46 results about "Acetic oxide" patented technology

The invention relates to the technical field of chemical engineering, and discloses a method for improving the chromaticity and purity of acetic anhydride based on a reflux ratio, and the method comprises the following steps: optimizing an evaporation tower, an acetic acid rectifying tower and an acetic anhydride rectifying tower, and installing an online detection instrument and an automatic control valve to construct an intelligent rectification control system; evaporating the crude acetic anhydride by using the optimized evaporation tower to obtain crude acetic anhydride steam; feeding the crude acetic anhydride steam into an acetic acid rectifying tower, calculating an initial reflux ratio, inputting the initial reflux ratio into a control system, and starting a reflux system to preliminarily remove acetic acid; monitoring the acetic acid content through an online gas chromatograph, and finely adjusting the reflux ratio until the reflux ratio reaches the standard when the measured acetic acid content is higher than a target value; feeding the crude acetic anhydride reaching the standard into an acetic anhydride rectifying tower, calculating an initial reflux ratio, inputting the initial reflux ratio into a control system, and starting to obtain an intermediate product; monitoring chromaticity and purity through an on-line platinum-cobalt colorimeter and an on-line gas chromatograph, and updating the reflux ratio to be qualified according to a bivariate adjustment formula; and finally, carrying out all-item detection on a finished product, and locking reflux ratio parameters after confirming that the finished product is qualified.

The utility model discloses a production device of 3-acetamino phthalic acid, and belongs to the technical field of chemical production devices. The device comprises an acylation reaction device, an acidification device and a solid-liquid filtering device. The acylation reaction device comprises an acylation reaction kettle with a stirring device, an acetic anhydride high-position metering tank with a first rotor flow meter, a solid feeding hole and a first conveying pump; the acidification device comprises an acidification reaction kettle with a stirring device, a hydrochloric acid high-position metering tank with a second rotor flow meter, an online pH meter and a second delivery pump; and the solid-liquid filtering device comprises solid-liquid separation equipment, a filtrate receiving tank and a product collecting tank. All the devices of the device are connected through pipelines and stop valves. According to the utility model, the dosage of hydrochloric acid is reduced by adjusting the dosage of acetic anhydride and controlling the acidification pH value, so that the production cost is reduced, and the quality and yield of the product 3-acetamino phthalic acid are improved.

This invention provides an ethyl-containing alkoxy-terminated organosilicon polymer, its preparation method, and its applications. The preparation method includes: S1, mixing methylvinylcyclotetrasiloxane, a solvent, and a first catalyst, introducing hydrogen gas, and reacting at 50-70°C until the methylvinylcyclotetrasiloxane content is no higher than 5%, filtering to remove impurities and obtain the product; S2, under nitrogen protection, ring-opening the product obtained in step S1 with acetic anhydride in the presence of a ring-opening catalyst, neutralizing and hydrolyzing, removing impurities, and obtaining the product; S3, under nitrogen protection, reacting the product of step S2 with hexamethyldisilazane at 40-50°C for 1-3 hours, adding N,N-diethylamino-trialkoxysilane, and reacting at 50-60°C for 1-3 hours. The polymer obtained by this invention, as a thermally conductive powder treatment agent, can effectively improve the dispersion performance of powders and enhance the heat resistance of products without reducing their tensile strength.

The invention relates to the technical field of chemical engineering, and discloses a rectification optimization process for improving the quality of acetic anhydride, the process realizes efficient pre-removal of high boiling impurities and colored substances in crude acetic anhydride by optimizing the structure of an evaporation tower, adopting combination of falling film evaporation and filler reinforcement, and accurately controlling the operation parameters of vacuum degree, temperature and feeding amount, so that the quality of the acetic anhydride is improved, and the quality of the acetic anhydride is improved. A traditional tower plate of the acetic acid rectifying tower is replaced with the efficient float valve tower plate, the internal part structure of the efficient float valve tower plate is optimized, the gas-liquid mass transfer efficiency in the rectifying tower is improved, and efficient and stable separation of acetic acid and acetic anhydride is achieved through precise linkage control over temperature and reflux ratio rectifying parameters. The main content of the product is improved; the impurity content is reduced; through whole-process online monitoring and regular optimization iteration in combination with a process parameter-product quality database, dynamic regulation and control and continuous improvement of the production process are realized, and finally the beneficial effects that the main content of acetic anhydride in the product is greater than or equal to 99.65% and the chromaticity is less than or equal to 6 are achieved.

