179 results about "Dehydration reaction" patented technology

The application discloses a continuous synthesis method of an amicarbazone intermediate 5-isopropyl-1,3,4-oxadiazole-2(3H)-ketone. The method comprises two continuous processes of hydrazinolysis and phosgenation: continuously feeding a mixture of isobutyric acid and a solvent, a mixture of hydrazine hydrate and a catalyst into a hydrazinolysis continuous reactor respectively, carrying out a warming reflux dehydration reaction, and obtaining an isobutyryl hydrazine solution shown in formula I; continuously feeding the isobutyryl hydrazine solution and phosgene into a phosgenation continuous reactor, carrying out a phosgenation reaction, and after distillation and desolventizing treatment of a reaction solution, obtaining 5-isopropyl-1,3,4-oxadiazole-2(3H)-ketone shown in formula II. The application has the advantages of simple reaction flow, high product yield, and significant production efficiency improvement, and is suitable for industrial large-scale production.

The application discloses a kind of high flame-retardant tpe materials and preparation method thereof, by polytetrahydrofuran, modified monomer and 4,4'-dicyclohexyl methane diisocyanate are reacted, chain extension is used with 1,4-butanediol, finally join flame-retardant additive, form branched structure, and the molecular structure of the pte material is branched structure, and molecular chain segment contains organic silicon composite organic phosphorus structure, when heat decomposition, can generate phosphoric acid, poly-metaphosphoric acid and other acidic substances, these acidic substances will catalyze pte molecule to occur dehydration reaction, accelerate its crosslinking, organic silicon chain segment will produce inorganic silicate or silicon-carbon, and then form a dense carbon layer on the surface of material, can heat insulation and oxygen isolation, prevent combustible gas to escape outward and oxygen diffusion inward, and slow down the further thermal decomposition of internal material, prevent carbon layer from being burnt through or collapse under high temperature, improve the durability of barrier, so that pte material has good flame-retardant effect.

The application discloses a catalyst for preparing malononitrile, a preparation method of the catalyst and a method for preparing malononitrile by using the catalyst. The catalyst is a solid catalyst, which is an acidic catalyst loaded with rare earth metal oxide. The method for preparing malononitrile is that cyanoacetic acid or cyanoacetate or cyanoacetamide and an ammonia source are subjected to ammoniation dehydration reaction in a continuous reactor to prepare malononitrile according to a certain molar ratio. Then, vacuum distillation (20 torr-25 torr) is carried out, and a fraction collected at 110 DEG C-120 DEG C is malononitrile product. The ammonia source can be ammonia gas, ammonia water, ammonium carbonate or urea. The method for preparing malononitrile can reduce production cost, improve production safety, reduce the discharge amount of three wastes in the preparation of malononitrile by using an existing process, and improve product quality, and is a sustainable and green synthesis route.

The invention discloses a hydrolysate deacidification-dehydration coupling process and a byproduct recovery method, and belongs to the technical field of hydrolysate treatment. The method comprises the following steps: pretreating a hydrolysate raw material through two-stage filtration; adding the pretreated hydrolysate, a deacidification agent and a dehydration auxiliary agent into a coupling reaction device, and synchronously carrying out deacidification-dehydration reaction under the conditions of 60-120 DEG C and 0.1-0.5 MPa; after the reaction, separating to obtain a deacidification and dehydration product and a mixed solid phase; and dissolving and crystallizing the mixed solid phase to recover high-purity byproducts. The deacidification and dehydration synergistic interaction is achieved, the acidity reduction rate is larger than or equal to 85%, the water content is smaller than or equal to 5%, and the process time consumption is shortened by 28.6%; the byproduct purity is not less than 90%, and the recovery rate is not less than 80 A tail gas treatment system is additionally arranged to ensure that environmental protection reaches the standard. The process is suitable for biomass, polysaccharide and protein hydrolysate treatment, has the advantages of high efficiency, good resource utilization rate and the like, and provides an efficient solution for hydrolysate industrial treatment.

