catalytic material only needs to be continuously synthesized at a lower temperature and can be used as an efficient electrocatalytic reduction of carbon dioxide catalyst without further treatment. The octahedral BIF-29 catalytic material in the present invention has an electrocatalytic carbon dioxide reduction conversion efficiency of up to 93.7% when participating in the electrocatalytic carbon dioxide reduction reaction.

The invention provides a preparation method and application of a cobalt-based super-crosslinked polymer-based porous material for wastewater purification. According to the preparation method of the cobalt-based super-crosslinked polymer, sodium borohydride / potassium borohydride is used as a reducing agent to reduce cobalt nitrate, so that cobalt is loaded on the surface of the super-crosslinked polymer to obtain a composite material of the super-crosslinked polymer and transition metal, namely a catalytic oxidation method is introduced on the basis of adsorption, PMS is activated through the transition metal to generate free radicals, and the cobalt-based super-crosslinked polymer is obtained. The removal effect of the super-crosslinked polymer on the anion organic pollutant brilliant blue is further improved. The invention verifies that the cobalt-based super-crosslinked polymer has good adsorption and degradation properties on various pollutants. The invention researches the application of the adsorption-degradation system of the cobalt-based super-crosslinked polymer in the actual water body, and the experimental result shows that the adsorption-degradation system has a good removal effect on the anion organic pollutants and has the potential of removing the anion organic pollutants in the actual water environment.

The application is a kind of continuous preparation method and application of core-shell type reduced Cu-based catalyst. The method uses membrane dispersion micro-reactor technology, adopts liquid phase chemical reduction method with potassium borohydride-hydrazine hydrate as double reducing agent, continuously prepares reduced Cu-based nanoscale catalyst, does not need high temperature calcination and hydrogen reduction, can be directly used as active catalyst for catalytic reaction, and realizes green and efficient preparation. The catalyst prepared by the application is used in the reaction of preparing N-butyl-2,2,6,6-tetramethyl-4-piperidinamine from 2,2,6,6-tetramethyl-4-piperidinone and n-butylamine through reductive amination, and excellent catalytic activity and stability are shown.

The present application belongs to the technical field of wastewater treatment, and particularly relates to a method for removing total nitrogen in wastewater. Iron salt and carbon material containing hydroxyl and carbonyl are added into water, and then potassium borohydride is added, and the obtained mixture is freeze-dried under argon protection atmosphere to obtain iron-carbon filler; the iron-carbon filler is added into wastewater, the wastewater is adjusted to be weakly acidic, and stirring reaction is carried out for 0.5-1.5 h to obtain reduced effluent; persulfate is added into the reduced effluent, the wastewater is adjusted to be alkaline, and stirring reaction is carried out for 0.5-1.5 h, and then solid-liquid separation is carried out, and the obtained supernatant is treated effluent. The present application can remove total nitrogen in wastewater only by using iron-carbon filler and persulfate at normal temperature and pressure, and has the advantages of fast conversion rate, strong anti-interference ability, no secondary pollution and the like compared with traditional chemical oxidation-reduction technology; the reaction has wide original sources, low price, simple operation, and is environment-friendly, and has obvious economic and environmental benefits.

This invention provides a PVP-coated Cu-based electrocatalytic material, its preparation method, an electrode for electrocatalytic carbon dioxide reduction, and its application. Copper chloride dihydrate, polyvinylpyrrolidone (PVP), and dimethylformamide are mixed to obtain a mixture. Under a protective atmosphere and with stirring, potassium borohydride solution is added dropwise to the mixture, generating a precipitate. The precipitate is then centrifuged and dried to obtain the PVP-coated Cu-based electrocatalytic material. This invention introduces PVP, which has the advantages of low cost and wide availability. Cross-linked nanosheet-like copper-based catalytic materials are successfully prepared by reducing divalent copper ions with potassium borohydride solution. During the reduction process, 0.18–0.22 g of PVP (based on 2 mmol of copper) is introduced to coat the copper nanosheet structure, effectively regulating the valence state change of divalent copper ions during the reduction process, controlling it between monovalent and divalent copper, thus making it more favorable for the formation of C2 products.

