733 results about "Bromide" patented technology

The invention discloses a synthesis method of 7-dehydrocholesterol and derivatives thereof, which comprises the following steps: cooling a compound (I), cuprous bromide and dimethyl sulfide compound under the protection of inert gas to obtain a reaction system, adding a Grignard reagent (II) or a Grignard reagent (III), stirring, reacting at room temperature, carrying out heating reaction, and cooling to obtain the 7-dehydrocholesterol. Performing post-treatment to obtain a product; if the product is the Grignard reagent (II), the product is 7-dehydrocholesterol and the derivative thereof; if the reagent is the Grignard reagent (III), the product is 25-hydroxy-7-dehydrocholesterol and the derivative thereof. The method is high in total yield, mild in reaction condition, simple in process route, high in product purity, low in three-waste generation amount, simple in post-treatment, environment-friendly and low in equipment requirement, the purity of 95% or above can be obtained through simple recrystallization, and conventional chemical equipment can be used for production.

The invention relates to a method for preparing a high-quality quasi-two-dimensional perovskite thin film on a gallium nitride substrate, and relates to the technical field of semiconductors. The method for preparing the high-quality quasi-two-dimensional perovskite thin film on the gallium nitride substrate comprises the following steps: cleaning the gallium nitride substrate, and carrying out Plasma treatment; spin-coating a perovskite precursor solution on the processed gallium nitride substrate; the solute of the perovskite precursor solution is butylamine bromide powder, lead bromide powder and cesium bromide powder, and the solvent is a mixed solution of DMF (Dimethyl Formamide) and DMSO (Dimethylsulfoxide); adding a brominated metal salt into the perovskite precursor solution; and performing thermal annealing treatment on the perovskite thin film. According to the invention, a technology of growing a high-quality quasi-two-dimensional perovskite thin film by adopting a spin-coating process is adopted, and the high-quality thin film with uniform phase distribution is obtained by optimizing the proportion of a precursor solution and introducing inorganic salt to regulate and control growth kinetics.

The invention belongs to the technical field of silicon dioxide preparation, and relates to a preparation method of spherical porous silicon dioxide, which comprises the following steps: S1, preparing a mixed solution, namely preparing a template solution, namely dissolving 0.5 g of hexadecyl trimethyl ammonium bromide into 100ml of deionized water mixed solution, and stirring by using a stirring mechanism until the solution is clear; adjusting the alkaline environment: adding 1ml of ammonia water, and adjusting the pH value to 10-11; s2, silicon source hydrolysis: slowly dropwise adding 2ml of tetraethyl orthosilicate into the solution in the step S1, and then carrying out stirring reaction; s3, aging and centrifugal washing: aging: stopping stirring, and standing for 12 hours to stabilize the structure; centrifugal washing: centrifuging for 5 minutes at 8000rpm, and sequentially washing for 3 times by using ethanol and water to remove unreacted substances; the spherical silicon dioxide can be protected by a simple sol-gel method without using a complex auxiliary agent, the mesoporous size of the spherical silicon dioxide is relatively uniform, the supercritical carbon dioxide is adopted for drying in a drying box, the pore structure is kept complete, and the use effect is improved.

A composite material for passive cooling includes a porous structure including an expanded graphite and a surfactant, the porous structure being provided with at least one crystalline deliquescent salt that is selected from the group consisting of chloride, bromide, sulphate, and nitrate. The uses of the composite material in passive cooling are also addressed.

The invention relates to the technical field of catalyst processing, and discloses a high-activity transition metal phosphide electrolyzed water catalyst and a preparation method thereof, and the high-activity transition metal phosphide electrolyzed water catalyst comprises the following components by weight: 1-3 parts of cobalt chloride hexahydrate; 0.5 to 1.5 parts of ruthenium trichloride; 0.5 to 1.5 parts of iridium chloride (III) hydrate; 1-2 parts of copper sulfate pentahydrate; 2 to 4 parts of sodium hypophosphite; 1 to 2 parts of urea; 1 to 2 parts of glucose; 1-2 parts of sodium sulfide nonahydrate; 0.5 to 1 part of crystalline aluminum chloride; 50 to 100 parts of deionized water; and 0.1 to 0.5 part of hexadecyl trimethyl ammonium bromide. By introducing the plasma auxiliary treatment technology, the electronic structure of the catalyst is optimized, the conductivity and stability of the catalyst are improved, and the efficiency and durability of hydrogen production through water electrolysis are enhanced.

