75 results about "Methylhydrazine" patented technology

The invention relates to a preparation method of 1-methyl-5-hydroxypyrazole, which comprises the following steps: (a) methylation reaction: fully dissolving pyrazole in a reaction solvent a, dropwise adding a methylation reagent into the reaction solvent a to carry out methylation reaction, adding water into the reaction solvent a to carry out quenching reaction after the reaction is completed, fully washing and concentrating to generate 1-methylpyrazole; (b) bromination hydrolysis reaction: fully dispersing 1-methylpyrazole in a reaction solvent b, dropwise adding bromine into the reaction solvent b to perform bromination reaction, dropwise adding liquid caustic soda and a sodium thiosulfate solution into the reaction solvent b to perform quenching reaction after the reaction is completed, adding the liquid caustic soda into the reaction solvent b after extraction and concentration, and performing heating hydrolysis and cooling crystallization to obtain the 1-methyl-5-hydroxypyrazole. The preparation method of the 1-methyl-5-hydroxypyrazole is reasonable in design, not only reduces the isomer 1-methyl-3-hydroxypyrazole, but also avoids the use of liquid with pungent smell, such as ethylenediamine, and precursor reagents, such as methylhydrazine, improves the operation safety, is environment-friendly, and is beneficial to industrial production.

The present application relates to a kind of preparation method of trifluoromethyl pyrazole compound, belong to the technical field of organic synthesis.The specific method is: (1) trifluoroacetyl ethyl acetate is first with hydrazine hydrate cyclization reaction and generates compound of formula III;(2) under the catalysis of base, compound of formula III is reacted with difluoromethylation reagent and generates compound of formula II;(3) compound of formula II is reacted with methylating agent and obtains compound of formula I;The difluoromethylation reagent is difluoro-monochloromethane or sodium difluoro-monochloroacetate;The methylating agent is chloromethane, bromomethane, iodomethane, dimethyl sulfate or dimethyl carbonate.The present application is prepared by changing reaction route, and the higher-priced raw material methylhydrazine is replaced, and isomer impurity is no longer generated in the product prepared.Not only raw material cost is reduced, but also the purity of product is improved.

The application belongs to the technical field of organic synthesis and particularly relates to a preparation method of 1-methyl-3-(trifluoromethyl)-1H-pyrazol-5-ol, which comprises the following steps: (1) adding acid into a reaction container, adding 40% methylhydrazine aqueous solution and stirring uniformly; (2) adding trifluoroacetyl acetic acid ethyl ester dropwise into the reaction system of step (1), heating after dropwise addition is completed, performing heat preservation reaction and monitoring the reaction by TLC; (3) after the reaction is completed, adding water into the reaction system of step (2) to perform crystallization, performing suction filtration after cooling, washing the filter cake with water and drying to obtain 1-methyl-3-(trifluoromethyl)-1H-pyrazol-5-ol crude product, and purifying to obtain the final product 1-methyl-3-(trifluoromethyl)-1H-pyrazol-5-ol. The application has the beneficial effect that by controlling the feeding sequence, the acid amount and the reaction temperature, the methylhydrazine addition amount is reduced, methylhydrazine is avoided from being left in waste water, and thus the treatment difficulty of waste water is reduced.

The invention discloses a preparation method of 1-[2-(aminooxy) ethyoxyl] ethylene, which comprises the following steps: taking N-hydroxyphthalimide and 2-chloroethyl vinyl ether as raw materials, and reacting in a reaction solvent under the action of alkali to obtain 2-[2-(ethyleneoxy) ethyoxyl] isoindoline-1, 3-diketone; then, the 2-[2-(ethyleneoxy) ethyoxyl] isoindoline-1, 3-diketone and hydrazine hydrate are subjected to a reaction in a reaction solvent, and 1-[2-(aminooxy) ethyoxyl] ethylene is obtained. According to the preparation method, the reaction controllability is better, low-temperature feeding and room-temperature feeding are not needed, the exothermic effect is not obvious, and the risk of a substrate is lower; according to the preparation method, a highly toxic product methylhydrazine does not need to be used, and hydrazine hydrate is used for replacing conditions, so that the safety is higher; the preparation method is low in raw material cost, simple in process, mild in condition, low in energy consumption, simple in product separation, better in atom economy, convenient to purify and capable of realizing amplified continuous production.

