31results about How to "Fewer side effects" patented technology

The invention provides a preparation method of a 1,2,4-thiadiazole oximido acetic acid compound, relating to the technical field of preparation technology of 7-site side chain 1,2,4-thiadiazole oximido acetic acid compound of fourth-generation cephalosporin and fifth-generation cephalosporin. The product is obtained by alkali hydrolysis reaction of the derivative of the 1,2,4-thiadiazole oximido acetic acid compound, and the temperature of the hydrolysis reaction system is controlled to be below 150 DEG C. The method of the invention has peculiar principle, and solves the problems of various technical steps, complex operation and the like in the prior art; in addition, product purification technology and operation technology are simple, the operation steps for manufacturing the thiadiazole oximido acetic acid compound are greatly shortened and reaction yield and product purity are higher. A byproduct which can be detected in a reaction mixture can be lower than 5%, reaction yield can be improved to 75-85%, and purity can be more than 97%. The method of the invention is especially suitable for producing the thiadiazole oximido acetic acid compound products with high purity.

The invention discloses a method for preparing N-ethoxy oxalyl alanine ethyl ester. The method comprises the following steps: heating and dissolving alanine, oxalic acid and alcohol, and then adding a catalyst, a water-carrying agent benzene and diethyl oxalate, wherein the catalyst is a mixture of sulfuric acid and urea in a molar ratio of 1: (1-3); heating the obtained mixture to 60-100 DEG C; carrying out reflux rectification reaction for 10-150 hours, wherein in the process of reaction, the water produced in the process of reaction is timely evaporated by using the water-carrying agent benzene; and after the reaction is finished, carrying out after-treatment so as to obtain a target product, namely, the N-ethoxy oxalyl-alanine ethyl ester. Compared with the prior art, the method disclosed by the invention has the following advantages that: the catalyst is the mixture of sulfuric acid and urea, therefore, the catalyst has acidity catalytic activity and contains ammonium salt cations, and the ammonium salt cations can be adsorbed on the surface of metal, thereby reducing the corrosion of the catalyst on equipment; and meanwhile, the catalytic efficiency is high, the reaction yield is high, and the side reaction is less.

The invention discloses a compound stabilizer for the epoxidation reaction of an unsaturated compound and an application method of the compound stabilizer. The compound stabilizer comprises carbamide, ethylene diamine tetraacetic acid, potassium sodium tartrate and sodium silicate. Peroxide and a peroxoic acid stabilizer including the ethylene diamine tetraacetic acid, the potassium sodium tartrate, concentrated sulfuric acid and 732 resin are uniformly mixed; the addition of the peroxoic acid stabilizer is 0.1 to 5 wt% of that of the peroxide; organic acid is dropwise added to the peroxide and the peroxoic acid stabilizer at 25 to 35 DEG C, so that peroxoic acid mixed solution is obtained after reaction; an epoxidation stabilizer including the carbamide, the ethylene diamine tetraacetic acid, and the potassium sodium tartrate and the sodium silicate is added into the unsaturated compound, and then the peroxoic acid mixed solution is added into the epoxidation stabilizer at 65 to 95 DEG C, so that an epoxidation compound is obtained after epoxidation reaction. The compound stabilizer has the advantages that the coordination of various stabilizers improves the stability of hydrogen peroxide and peroxoic acid in reaction solution, the frequency of the occurrence of secondary reaction is reduced, the reaction time is shortened, and the production cost is reduced.

The invention relates to a medicinal intermediate and a purification method of the medicinal intermediate, in particular to a method for purifying an aldehyde-oil methanol solution. The aldehyde-oil methanol solution is prepared from ethyl vinyl ether, dimethylformamide and phosphorus trichloride, and a preparation method of the medicinal intermediate comprises the steps of: performing an additionreaction by adopting kerosene as solvent to prepare aldehyde oil, diluting the obtained aldehyde oil with anhydrous methanol, and carrying out extraction and purification with petroleum ether to obtain the medicinal intermediate, i.e., the aldehyde-oil methanol solution. The medicinal intermediate can be applied to the production of chemical raw material sulfadiazine products, wherein the petroleum ether, the kerosene, the ethyl vinyl ether and the anhydrous methanol can be reused after fractional distillation. The preparation method of the medicinal intermediate has the advantages of mild reaction conditions and high product yield, the aldehyde-oil methanol solution is good in quality and high in purity, and the improvement of the quality of the chemical raw material sulfadiazine products is facilitated; since the petroleum ether, the kerosene, the ethyl vinyl ether and the anhydrous methanol can be recycled and reused, material consumption can be reduced, postprocessing of the production of follow-up products can be reduced, and pollution on the environment can be reduced.

The invention discloses a process method for fully continuous preparation of water-based polyurethane by prepolymerization-emulsification. In this method, the sonochemically strengthened twin-screw extruder is used as the water-based polyurethane prepolymerization and neutralization reactor, and the static mixer and tubular emulsifier are used as the prepolymer emulsification device. The prepolymerization and emulsification are fully continuous, and the production efficiency is high. , low cost, stable product quality, especially suitable for the production of high-solid aqueous polyurethane. More importantly, in a specific area of ​​the twin-screw extruder, a special ultrasonic generator is installed to perform sonochemical treatment on the prepolymerization intermediate, which can significantly improve the reactivity of the material, so that the late stage of the prepolymerization reaction can be at 70‑80 It is completed quickly under low temperature conditions, the production process is energy-saving and environmentally friendly, and side reactions such as branching, cross-linking, and degradation caused by high temperatures in the later stage are avoided. The obtained water-based polyurethane has a controllable structure and stable quality. The above process method does not use any organic solvent, has no selectivity to raw materials, and is applicable to the synthesis of any type of water-based polyurethane.

A kind of one-component polyurethane sealant and the one-component polyurethane sealant of the low-temperature, fast preparation method have high tensile strength, shear strength and tear strength, moderate viscosity, and good storage stability; the single-component polyurethane sealant of the present invention The preparation method of the component polyurethane sealant takes a short time, and the preparation of the product can be completed in 2 to 3 hours, and the production efficiency is high; the reaction temperature during the preparation process does not exceed 100°C, the high-temperature reaction time is kept for a short time, and there are few side reactions. Low energy consumption, the preparation method of the one-component polyurethane sealant of the present invention, the preparation process is simple and easy to operate, and can be completed by using existing equipment, and the preparation of the prepolymer is no longer limited to the reaction kettle, which greatly reduces the Equipment cost and labor cost; the preparation process of the one-component polyurethane sealant of the present invention, the prepolymer molecule always coexists with the filler and the functional auxiliary molecule during the production and formation process, and the organic material and the inorganic material can better cooperate and interweave , The shear, tensile strength and elongation at break of the product.

The invention discloses a preparation method of a comb-shaped polymer phase change energy storage material. The preparation method comprises the following steps: 1) adding polyethylene grafted maleic anhydride and alcohol with a hydroxyl active group on a terminal group, ether with a hydroxyl active group on a terminal group or mercaptan with a sulfydryl active group on a terminal group which are in a molar ratio of 1 to (0.5-5) into a reaction container, in the presence of nitrogen gas, adding an organic solvent subjected to water removal and a catalyst, and reacting for 6-12 hours at 60-120 DEG C to obtain reaction primary products; 2) cooling the reaction primary products, and washing and drying after removing the solvent to obtain the comb-shaped polymer phase change energy storage material. The preparation method disclosed by the invention is fewer in side reactions, high in yield, high in reaction speed, and convenient and simple in preparation. The prepared comb-shaped polymer phase change energy storage material has good crystallization property, thermal stability, setting performance and machinable property.