The application discloses a PAG bonding type photosensitive photoresist resin and a preparation method and application thereof. The photoresist resin is as follows: formula. The PAG bonding type resin is prepared through the following reaction process: 1) performing a RAFT polymerization reaction on p-acetoxystyrene, p-styrene sulfonamide trifluoromethyl potassium salt and a RAFT chain transfer agent under the action of an initiator to obtain an intermediate I, 2) performing a hydrolysis reaction on the intermediate I to obtain an intermediate II, 3) performing a protection group introduction reaction on the intermediate II and di-tert-butyl dicarbonate to obtain an intermediate III; and 4) performing an ion exchange reaction on the intermediate III and triphenylsulfonium bromide. The application realizes the bonding of the PAG into the resin skeleton, and improves the problems of poor compatibility between the PAG and the resin, phase separation, uneven distribution of the PAG and the like. Therefore, the photoresist prepared from the resin has the photo-generated acid bound by the polymer main chain and limited diffusion, the resolution is improved, and the photoetching effect is excellent.

The invention belongs to the technical field of drilling fluid additives for petroleum drilling, and discloses a heat-resistant water-based drilling fluid additive as well as a preparation method and application thereof. The water-resistant water-based drilling fluid additive is a high-molecular compound which is formed by taking water as a solvent, dissolving animal bone glue to form a glue solution, and performing etherification reaction on the glue solution and bromoethane under the action of a chain transfer agent and a base catalyst. The preparation method comprises the following steps: adding animal bone glue into water, dissolving to obtain a glue solution, sequentially adding sodium hydroxide, sodium carbonate and bromoethane to form a reaction system solution, then adding a chain transfer agent, and heating and refluxing to react to obtain the water-resistant water-based drilling fluid additive. According to the prepared bromoethane modified bone glue, the chain transfer agent is added in the modification process, the technical defect that the molecular weight of the bone glue cannot be manually controlled is overcome, the inhibition effect is obvious, meanwhile, the rheological property of drilling fluid is not affected, and the problems of borehole wall instability and the like caused by shale hydration expansion in the drilling process can be effectively solved.

The invention discloses a synthesis method of a novel benzosuberone compound, and belongs to the field of organic synthesis. The preparation method comprises the following steps: uniformly stirring methyltriphenylphosphonium bromide in a solvent at room temperature, dropwise adding an n-hexane solution of n-butyllithium in an ice-water bath, stirring a reaction system at room temperature for 30-40 minutes after dropwise adding is completed, then adding an initial raw material phenanthrenequinone 1 in the ice-water bath, transferring the reaction system to 40 DEG C for reaction, and after the reaction is monitored to be complete by a TLC (Thin Layer Chromatography) dot plate, filtering, washing and drying to obtain the phenanthrenequinone 1. And pouring the reaction liquid into a silica gel chromatographic column, and simply filtering by using dichloromethane as an eluent to remove salt and phosphine oxide. And performing rotary evaporation to remove the organic solvent to obtain a crude product, and separating and purifying to obtain a target product 2. The method is short in reaction time and low in reaction cost, provides a practical method for obtaining the seven-membered rigid ring skeleton, and has potential value for synthesis of natural products and bioactive molecules.