The invention discloses a pyrimidine derivative containing a thiosemicarbazide structure and application of the pyrimidine derivative, and relates to the technical field of medicines, the compound has good oxidation resistance and alpha-glucosidase resistance activity, and the compound is 2-(4, 4 '-difluorophenyl)-2-(4, 4'-difluorophenyl)-2-(4, 4 '-difluorophenyl)-2-(4, 4' The IC50 values of the compound 2-(4, 6-dimethyl pyrimidine-2-yl)-N-methylhydrazine-1-methylsulfamide on DPPH (1, 1-diphenyl-2-picrylhydrazyl) scavenging activity and ABTS (2, 2, 6-dimethyl pyrimidine-2-yl)-N-methylhydrazine-1-methylsulfamide are 3.96 mu g / mL and 2.01 mu g / mL respectively, the IC50 value of the compound 2-(4, 6-dimethyl pyrimidine-2-yl)-N-methylhydrazine-1-methylsulfamide on alpha-glucosidase inhibitory activity is 38.62 mu g / mL, the effect is best, and the compound 2-(4, 6-dimethyl pyrimidine-2-yl)-N-methylhydrazine-1 The pyrimidine derivative containing the thiosemicarbazide structure has a general formula shown in the specification, and is superior to control medicaments such as vitamin C, vitamin E and acarbose.

This invention belongs to the field of compound synthesis, specifically relating to a method for synthesizing 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid. The invention involves a condensation reaction of difluoroacetaldehyde half-ethanol and cyanoacetaldehyde under a catalyst; the resulting intermediate is then washed with water and reacted directly with hydrazine hydrate to obtain an intermediate product. Finally, the intermediate product is reacted with formaldehyde under a catalyst to undergo cyclization and aromatization, followed by hydrolysis to the final product. This invention provides a novel method for synthesizing 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid, using difluoroacetaldehyde half-ethanol as the fluorinating agent in the reaction process, resulting in a simple synthesis method. This invention is the first to use the less expensive hydrazine hydrate instead of methylhydrazine to synthesize 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid, resulting in lower cost, simpler operation, and less waste generation, thus possessing higher economic and environmental value and being more suitable for industrial production.

The present application relates to the technical fields of reaction kettle, and discloses a reaction kettle for preparing methylhydrazine aqueous solution, which comprises a reaction kettle, a rotating shaft arranged in the reaction kettle, an end cover arranged at the top end of the reaction kettle, a stirring frame arranged on the rotating shaft, the stirring frame comprising an upper cross beam, a lower cross beam and a connecting rod, the two ends of the connecting rod being connected with the upper cross beam and the lower cross beam respectively, a conveying belt arranged on the stirring frame, the conveying belt being rotatably arranged on the stirring frame, a first driving mechanism arranged on the stirring frame and used for driving the conveying belt to rotate, a discharge chute arranged on the side wall of the rotating shaft, the side of the conveying belt being abutted against the side wall of the discharge chute, the other side of the conveying belt having a gap with the side wall of the discharge chute, the rotating shaft being a hollow shaft, a screw blade being arranged in the rotating shaft, a liquid passage being arranged on the rotating shaft close to the bottom of the reaction kettle, and a discharge port being arranged at the bottom end of the reaction kettle; the reaction kettle for preparing methylhydrazine aqueous solution can separate the catalyst from the liquid after reaction.

The invention relates to the field of preparation of fluxapyroxad, and discloses a preparation method of fluxapyroxad. The preparation method comprises the following steps: 1, heating 4, 4-difluoro-3-oxobutanamide and triethyl orthoformate in an organic solvent for reaction to obtain a compound a; 2, adding the compound a into a mixed solution of methylhydrazine and an organic solvent under an ice bath condition, and then reacting under a heating condition; and after the reaction is completed, evaporating out the solvent and concentrating to obtain a compound b. 3, under the action of an alkaline reagent and a metal catalyst, adding the compound b and 2-bromochlorobenzene into an organic solvent, and heating for condensation reaction to generate a compound c; and 4, adding the compound c and 3, 4, 5-trifluorophenylboronic acid into a solvent to carry out Suzuki reaction under the protection of nitrogen and the action of an alkaline reagent and a metal catalyst. And after the reaction is completed, evaporating out the solvent and concentrating to obtain the fluxapyroxad. The method disclosed by the invention has the characteristics of overall economy, environmental protection, safety and high efficiency, and also has relatively strong industrial application potential.