This invention relates to the field of organic synthesis technology and discloses a method and system for preparing adiponitrile. The method includes: S1: atomizing molten adipic acid and mixing it with ammonia gas, followed by an ammoniation reaction to generate an ammoniation product; S2: dividing the ammoniation product into two parts, a and b. Part a undergoes a countercurrent, non-contact heat exchange with hot material to generate crude adiponitrile through heating and dehydration, while part b is recycled back to step S1 to participate in the reaction. The ratio of the ammoniation product in part a to that in part b is (1~5):1. The temperature of the hot material is higher than the temperature of the ammoniation product in part a. This invention improves the efficiency of the ammoniation reaction, reduces the decomposition side reactions of adipic acid and the residue of adipic acid, and significantly improves the conversion rate of the dehydration reaction and the selectivity of adiponitrile.

The invention relates to a biomass low-temperature carbonization accelerant as well as a preparation method and application thereof. The preparation method comprises the following steps: carrying out water washing pretreatment on powder obtained by crushing a biomass raw material, and then carbonizing in an inert atmosphere to obtain biomass carbon powder; acidizing the biomass carbon powder to obtain carbon-based solid acid; the carbon-based solid acid and a transition metal salt auxiliary agent are mixed and ground, and the biomass low-temperature carbonization accelerant is prepared. The biomass low-temperature carbonization accelerant is a composite catalyst composed of carbon-based solid acid and transition metal salt; wherein the carbon-based solid acid is used as a main catalytic substrate, provides abundant Bronsted acid loci-SO3H, and is mainly used for catalyzing the dehydration reaction of biomass; transition metal ions are used as Lewis acid sites and generate a synergistic effect with the carbon-based solid acid to jointly catalyze depolymerization, dehydrogenation and aromatization reactions, so that deep carbonization can be initiated and completed at a relatively low temperature of 250-400 DEG C, and the carbonization rate is remarkably higher than that of an existing carbonization catalyst.

This invention discloses a method for preparing the DPP1 inhibitor bresocarte, belonging to the field of pharmaceutical synthesis. Specifically, the method includes the following steps: N-tert-butoxycarbonyl-L-4-bromophenylalanine reacts with methanesulfonyl chloride or 4-nitrobenzenesulfonyl chloride in the presence of a base, followed by amination substitution to obtain intermediate 1; then, it undergoes dehydration in the presence of trifluoroacetic anhydride to obtain intermediate 2; next, it undergoes a coupling reaction with pinacol diboronate to obtain intermediate 3; then, it undergoes a coupling reaction with bromide compound 4 to obtain intermediate 5; then, it undergoes cyclization with di-tert-butyl dicarbonate in the presence of sodium methoxide to obtain intermediate 6; then, it undergoes deprotection in the presence of hydrogen chloride to obtain intermediate 7; next, it undergoes condensation with compound 8 to obtain intermediate 9; finally, it undergoes deprotection in the presence of hydrogen chloride to obtain the inhibitor bresocarte. This method provides a new synthetic approach, with low overall cost, simple operation, high yield, and suitability for industrial production.

The invention relates to a synthesis method of sulfopropionic anhydride. The synthesis method comprises the following steps: (1) mixing 3-bromopropionic acid and sodium sulfite in water, and carrying out sulfonation reaction to obtain a mixture; (2) mixing the mixture with an acidifying agent, and carrying out acidification reaction to obtain 3-sulfonyl propionic acid; and (3) mixing the 3-sulfonyl propionic acid with a dehydrating agent and an organic solvent, and carrying out a dehydration reaction to obtain the sulfopropionic anhydride. According to the invention, compounds such as 3-bromopropionic acid and sodium sulfite are used as reaction raw materials to prepare sulfopropionic anhydride. The method has the advantages of cheap and easily available raw materials, simple operation and high yield, and is suitable for large-scale production.

The present invention relates to a method for dehydrating isopropanol to produce propylene, a method for producing propylene from acetone as a raw material including the process, and a related production apparatus. The dehydration method of the present invention includes a step of dehydrating a raw material containing isopropanol in the presence of a dehydration catalyst containing alumina to produce a product containing propylene, wherein the water content of the raw material is 0.1-10.0 wt% (, relative to the total mass of the raw material being 100 wt%), and the content of C3-C4 unsaturated impurities in the product is 30 ppm or less. According to the present invention, the production of undesirable by-products can be significantly suppressed while improving the conversion rate of isopropanol.