The present invention discloses a tridentate pincer manganese complex, a preparation method thereof and an application thereof in alcohol dehydrogenation olefination reaction. The tridentate pincer manganese complex has the following structure: #imgabs0# wherein R is selected from a group containing C1-C 20 The method for preparing the tridentate manganese pincer complex comprises: using 8-aminoquinaldine as a raw material to synthesize a tridentate pincer ligand through multiple steps, and coordinating the tridentate pincer ligand with pentacarbonyl manganese bromide to prepare a novel tridentate manganese pincer complex. The tridentate manganese pincer complex prepared by the present invention has a novel skeleton structure, a simple and efficient preparation method, and high practicality. The obtained manganese complex has high activity as a catalyst in the dehydrogenation olefination reaction of alcohols and has very important application prospects.

The invention provides an iridium-ruthenium oxide composite catalyst, a preparation method thereof and a proton exchange membrane water electrolysis device, and relates to the field of hydrogen production through water electrolysis. The preparation method of the iridium-ruthenium oxide composite catalyst comprises the following steps: mixing sodium nitrate, ruthenium chloride and water to prepare a mixed solution, and then drying and grinding to obtain a mixture; placing the mixture on the surface of nickel foil, carrying out first heating by using Joule heating equipment, and then cooling to obtain ruthenium oxide; mixing ruthenium oxide, hexadecyl trimethyl ammonium bromide and ethylene glycol, and performing ultrasonic dispersion to obtain a ruthenium oxide solution; and mixing the ruthenium oxide solution, H2IrCl6 and potassium hydroxide, adjusting the pH value of the system to be alkaline, then carrying out second heating until reflux and constant-temperature reaction, carrying out solid-liquid separation on the reaction product, and washing to obtain the iridium-ruthenium oxide composite catalyst. The iridium-ruthenium oxide composite catalyst provided by the invention has high activity, high stability and high water electrolysis efficiency.

A method of obtaining a purified rare earth metal deposit from a rare earth metal halide salt, by: (i) producing a rare earth metal borohydride salt by the following reaction:n·ABH4+m·(RE)X3→RE(BH4)3+n·AXwherein the variables are defined as follows: A is an alkali metal cation; RE represents one or more rare earth metal cations; X represents a halide selected from chloride, bromide, and iodide; n is the molar amount of ABH4; and m is the molar amount of (RE)X3; wherein the ratio of n:m is 3:1 to 5:1; (ii) mixing RE(BH4)3 and AX with a halogen-free organic solvent to form a solution containing the RE(BH4)3 salt dissolved therein and with AX undissolved and precipitated; and (iii) contacting the solution from step (ii) with an anode and cathode in electrical communication, and electrically charging the anode and cathode to electroplate the rare earth metal onto the cathode.

The invention relates to the field of protective films, and discloses a liquid crystal light guide plate high-transmittance tpe protective film and a preparation method thereof.The protective film comprises SEBS, polypropylene, modified halloysite nanotubes, modified silicon dioxide and auxiliaries; the modified halloysite nanotube is prepared by reacting a functional additive prepared by grafting an isocyanato antioxidant component and a modified benzothiazole-containing monomer with 3-chloropropyltrimethoxysilane, and then grafting on the surface of the halloysite nanotube; the isocyanated antioxidant component is prepared by reacting 3-(3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid with N-hydroxymethyl acrylamide, then reacting the product with 2-mercaptoethanol to obtain a hydroxylated antioxidant component, and then reacting the hydroxylated antioxidant component with isophorone diisocyanate; the modified benzothiazole-containing monomer is prepared by reacting 2-aminobenzothiazole with bromoacetyl bromide and then reacting with 3, 5-dihydroxybenzylamine, and the protective film prepared by the invention has good thermo-oxidative aging resistance, antibacterial property, heat resistance and tensile property.

The invention belongs to the technical field of preparation of transition metal organic photocatalysts, and particularly relates to design and a preparation method of a carbazole terpyridyl nickel catalyst. The invention aims to design and synthesize a carbazole terpyridyl nickel catalyst with light / nickel synergistic catalytic activity. The preparation method comprises the following specific synthesis steps: reacting different types of alpha-pyridone pyridinium and alpha, beta-unsaturated ketone in methanol, and carrying out suction filtration, washing, drying and other operations to obtain the corresponding carbazole terpyridyl ligand. The carbazole terpyridyl ligand and anhydrous nickel bromide are subjected to a heating reflux reaction in a tetrahydrofuran solution, and the corresponding carbazole terpyridyl nickel catalyst is obtained through methanol washing, suction filtration, drying and other operations. The terpyridyl nickel catalyst has high catalytic activity in a C-N, C-O and C-S coupling reaction promoted by visible light.