The invention provides a method for preparing 1-methyl-3-difluoromethyl-1H-pyrazole-4-carboxylic acid with high selectivity, which comprises the following steps: reacting methylhydrazine with a protective agent in an inert solvent to obtain single-protection methylhydrazine (IV); in the presence of alkali, carrying out condensation reaction on the single protection methylhydrazine (IV) and 2-ethoxymethylene-4, 4-difluoro-3-oxobutyric acid ethyl ester (I) to obtain an intermediate (V); adding acid into the reaction system obtained in the step S2 to synchronously remove the protecting group R and form a pyrazole ring, so as to obtain 1-methyl-3-difluoromethyl-1H-pyrazole-4-ethyl formate (II); alkali is added into the 1-methyl-3-difluoromethyl-1H-pyrazole-4-ethyl formate (II) for hydrolysis, then the hydrolysis product is acidified with acid, and suction filtration is performed to obtain the 1-methyl-3-difluoromethyl-1H-pyrazole-4-carboxylic acid (III). The content of regioisomers in the prepared product is less than or equal to 1%, the HPLC purity of the product is more than or equal to 98.0%, the content of single impurities is less than or equal to 0.15%, the moisture content is less than or equal to 0.1%, the residual acid content is less than or equal to 50 ppm, and the downstream reaction requirement can be met without secondary refining.

The invention provides a method for determining the content of methylhydrazine by pre-column derivatization-high performance liquid chromatography, which comprises the following steps: S1, uniformly mixing a methylhydrazine hydrate sample solution, 9-fluorenylmethoxycarbonyl chloride and an alkaline solution, standing for 20-50 minutes at room temperature to perform a derivatization reaction, and adding an acid solution to terminate the reaction; and S4, detecting the sample derived in the S1, establishing a chromatogram of methylhydrazine in the sample solution to be detected, obtaining a chromatogram retention time range of methylhydrazine, and calculating the content of methylhydrazine in the methylhydrazine hydrate according to the standard curve fitted in the S3. The pretreatment method is simple, the reaction condition is mild, the reaction rate is high, the detection sensitivity is high, the methylhydrazine derivative generated in a pre-column derivatization mode has ultraviolet absorption, a methylhydrazine derivative peak can be separated from a 9-fluorenylmethoxycarbonyl chloride chromatographic peak through reversed-phase high performance liquid chromatography, and detection of methylhydrazine is not interfered.

This invention provides a method for synthesizing 1,5-diazabicyclo[3.1.0]hexane compounds, their preparation, and their applications, belonging to the fields of organic synthesis and liquid propellant technology. 1,3-Propanediamine is dispersed in a suitable amount of chlorinated hydrocarbon solvent, and the corresponding aldehyde or ketone, a suitable amount of trifluoromethane sulfonate, and diisopropylethylamine are added sequentially. After half an hour, N-chlorosuccinimide is slowly added, and the reaction continues for 6-48 hours. The reaction is quenched with a suitable amount of water, and the mixture is extracted with dichloromethane. After concentrating the filtrate, column chromatography is used to obtain the corresponding 1,5-diazabicyclo[3.1.0]hexane compounds. Experiments have confirmed that 1,5-diazabicyclo[3.1.0]hexane compounds can rapidly and spontaneously ignite with fuming nitric acid and dinitrogen tetroxide, showing promising application prospects as a green fuel to replace methylhydrazine in the field of bicomponent liquid propellants.

The invention relates to the technical field of methylhydrazine production, and provides a method for reducing the concentration of free alkali NaOH in evaporated liquor to be desalted by adding specific calcium chloride under specific conditions, so that evaporation and desalination can be continuously and stably operated without discharging mother liquor. Used devices comprise a calcium chloride solution preparation system, a monitoring instrument, a feeding system and a separation and removal system. The monitoring instrument comprises a mother liquor alkalinity detector, a mother liquor flow meter, a feeding flow meter and the like; the feeding system comprises a feeding pipeline, a diaphragm pump and the like; the method comprises the steps of calcium chloride solution preparation, linkage setting of flow of a feeding system, mother liquor alkalinity and mother liquor flow, linkage mixing and feeding, separation and removal and the like, the Ca < 2 + > / OH <-> ratio is controlled by reasonably controlling the calcium chloride addition amount and the addition mode, calcium hydroxide precipitates capable of flowing backwards along with feed liquid are generated, the content of free alkali is reduced, and the calcium hydroxide content is increased. And long-time continuous operation can be achieved, and remarkable economic benefits and industrial application value are achieved.