The invention relates to the technical field of acetic anhydride storage, and provides an acetic anhydride storage tank anti-explosion pressure relief device which comprises a blocking block, a valve body, a valve cover and a valve element. The valve body comprises an outer valve seat and an inner valve seat, a pressure relief cavity is formed in the inner valve seat, and the valve element is arranged in the pressure relief cavity in a sliding mode. A spiral flow guide cavity is formed in the blocking block, a communicating cavity is formed in the valve element, and a low-pressure cavity, a medium-pressure cavity and a high-pressure cavity are formed between the valve element and the inner valve seat from bottom to top in sequence. A gas-liquid separation cavity is formed in the valve deck, the communicating cavity communicates with the spiral flow guide cavity and the low-pressure cavity, and the high-pressure cavity communicates with the gas-liquid separation cavity. A liquid return pipe is arranged on the valve cover in the radial direction, the other end of the liquid return pipe is connected to the position below the feeding port of the tank body, and a one-way valve is arranged on the liquid return pipe. When the valve element moves from bottom to top, the elastic piece is compressed to store energy, and the low-pressure cavity is firstly communicated with the medium-pressure cavity. The pressure relief device adapts to acetic anhydride storage pressure gradient change, and stable and smooth pressure relief is achieved.

The invention relates to a preparation method of acetylated distarch phosphate with high transparency, and belongs to the technical field of starch deep processing. The method comprises the following steps: by taking waxy corn starch as a raw material, dispersing the waxy corn starch into starch milk, and carrying out ultrasonic pretreatment; then sequentially carrying out acetylation and cross-linking reaction under a step-by-step optimization condition: firstly, taking acetic anhydride as a reagent, carrying out reaction at the pH value of 8.0-9.0 and the temperature of 20-35 DEG C, neutralizing until the pH value is 6.0-7.0, then taking sodium trimetaphosphate as a cross-linking reagent, adding sodium chloride as an accelerant, and carrying out reaction at the pH value of 10.0-11.0 and the temperature of 35-50 DEG C; and finally, neutralizing, washing with a 70-90% ethanol water solution, and drying to obtain the product. The product disclosed by the invention is excellent in transparency and good in freeze-thaw stability, and can be efficiently applied to preparation of transparent gel foods, frozen desserts and neutral transparent beverages.

The invention relates to a pharmaceutical intermediate (S)-9-(2, 3-di-O-acetyl propyl)-N2-acetyl guanine and a synthesis method thereof.In the synthesis method, a compound 2 serves as a starting material, sodium acetate, acetic acid and acetic anhydride are added, reaction, concentration and column chromatography purification are performed at the temperature of 110-130 DEG C, and the target product (S)-9-(2, 3-di-O-acetyl propyl)-N2-acetyl guanine is obtained. The invention relates to 2, 3-di-O-acetyl propyl)-N2-acetyl guanine. The invention discloses a novel medical intermediate and designs a feasible synthesis process, through the synergistic effect of all reagents, the reaction can be stabilized under mild conditions, side reactions are effectively avoided, the purity and stability of the product are ensured, and a foundation is laid for popularization of new drugs.

The utility model discloses a system for recycling chloroacetic acid by dechlorinating dichloroacetic acid through photocatalysis, which relates to the technical field of chloroacetic acid synthesis equipment and comprises a collecting tank I used for collecting mother liquor containing dichloroacetic acid during preparation of chloroacetic acid, and the collecting tank I is sequentially connected with a plurality of stages of condensers and a filter I through pipelines. A filtrate outlet I of the filter I is sequentially connected with a storage tank, a photocatalytic reaction kettle, a plurality of stages of condensers and a filter II; a filtrate outlet II of the filter II is connected with the storage tank through a reflux pipeline; stirring mechanisms are arranged in the collecting tank I and the photocatalytic reaction kettle, an ultraviolet visible light lamp is mounted in the photocatalytic reaction kettle, a material inlet of the photocatalytic reaction kettle is connected with a mother liquor supply pipeline, a water supply pipeline, a catalyst supply pipeline and a hydrogen supply pipeline, and the collecting tank I is connected with a nitrogen pipeline. The yield of chloroacetic acid prepared by an acetic anhydride catalysis method is improved, the generation of waste liquid is reduced, and the treatment cost of wastewater is reduced.