The invention discloses a nitrogen-phosphorus-boron-iron co-doped coconut shell activated carbon carrier and a preparation method and application thereof, the method comprises the following steps: S1, crushing coconut shell activated carbon, and carrying out Ar / water vapor activation treatment to obtain pretreated activated carbon; s2, after the chitosan solution and the urea solution are mixed, phytic acid is added, the pH is adjusted to 5.5-6.0, stirring is conducted, and a wetting agent is obtained; s3, adding a wetting agent into the pretreated activated carbon, heating, stirring, filtering, washing, and drying in vacuum to obtain pre-activated activated carbon containing nitrogen and phosphorus; and S4, dissolving ammonium ferric citrate and sodium citrate in deionized water, adding ethylene glycol, stirring, then adding the pre-activated activated carbon containing nitrogen and phosphorus, heating, stirring again, then dropwise adding a potassium borohydride mixed solution, and roasting to obtain the nitrogen, phosphorus, boron and iron co-doped coconut shell activated carbon carrier. After the nitrogen-phosphorus-boron-iron co-doped coconut shell activated carbon carrier provided by the invention is loaded with the metal catalyst, the common problems of low conversion rate and poor selectivity in nitro hydrogenation reaction can be solved.

The invention discloses an efficient and safe microwave digestion-atomic fluorescence detection method for total selenium in soil, and belongs to the technical field of analytical chemistry and environmental detection.According to the method, the content of total selenium in selenium-rich soil is rapidly, accurately and safely measured by optimizing the sample weighing amount, the microwave digestion procedure and the detection conditions, and the detection accuracy is improved. The method comprises the following specific steps: weighing 0.1 g of an air-dried and sieved selenium-rich soil sample, adding 5mL of concentrated nitric acid, then carrying out a microwave digestion process of heating to 175 DEG C for 12 minutes and maintaining for 48 minutes, after digestion, adding 5mL of 6mol / L hydrochloric acid, carrying out acid removal reduction at 140 DEG C, fixing the volume to 15mL by using 5% diluted hydrochloric acid, and finally determining by using an atomic fluorescence spectrophotometer by using 5% hydrochloric acid as a carrier current and 1% potassium borohydride and 0.5% potassium hydroxide as reducing agents. According to the method, the use of dangerous reagents such as hydrofluoric acid and perchloric acid is avoided, the detection period is remarkably shortened, the linear range is 0-10 mu g / L, and the correlation coefficient is Rgt; the average recovery rate is up to 101.13%-101.51%, and the precision is RSDlt (Research Standard Defect); the requirements of rapid detection of the total selenium content of the selenium-rich soil, agricultural production and environmental evaluation are met.

The utility model provides a liquid chromatography-atomic fluorescence flow path analysis system, which relates to the technical field of chemical analysis, and comprises a mobile phase processing device, a sample online reaction device, a gas path device and a gas-liquid separation device, the sample online reaction device is used for carrying out separation, online ultraviolet digestion and hydride generation on a sample; according to the device, the mobile phase does not need to be degassed manually, an experimenter only needs to prepare the mobile phase and place a pipeline in a corresponding reagent bottle, and an instrument can perform online degassing on the mobile phase, so that the time required for preparing the mobile phase is saved, hydrogen is supplemented when a sample reacts with a reducing agent to generate gaseous hydride, the dosage of potassium borohydride is effectively reduced, and the production cost is reduced. While the physical health of experimenters is ensured and a friendly laboratory environment is provided, the influence of water vapor on a test result can be reduced, and the sensitivity and the stability of an instrument are improved.

The invention provides an efficient preparation method of 6-hydroxy-8-chloro caprylic acid ester. The method comprises the following steps: synthesizing adipic acid into adipic acid monoester acyl chloride, then carrying out addition on the adipic acid monoester acyl chloride and ethylene under the catalytic action of aluminum trichloride, then treating by using sodium isopropoxide, and converting carbonyl into hydroxyl by using a Meerwein-Ponndorf-Verley reduction method to obtain 6-hydroxy-8-chloro caprylate. Compared with an existing preparation method, potassium borohydride reduction is avoided, the manufacturing cost is reduced, and the operability of the production process is improved. The high-efficiency preparation method of 6-hydroxy-8-chloro caprylate provided by the invention has the advantages of simplicity and convenience in operation, clear steps, high product purity and the like, is suitable for industrial production of 6-hydroxy-8-chloro caprylate compounds, and has a good application prospect and a wide market demand.

The invention discloses a catalyst for preparing citronellal by selective reduction of citral and a preparation method thereof. A magnesium oxide carrier is obtained by calcining a magnesium salt at high temperature, a palladium precursor is uniformly loaded on magnesium oxide by adsorption, palladium is reduced with sodium borohydride, potassium borohydride or sodium formate, and then a hydrophobic hydrogenation catalyst is obtained by modification with 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane. The catalyst prepared in this way has high catalytic activity and selectivity for the reaction of preparing citronellal by selective reduction of citral. The catalyst active components of the present invention are highly dispersed, highly active, and have a selectivity of ≥98%, and the catalyst cost is low, and has a high industrial application value.