The application relates to a rectification equipment for preparing high-purity methylhydrazine and relates to the technical field of rectification equipment; the rectification equipment for preparing high-purity methylhydrazine comprises a rectification kettle and a rectification tower, a gas outlet is further arranged at the top of the rectification tower, a gas outlet pipe is arranged at the gas outlet, a water sprinkling mechanism is further arranged at the top of the rectification tower, the water sprinkling mechanism comprises a water passing pipe and a water sprinkling disc, one end of the water passing pipe is used for connecting a water source, the other end of the water passing pipe extends into the top of the rectification tower and is communicated with the water sprinkling disc, and a plurality of water sprinkling nozzles are arranged at the bottom of the water sprinkling disc. The application has the effect of reducing the concentration of 1,1-dimethylhydrazine at the gas outlet of the rectification tower, thereby improving the preparation safety.

The invention discloses a methylhydrazine continuous flow synthesis process based on coupling of a microchannel reactor and a tubular reactor, and relates to the technical field of chemical engineering. The method comprises the following steps: by taking hydrazine hydrate, hydrochloric acid and methanol as raw materials, continuously introducing the raw materials into a micro-channel reactor through a metering pump to realize rapid mixing, preheating and preliminary methylation reaction so as to generate a reactant flow containing methylhydrazine hydrochloride; introducing the material flow into a series tubular reactor, carrying out constant-temperature and constant-pressure curing reaction, and prolonging the retention time so as to improve the conversion rate; and carrying out continuous dissociation and rectification separation to obtain a high-purity methylhydrazine product. The process overcomes potential safety hazards and efficiency limitation of traditional intermittent kettle reaction, enhances heat and mass transfer, improves reaction controllability and industrial applicability, and is suitable for continuous production of high-heat-release and high-risk methylation reaction.

To provide a novel pharmaceutical composition and a process for preparing the same.SOLUTION: There are provided a novel pharmaceutical composition containing 3'-[(2Z)-[1-(3,4-dimethylphenyl)-1,5-dihydro-3-methyl-5-oxo-4H-pyrazol-4-ylidene]hydrazino]-2'-hydroxy-[1,1'-biphenyl]-3-carboxylic acid bis-(monoethanolamine) (eltrombopag olamine) and a process for preparing the same.SELECTED DRAWING: None

The invention relates to a method for industrial production of 1-methyl-5-hydroxypyrazole. The method comprises the following steps: taking methyl 3-methoxyacrylate and methylhydrazine as raw materials, taking organic alkali as an acid-binding agent, desolventizing after reaction, and recrystallizing by using a proper solvent to obtain the high-purity 1-methyl-5-hydroxypyrazole. The method has the advantages that excessive methylhydrazine, high-temperature reaction and generation of isomers and tar are avoided, meanwhile, crystallization conditions of 1-methyl-5-hydroxypyrazole are developed, and the obtained product is good in solid character and quantitative in purity gt; the content is 99.5%. The technology has the advantages of simple three-waste treatment and high yield, can obtain high-purity 1-methyl-5-hydroxypyrazole, and has great industrial value.

The application discloses a synthesis process of trimethylhydrazine and a product, and relates to the technical field of chemical synthesis. The synthesis process takes methanol and hydrazine hydrochloride as raw materials in a molar ratio of 3-5:1, and obtains trimethylhydrazine hydrochloride through alkylation, and then obtains trimethylhydrazine by freeing the trimethylhydrazine hydrochloride with sodium hydroxide, and through distillation and rectification. The reaction process is simple, the reaction route is short, and the large-scale industrial production is facilitated. In the whole reaction process, the conversion rate during the reaction is greatly improved by making the methanol excessive relative to the hydrazine hydrochloride and strictly controlling the excessive ratio of the methanol, the generation of by-products such as methylhydrazine and dimethylhydrazine is inhibited, the reaction selectivity during the preparation of trimethylhydrazine is improved, the yield of the trimethylhydrazine is greatly improved, and the realization of the industrialized large-scale preparation of the trimethylhydrazine is further facilitated.

