415 results about "Transesterification reaction" patented technology

The invention discloses a method for preparing regenerated flame-retardant high-shrinkage polyester by a methanol alcoholysis method, and belongs to the technical field of polyester. The method comprises the following steps: (a) mixing the waste polyester fabric with methanol, and carrying out catalytic depolymerization to obtain a regenerated DMT mixed solution; (b) carrying out impurity separation and methanol recovery treatment on the regenerated DMT mixed solution, and then carrying out cooling crystallization, centrifugal drying and rectification purification treatment to obtain pure DMT; (c) carrying out transesterification on pure DMT, ethylene glycol, a transesterification catalyst and a DEG inhibitor; (d) after the ester exchange reaction, adding CEPPA-EG and IPA-EG for copolymerization; adding a polymerization catalyst, a stabilizer and an antioxidant for polymerization reaction to obtain a modified polyester melt; and (e) granulating and drying to obtain the slices. The regenerated polyester prepared by the method has multiple functions of flame retardance, high boiling water shrinkage, low-temperature dyeing and the like, and is suitable for the fields of high-end clothing, automotive trim, electronic packaging materials and the like.

The present invention relates to the technical field of seawater desalination membranes, and discloses a durable seawater desalination membrane and a preparation method thereof. The present invention uses pentaerythritol as an initiator, uses propylene oxide and ethylene oxide as raw materials to synthesize a hyperbranched polyether, and then undergoes an ester exchange reaction with 2-aminoethyl acetate to synthesize a modified hyperbranched polyether. The ZIF-8 material is then synthesized by a hydrothermal method, and MoS2 nanosheets are coated on its surface to obtain a MoS2 / ZIF-8 composite material, which is then surface-modified by a silane coupling agent to obtain a modified MoS2 / ZIF-8 composite material. Finally, a casting solution is formed using polysulfone and a modified MoS2 / ZIF-8 composite material to obtain a base membrane, and the base membrane is then sequentially immersed in an aqueous phase solution and an oil phase solution to form a polyamide film layer, thereby obtaining a durable seawater desalination membrane. The seawater desalination membrane prepared by the present invention has excellent water flux, desalination rate and durability.

The present invention provides a system and a method for preparing a polyester polyol prepolymer. The system comprises an atmospheric pressure bubbling reaction rectifying tower and a reduced pressure heating reaction rectifying tower. The method comprises: introducing a protective gas into an atmospheric pressure bubbling reaction rectifying tower, introducing a raw material for preparing a polyester polyol prepolymer into the atmospheric pressure bubbling reaction rectifying tower, and carrying out a primary esterification reaction or an ester exchange reaction; and introducing the primary esterification product or the ester exchange product into a reduced pressure heating reaction rectifying tower, and carrying out one or more of a deep esterification reaction, an ester exchange reaction, and a pre-polycondensation reaction to obtain the polyester polyol prepolymer. The present invention has the advantages of high reaction efficiency, stable product quality, easiness in product separation, convenience in large-scale production and the like.

The invention belongs to the technical field of polyester polyol, and particularly relates to high-functionality low-viscosity polyester polyol and a step-by-step synthesis method thereof. Comprising the following steps: (1) adding dihydric alcohol, dicarboxylic acid, a catalyst and an antioxidant into a reaction kettle, heating and vacuumizing, and carrying out esterification and ester exchange reaction to prepare a polyester polyol intermediate; and (2) cooling the polyester polyol intermediate prepared in the step (1), adding polyol into the reaction kettle, and continuously carrying out ester exchange reaction to obtain the high-functionality low-viscosity polyester polyol after the reaction is finished. According to the step-by-step synthesis method, the problems that in the prior art, high-functionality polyester polyol is large in viscosity and low-viscosity products are difficult to prepare are solved, the viscosity of the high-functionality polyester polyol can be effectively reduced under the same raw material system and hydroxyl value conditions through specific raw material selection and process control, and the method is simple in process and easy to implement. The industrial production is convenient.