The invention discloses a carbamoyl-substituted diarylethene derivative as well as a preparation method and application thereof, and the preparation method comprises the following steps: reacting R-substituted 3-bromo-2-hydroxybenzaldehyde with an arylmethyl triphenylphosphonium bromide compound or an aryl acetic acid compound to obtain an intermediate A; then the intermediate A and cuprous cyanide are subjected to a heating reaction in N, N-dimethylformamide and nitrogen atmosphere, and an intermediate B is obtained; and finally, heating the intermediate B, acetaldoxime and indium trichloride in toluene for reaction to obtain the carbamoyl-substituted diarylethene derivative. The carbamoyl-substituted diarylethene derivative disclosed by the invention has a remarkable effect in an in-vitro anti-tumor activity test, particularly has excellent anti-proliferation ability to human BRCA mutant tumor cells, and can be used for preparing medicines for treating PARP-1 activity abnormity related diseases. The synthesis route is simple, the cost is low, and large-scale implementation is facilitated.

The invention relates to the technical field of electrocatalytic reduction of carbon dioxide, and provides a water-phase ultrafast green preparation method of a bismuth-based metal organic framework, and the preparation method of the bismuth-based metal organic framework material comprises the following steps: taking bismuth nitrate pentahydrate as a bismuth source, taking trimesic acid as a ligand, and preparing the bismuth-based metal organic framework material through a surfactant-mediated sonochemistry method. A complex topological bismuth-based metal organic framework (CAU-17) is synthesized in water under an environmental condition. The synthesis method is rapid, environmentally friendly, low in cost and easy to operate, cetyltrimethylammonium bromide (CTAB) amphiphilic molecules are used as a structure inducer, removal (dehydration) of non-coordinated water is controlled, the deprotonation degree of ligands is improved, therefore, coordination and crystallization in an aqueous solution are adjusted, and by adjusting the dosage of the added CTAB, the deprotonation degree of the ligands is increased. And the crystal structure evolution from a preferentially generated compact sheet structure to a porous rod-shaped structure is realized. Meanwhile, the synthesized CAU-17 catalyst shows relatively high current density and Faraday efficiency in electrocatalytic reduction of carbon dioxide into formic acid, and has relatively good selectivity.

The invention discloses application of a quaternary ammonium salt additive in a zinc-bromine flow battery electrolyte, and belongs to the technical field of electrochemical energy storage, the chemical name of the quaternary ammonium salt additive is N-(2-ethoxyl)-N-methyl-pyrrolidinium bromide, and the quaternary ammonium salt additive is added into the zinc-bromine flow battery electrolyte as a complexing agent of elemental bromine. According to the invention, the low-temperature range of operation of the zinc-bromine flow battery is widened, and the zinc-bromine flow battery added with the novel additive can work at-20 DEG C for more than 200 hours; the dynamic characteristics of the battery are improved, and the normal-temperature and low-temperature cycle life of the battery is prolonged.

The invention discloses a tellurium-doped carbon quantum dot and a preparation method and application thereof, the tellurium-doped carbon quantum dot is obtained by using 2, 2 '-diaminodiphenyl telluride as a precursor, the average particle size is 1.9 nm, the thickness is about 2.1 nm, and the surface is rich in amino groups. And fixing (4-carboxybutyl) triphenylphosphonium bromide, 3-morpholinopropionic acid or 3-((4-methylphenyl) sulfonamide) propionic acid on the surfaces of the tellurium-doped carbon quantum dots to prepare Mito-Te-CDs, Lyso-Te-CDs and ER-Te-CDs with an organelle targeting function. The Mito-Te-CDs, the Lyso-Te-CDs and the ER-Te-CDs are good in biocompatibility, can be used as fluorescent probes for targeted imaging of organelles, can be used for recognition and removal of superoxide anions in specific organelles, have a protection effect on cells and can be used for effectively treating acute kidney injury.