The present application provides a method for preparing 5-hydroxy-1-methylpyrazole, which comprises the following steps: S1: subjecting N,N-dimethylamino alkyl acrylate and methylhydrazine to a Michael addition reaction in a two-phase solvent system consisting of water and a non-polar organic solvent in the presence of a phase transfer catalyst and a polymerization inhibitor to obtain a β-hydrazino ester intermediate; S2: subjecting the β-hydrazino ester intermediate to an internal cyclization reaction, and removing dimethylamine and low-carbon alcohol byproducts to obtain 5-hydroxy-1-methylpyrazole. This method can effectively improve the site selectivity of 5-hydroxy-1-methylpyrazole, significantly inhibit the formation of structural isomers, and particularly avoid the common 3-hydroxy-1-methylpyrazole byproduct in the prior art, thereby improving the purity and yield of the main product and having good reaction stability and scale-up adaptability.

The invention relates to a method for determining chloride ions in a process of synthesizing methylhydrazine by a hydrazine hydrochloride methanol method, and belongs to the technical field of medical analysis. The method comprises the following steps: (1) precisely weighing a methylhydrazine reaction solution in a beaker, monitoring the pH value of the solution, respectively adjusting the pH value to 3-5, adding water to a constant volume, titrating by using a potentiometric titrator, inserting a glass electrode and a silver electrode into the solution, putting a rotor, starting a stirrer, titrating by using a 0.1 mol / L silver nitrate titrating solution, and measuring the concentration of the silver nitrate titrating solution; recording data; (2) calculating the chlorine content; according to the method, a potentiometric titrator is adopted, the pH value of the solution is adjusted to 3-5, the chlorine ion content can be rapidly and accurately detected in the presence of methylhydrazine and hydrazine hydrate, the method is rapid and simple to operate, high in sensitivity, good in repeatability and accurate in result, and the chlorine ion content of reaction liquid in multiple steps in the methylhydrazine synthesis process can be quantitatively detected.

The invention discloses a preparation method of 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-formic acid, which comprises the following steps: (1) reacting methylhydrazine with benzaldehyde substances in an organic solvent to obtain a reaction solution A, (2) firstly adding 2-(dimethylaminomethylene)-4, 4 '-diazole-4-carboxylic acid into the reaction solution A, and (3) adding 2-(dimethylaminomethylene)-4, 4'-diazole-4 '-carboxylic acid into the reaction solution A to obtain the 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid. And (3) adding a basic salt into the reaction liquid B for reaction, then separating a water phase, adding hydrochloric acid into the water phase for reaction to obtain a reaction liquid C, and filtering the reaction liquid C to obtain a solid product, namely 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-formic acid. According to the method, the hidden danger of isomer generation is eliminated, the separation and purification mode is simplified, the overall yield of the reaction is greatly increased, the reaction condition is mild, the organic solvent can be used mechanically, the preparation cost is reduced, three wastes are reduced, the practical value is high, and the method is suitable for industrial production.

The invention provides a method for preparing 5-hydroxy-1-methylpyrazole, which comprises the following steps: S1, carrying out Michael addition reaction on N, N-dimethylamino alkyl acrylate and methylhydrazine in a two-phase solvent system formed by water and a non-polar organic solvent in the presence of a phase transfer catalyst and a polymerization inhibitor to obtain 5-hydroxy-1-methylpyrazole; a beta-hydrazino ester intermediate is obtained; s2, the beta-hydrazino ester intermediate is subjected to an internal cyclization reaction, dimethylamine and low-carbon alcohol by-products are removed, and the 5-hydroxy-1-methylpyrazole is obtained. According to the method, the site selectivity of the 5-hydroxy-1-methylpyrazole can be effectively improved, generation of structural isomers is remarkably inhibited, particularly, common 3-hydroxy-1-methylpyrazole by-products in the prior art are avoided, the purity and yield of main products are improved, and the method has good reaction stability and amplification adaptability.

The invention discloses a preparation method of a carptorelin intermediate based on catalytic oxidation of yeast alcohol dehydrogenase, which comprises the following operation steps of: generating an intermediate product 1 from N-Boc-4-piperidinol by adopting a method of catalytic oxidation of yeast alcohol dehydrogenase oxidase, purifying, adding semicarbazide, and reacting to obtain the carptorelin intermediate. The preparation method comprises the following steps: reacting at least one of tert-butyloxycarboryl hydrazine or methyl carbazate with alkali to generate an intermediate product 2, adding DMF-DMA to react with alkali to generate an intermediate product 3, adding benzyl bromide to react with basic salt to generate an intermediate product 4, and adding acid to react to generate the carprorelin intermediate. According to the method, a brand new synthesis route is used, the semicarbazide which is low in price and easy to obtain is adopted in the new process route, hydrazine hydrate which seriously pollutes a water body is prevented from being used, highly toxic methylhydrazine is prevented from being used, a shrinkage process and a micro-channel continuous flow process can be adopted in the synthesis steps, and the method is simple in process, high in yield, good in safety and high in product quality.