The invention discloses a fermentation type seaweed granular fertilizer and a fermentation method thereof, and belongs to the technical field of biological fertilizers, plant active substances of enzymolysis seaweed active powder, grain byproducts and organic nutrition of soybean meal are fused, after microbial fermentation, nutrition release is more balanced, robust growth of crops can be promoted, and the yield and quality can be improved; seaweed residues are secondarily utilized through an enzymolysis technology, macromolecular substances are degraded into micromolecular active components through alginate lyase and cellulase, enzymolysis seaweed active powder is prepared, the nutritive value of seaweed is excavated to the maximum extent, the cost of raw materials is reduced, nano zeolite serves as a carrier of microelements, iron ions are reduced and stabilized through potassium borohydride, and then iron ions are reduced and stabilized through potassium borohydride; and then the nitrohumic acid is used for chelating elements such as zinc, iron and boron, and the adsorption performance of the nano zeolite is combined, so that the double stability of the chelated trace elements and the porous carrier is realized.

The application discloses a preparation method of an anode material for treating organic wastewater, and comprises the following steps: (1) dissolving silver nitrate, ammonia water, sodium hydroxide and formaldehyde in deionized water to obtain a precursor solution, then fixing a commercial electrode in the precursor solution, and performing heating and stirring treatment to obtain an Ag / commercial electrode sheet; (2) preparing a plating solution by using nickel salt, ethylenediamine, potassium borohydride and sodium hydroxide, then fixing the Ag / commercial electrode sheet obtained in the step (1) in the plating solution, and performing heating and stirring treatment, and then performing washing and drying to obtain the anode material. When the electrode material is used for electrocatalytic oxidation treatment of 3-aminomethyl-3, 5, 5-trimethylcyclohexylamine wastewater, the ammonia oxidation rate is higher, and the COD and NH4-N values of the organic wastewater can be effectively reduced. The application further discloses the anode material obtained by the preparation method and application thereof.

The application provides a preparation method of an nZVCu@AF composite material and application thereof, and comprises the following steps: under the protection of nitrogen, equal-volume-ratio 0.01-0.1M Cu(II) solution and 0.2-2.0M potassium borohydride solution are simultaneously added drop by drop into amyloid fiber suspension liquid, the volume ratio of the dropwise added solution to the amyloid fiber suspension liquid is 1:2, and the obtained material is sufficiently stirred and reacted for 2-6h; the obtained material is repeatedly washed with ultrapure water to remove impurities, and then vacuum freeze-dried to obtain the nZVCu@AF composite material. The application solves the problems that organic phosphorus compounds are difficult to degrade and have low mineralization rate, and constructs a one-step deep treatment method for water body organic phosphorus, which can efficiently induce inorganic conversion of organic phospholipid and realize in-situ phosphorus recovery.

The invention relates to a production method for improving photo-thermal stability of a chloromethyl ethyl ether industrial product, and belongs to the technical field of chloromethyl ethyl ether processing.The preparation of an intermediate 1 comprises the steps that 80-120 mL of ethyl alcohol, 20-25 g of 3, 5-di-tert-butyl-4-hydroxybenzaldehyde and 6-10 g of n-butylamine are added into a 250 mL four-opening bottle provided with a backflow water diversion device, the temperature is increased to 60 DEG C, a reaction is carried out for 1 h, and an intermediate 2 is obtained; cooling to 0 DEG C by adopting an ice salt bath, adding 1-3g of potassium borohydride in batches, keeping the temperature at 0 DEG C, continuing to react for 0.5 hour, and adding a 5% citric acid aqueous solution to adjust the pH value to 2.0-3.0; the special photo-thermal stabilizer is synthesized and compounded with the epoxidized soybean oil, a single stabilizer and a special formula free of chloromethyl ether are generally adopted in the traditional method, the photo-thermal stabilizer containing the hindered phenol and piperazine structure is synthesized by the method, synergistic protection of light shielding, thermal stability and acid capture is achieved after compounding, and the product performance is remarkably improved; and the purity retention rate is 95-97% after 168h of ultraviolet aging.

The application relates to the field of photocatalysis, in particular to a composite material for photocatalytic degradation of PFOA and a preparation method thereof. The composite material comprises the following steps: step one: using titanium foil as an anode and a nickel sheet as a cathode, carrying out anodic oxidation, and then annealing to obtain TiO2-NT; step two: first, acid pickling TiO2-NT, and then preparing TiO2-NT suspension liquid; adding chloroplatinic acid, a dispersing agent and potassium borohydride into the TiO2-NT suspension liquid to prepare a Pt / TiO2-NT composite material; step three: coating ammonium perrhenate on the Pt / TiO2-NT composite material, and then sintering, repeating 1-2 times to obtain a modified Pt / TiO2-NT composite material; and step four: preparing a MIP-Pt / TiO2-NT composite material through a molecular imprinting technology.