The invention relates to the technical field of organic synthesis, in particular to a method for homogeneous catalytic synthesis of dimethyl carbonate by using a liquid separation method to separate a catalyst, which comprises the following steps: by using 0.3-15% long-chain tertiary amine as a homogeneous catalyst, carrying out homogeneous reaction on cyclic carbonate and methanol in a mass ratio of 1: (1.2-5.5) at 60-80 DEG C for 4-7 hours. And after the homogeneous transesterification reaction is completed, carrying out atmospheric distillation on the reaction mixture, and collecting fractions to obtain the target product dimethyl carbonate. Carrying out liquid separation on the heterogeneous atmospheric distillation residual liquid, and collecting a lower-layer material to obtain a by-product; and the collected material is a catalyst which can be directly recycled subsequently. The dimethyl carbonate synthesis method provided by the invention has the characteristics of high catalytic efficiency, easy catalyst separation, environmental protection, energy saving and the like.

The invention discloses a method for preparing immobilized lipase Janus particles by an emulsion template one-step method based on a zymoprotein directional adsorption strategy and application of the immobilized lipase Janus particles in a Pickering emulsion catalytic system. The natural hydrophilicity of lipase protein is utilized to drive the lipase protein to form directional adsorption on the surfaces of hydrophobic particles, and the Janus particles with hydrophilic and hydrophobic characteristics are constructed. Firstly, an organic phase containing hydrophobic particles and a water phase containing lipase are oscillated to form an emulsion, so that the lipase in the water phase is accurately adsorbed on the single side of the surface of the particles, and directional connection of zymoprotein and a hydrophobic matrix is realized. Afterwards, the Janus particles are used for constructing a Pickering emulsion system, and a microreactor is built, so that the catalytic efficiency of lipase in hydrolysis, ester synthesis and transesterification reaction is improved. The method is easy to operate, efficient and stable enzyme immobilization can be achieved, the obtained immobilized lipase Janus particles are remarkably superior to free enzyme in biological catalytic activity and cyclic utilization performance, and the application value of lipase in industrial large-scale production is remarkably improved.

The invention discloses a full bio-based copolymer based on a citric acid bicyclic monomer, a preparation method and an application, and belongs to the technical field of material synthesis, citric acid-derived bicyclic OPD diol and OPBMC diester are synthesized through oxidation reduction and transesterification, and then 1, 4-butanediol is partially replaced with OPD or 2, 4-butanediol is partially replaced with OPBMC through melt phase polycondensation reaction. Two series of random copolyester PBxOyF copolymer and PBOmFn copolymer of the PBF are prepared by adding 2, 5-dimethyl furandicarboxylate into the PBF, and then adding the PBxOyF copolymer and the PBOmFn copolymer into the PBF. According to the full-bio-based copolymer based on the citric acid bicyclic monomer, the preparation method and the application, the citric acid bicyclic monomer obviously improves the glass transition temperature and shows good mechanical properties; therefore, the bicyclic monomer based on citric acid has huge potential in the aspect of synthesizing novel bio-based copolyester with expected thermodynamic properties, and is expected to further expand the application range of the 2.5 furandicarboxylic acid-based polyester.

The invention relates to the technical field of immobilized lipase, in particular to immobilized lipase taking modified nano SiO2 as a carrier as well as a preparation method and application of the immobilized lipase. The immobilized lipase sold in the market is high in price and poor in mechanical strength, the enzyme loss is too large due to shear force or carrier structure damage in the continuous production process, and the transesterification efficiency is poor. In order to solve the technical problems, the invention provides the immobilized lipase taking the modified nano SiO2 as the carrier, the immobilized lipase is obtained by sequentially grafting a modified nano silicon dioxide carrier with an amino silane coupling agent and an epoxy silane coupling agent and loading lipase on the surface of the modified nano silicon dioxide carrier, according to the method, the immobilized lipase forms an enzyme column in a chromatographic column and then serves as a reactor, damage of mechanical stirring to lipase particles is avoided, the ester exchange degree is more effectively controlled by adjusting the flow speed of a substrate, the production cost of an enterprise can be remarkably reduced, and the product quality is improved.