The application provides a monomethylhydrazine production process and device, relates to the monomethylhydrazine production technical field, and comprises a salting kettle, a reaction kettle, a methanol distillation kettle, a rectification kettle and a refining distillation kettle, two groups of symmetrically-distributed U-shaped heat medium pipes and U-shaped cold medium pipes are welded through the circumferential wall of the tank body, and an arc-shaped spacing space is formed between each group of U-shaped heat medium pipes and U-shaped cold medium pipes and the inner circumferential wall of the tank body; four circumferentially-distributed pump cylinders are fixedly installed on the inner circumferential wall of the tank body, a water spraying ball is integrally formed at the bottom end of the vertical guide pipe, the water spraying ball is a hollow structure, a plurality of water spraying grooves are uniformly distributed on the spherical sidewall of the water spraying ball, and the water spraying ball and the vertical guide pipe are located in the arc-shaped spacing space; a bottom end portion of the vertical transmission shaft is fixedly sleeved with an impeller, and the impeller is located in the pump cylinder. The application can eliminate the restriction of the U-shaped heat medium pipes and the U-shaped cold medium pipes on the stirring effect of the chemical materials in the arc-shaped spacing space, and promote the overall uniform stirring of all chemical materials in the salting kettle and the reaction rate.

This invention discloses a continuous method for preparing 3-difluoromethyl-1-methyl-1H-pyrazole-4-carboxylic acid based on a cascaded process of cyclization-de-alcoholization-scraped membrane fluorination, belonging to the field of continuous synthesis technology in fine chemicals. The method includes: cyclizing ethyl 2-ethoxymethylene-4,4-dichloroacetoacetate with methylhydrazine in a loop reactor with forced external circulation, controlling the circulation ratio boundary at 15:1 to 18:1 to improve the selectivity of the target isomer; continuously removing at least some ethanol from the cyclized liquid and adding sulfolane for solvent replacement, ensuring that the ethanol content in the system before entering the fluorination stage is no higher than 1.0% (wt) and the water content is 0.1-0.2% (wt); subsequently, the resulting intermediate material, along with anhydrous potassium fluoride and 18-crown-6 to form a heterogeneous slurry, is fed into a vertical scraped membrane reactor, with a residence time strictly controlled at 169-171°C for 80-100 seconds, and rapid cooling within 3 seconds after discharge; finally, the target product is obtained through hydrolysis and acidification. This specific combined process can achieve high 1,3-isomer selectivity, high fluorination conversion, low aldehyde byproduct levels, and good long-term continuous operation stability without separating the cyclization intermediate.

The application discloses a preparation method of a compound of formula V-1, and comprises the following steps: a, a compound of formula I-1, 5-chlorosalicylic acid, is reacted with dimethyl sulfate to obtain a compound of formula II-1; the compound of formula II-1 is reacted with an ammonia source reagent to obtain a compound of formula III-1; the compound of formula III-1 is reacted with a methyl source compound to obtain a compound of formula IV-1; and the compound of formula IV-1 is reacted with methylhydrazine under the condition of an alkaline reagent to obtain the compound of formula V-1. The method improves the yield of a triazole ring obtained through cyclization of a compound of formula V, thereby improving the yield of 2-methoxy-3-(1-methyl-1H-1,2,4-triazol-3-yl)aniline; the preparation method of the compound of formula V is simple and easy to obtain, the cost is greatly reduced, and the method is convenient for industrialization.

The invention relates to the technical field of reaction kettles, and particularly discloses a reaction kettle for preparing a methylhydrazine aqueous solution, which comprises a reaction kettle, a rotating shaft arranged in the reaction kettle, an end cover arranged at the top end of the reaction kettle, a stirring frame arranged on the rotating shaft, the stirring frame comprises an upper cross beam, a lower cross beam and a connecting rod, and two ends of the connecting rod are respectively connected with the upper cross beam and the lower cross beam. A conveying belt is arranged on the stirring frame and rotationally matched with the stirring frame, a first driving mechanism is arranged on the stirring frame and used for driving the conveying belt to rotate, a discharging groove is formed in the side wall of the rotating shaft, one side of the conveying belt abuts against the side wall of the discharging groove, a gap is formed between the other side of the conveying belt and the side wall of the discharging groove, and the rotating shaft is a hollow shaft. A liquid through hole is formed in the rotating shaft close to the bottom of the reaction kettle, and a discharge hole is formed in the bottom end of the reaction kettle; the reaction kettle for preparing the methylhydrazine aqueous solution can separate a catalyst from reacted liquid.