The invention provides a method for preparing 2, 5-diformyl furan by catalyzing fructose by using an ionic liquid and a vanadium complex, which comprises the following steps: carrying out dehydration reaction by using the fructose as a raw material and the ionic liquid as a reaction solvent and a catalyst to obtain 5-hydroxymethylfurfural, then adding a V / HCP-AQ catalyst, and carrying out oxidation reaction on the 5-hydroxymethylfurfural in an oxygen atmosphere to obtain the 2, 5-diformyl furan. And 3, 5-diformyl furan is obtained. According to the method, the ionic liquid is adopted to replace DMSO to serve as a fructose dehydration and oxidation solvent, ethyl acetate is added into a reaction system for extraction after the reaction is finished, the product 2, 5-diformyl furan can be obtained, and the problem that the product is difficult to separate in the process of preparing the 2, 5-diformyl furan through the fructose one-pot method under a traditional catalytic system is solved.

This application discloses a process for improving the yield of HCN prepared by the Andruse process, belonging to the field of HCN preparation technology. This application utilizes the tail gas after HCN removal and dehydration reactions, using residual methane in the tail gas to increase methane conversion, using CO in the tail gas to inhibit methane decomposition and improve methane selectivity, and using H2 in the tail gas, with H2 combustion providing heat instead of the heat provided by methane decomposition. This improves the conversion rate of methane to HCN, increases the overall reaction yield, and eliminates ammonia residue in the post-reaction gas, saving the ammonia removal step. Simultaneously, it reduces air consumption and increases the ratio of ammonia to methane to oxygen, allowing the reaction to proceed far from the explosion zone, thus improving process safety.

The invention belongs to the technical field of preparation of organic chemicals, and particularly relates to 2-methyl-5-trifluoromethyl furan and a preparation method thereof. The preparation method comprises the following steps: adding a solvent into trifluoroacetone, adding alkali under an ice bath condition, adding 1-chloro-2-methyl ethylene oxide, reacting at room temperature, adding acid, reacting at 40-60 DEG C to complete a dehydration reaction, then adding alkali for aromatization, continuing to complete an aromatization reaction, adding water to extract a reaction system, taking an organic phase, filtering, washing and drying to obtain the 1-chloro-2-methyl ethylene oxide. And rectifying to obtain the 2-methyl-5-trifluoromethyl furan. According to the 2-methyl-5-trifluoromethyl furan and the preparation method thereof provided by the invention, the reaction conditions are mild, the steps are simple, and the prepared 2-methyl-5-trifluoromethyl furan is high in yield and suitable for industrial production.

A process for dehydrating ethanol to ethylene. The steps include: (a) reacting an ethanol feed stream over a dehydration catalyst to produce ethylene in a dehydration product stream; (b) separating said dehydration product stream into a product liquid stream comprising water and dissolved oxygenates and a product vapor stream of ethylene; (c) taking a bypass stream from said product liquid stream; and, (d) sending the bypass stream to the dehydration reactor bypassing a wastewater stripping column.

A process of converting an ethanol feed stream to ethylene comprising sending portions of said ethanol feed stream to two reactors in parallel and then sending the combined product to a third reactor that is operated at a higher temperature to prevent the formation of ethers such as diethyl ether.

The application discloses a kind of phosphogypsum solid waste's step-by-step modification calcination preparation method, belong to solid waste treatment technical field.The method includes: (1) pre-coating treatment: the original state of containing attached water dihydrate phosphogypsum is mixed with composite modifier and is ground, and pre-coated phosphogypsum is obtained;(2) temperature control calcination: the pre-coated phosphogypsum obtained in step (1) is sent into calcining kiln, and dehydration reaction is carried out at 165 DEG C~180 DEG C temperature, and hemihydrate gypsum powder is obtained;(3) hygroscopic aging: the hemihydrate gypsum powder obtained in step (2) is cooled and aged 24h~48h, and the components in powder are used to absorb moisture in air to carry out hydration reaction, and the final product is obtained.The method is free of water washing, short process, and the obtained phosphorus building gypsum standard consistency water consumption is 45%~50%, and 2 hour compressive strength is greater than or equal to 6.5MPa.