The present invention provides an acetylated surfactant for reducing the minimum miscibility pressure of CO2 miscible flooding, its preparation method and application, belonging to the technical field of CO2 enhanced oil recovery. The preparation method of the acetylated surfactant of the present invention includes the steps of: under the action of catalyst A, reacting an aqueous solution of gluconic acid and n-octanol to obtain n-octyl gluconate; under the action of catalyst B, reacting n-octyl gluconate and acetic anhydride to obtain an acetylated surfactant for reducing the minimum miscibility pressure of CO2 miscible flooding. The preparation method of the surfactant of the present invention is simple, the raw materials are cheap and widely available, green and low in cost; the obtained surfactant can interact with CO2, has high CO2 affinity, and can effectively reduce the minimum miscibility pressure of CO2 miscible flooding.

The invention relates to the technical field of acetic anhydride production, and discloses a safety production device for acetic anhydride production and an online control system, and the system achieves the whole-process precise management and control through the cooperation of multiple modules: an acetic anhydride production equipment optimization module upgrades the performance of core equipment; the acetic anhydride production parameter design module scientifically sets a process reference and a dynamic range; the crude acetic anhydride parameter acquisition module acquires initial data in real time; the multi-section process monitoring module monitors process parameters in the whole time period; the evaporation tower optimization control module accurately removes high-boiling impurities, the acetic acid rectifying tower regulation and control module deeply separates acetic acid, and the acetic anhydride rectifying tower reflux regulation module synergistically optimizes purity and chromaticity; the quality analysis and feedback module controls the quality of finished products in a closed-loop mode, the safety early warning module is in linkage with emergency response, and the data storage module supports process optimization; the central control module overall plans global instructions, and the production execution module drives the equipment, so that the system gives consideration to efficiency, energy consumption and safety, and the final acetic anhydride content is greater than or equal to 99.6% and the chromaticity is less than or equal to 6.

The invention relates to the field of cellulose diacetate, and particularly discloses a production process for synthesizing cellulose diacetate from wood pulp. A production process for synthesizing cellulose diacetate from wood pulp comprises the following specific steps: mixing an acidic activating solution, wood pulp and an acid catalyst, reacting and activating to obtain a wood pulp activating solution, mixing glacial acetic acid with acetyl chloride, sequentially performing reflux reaction and reduced pressure distillation to obtain acetic anhydride, mixing the acetic anhydride with the wood pulp activating solution and the acid catalyst, and performing heating esterification reaction to obtain cellulose diacetate. The cellulose diacetate is synthesized; through combination of the processes, the purity of acetic anhydride is improved, interference of impurities on subsequent esterification reaction of acetic anhydride is reduced, and the reaction efficiency of wood pulp cellulose and acetic anhydride is improved.

The invention discloses a purification treatment device for acetic anhydride-containing waste gas in organic silicon synthesis, and relates to the technical field of waste gas treatment.The purification treatment device comprises a treatment tank, and an inner cavity of the treatment tank is sequentially provided with a primary purification cavity, a secondary purification cavity, a tertiary purification cavity and an activated carbon filtering cavity from bottom to top; a lower-layer hollowed-out partition plate is arranged between the primary purification cavity and the secondary purification cavity, a middle-layer hollowed-out partition plate is arranged between the secondary purification cavity and the tertiary purification cavity, and an upper-layer hollowed-out partition plate is arranged between the tertiary purification cavity and the activated carbon filtering cavity. The purification efficiency is improved, chemicals are saved, accurate matching of waste gas treatment capacity under different working conditions is achieved through triple linkage adjustment of gas inflow, space adjustment and a gas flowing channel, waste of alkali liquor is avoided, it is ensured that the device can keep a stable purification effect in the high-load state and the low-load state, and the device is suitable for popularization and application. The energy consumption and the efficiency of the whole purification treatment system are optimized.

The invention relates to the technical field of compound preparation, in particular to a preparation process of 2, 2, 2-trifluoroethyl diphenyl sulfonium trifluoromethanesulfonate. Comprising the following steps: reacting 2, 2, 2-trifluoroethanol, formic acid and acetic anhydride, rectifying the reaction liquid, and collecting a target fraction to obtain 2, 2, 2-trifluoroethyl formate; according to the method, 2, 2, 2-trifluoroethyl formate, diphenyl sulfide and trifluoromethanesulfonic acid are subjected to a reaction, reaction liquid is cooled, solids are separated out, organic solvent washing is carried out, 2, 2, 2-trifluoroethyl diphenyl sulfonium trifluoromethanesulfonate is obtained, the purity can reach 99.7%, and the total reaction yield can reach 78.93%. The preparation process provided by the invention has the advantages of cheap and easily available raw materials, simple operation, high reaction yield, mild reaction conditions, high safety and simple reaction post-treatment, and is suitable for industrial large-scale production.