The application belongs to the technical field of chemical synthesis, and particularly relates to a continuous catalytic synthesis process of methylhydrazine, which specifically comprises two steps: S1, preparation of hydrazine hydrochloride solution; and S2, mixing of hydrazine hydrate, hydrochloric acid and methanol in a micro-channel reactor under continuous catalytic reaction of zinc chloride to obtain methylhydrazine with a molar conversion rate of 40-42%. The application has a more mild reaction environment, is more convenient to operate, has low requirements on equipment, and solves the problems of long time consumption in auxiliary operations such as loading and packing of manual operation kettle type reactors or pressure reaction containers, process discontinuity in the auxiliary operation process, unstable product quality, small heat exchange area and low control ability on strong exothermic reactions, realizes continuous catalysis of methylhydrazine in the actual sense in the synthesis reaction process, shortens the reaction time, improves the reaction efficiency, and ensures large-scale industrial production.

This invention belongs to the field of methylhydrazine preparation technology, and particularly relates to a combined methylhydrazine preparation apparatus and method. The combined methylhydrazine preparation apparatus includes an evaporator crystallizer, a forced circulation evaporator, a distillation column, a crystallization circulation pump, a thickener, a falling film evaporator, a thermosiphon reboiler, a falling film circulation pump, a forced circulation pump, a bottom pump, and a horizontal centrifuge. The methylhydrazine feedstock enters the evaporator crystallizer, where the material is circulated by the forced circulation pump. Forced circulation evaporators are installed at the inlet and outlet of the forced circulation pump to heat the material. The top steam of the distillation column is used as the heat source. The evaporated gas in the evaporator crystallizer enters the distillation column under pressure. Salts in the feed are enriched and crystallized out, then transported by the crystallization circulation pump to the thickener for temporary storage. This replaces the original process of steam + vacuum pump + multi-effect evaporation crystallization, employing distillation + MVR evaporation crystallization, reducing process costs, improving process efficiency, and increasing market product profits.

The invention discloses a continuous catalysis system and method for synthesizing methylhydrazine, and relates to the technical field of methylhydrazine synthesis. Comprising the following steps: mixing hydrazine hydrochloride with pure water, heating in a water bath, and stirring until solids are completely dissolved to form a clear and transparent solution to obtain a methanol catalytic solution; the hydrazine hydrochloride raw material liquid and the methanol catalytic liquid are synchronously conveyed to a continuous reaction device with a microchannel connected with a subsequent reaction section in series, and a continuous catalytic alkylation reaction is completed; the method comprises the following steps: removing methanol from reaction discharge liquid through normal-pressure distillation, recovering, adding caustic soda liquid into residual liquid, stirring, standing for layering, taking an organic phase, carrying out reduced-pressure rectification, collecting a target fraction to obtain a methylhydrazine product, and carrying out gradient heating and precise pressure regulating technologies to realize stable control of reaction pressure. The small-volume continuous flow design is used for replacing the traditional large-volume intermittent kettle reaction, so that the core problems of prominent high-pressure risk and high danger coefficient of the traditional process are solved, and the intrinsic safety level of methylhydrazine synthesis is improved.

The invention discloses a preparation method of fluxapyroxad, aiming at the defects of high raw material cost and low yield in the existing process method, raw materials and intermediates required by reaction are prepared autonomously, and the yield of the intermediates is further improved by using a catalyst p-toluenesulfonic acid in the synthesis of 2-(ethoxymethylene)-4, 4-difluoro-3-oxobutyric acid ethyl ester. In the cyclization reaction of 2-(ethoxymethylene)-4, 4-difluoro-3-oxobutyric acid ethyl ester and methylhydrazine, the reaction system is optimized, so that the generation of an isomer is avoided, and the yield and the selectivity of the 3-difluoromethyl-1-methyl-pyrazole-4-carboxylic acid are remarkably improved.