The invention discloses a flame-retardant PA66 material and a preparation method thereof.The flame-retardant PA66 material is prepared from, by weight, 80-100 parts of a modified PA66 material, 3-5 parts of modified graphene, 15-30 parts of a flame-retardant additive and 0.1-0.5 part of tetraphenylphosphorus bromide, a molecular chain of the flame-retardant additive contains an organic silicon chain segment and an organic phosphorus structure and is doped with nitrogen and boron elements, and when the material is burnt, the flame-retardant PA66 material has a flame-retardant effect, and the flame-retardant PA66 material has a flame-retardant effect. The organic phosphorus can be dehydrated to form a phosphoric acid carbon layer, the nitrogen element can release inert gas, dilute combustible gas and generate an expansive phosphorus-nitrogen carbon layer with the organic phosphorus, the boron element can improve the compactness and high-temperature stability of the carbon layer, and the organic silicon can form a cross-linked network shape, so that the continuity of the carbon layer is improved; a fluorine-containing polysiloxane chain segment of a side chain of the flame-retardant additive is embedded among molecules of the modified PA66 material, and is decomposed to generate fluorine free radicals during combustion, and active free radicals in a combustion chain reaction are quenched, so that a rapid flame-retardant effect is achieved.

The invention provides a method for reversibly regulating and controlling the water solubility of long-chain alkyl trimethyl ammonium bromide, which comprises the following steps of: mixing sodium benzyl selenopropionate serving as an auxiliary agent with long-chain alkyl trimethyl ammonium bromide, adding water for dissolving, reducing the Krafft temperature of the long-chain alkyl trimethyl ammonium bromide to 10 DEG C or below, and then adding sodium benzyl selenopropionate, according to the method, benzyl selenium sodium propionate is oxidized into benzyl selenium oxygen sodium propionate by adding an oxidizing agent, so that the KT of long-chain alkyl trimethyl ammonium bromide is increased, and the water solubility of the long-chain alkyl trimethyl ammonium bromide is reduced, so that the long-chain alkyl trimethyl ammonium bromide is crystallized and separated out from an aqueous solution, and the separation, recovery and reutilization of the long-chain alkyl trimethyl ammonium bromide are realized; the residual water phase solution after the long-chain alkyl trimethyl ammonium bromide is recovered can be used as the plant leaf selenium fertilizer.

The invention relates to the technical field of air filter elements, in particular to an iron-manganese-based filter element material for catalyzing and purifying VOCs (volatile organic compounds) at room temperature and a preparation method of the iron-manganese-based filter element material. The iron-manganese-based filter element material for catalyzing and purifying the VOCs at the room temperature is prepared from the following raw materials in parts by mass: 20 to 30 parts of ferrous sulfate, 30 to 40 parts of manganese sulfate, 0.1 to 1 part of ceric ammonium nitrate, 1 to 2 parts of hexadecyl trimethyl ammonium bromide, 1 to 3 parts of urea steam, 5 to 15 parts of attapulgite clay, 1 to 5 parts of aerogel aid and 1 to 5 parts of sodium alginate. The preparation method is simple, the adsorption capacity and the adsorption capacity of indoor volatile organic pollutants such as formaldehyde are greatly improved, the formaldehyde removal efficiency can be improved, the service life of the material can be prolonged, and the material is suitable for large-scale popularization and application.