The invention belongs to the technical field of chemical production, and particularly relates to high-purity dimethyl carbonate and a preparation method thereof. The preparation method comprises the following steps: taking ethylene carbonate and methanol as raw materials, taking an alkali alcohol solution as a catalyst, carrying out transesterification in a rectifying tower to obtain dimethyl carbonate and methanol azeotrope, and extracting the azeotrope from the top of the rectifying tower; separating the dimethyl carbonate and methanol azeotrope by adopting pressurized azeotropic distillation to obtain a dimethyl carbonate crude product; and conveying the dimethyl carbonate crude product into a falling film crystallizer for continuous falling film crystallization, controlling the temperature of low-temperature chilled water in the falling film crystallizer to be-10 to 2 DEG C and the circulating material amount to be 3-5 times of the mass of the product required to be produced, and heating to melt the material to obtain the high-purity dimethyl carbonate product. According to the preparation method provided by the invention, rectification crude purification and continuous falling film crystallization processes are adopted, and dimethyl carbonate with the purity of 99.99% or above is obtained.

The present invention provides a binary or ternary complex. The complex can improve the stability of a drug, and in particular, inhibit the transesterification reaction within drug molecules. The complex can also improve the efficacy formulation performance of the drug, improving the safety and effectiveness of the drug.

The invention relates to the technical field of polyester fibers, in particular to a negative ion polyester fiber which is prepared from the following raw materials in percentage by mass: 85-92% of polyethylene glycol terephthalate, 3-8% of nano tourmaline composite powder, 2-5% of a titanium dioxide / graphene composite carrier, 0.5-1.5% of a coupling agent and 0.3-0.8% of an antioxidant. The invention also discloses a preparation method of the composition. According to the invention, the core-shell structure optimization design is adopted, the core layer ensures the high loading capacity of the tourmaline composite powder, the shell layer has the synergistic effect of the titanium dioxide / graphene composite carrier, the negative ion release efficiency is obviously enhanced, the particle size of the nanoscale tourmaline is controlled to be 50-100nm, the nanoscale tourmaline is uniformly dispersed, the nanoscale tourmaline and graphene form a heterojunction structure, and the electron transmission capability is greatly improved; the negative ion release amount meets the JIS standard, a chemical bonding interface is formed through transesterification, the structural stability is enhanced, and the retention rate of the negative ion release performance is still high even after multiple times of washing.

Provided are industrial processes for producing an organic acid alky ester from a feedstock containing organic acids and / or saponifiables, comprising: countercurrently contacting a feedstock with an organic alkylating reagent over two or more vessels or stages at temperature between 100° C. and 400° C. and pressure between 0.1 barg and 355 barg while simultaneously removing water and / or glycerin with unreacted alkylating reagent from the final vessel or stage to result in a first reaction method product containing organic acid alkyl esters, followed by a choice of using the alkyl esters as-is, purifying the organic acid alkyl esters from the first reaction product mixture or subjecting the first reaction product mixture to an additional transesterification reaction to convert saponifiables into additional organic acid alkyl esters, then purifying the organic acid alkyl esters from this second reaction method product.

The polyester resin is described, which has repeating units derived from a diester component of a dicarboxylic acid; and a diol component. The diester of the aliphatic dicarboxylic acid includes a succinic acid diester, the diol component comprises 50 to 100 mol % of an anhydrosugar alcohol, based on 100 mol % of the total diol component, and the number average molecular weight (Mn) of the polyester resin is 10,000 g / mol or more. A method for preparing a polyester resin comprises (1) esterification or transesterification of a diester component of a dicarboxylic acid comprising a diester of an aliphatic dicarboxylic acid and a diester of an aromatic dicarboxylic acid and a diol component comprising an anhydrosugar alcohol; and (2) polycondensation of the reaction product obtained in step (1). The polyester resin has excellent heat resistance and mechanical properties and also has excellent biodegradability.

The invention relates to the technical field of rubber production, and discloses a micro-nano cellulose reinforcing filler, a preparation method thereof and a cellulose-rubber composite material. The preparation method of the micro-nano cellulose reinforcing filler comprises the following steps: carrying out oxidation treatment on cellulose to obtain modified cellulose with carboxyl functional groups; and carrying out transesterification on the modified cellulose and an unsaturated ester compound to obtain the micro-nano cellulose reinforcing filler. The method does not need traditional homogenization treatment, and is low in energy consumption and high in yield; the hydrogen bond acting force between cellulose molecules is reduced, the aggregation of the nano cellulose caused by hydrogen bonds can be effectively prevented, and the preparation process is simplified. The cellulose reinforcing filler prepared by the invention is a nanoscale cellulose sheet, and has high dispersity and good compatibility in polar rubber; high fraction filling can be realized, the thickness of an interface layer is improved, and external stress is effectively dissipated; the prepared cellulose-rubber composite material is low in compression temperature rise and rolling resistance and excellent in wet skid resistance.