The application discloses a method for efficiently preparing 1,4-anhydro mannitol, comprising the following steps: mixing bio-based mannitol, a ketone compound and a solid acid catalyst in a reactor to generate a dehydration reaction, hydrolysis, crystallization, and obtaining 1,4-anhydro mannitol; by introducing a ketone compound as a ketal reagent, and through environment-friendly solid acid catalysis, 1,4-position selective dehydration of mannitol is realized, and 1,4-anhydro mannitol ketal and monodehydration mannitol by-product are easy to separate, and the product separation process is simplified. The efficient preparation method of 1,4-anhydro mannitol provided by the application simultaneously solves the problems of low selectivity of 1,4-anhydro mannitol and difficult product separation, and opens up a new route for the preparation of 1,4-anhydro mannitol.

The invention discloses a cation modified gallium-silicon MTW molecular sieve catalyst as well as a preparation method and application thereof, and relates to the technical field of molecular sieve catalysts. The cation modified gallium-silicon MTW molecular sieve catalyst provided by the invention at least comprises a gallium-silicon MTW molecular sieve; the alkali metal cations are loaded on the gallium-silicon type MTW molecular sieve; the acid sites of the cation modified gallium silicon type MTW molecular sieve catalyst comprise a Bronsted acid and a Lewis acid. The cation-modified gallium-silicon MTW molecular sieve catalyst prepared by the invention takes gallium and silicon as main framework elements, and after being modified by alkali metal cations, the cation-modified gallium-silicon MTW molecular sieve catalyst has appropriate acid strength, uniform acid site distribution and unique one-dimensional twelve-membered ring pore channel shape-selective effect of the MTW molecular sieve, and is used for preparing acrylic acid by dehydrating lactic acid; the activity, selectivity and stability of the catalyst in a lactic acid dehydration reaction are improved.

The invention belongs to the technical field of catalytic reaction and separation and purification, and particularly relates to a preparation method of isotope dimethyl ether. The method comprises the following steps: by taking a mixture of a metal oxide nanosheet and a nanosheet-shaped ZSM-5 molecular sieve as a catalyst, carrying out dehydration reaction on isotope methanol under the action of the catalyst; after the reaction is finished, a reaction product enters a U-shaped pipe filled with a water absorption drying agent, is subjected to first-stage separation and purification in an ice salt bath environment, then enters an adsorption bottle I, is subjected to second-stage separation and purification in a liquid nitrogen and ethanol mixed bath environment, and then enters an adsorption bottle II; third-stage separation and purification are carried out in a liquid nitrogen and isopropanol mixed bath environment, finally, reaction products enter an absorption bottle III, and fourth-stage separation and purification are carried out in the liquid nitrogen and isopropanol mixed bath environment. The method provided by the invention can realize high-conversion-rate and high-selectivity generation of dimethyl ether from methanol, and realizes 100% isotope methanol recovery efficiency and 100% separation and collection of isotope dimethyl ether.

The invention discloses a method for preparing vinyl alkyl ether from ethylene oxide through ethylene glycol monoalkyl ether. The ethylene glycol monoalkyl ether prepared through ring opening etherification of ethylene oxide and alcohol is further subjected to a gas-phase dehydration reaction, and a reaction product is subjected to fractional refining to obtain the vinyl alkyl ether. According to the method, bulk chemicals ethylene oxide and alcohol are used as raw materials, two-step reaction of novel solid acid catalytic addition etherification and novel solid base catalytic dehydration is adopted, ethylene glycol monoalkyl ether and vinyl alkyl ether compounds with high additional value are prepared, the raw materials are low in price and easy to obtain, the product yield is high, the production cost is low, the application range is wide, and the development potential is large; a catalytic reaction process and a grading refining process are adopted, the process is efficient, safe and environment-friendly, and the device can be large-scale; the product scheme is flexible, and a series of ethylene glycol monoalkyl ether and vinyl alkyl ether products can be produced by switching the raw material alcohol.