The invention discloses preparation of a nitrogen-rich ionic organic single crystal material and application of the nitrogen-rich ionic organic single crystal material in iodine adsorption, and belongs to the technical field of functional materials and radioactive pollutant treatment. The material is formed by self-assembly at room temperature through a solution method by taking biphenyl tetracarboxylic acid tetrabutylamine as an anion ligand and tetra (4-ethyl pyridine phenyl) ethylene bromide or tetra (4-imidazole phenyl) ethylene bromide as a cation ligand. The method is simple in preparation process, mild in condition and high in yield. The skeleton of the obtained material is rich in nitrogen sites and has a large cavity, the material shows extremely high adsorption capacity and rapid adsorption kinetics for iodine in a gas phase and a liquid phase, the maximum adsorption capacity of the material for iodine steam reaches up to 5.16 g / g, the retention rate of 95% or above can still be kept within 7 days after adsorption, and the material has good recycling performance. The material provides a novel and reliable solution for efficiently capturing and fixing radioactive iodine, and has a wide application prospect in the field of nuclear waste treatment.

This invention relates to the field of chemical synthesis technology and discloses a method for preparing 2,5-furandicarboxylic acid from fructose, comprising the following steps: preparing reaction system A containing fructose, an organic bromide, a solid acid catalyst, and water; performing a dehydration reaction to separate the solid acid catalyst and obtain a fructose dehydration reaction solution; preparing reaction system B containing the fructose dehydration reaction solution, a co-oxidant, an oxidation catalyst, and acetic acid; performing an oxidation reaction under an oxidizing gas atmosphere; separating the product to obtain 2,5-furandicarboxylic acid. This invention utilizes a co-oxidant, which can reduce the requirement for fructose concentration in the one-pot preparation of 2,5-furandicarboxylic acid while ensuring the yield and purity of FDCA, thereby improving production efficiency. Furthermore, it reduces or even eliminates the use of hydrobromic acid in the oxidation reaction, thus reducing corrosion to equipment.

The invention discloses a fluorescent probe for targeting mitochondrial ferric ions as well as preparation and application of the fluorescent probe. The fluorescent probe is prepared by reacting cucurbit [7] uril with (E)-4-(4-(dimethylamino) styryl)-1-(3-(triphenylphosphonium) propyl) pyridine-1-onium bromide according to a molar ratio of 1: 1. The fluorescent probe can be used for detecting Fe < 3 + > ions, and has the characteristics of simple preparation method, convenience in operation, high sensitivity, high selectivity, low cost and rapidness in detection.

The invention discloses a laser-induced breakdown spectroscopy detection method and a treating fluid used by the method and capable of enhancing detection sensitivity. The laser-induced breakdown spectroscopy detection method comprises the following steps: preparing a trisodium citrate aqueous solution, a cetyltrimethylammonium bromide aqueous solution and a 11-mercaptoundecanoic acid ethanol solution, sequentially adding the trisodium citrate aqueous solution and the cetyltrimethylammonium bromide aqueous solution into metal nanoparticle sol, and reacting; then adding a 11-mercaptoundecanoic acid solution, dripping the mixed solution on a silicon wafer, dripping a to-be-detected sample solution after the silicon wafer is dried to obtain a to-be-detected sample, and directly carrying out laser-induced breakdown spectroscopy detection on the to-be-detected sample. The method provided by the invention can enhance the NEELBS signal strength by at least three times, and has the advantages of low cost, simple sample preparation, remarkable enhancement effect and the like.

A zinc / bromine flow battery comprises an electrolyte. The electrolyte comprises an active substance, a supporting electrolyte, and an additive. The additive is selected from at least one of 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium chloride, 1-carboxymethyl-3-methylimidazolium bromide, and 1-carboxymethyl-3-methylimidazolium chloride. The use of the additive can regulate the deposition morphology of zinc and suppress zinc dendrites, and can also inhibit the diffusion of bromine on the positive electrode side, thereby improving the coulombic efficiency of the battery. Moreover, the complex product formed by the additive complexed with bromine does not produce solids during long-term cycling, whereas the complex product of conventional MEP in the later stage of battery cycling forms solids which are unevenly distributed on the electrode surface, reducing the voltage efficiency of the battery and shortening the service life of the battery.

