63 results about "Acetic oxide" patented technology

The invention discloses a method and device for intelligently monitoring the content of acetic anhydride, and relates to the technical field of acetic anhydride monitoring. An L-shaped fixing plate is arranged at the top of the base, a solvent tank is arranged in the L-shaped fixing plate, a feeding pipe is arranged on the left side of the solvent tank, a circulating pump is arranged on the right side of the top of the base, the left side of the circulating pump communicates with the solvent tank through a straight pipe, a circulating pipe is arranged between the top of the circulating pump and the solvent tank, and a refraction assembly is arranged in the L-shaped fixing plate. The stirring net plate is used for stirring and mixing a bottom solution and a top solution of the solvent tank, the precipitation phenomenon of acetic anhydride components in the long-term storage process is prevented, and the situation that the acetic anhydride content of the solution at different depths is different, and then the acetic anhydride content detection effect is affected is avoided.

The utility model relates to the technical field of acetic anhydride production, in particular to a waste gas treatment device in an acetic anhydride synthesis process, which comprises a waste gas treatment tank and a controller, a catalyst layer is arranged in the waste gas treatment tank, and a waste gas discharge port is arranged at the top of the waste gas treatment tank. Wherein the waste gas input pipe is provided with a sensor assembly used for monitoring the inlet amount of carbon monoxide, the oxygen input pipe is provided with an air pump, and when waste gas generated in the acetic anhydride synthesis process is treated, firstly, external waste gas enters the waste gas treatment tank through the waste gas input pipe; oxygen enters the waste gas treatment tank through the oxygen input pipe and is mixed in the waste gas treatment tank, carbon dioxide is generated under the catalytic action of the catalyst layer, and carbon monoxide is removed, so that the waste gas in the acetic anhydride production process is treated.

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 an advanced mixed acid feeding control method for cellulose acetification reaction, which comprises the following steps of: measuring the heat change of a system under actual production conditions to obtain the actual unit mass reaction heat of exothermic reaction of water and acetic anhydride and the actual consumed mixed acid amount when the temperature of the system is increased by 1 DEG C, and eliminating the inherent noise variables of stirring, jacket cooling, heat preservation and other equipment; comparing the heat change before and after the reaction neutralizer is added into the system with the actual unit mass reaction heat of the exothermic reaction of the water and the acetic anhydride, and calculating the system temperature variation (TSR) caused by the exothermic reaction of the water and the excessive acetic anhydride according to the actual consumed mixed acid amount when the temperature of the system is increased by 1 DEG C; a relation model between core process parameters such as reaction neutralizer feeding amount, feeding temperature and system temperature change and TSR is established, a control algorithm is written, advanced control is performed on mixed acid feeding according to real-time data of the process parameters, and the purpose of reducing mixed acid consumption is achieved.

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 utility model discloses an energy recovery system, which is used in the process of preparing acetic anhydride by cracking acetic acid, and comprises a heat exchanger and a first gas-liquid separator, a heat exchange pipe is arranged in the heat exchanger, the water inlet end of the heat exchange pipe is connected with a first pipeline, the water outlet end of the heat exchange pipe is connected with a second pipeline, and the second pipeline is connected with a third pipeline. The water outlet end of the second pipeline is connected to the first gas-liquid separator, condensed water enters the heat exchanger through the first pipeline, and the first pipeline is further connected with a pressure pump. According to the energy recovery system, high-heat material flow is used for heating condensed water, a large amount of low-pressure steam is obtained, the low-pressure steam is pressurized and heated to form dry pressurized steam, the energy recovery system is suitable for more use scenes, part of saturated steam can be replaced, consumption of the saturated steam in the production process is reduced, and therefore efficient recovery of heat energy is achieved; and meanwhile, the cooling capacity consumption in the production process can be reduced, and energy conservation and consumption reduction are really achieved.

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 utility model discloses an acetic anhydride vaporization preheating mechanism, which belongs to the technical field of chemical industry. The utility model comprises a fixed frame, on which a plurality of tank bodies containing acetic anhydride raw materials are arranged; an inlet pipe fitting with a plurality of output ends, the inlet pipe fitting output ends are connected with the tank bodies, and a first valve is arranged on the inlet pipe fitting; and an outlet pipe fitting with a plurality of input ends, the outlet pipe fitting input ends are connected with the tank bodies, and a second valve is arranged on the outlet pipe fitting. The utility model introduces the acetic anhydride raw materials into the plurality of tank bodies at different time points and at the same time intervals. In the process of continuous introduction, the first tank body receiving the acetic anhydride raw materials will first complete the preheating operation of the acetic anhydride raw materials, and then export them. After the exporting, the second tank body receiving the acetic anhydride raw materials will then complete the preheating operation of the acetic anhydride raw materials.

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.

According to the preparation method of the oseltamivir chiral isomer, a three-membered ring compound A is subjected to ring opening to obtain a compound B, the compound B reacts with substituent sulfonyl chloride under the action of an acid-binding agent to obtain a compound C, a compound D with inverted configuration is obtained under the action of tert-butylamine or allyl amine, then the compound D reacts with acetic anhydride or acetyl chloride to obtain a compound E, and the compound E reacts with acetic anhydride or acetyl chloride to obtain the oseltamivir chiral isomer. Deprotecting the compound E to obtain a compound F, finally obtaining a compound G under the catalytic action of a positive ion trapping agent and a catalyst, and treating with an ethanol solution of hydrogen chloride to obtain the oseltamivir non-enantiomer H, namely a hydrochloride form. A white solid obtained after purification by an ethanol solution of hydrogen chloride and ethyl acetate is easy to store; the preparation method disclosed by the invention avoids introduction of azido, raw materials are easy to obtain, reaction conditions are mild, the method is safe and easy to operate, the product purity is high, and solid storage is more convenient.

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 relates to a preparation process of medicinal cellulose diacetate, which comprises the following steps: A, activating 1 part by weight of cellulose by using 8-15 parts by weight of glacial acetic acid and 0.005-0.05 part by weight of catalyst at 20-50 DEG C; b, 3-6 parts by weight of acetic anhydride is added into the solution obtained in the step A for esterification, the esterification temperature is 40-75 DEG C, and the esterification time is 2-5 hours; c, at the esterification temperature, adding 0.004-0.008 part by weight of a neutralizing agent for neutralization, so that the residual sulfuric acid is completely neutralized; d, after the neutralization is finished, adding a hydrolysis catalyst and purified water, heating to 105-115 DEG C, and hydrolyzing for 5-10 hours; e, adding 20-25 parts by weight of purified water at the temperature of 60-90 DEG C into the reaction liquid in the step D, precipitating and centrifuging; respectively carrying out alkali washing, water washing and alcohol washing on the obtained solid; and F, dissolving the solid in the step E with an organic solution, filtering, adding purified water for precipitation, centrifuging, and drying to obtain the product cellulose diacetate. The process is easy to operate, the product quality is controllable, and the viscosity is low.

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.