The application relates to the technical field of alpha-olefin preparation, and discloses a method for preparing 4-methyl-1-pentene from 4-methyl-2-pentanone, which comprises the following steps: (1) mixing 4-methyl-2-pentanone with hydrogen in the presence of a hydrogenation catalyst to perform a hydrogenation reaction, so as to obtain a 4-methyl-2-pentanol-containing stream; (2) performing ketone removal on the 4-methyl-2-pentanol-containing stream, so as to obtain 4-methyl-2-pentanone and 4-methyl-2-pentanol crude products; and (3) performing dehydration reaction on the 4-methyl-2-pentanol crude products obtained in the step (2) in the presence of a dehydration catalyst, so as to obtain a 4-methyl-1-pentene-containing stream. The method for preparing 4-methyl-1-pentene from 4-methyl-2-pentanone can be simply and effectively used for preparing 4-methyl-1-pentene products, 4-methyl-2-pentanone raw materials are easy to obtain, the reaction conditions are relatively mild, the product distribution is simple, and high-purity 4-methyl-1-pentene products can be prepared.

The invention belongs to the technical field of organic compounds, and particularly discloses a method for preparing acrylic acid by taking lactic acid as a raw material, which comprises the following steps: under the action of a composite catalyst, performing dehydration reaction on lactic acid to generate acrylic acid, the composite catalyst comprises a carrier, and an active component and an additive which are loaded on the carrier, the carrier comprises silicon dioxide, the active component comprises Ca3 (PO4) 2, and the additive comprises K2CO3. The composite catalyst can efficiently convert lactic acid into acrylic acid, the yield and selectivity of acrylic acid are improved, the severe degree of reaction conditions is reduced, and the production cost and environmental pollution are reduced.

This invention provides a non-fired magnesia-calcium brick and its preparation method, belonging to the field of refractory materials. Its raw materials include aggregates, fine powder, graphite, binders and composite additives, wherein the composite additives contain calcium nitrate tetrahydrate. The non-fired magnesia-calcium brick of this invention has the following beneficial properties: (1) The composite additives are uniformly distributed in a network in the non-fired magnesia-calcium brick. Due to the dehydration reaction of calcium nitrate tetrahydrate in the composite additives during the brick drying process, a uniform network crack is formed in the finished brick, thereby improving the thermal shock resistance of the product; (2) The calcium nitrate formed by the dehydration of calcium nitrate tetrahydrate has strong water absorption, effectively protecting the CaO in the brick from hydration and improving the hydration resistance of the product; (3) During the high-temperature use of the finished non-fired magnesia-calcium brick, the calcium nitrate undergoes melting and decomposition to transform into highly active CaO, and reacts with SiO2 introduced in the composite additives to form a combined phase, improving the medium-temperature performance of the non-fired magnesia-calcium brick.

The application discloses a preparation method of 2-methylamino-5-tert-butyl-1,3,4-thiadiazole, which comprises the following steps: under water bath cooling, first toluene solvent, 4-methylaminothiourea, a dehydration reaction catalyst and pivaloyl chloride are sequentially added into a reaction bottle and stirred, the temperature is increased to 60-100 DEG C for reaction, after the reaction is completed, cooling and filtering are carried out, the filter cake is added into second toluene solvent, the temperature is increased to 50-80 DEG C, then the filter cake is neutralized by liquid alkali, the water phase is separated, the organic phase is refluxed to remove water and dissolve, and 2-methylamino-5-tert-butyl-1,3,4-thiadiazole is obtained. The preparation method can avoid the phenomena of stirring failure and flying temperature, has high yield, is safe and simple to operate, and is low in cost.