The invention belongs to the technical field of molecular biology, and discloses an RNA cyclization composition for improving cyclization efficiency, and a preparation method and application of circRNA. The composition for RNA cyclization comprises a precursor fragment and a cyclization induction fragment, the cyclization induction fragment comprises an affinity arm I and an affinity arm II which are complementarily paired with two ends of a to-be-cyclized sequence respectively, and the space distance of 3 '-intron and 5'-intron is effectively shortened through the bridging effect of the cyclization induction fragment, so that the cyclization effect of the RNA is improved, and the cyclization effect of the RNA is improved. According to the present invention, the two transesterification reactions are introduced, such that the active sites for catalyzing the two transesterification reactions are close to each other, the precursor fragment has excellent in-vitro cyclization efficiency, and the circRNA obtained through cyclization has characteristics of extremely low exogenous nucleotide residue and high biological safety.

The invention relates to the technical field of polymer dye synthesis, and discloses a monomer for a blue polyester fiber and a preparation method thereof.According to the monomer for the blue polyester fiber, 1, 4-arylamino substituted anthraquinone serves as a color development mother nucleus, a benzoate group is introduced to aryl of the 1, 4-arylamino substituted anthraquinone mother nucleus, and the monomer for the blue polyester fiber is obtained; the benzoate group is connected with the chromophoric parent nucleus through a carbon-carbon bond; the molecular terminal of the monomer for the blue polyester fiber is connected with an exposed ester group through an aryl group, and the exposed ester group is used for transesterification with dihydric alcohol under the melt polycondensation condition of polyester. The novel monomer for the blue polyester fiber, provided by the invention, has excellent color development performance and thermal stability, can be directly used for in-situ synthesis of blue polyester and can be directly used for melt spinning, and the color fastness and coloring uniformity of a product are improved; meanwhile, the monomer for the blue polyester fiber, provided by the invention, is simple in preparation method, low in cost and easy for large-scale production.

The invention provides a high-flowability and high-chemical-resistance ABS (acrylonitrile butadiene styrene) composition and a preparation method thereof. The composition is prepared from the following components in percentage by weight: 20 to 65 parts of ABS (Acrylonitrile Butadiene Styrene) resin, 0.5 to 1.5 parts of compatilizer, 30 to 50 parts of PET (Polyethylene Terephthalate) ester exchange master batch, 5 to 30 parts of ABS rubber powder, 0.01 to 0.05 part of chain extender, 0.1 to 0.5 part of antioxidant and 0.3 to 0.5 part of lubricant. Compared with the prior art, the PET resin with specific viscosity is selected, and more block copolymers are generated by utilizing the characteristic that the PET resin and a polyester resin material are easy to generate ester exchange reaction, so that the crystallization degree and the viscosity of the PET resin are reduced, the flowability of the PET resin is higher, and the preparation of the high-flowability ABS composition is facilitated; meanwhile, the crystallinity of the PET resin is reduced, so that the dispersed phase of the PET resin in the ABS is not easy to crystallize, the toughness of the composition can be improved, and the mechanical property and the fluidity of the composition are considered on the basis of improving the chemical resistance.

The invention provides an ester exchange reaction separation coupling device and method, and belongs to the technical field of chemical engineering, the ester exchange reaction separation coupling device comprises a reaction kettle, a circulation pipeline and a catalyst preparation tank; the top of the reaction kettle is provided with a feed port, and the bottom is provided with a discharge port; the circulating pipeline is located on the outer side of the reaction kettle, and the two ends of the circulating pipeline are communicated with the feeding port and the discharging port respectively; the circulating pipeline is sequentially connected with a membrane filtering unit, a micro-interface strengthening mixer and a pre-reactor from the discharging opening to the feeding opening, and the circulating pipeline is further connected with a circulating pump; the catalyst preparation tank is connected to the position, between the membrane filtration unit and the micro-interface strengthening mixer, of the circulation pipeline through a feeding pipe; the circulating pipeline is provided with a waste catalyst discharging pipe at the upstream of the feeding pipe, and when part of the waste catalyst in the circulating pipeline is regularly discharged, a new catalyst is supplemented to the circulating pipeline at the same time; according to the arrangement, after mixed feed liquid is introduced into the reaction kettle, the influence of discharge of a waste catalyst on the transesterification reaction in the reaction kettle can be reduced.