The invention discloses a synthesis method of hexafluorodianhydride, which belongs to the field of chemical synthesis, and specifically comprises the following steps: (1) bisphenol AF and an alkaline substance react under a heating condition; then carrying out Kolbe-Schmitt reaction on the reaction product I and carbon dioxide at high temperature and high pressure, and acidifying by adopting inorganic acid to obtain an intermediate I; (2) dissolving the intermediate I in a reaction solvent, adding inorganic alkali, transferring into a nitrogen atmosphere, adding a nickel catalyst, a ligand and metal manganese, transferring into a carbon dioxide atmosphere, carrying out carboxylation reaction, and sequentially quenching, extracting, drying, filtering and carrying out reduced pressure distillation on a reaction product II to obtain an intermediate II; and (3) carrying out heating reflux on the intermediate II and acetic anhydride, and carrying out a dehydration reaction to obtain hexafluorodianhydride. Through the limited three-step synthesis method, the synthesis route is simplified, the synthesis time is shortened, a large amount of waste generated in the synthesis process is avoided, and the yield of hexafluorodianhydride is also improved.

The invention provides a processing method of esterification modified radix trichosanthis traditional Chinese medicine decoction pieces, and relates to the technical field of traditional Chinese medicine processing. The processing method of the esterified modified radix trichosanthis traditional Chinese medicine decoction piece comprises the following processing steps: putting radix trichosanthis into an alkaline solution with the temperature of 35 DEG C and the pH value of 9, mixing according to the ratio of V (acetic anhydride) to V (absolute ethyl alcohol) of 1: 2 to prepare a mixed solution, dropwise adding the mixed solution into the alkaline solution under the stirring condition to perform esterification reaction, filtering, washing, and drying to obtain the esterified modified radix trichosanthis traditional Chinese medicine decoction piece. In the process of dropwise adding the mixed solution, synchronous ultrasonic treatment is carried out, the temperature and pH of a reaction system are controlled to be unchanged, esterification reaction is finished after esterification treatment is carried out for 2-4 h, radix trichosanthis is dried, and the esterification modified radix trichosanthis decoction pieces are obtained. According to the radix trichosanthis decoction pieces obtained in the invention, the acetate starch is generated through acetylation, the substitution degree of the acetate starch is high, the content of RS4 resistant starch is large, and the acetate starch has a good blood sugar resisting effect and is an excellent raw material choice for a blood sugar reducing medication scene.

The application discloses a method for determining the end-capping rate of linear ester end-capped polylactic acid, which is detected by using a nuclear magnetic resonance spectroscopy method, specifically, the content of hydrogen of the oxygen atom adjacent carbon in the end-capped ester group of a test sample is detected first, so that the content of the end-capping group is calculated, then the end hydroxyl group of the test sample is derivatized by using trifluoroacetic anhydride, the content of fluorine is detected, so that the content of the end hydroxyl group is calculated, and finally the end-capping rate is calculated by the ratio of the content of the end-capping group and the content of the end hydroxyl group. In the application, the trifluoroacetic anhydride derivatization is combined with the nuclear magnetic method to detect the hydroxyl group content of the high molecular polylactic acid, so that the end-capping rate of the linear ester end-capped polylactic acid is calculated, and a technical blank for detecting the hydroxyl group content of the high molecular polylactic acid is filled.

This invention provides a method for preparing 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one, relating to the field of compounds. The preparation method of this invention includes the following steps: (1) reacting anthranilic acid with terephthaloyl chloride in an organic solvent to generate intermediate A; (2) centrifuging the reaction product of step (1) to separate the wet crystalline intermediate A and the centrifugal mother liquor; (3) performing a cyclization reaction between the wet crystalline intermediate A from step (2) and acetic anhydride; (4) centrifuging, washing, and drying the reaction product of step (3) to obtain the target 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one product. This invention prepares 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one with not only low yellowness values ​​and high purity, but also high yield. The preparation method of the present invention has significant industrial value, and is particularly applicable to the field of polymer material additives where strict requirements are placed on product purity and yellowness.