The invention relates to the technical field of chemical mechanical polishing solutions, in particular to a chemical mechanical polishing solution for silicon carbide and a preparation method thereof, the polishing solution comprises a catalyst, abrasive particles, a dispersing agent, an oxidizing agent, a surfactant, an acid-base regulator and deionized water; the catalyst is nano platinum particles; the abrasive particles are aluminum oxide; the dispersing agent is at least one of sodium polyacrylate, sodium hexametaphosphate, hexadecyl trimethyl ammonium bromide and the like. The oxidizing agent is at least one of permanganate, pypocholoride, dichromate and the like; the surfactant is at least one of sodium dodecyl benzene sulfonate, organic bentonite and the like; the pH regulator is at least one of phosphoric acid, nitric acid, oxalic acid and citric acid. The polishing solution can effectively improve the removal rate of silicon carbide, and meanwhile, a polished silicon carbide wafer is high in flatness and free of scratches.

The invention provides a series of polybenzyl bromide or polybenzyl iodide-based monomolecular resin photoresists as well as a preparation method and application thereof. The monomolecular resin can be used as a main body material of the photoresists. The raw materials are cheap and easily available, and the synthesis process is simple. According to the compound disclosed by the invention, adamantane is taken as a core unit, a plurality of benzyl bromide or benzyl iodine groups, adamantane and a benzene ring are externally connected, and bromine atoms or iodine atoms are additionally introduced, so that the sensitivity and the etching resistance of the photoresist can be improved to the maximum extent.

The present invention discloses a method and system for producing hexafluorobutadiene, which includes the following steps: In step (1), an organic solution of bromotrifluoroethylene and zinc powder are respectively introduced into a first reactor containing an initiator, zinc powder, and an organic solvent, followed by a second reactor, and reacted to obtain a trifluorovinylzinc bromide solution. The reaction solution is then introduced into a precipitator to separate excess zinc powder, resulting in a zinc-free trifluorovinylzinc bromide solution. The excess zinc powder is then filtered and reused. In step (2), the trifluorovinylzinc bromide solution obtained above and a pre-prepared composite catalyst solution are introduced into a third reactor and subjected to a coupling reaction to obtain crude hexafluorobutadiene. In step (3), the crude hexafluorobutadiene obtained above is purified to obtain a product with a purity of ≥ 99.9%.

The present application relates to a method for liquid phase oxidation of durene, which comprises: a first stage, in the presence of a catalyst, with acetic acid as a solvent, a liquid phase oxidation reaction of an oxidant source and durene to produce an intermediate mixture, the catalyst containing Co salt, Mn salt, Zr salt and bromide compound; a second stage, adding a mixture of bromide and pure water to the intermediate mixture, and continuing the oxidation reaction with the oxidant source to produce pyromellitic acid; wherein the concentration of oxidant in the oxidant source of the first stage is lower than the concentration of oxidant in the oxidant source of the second stage. By controlling the concentration of oxidant in the oxidant source of the first stage to be lower than the concentration of oxidant in the oxidant source of the second stage in the liquid phase oxidation process of durene, the yield of pyromellitic acid and the purity of crude pyromellitic acid are significantly improved.

The application discloses a preparation method of benzoic acid, and belongs to the technical field of organic chemical synthesis. The method uses toluene as raw material, adopts a bromine-free composite supported catalyst, cooperates with a three-stage gradient temperature oxidation process, and obtains benzoic acid products through the steps of raw material premixing, segmented temperature control oxidation, catalyst separation and recovery, desolventizing and crude product refining. The method completely abandons the bromide initiator of the traditional process, solves the problems of bromine pollution and equipment corrosion from the root, and overcomes the defects of the prior art, such as difficult recovery of the catalyst, difficult consideration of toluene conversion rate and benzoic acid selectivity, and low product purity. The method has the advantages of mild reaction conditions, efficient recovery and recycling of the catalyst and the solvent, excellent catalytic activity and selectivity, high product purity, low heavy metal residue, and good industrial application prospect.