The invention belongs to the technical field of polyester recycling, and relates to a recycled polyester pore-foaming agent as well as a preparation method and application thereof. The preparation method comprises the following steps: firstly, carrying out ester exchange reaction on waste polylactic acid and aliphatic dibasic acid to obtain a double-carboxyl-terminated polylactic acid oligomer, then mixing the double-carboxyl-terminated polylactic acid oligomer, polyether glycol, oligomer diol and an inorganic porous material, and carrying out polycondensation reaction, the recycled polyester pore-foaming agent containing the water-soluble polylactic acid and the inorganic porous material is obtained. According to the application, the regenerated polyester pore-foaming agent and fiber-grade polyester are subjected to melt blending spinning to prepare blended fibers, and then the blended fibers are subjected to soaking treatment to prepare the porous fibers. The method not only solves the problem of resource waste of waste polylactic acid, but also provides a new way for green preparation of porous fibers, and has important practical significance and environmental protection value.

The invention belongs to the technical field of flame-retardant master batches, and particularly relates to a flame-retardant master batch for polypropylene and a preparation method thereof.The preparation method comprises the steps that tris (2-hydroxyethyl) isocyanurate is heated and molten, tetrabutyl titanate and DOPO-DPP are added into the molten tris (2-hydroxyethyl) isocyanurate, the mixture reacts for 3-4 h, melamine and cyanuric acid are added into the molten tris (2-hydroxyethyl) isocyanurate, the mixture reacts for 30 min, cooling and smashing are conducted, and a macromolecular flame retardant TDMC is obtained; the preparation method comprises the following steps: carrying out ester exchange reaction on 2, 4-diphenyl-6-[2-hydroxy-4-(ethoxycarbonyl methoxy) phenyl]-1, 3, 5-triazine and 2, 2, 6, 6-tetramethyl piperidinol to prepare a free radical capturing agent; the polypropylene, the TDMC, the free radical scavenger and the zeolite are put into a high-speed mixer to be stirred and mixed, and then extrusion granulation is performed. The macromolecular flame retardant TDMC is adopted, the molecular weight of the macromolecular flame retardant TDMC is large, the water resistance is good, and the compatibility and damp-heat stability of the flame-retardant master batch in polypropylene are improved.

The invention discloses an ethylene glycol-resistant nylon material and a preparation method thereof. The ethylene glycol-resistant nylon material comprises the following raw materials in parts by mass: 100 parts of nylon 66; 30 to 35 parts of glass fiber; 0.8 to 1.4 parts of a silane coupling agent; 6.7 to 9.2 parts of modified graphene oxide; the modified graphene oxide is obtained by modification after transesterification of hydroxyl groups on the surface of graphene oxide and phosphite triester, the phosphite triester modified graphene oxide can enhance the strength of polyamide, on the other hand, the electron cloud effect of the graphene oxide is enhanced through the introduced phosphite ester, and by means of the electron mobility of the phosphite ester, the polyamide can be effectively dispersed in the graphene oxide. The electropositivity of carbonyl carbon in polyamide is weakened, the possibility that carbonyl in polyamide reacts with hydroxyl in ethylene glycol is reduced, and the ethylene glycol resistance of the nylon material is improved; the phosphite ester can also preferentially replace carbonyl carbon in polyamide to react with hydroxyl in ethylene glycol, so that alcoholysis of polyamide is delayed, and the nylon material has excellent strength and ethylene glycol resistance.

The invention relates to the technical field of organic carbonate synthesis, in particular to a method for synthesizing methyl ethyl carbonate by using a liquid heterogeneous catalyst to catalyze transesterification, which comprises the following steps: by taking long-chain tertiary amine as a catalyst, catalyzing dimethyl carbonate and diethyl carbonate to perform transesterification reaction in a liquid heterogeneous manner to synthesize the methyl ethyl carbonate. The liquid heterogeneous catalyst expands the variety of catalysts for synthesizing methyl ethyl carbonate through ester-ester exchange, does not need to be specially filled, is high in equipment utilization rate and free of abrasion and corrosion to equipment, and has the advantages of being easy to disperse uniformly, high in catalytic efficiency, convenient to feed, convenient to use and the like.