The invention discloses a high-heat-resistance low-dielectric thermotropic liquid crystal polyester containing a large-volume side group and a preparation method thereof. The preparation method comprises the following steps: respectively carrying out acetylation reaction on a monomer 6-hydroxy-2-naphthoic acid and bisphenol AP with a mixture of acetic anhydride and 1-methylimidazole, and then recrystallizing and refining; and adding the refined 6-acetoxy-2-naphthoic acid monomer, the refined acetylated bisphenol AP monomer, terephthalic acid and zinc acetate into a container, heating, carrying out melt polycondensation reaction, after the reaction is finished, cooling the product, crushing, and drying, so as to obtain the high-heat-resistance low-dielectric thermotropic liquid crystal polyester containing the large-volume side group. The low-dielectric thermotropic liquid crystal polyester material is prepared by introducing a bisphenol monomer containing a large-volume side group in a melt polymerization manner; the dielectric constant and dielectric loss of the liquid crystal polymer are greatly reduced, the melting point of the liquid crystal polyester can be improved, and the prepared liquid crystal polymer has excellent insulating property and thermal property and can meet the application requirement under 5G high frequency.

The invention discloses a method for realizing continuous synthesis and crystallization control of HMX by a continuous flow multi-stage stirring reactor. The method comprises the following steps: preparing a mixed material I from urotropine and acetic acid, and preparing a mixed material II from fuming nitric acid and ammonium nitrate; setting the reaction temperature and the vibration frequency of the continuous flow multi-stage stirring reactor; respectively introducing the mixed material I, the mixed material II and acetic anhydride into a first-section reactor; introducing a part of the mixed material II and acetic anhydride into a second-section reactor; and introducing water into the third-section reactor. According to the invention, continuous synthesis of HMX is realized, the problem that a solid product is separated out to block a pipeline is solved, the reaction time is shortened, the highest yield of the product is 67%, and the highest liquid chromatographic purity of the product is greater than 99%; continuous crystallization and particle size control of HMX are realized, and accurate particle size control of the product can be realized by adjusting conditions of the reactor; the liquid holdup of the reaction is greatly reduced, the safety of the reaction is improved, and a foundation is laid for large-scale production.

The present invention relates to the technical field of starch processing, and in particular to a preparation method and application of modified starch. The modified starch is prepared from the following raw materials in parts by mass: 15-30 parts of pre-modified starch A and 55-70 parts of pre-modified starch B; the pre-modified starch A is prepared from pre-treated starch A, acetic anhydride and acetaldehyde dehydrogenase; the pre-treated starch A is starch subjected to freeze ball milling; the pre-modified starch B is prepared from pre-treated starch B and octenylsuccinic anhydride; the pre-treated starch B is starch subjected to step-by-step toughening treatment; the step-by-step toughening treatment comprises first subjecting the starch to a low-temperature sealing treatment and then to short-time ultrasound, then subjecting the starch to a heating reaction and then to a secondary ultrasound, and then subjecting the starch to a high-temperature treatment and then to a further ultrasound. The pre-modified starch A and the pre-modified starch B are mixed in a specific proportion to obtain a modified starch having high solubility and freeze-thaw stability and being widely applicable to the fields of food, papermaking, textile and medicine.

The application relates to a preparation method of a biotin intermediate cyclic anhydride, which comprises the following steps: under the condition of a catalyst, carrying out a dehydration reaction on a cyclic acid metal salt (II) and acetic anhydride in an aromatic hydrocarbon solvent to generate the cyclic anhydride (I). The method replaces the cyclic acid in the current process with the cyclic acid metal salt with better stability, omits the use of hydrochloric acid in the production of the cyclic acid, reduces the side reaction in the cyclic anhydride synthesis reaction process, effectively improves the purity and yield of the cyclic anhydride, and has a wide industrial application prospect.

The invention discloses equipment convenient for preparing acetyl tri-n-butyl citrate, and relates to the technical field of chemical equipment. The reaction kettle comprises a kettle body and a kettle cover assembled at the top opening end of the kettle body in a matched mode, a jacket A is arranged on the peripheral side wall of the kettle body, and a jacket B is arranged on the peripheral side wall, located outside the jacket A, of the kettle body; a first constant-temperature heating cavity is formed between the jacket A and the peripheral side wall of the kettle body, and a second constant-temperature heating cavity is formed between the jacket B and the peripheral side wall of the kettle body. The jacket A and the jacket B are arranged on the outer side of the kettle body, and the jacket A is wrapped in the jacket B, so that a heating liquid with the heating temperature of 130 DEG C is injected into the jacket A during use, water is injected into the jacket B, and the reaction is carried out at different temperatures in different stages accompanying the reaction; then, citric acid, n-butyl alcohol and acetic anhydride which serve as raw materials react through one device to prepare a crude product of acetyl tri-n-butyl citrate.