The invention discloses a method for detecting arsenic content in a lithium-based new energy raw material. A nitric acid-hydrofluoric acid-hydrogen peroxide three-step digestion system is adopted to treat a sample, thiourea-ascorbic acid is combined as a reduction system, and interference is eliminated by controlling the concentration of hydrochloric acid and the flow velocity of potassium borohydride. Experiments prove that the relative standard deviation (RSD) of lithium carbonate sample determination by the method is 1.2%, the adding standard recovery rate is 98.5-101.3%, the detection limit reaches 0.008 microgram / g, and the method has the advantages of accurate detection, strong interference resistance and the like, and is suitable for arsenic content detection in various lithium-based new energy raw materials such as lithium carbonate, lithium hydroxide and the like.

The invention discloses a total arsenic online monitoring reagent formula and a preparation method, the total arsenic online monitoring reagent formula comprises a reagent A, a reagent B, a reagent C, a reagent D and a total arsenic standard solution, the reagent A is composed of sulfuric acid, potassium persulfate and pure water, the reagent B is composed of sodium acetate trihydrate, glacial acetic acid, an emulsifier OP-10, silver carbonate, absolute ethyl alcohol and pure water, the reagent C is composed of sulfuric acid, tartaric acid and pure water, and the reagent D is composed of sodium acetate trihydrate, glacial acetic acid, an emulsifier OP-10, silver carbonate, absolute ethyl alcohol and pure water. The reagent D is composed of potassium hydroxide, potassium borohydride and pure water, and the total arsenic standard solution is mother liquor with the concentration of 1000 mg / L. Through the synergistic effect of silver carbonate in the reagent B and the emulsifier OP-10, interference substances such as sulfides and heavy metal ions can be effectively shielded, the relative standard deviation of a monitoring result is smaller than or equal to 5%, and the accuracy of monitoring data is improved.

The invention provides a method for preparing a lanthanum hydroxide phosphate adsorbent through potassium borohydride reduction, and belongs to the technical field of adsorbents. The adsorption mechanism is based on chemical adsorption phosphorus removal, potassium borohydride is added into a lanthanum nitrate solution to realize reduction oxidation of lanthanum ions, a nano phosphorus removal material with the average size smaller than 10 nanometers is formed, and the porous non-fixed type porous hydrogel is formed through a series connection process. Compared with a conventional powdery adsorbent and a directly synthesized lanthanum hydroxide adsorbent, the lanthanum hydroxide adsorbent has the advantage that the adsorption performance of lanthanum hydroxide to phosphate is multiplied by introducing a reduction-oxidation process.

The invention provides a pretreatment method of activated carbon and a method for refining sugammadex sodium by using the pretreated activated carbon, and the pretreatment method of the activated carbon comprises the following steps: treating the activated carbon by using specific reducing agents such as sodium borohydride, potassium borohydride and the like to remove oxidizing groups in the activated carbon; therefore, the increase of oxidation impurities in the refining process of sugammadex sodium is inhibited. According to the method, high-purity sugammadex sodium can be efficiently obtained.

The application relates to the technical field of cement grinding aids, and particularly discloses a high-efficiency composite Portland cement clinker grinding aid and application thereof. The grinding aid comprises separated A liquid and B liquid. The A liquid comprises a mixed solution of ethylene glycol and water and dihydrogen iron phosphate, wherein the volume ratio of the ethylene glycol to the water is 3-3.7:1, and the dihydrogen iron phosphate in the mixed solution is in a saturated state. The B liquid comprises a sodium borohydride and / or potassium borohydride solution, a polycarboxylic acid water reducing agent and modified magnesium oxide powder. The mass fraction of the sodium borohydride and / or potassium borohydride solution is 3-5%, the mass fraction of the polycarboxylic acid water reducing agent in the B liquid is 12-17%, and the content of the modified magnesium oxide powder is 4.5-7 g / L. The above grinding aid can effectively eliminate the electrostatic effect of cement particles, reduce the re-agglomeration between the particles, improve the dispersity of the cement clinker particles, and thus improve the grinding efficiency.