The present invention provides binary or ternary complexes capable of improving the stability of a drug, particularly inhibiting transesterification within a drug molecule. The compound can also improve the pharmacodynamic preparation performance of the medicine and improve the safety and effectiveness of the medicine.

DNA molecules for making a circular RNA are provided. The DNA molecule may include elements operably connected and arranged, from a 5′ to 3′ direction, in the following order: (a) an intron fragment that includes a full-length intron; (b) an E2 fragment which includes a downstream exon of the full-length intron; and (c) an E1 fragment which includes an upstream exon of the full-length intron. 3′ end of the E1 fragment is configured to produce a hydroxyl group in an in vitro transcription reaction; the hydroxyl group is capable of initiating splicing in a one-step transesterification reaction at a splice site between RNA fragments transcribed from the intron fragment and the E2 fragment in a linear RNA that is produced from the DNA molecule in the in vitro transcription reaction, such that the linear RNA is configured to self-circularize to produce the circular RNA.

The invention relates to a reaction process for recovering BHET by depolymerizing PET, belonging to the technical field of high polymer material recovery. The process comprises the following steps: mixing a raw material containing waste PET particles and ethylene glycol with a sylvite catalyst, placing the mixture in a closed container, carrying out a depolymerization reaction in an inactive atmosphere to obtain a depolymerization solution, mixing the depolymerization solution with methanol and BHET seed crystals, carrying out an ester exchange reaction to obtain a reaction solution, cooling the reaction solution to 25 DEG C at a speed of 10 DEG C / min, crystallizing for 3-6 hours, carrying out acid pickling, and drying to obtain the PET / BHET composite material. A BHET crystal is obtained; pressure oscillation is intermittently carried out in the depolymerization reaction process. The low-temperature depolymerization rate is increased by adopting the potassium salt catalyst, and meanwhile, directional migration of impurities is induced through periodic pressure change, so that full-continuous operation is realized.

The present invention relates to a method for preparing an isohexide-based polycarbonate copolymer. The isohexide-based polycarbonate copolymer is obtained by sequentially carrying out a transesterification reaction, a pre-polycondensation reaction, and a final polycondensation reaction on diol and dialkyl carbonate under the action of a catalyst, wherein the diol includes diol A1 and diol A2, or further includes diol A3; the diol A1 is isohexide; the molecular structural formula of the diol A2 contains a cyclic ether structure and two primary hydroxyl groups, and the primary hydroxyl groups are linked to the cyclic ether structure via a methylene group; the diol A3 is a dihydroxy compound; and during the pre-polycondensation reaction, the temperature is first gradually increased to 180-200ºC within 5-15 min, the pressure is gradually reduced to 45-55 kPa within 5 min, and finally, gradient heating and gradient pressure reduction are carried out. The copolymer prepared by the present invention has high molecular weight, high heat resistance, high strength, high toughness, and transparency, and thus has a wide range of applications.

The present invention relates to a method of preparing a heterogeneous linear carbonate, the method including performing a transesterification reaction of dimethyl carbonate (DMC) and ethanol (EtOH) in the presence of a catalyst, wherein the catalyst is one or more selected from the group consisting of lithium methoxide (LME), lithium ethoxide (LEE), sodium methoxide (SME), sodium hydroxide (NaOH), and a mixture thereof, and the catalyst is input in a state of being dissolved in a sulfoxide-based solvent.

This invention discloses a method for preparing a composite alcohol-base catalyst suitable for transesterification reactions, relating to the fields of catalyst preparation technology and organic synthesis technology. This invention uses anhydrous alcohol phase in-situ alcoholization reaction treatment to make the catalyst surface cleaner, reduce the impact of impurities on catalyst activity, and enhance the structural stability of the catalyst. This catalyst can maintain high catalytic activity after multiple uses, extending the catalyst's service life and reducing production costs.

The invention relates to the production of a triglyceride with Palmitic acid (P) in the middle position (XPX). A first transesterification process is used to produce a vegetable fat composition rich in palmitic acid and said intermediate composition is then further processed to produce triglycerides having a high proportion of its palmitic acid in the middle position.