The invention discloses a preparation method of tetrathiafulvalene, which comprises the following steps: piperidine, carbon disulfide and an alkaline sodium-containing compound are mixed to react to generate an intermediate 1, and then bromoacetaldehyde ethylene glycol is added to react to obtain an intermediate 2; mixing and reacting the intermediate 2 with concentrated sulfuric acid and hexafluorophosphorus to obtain an intermediate 3; reacting the intermediate 3 with sodium borohydride to obtain an intermediate 4; reacting the intermediate 4, acetic anhydride and hexafluorophosphoric acid to obtain an intermediate 5; and reacting the intermediate 5 with alkali in an organic solvent to obtain tetrathiafulvalene. In the synthesis route, the reaction conditions of the preparation process from the intermediate 2 to the intermediate 3 are adjusted, the intermediate 3 is prepared by a one-pot method, the step of purifying the intermediate in the preparation process from the intermediate 2 to the intermediate 3 in the prior art is avoided, the synthesis time is shortened, and the efficiency is greatly improved; the synthesis route from the intermediate 5 to the tetrathiafulvalene is adjusted in one step, so that the step of converting hexafluorophosphate into iodized salt is avoided, and the synthesis efficiency is further improved.

The invention relates to the technical field of preparation of organic photoelectric materials, in particular to a preparation method of 1, 3-dimethyl-1, 2, 3, 4-cyclobutane tetracarboxylic dianhydride. The preparation method comprises the following steps: (1) carrying out addition reaction on dimethyl carbonate, a catalyst and dimethyl citraconate under the irradiation of a mercury lamp source to obtain an intermediate S1; (2) adding the intermediate S1 into an acidic solution, heating and carrying out hydrolysis reaction to obtain an intermediate S2; and (3) adding the intermediate S2 into acetic anhydride, heating and stirring, and carrying out dehydration ring closing reaction to obtain the finished product 1, 3-DMCBDA. According to the method, the defects in the prior art are overcome, the purity of the produced 1, 3-dimethyl-1, 2, 3, 4-cyclobutane tetracarboxylic dianhydride is improved, and the content of isomers and the content of metal impurities are greatly reduced.

The invention provides a solar-assisted heating acetic anhydride reaction device, and relates to the field of chemical reaction equipment. The front side of the reaction kettle body is fixedly connected with a solar heat collector, the top of the reaction kettle body is rotatably connected with a driving assembly, the middle of the top end face of the reaction kettle body is rotatably connected with a reaction mixing shaft, the middle of the reaction mixing shaft is connected with a liquid supply pipe in a penetrating manner, and the bottom of the reaction mixing shaft is connected with an extraction pump in an inserted manner. Through the synergistic effect of the solar heat collector, the circulating pipeline and the auxiliary heating cavity and the heat preservation layer of the reaction kettle body, an efficient and energy-saving heating system is constructed, the system can fully utilize the clean energy, namely solar energy, uniform heating of the reaction kettle is achieved, heat loss is reduced through the heat preservation layer, a continuous and stable temperature environment is provided for acetic anhydride reaction, and the heating efficiency is improved. The reaction rate and the product purity are improved, efficient reaction is guaranteed, and the problems that the heating energy consumption is high, stirring is uneven, conveying is unstable, and the reaction effect is affected are solved.

The invention discloses a synthesis method of L-mannose, and belongs to the technical field of sugar chemistry. The synthesis method comprises the following steps: by taking 1, 2, 3, 4, 6-penta-O-acetyl-beta-L-glucopyranose as a raw material, carrying out five-step continuous feeding reaction, sequentially using PCl5, DMF (Dimethyl Formamide), water, acetic anhydride, sodium borohydride and sodium methoxide, and separating after monitoring that the raw material disappears, thereby finally obtaining the L-mannose. The method overcomes the difficulty of preparing the L-mannose by a traditional method, and promotes the development and application of the functions of the L-mannose. According to the method disclosed by the invention, commercialized beta-pentaacetyl-L-glucopyranose which is easy to obtain is taken as a starting raw material, and the L-mannose is efficiently obtained through five-step continuous feeding conversion. The method is safe and simple to operate, easy to purify, low in cost and suitable for large-scale production, so that application and development of the L-mannose can be promoted.