The application discloses a preparation method of high-purity Fmoc-S-trityl-L-penicillamine and belongs to the field of synthetic chemistry. The method is characterized in that L-penicillamine is used as a starting material, dehydrated with methyl boronic acid to generate a cyclic protective structure, then a thiol group is selectively protected by trityl, and an acid is used to open a ring to obtain an S-trityl-L-penicillamine intermediate; then, in a sodium bicarbonate buffered water / dioxane weak alkaline system, Fmoc-OSu (9-fluorenylmethoxycarbonyl succinimidyl ester) is used to react with the S-trityl-L-penicillamine intermediate to protect an amino group, and racemization is effectively inhibited; finally, the product is refined by recrystallization in an ethyl acetate / n-heptane system to obtain a high-purity end product. The process route is simple and efficient, the conditions are mild, the purification method is unique and effective, the obtained product has high chemical purity and optical purity, good stability, is suitable for large-scale production, and can meet the needs of high-end polypeptide drug synthesis.

The present application relates to the technical field of producing 4-methyl-1-pentene, and discloses a method for preparing 4-methyl-1-pentene, characterized in that the method comprises the following steps: (1) carrying out a hydrogenation reaction on methyl isobutyl ketone and hydrogen gas in the presence of a hydrogenation catalyst to obtain a stream containing methyl isobutyl carbinol; (2) carrying out a dehydration reaction on the stream containing methyl isobutyl carbinol in the presence of a dehydration catalyst to obtain a stream containing 4-methyl-1-pentene. The method provided by the present application can simply and efficiently prepare 4-methyl-1-pentene, the raw material methyl isobutyl ketone is easy to obtain, the reaction condition is relatively mild, the product distribution is simple, and a high-purity 4-methyl-1-pentene product can be prepared.

This invention discloses a method for preparing sulindac. The method involves first performing an Arbuzov reaction and a Wittig-Horner reaction sequentially to obtain 6-fluoro-3-(p-methylthiobenzyl)-2-methyl-1H-indene. 6-fluoro-3-(p-methylthiobenzyl)-2-methyl-1H-indene undergoes a condensation dehydration reaction with glyoxylic acid, followed by double bond rearrangement under acidic conditions to obtain (Z)-5-fluoro-2-methyl-1-(p-methylthiobenzyl)-1H-indene-3-acetic acid. Finally, it undergoes a single oxidation reaction with an oxidant to obtain sulindac. The raw materials and excipients used in this invention are readily available, and the entire reaction route is short, the reaction conditions are mild, the operation is safe and simple, the yield is high, the purity is high, the production cost is low, and the emissions of waste are minimal, conforming to green industrial production standards. The total yield of the obtained sulindac product is over 75%, which is conducive to industrial production.

An ethanol dehydration process is disclosed. The method includes adding an amount of steam to the feed to the dehydration reactor to provide a feed stream. The steam stream is mixed with the feed to the dehydration reactor such that the ratio of steam to ethanol is between about 0.5 weight / weight and about 5.0 weight / weight. The feed stream is passed to a dehydration reactor to produce a dehydrated stream. Steam may be input from outside the dehydration process, such as from oligomerization or dimerization reactions. Steam may be generated from the dehydrated stream.

This invention discloses a method for preparing p-acetoxystyrene, comprising the following steps: mixing [4-(1-hydroxyethyl)phenyl]acetate, organophosphoric acid, and a polymerization inhibitor, and reacting them thoroughly to obtain the desired p-hydroxystyrene. The method of this invention utilizes organophosphoric acid as a catalyst for the dehydration reaction of [4-(1-hydroxyethyl)phenyl]acetate, thus achieving the preparation of p-acetoxystyrene. Compared with traditional methods for preparing p-acetoxystyrene, this method does not require large amounts of acidic and alkaline dehydrating agents, generates less wastewater, and the organophosphoric acid catalyst can be recycled. Therefore, the method of this invention for preparing p-acetoxystyrene has advantages such as low waste, high yield, and environmental friendliness, and thus has good application value.

Disclosed herein is a system and method that has been developed that includes heating a reactor with an induction heater. The reactor includes a single catalyst bed including a catalyst and a ferromagnetic material. The system also includes an induction heater that is configured to heat the single catalyst bed.