The invention provides a preparation process of medicine-assisted isopropanol, and relates to the technical field of isopropanol purification. Comprising the following steps: by taking analytically pure isopropanol as a raw material, adding potassium borohydride and hydroxide according to a solid-to-liquid ratio of (6-8): 1000, and uniformly mixing; carrying out reflux reaction on the mixture at 80-85 DEG C for 3-5 hours; carrying out atmospheric distillation, controlling the top temperature to be 82.3-82.7 DEG C, and collecting a middle fraction; detecting the middle fraction, and obtaining the medicine-assisted grade isopropanol when the middle fraction reaches the standard; in the step S100, hydroxide is added in stages, potassium borohydride and 45%-55% of hydroxide are added into isopropanol at the same time, a reflux reaction is conducted, and the reaction lasts for 1.0-1.2 h; and slowly adding the residual hydroxide in the form of solid powder, and controlling the adding rate to be less than or equal to 0.5 g / min. Through the processes of staged alkali addition, synergistic reduction of potassium borohydride and hydroxide, precise distillation control and the like, the impurity removal efficiency is remarkably improved; the content of carbonyl compounds is reduced to 0.5 ppm; the qualified rate of a potassium permanganate oxidation test is increased to 100%; the absorbance at 230 nm is reduced to be less than or equal to 0.08.

The invention relates to the technical field of organic synthesis, and discloses a synthesis method of 2-cyano-5-fluorobenzyl bromide, which comprises the following steps: mixing a compound I with sulfuric acid, adding potassium bromate, reacting, adding water, layering, distilling and purifying to obtain a compound II; mixing the compound II, cuprous cyanide and DMF, carrying out reflux reaction under stirring, cooling, adding water, extracting and filtering with ethyl acetate, layering, washing with water, desolventizing, and recrystallizing and purifying with methanol to obtain a compound III; mixing the compound III, tetrahydrofuran, water and methanol, dropwise adding a mixed solution of potassium borohydride, water and methanol while stirring, adding water, layering, extracting, desolventizing, cooling to separate out a solid, and filtering to obtain a compound IV; and mixing the compound IV, DCM and DMF, dropwise adding boron tribromide in batches while stirring, adding water, layering, desolventizing, cooling to separate out a solid, and filtering to obtain the 2-cyano-5-fluorobenzyl bromide. The method is reasonable in design route, short in synthesis route, high in safety coefficient and suitable for industrial production.

The present invention discloses a powder metallurgy material and a preparation method thereof, belonging to the technical field of powder metallurgy. The raw materials include the following parts by weight: 0.5 - 1.1 parts of carbon nanotubes, 1.5 - 2.5 parts of copper, 1.8 - 3.2 parts of aluminum, 2.0 - 3.5 parts of nickel, 0.5 - 0.8 parts of titanium, 0.1 - 0.4 parts of pore-forming additive. Taking 100 parts as a reference, the balance is iron. Among them, the raw materials of the pore-forming additive include the following parts by weight: 30 - 50 parts of copper sulfate, 20 - 30 parts of titanium dioxide, 10 - 25 parts of silicon nitride, and 3 - 5 parts of potassium borohydride. In the technical solution of the present application, a pore-forming additive is creatively added to the iron-based powder metallurgy material. By reacting copper sulfate, titanium dioxide and silicon nitride in a reducing agent state, a porous material is generated, which can improve the porosity of the finished product in the processing of powder metallurgy materials; at the same time, combined with the billet sintering method of the present application, its hardness can also meet the ideal requirements.

The invention discloses a method for measuring selenium in farmland soil by atomic fluorescence spectrometry, which belongs to the technical field of chemical detection and comprises the following steps: mixing a soil sample with mixed acid, heating and digesting, adding concentrated hydrochloric acid, reducing and extracting while the solution is hot, adding a ferric trichloride solution after the extraction is finished, and filtering to obtain a filtrate; and measuring the selenium content by using an atomic fluorescence spectrophotometer. According to the method, a nitric acid, hydrofluoric acid and perchloric acid system and potassium borohydride are adopted as reducing agents, the selenium in the soil is measured through the atomic fluorescence method, the detection limit is low, the sensitivity is high, and the method is simple, convenient, economical, accurate, efficient and environmentally friendly and is the best choice for measuring the content of the selenium element in the soil.

The present invention belongs to the technical field of preparing diborane, and in particular, provides a process for preparing high-purity diborane. The process comprises the steps of using excess boron trifluoride and potassium borohydride as raw materials, reacting and preparing the diborane under low-temperature conditions, complexing the boron trifluoride in the diborane, distilling the crude diborane, reusing the boron trifluoride, and recovering the solvent. The present invention provides a safer, lower-cost, waste-liquid-free, and continuously waste-liquid-free preparation process for producing high-purity diborane, provided that the boron trifluoride used as the reaction raw material is in excess.