The invention discloses a method for preparing ethiprole by continuous flow, which comprises the following steps: 1) mixing glacial acetic acid or acetic anhydride with an oxidant in a first mixing device, and further mixing in a first reaction unit; and 2) respectively conveying the material obtained in the step 1) and an ethiprole oxidation precursor to a second mixing device for mixing, and carrying out an oxidation reaction in a second reaction unit to obtain a material containing ethiprole. The ethiprole continuous flow preparation process is created for the first time and has the advantages that operation is easy, the reaction rate is high, process controllability is good, the conversion rate of a target product is high, by-products are remarkably reduced, and the process is safe.

The invention provides an anti-explosion automatic pressure relief device for an acetic anhydride storage tank, and relates to the technical field of pressure relief devices. A threaded connecting base is welded to the bottom end face of the pressure release valve body and connected to the acetic anhydride storage tank in a threaded mode, a sealing cover is screwed on the pressure release valve body in a threaded mode, and a pressure release pipeline is welded to the outer wall of the pressure release valve body. A first baffle ring is welded to the inner wall of the pressure release valve body, a sealing block slides in the pressure release valve body, and the bottom end face of the sealing block makes contact with the top end face of the first baffle ring. In the pressure relief assembly, the pre-tightening force of a spiral spring can be changed by rotating a threaded pipe, the pressure relief pressure threshold value is directly adjusted, operation is easy and convenient, and precision is controllable; after a second hydraulic cylinder of the adjusting assembly drives a spring rod to make contact with a sealing block, additional resistance can be increased for upward movement of the sealing block, the pressure adjusting range is further refined, the adaptability of the device to different air pressure environments is greatly improved through a double-adjusting mechanism, and the problems that a traditional pressure release valve is single in pressure setting and difficult to flexibly adjust are solved.

The invention relates to the technical field of organic synthesis, in particular to a method for preparing five-membered cyclobutene lactone through palladium catalysis of formic acid. The method comprises the following steps: adding 1, 4-enyne into a mixed solution composed of 1, 4-bis (diphenylphosphine) butane, palladium trifluoroacetate, formic acid, acetic anhydride and benzonitrile in an inert atmosphere, carrying out a reaction, and after the reaction is completed, carrying out purification treatment to obtain the five-membered cyclobutene lactone. According to the present invention, the design is reasonable, the olefins with different structures are adopted as the raw materials, the palladium trifluoroacetate is adopted as the catalyst, the 1, 4-bis (diphenylphosphine) butane is adopted as the ligand, the formic acid is adopted as the carbonyl source, and the acetic anhydride is adopted as the auxiliary agent so as to effectively achieve the 1, 4-eneyne series carbonylation reaction process; the method has the advantages of easily available raw materials, mild reaction conditions, simple operation and high yield of 76%; the method has positive effects on organic synthesis, natural product synthesis and the like.

The invention relates to the technical field of chemical separation, and discloses a rectification process and device for efficiently separating impurities in crude acetic anhydride, and the process sequentially comprises the following steps: preheating the crude acetic anhydride, evaporating in an evaporation tower, purifying and conveying steam, separating in an acetic acid rectifying tower, transferring an intermediate product, refining in the acetic anhydride rectifying tower, and carrying out reflux regulation and collection. The high-efficiency wire mesh demister is integrated in the evaporation tower, so that high-boiling-point colored substances are separated and removed from a source and are prevented from entering a subsequent rectification system; high-purity nitrogen protection is applied in the high-temperature material transfer process, oxygen is effectively isolated, the situation that a semi-finished product generates a new chroma precursor due to an oxidation side reaction is avoided, step-by-step rectification of the efficient sieve-plate tower and the structured packing tower and optimized process parameter control are combined, efficient separation of various impurities in the crude acetic anhydride is achieved, and the yield of the crude acetic anhydride is increased. Finally, a high-quality acetic anhydride product with the purity higher than 99.6% and the chromaticity lower than 6 can be stably obtained, and the problems that the chromaticity of a product obtained through a traditional process is unstable, and the purity is difficult to improve are solved.