33results about "Preparation from ureas" patented technology

The present invention provides methods of forming carbamates, ureas, and isocyanates. In certain embodiments these methods include the step of reacting an amine with an ester-substituted diaryl carbonate to form an activated carbamate which can be further derivitized to form non-activated carbamate or a urea. The urea or carbamate can be subjected to a pyrolysis reaction to form isocyanate.

The invention relates to a multistage process for continuous and phosgene-free preparation of cycloaliphatic diisocyanates.

Cycloaliphatic diisocyanates can be prepared continuously and phosgene-free by reacting at least one cycloaliphatic diamine with at least one carbonic acid derivative and at least one alcohol to give a cycloaliphatic diurethane; freeing the cycloaliphatic diurethane of a low boiler, a medium boiler and mixtures thereof; thermally cleaving the cycloaliphatic diurethane in a cleavage apparatus to give a cycloaliphatic diisocyanate and a cleavage residue; continuously discharging a portion of the cleavage residue from the cleavage apparatus; removing the high boiler components from the discharge to obtain a purified discharge; reurethanizing the purified discharge with alcohol to obtain a reurethanized discharge; and recycling the reurethanized discharge into the process.

This invention relates to a manufacturing technique and its use of chlorine bromine isocyanuric acid. Urea and cyanamide are cyclized to cyanuric acid, and then be made into cyanuric acid suspension. Sodium hypochlorite and sodium hypobromite are added to make chlorination and bromination reaction. Chlorine bromine isocyanuric acid is got after filtration, scrubbing to filter cake, srying of the resultant. The compound of chlorine bromine isocyanuric acid and light fertilizer can be used to produce agriculture chemicals fungicide. The sodium hypochlorite and sodium hypobromite are added with no order, so its technique is convenient to control. Comparing to exist technique using chlorine and bromine gas, the sodium hypochlorite and sodium hypobromite used are liquor and hard to evaporate. The equipment request is not high, and the equipment cost can be reduced greatly, mass production cost also can be greatly reduced.

The invention provides a method for synthesizing isophorone diisocyanate, which comprises the following steps: (1) mixing isophorone diamine, a carbonylation agent, a first solvent and a catalyst, carrying out carbonylation reaction, carrying out solid-liquid separation, and carrying out purification treatment to obtain isophorone dicarbamate; and (2) mixing the isophorone dicarbamate with a second solvent to carry out pyrolytic reaction, and purifying the product to obtain the isophorone diisocyanate. The method is simple in process and free of pollution and potential safety hazards, and the intermediate product isophorone dicarbamate and the final product isophorone diisocyanate are high in yield and purity.

Low chlorine, multi-staged method for producing cycloaliphatic diisocyanates. The invention relates to a multi-staged method for the continuous low-chlorine production of cycloaliphatic diisocyanates, comprising the synthesis of diaminodipheynl alkanes, the hydration thereof into the corresponding cycloaliphatic diamines and the subsequent conversion of cycloaliphatic diamines to the corresponding cycloalkylene biscarbamates and the thermal cleaving of the latter into the cycloaliphatic diisocyanates and alcohol.

The invention discloses a preparation method of alkyl substitution diphenylmethane diisocyanate, which includes the following steps: weighing alkylaniline and urea, placing the alkylaniline and the urea in a reactor, heating the alkylaniline and the urea to the temperature ranging from 100 DEG C to 200 DEG C, stirring the mixture for 10 to 20 minutes, stopping reaction when red liquid is changed to solid, cooling the mixture to the room temperature, washing the mixture for 3 to 6 times through alcohol to obtain dialkyl group diphenyl urea, adding dimethyl carbonate into dialkyl group diphenyl urea, conducting back flowing reaction on the mixture under the temperature ranging from 110 DEG C to 250 DEG C for 6 to 12 hours, adding sodium methoxide into the mixture, conducting filtering after reaction is finished, conducting reduced pressure distillation on filtering liquid, conducting crystallization on normal hexane to obtain alkyl aniline methyl formate, adding lewis acid and methylation agent into the alkyl aniline methyl formate, increasing the temperature to the range from 70 DEG C to 100 DEG C, conducting reaction for 4 to 7 hours, cooling the mixture to the room temperature, conducting filtering on the mixture and washing the mixture through alcohol for 3 to 6 times to obtain alkyl aniline methyl formate and conducting decomposition reaction on the dialkyl group diphenylmethane dicarbamic acid ester. The preparation method of the alkyl substitution diphenylmethane diisocyanate is strong in stability, low in toxicity and controllable in reaction process.

The chemical synthesis of p-methoxyphenyl isocyanate is one process inside organic solvent with methoxyphenyl amine and di(trichloromethyl) carbonate as material and in the presence of catalyst. The process has the material molar ratio of methoxyphenyl amine to di(trichloromethyl) carbonate to catalyst being 1 to 0.34-0.8 to 0.01-0.1; organic solvent amount is 3-12 times mass of methoxyphenyl amine; the reaction temperature is 20-180 deg.c and reaction period is 4-10 hr. The organic solvent may be benzene, toluene, xylene, chlorobenzene, dichloro benzene, dichloro methane, trichloro methane, carbon tetrachloride, ethylidene dichloride, tetrafuran or hexaalkane epoxide. The said process uses no virulent phosgene and diphosgene, and is safe, reliable, high in yield, low in cost, and less corrosive and waste exhaust.

The invention relates to a multistage process for continuous and phosgene-free preparation of cycloaliphatic diisocyanates.

The invention discloses a system integrating fatty group or ring group diisocyanate synthesis and separation and purification and a synthesis method. The system comprises a wiped film vaporizer, a first rectifying tower, a second rectifying tower, a first heat exchanger and a second heat exchanger; the wiped film vaporizer is communicated with the first rectifying tower through a pipe, an outlet pipe of the first rectifying tower is communicated with the middle of the second rectifying tower, the bottom of the second rectifying tower is communicated with the first heat exchanger, and the top of the second rectifying tower is communicated with the second heat exchanger. By means of the system integrating fatty group or ring group diisocyanate synthesis and separation and purification, components generated by pyrolysis can be separated efficiently, and the system is quite suitable for a heat sensitivity material system; by the adoption of the system, materials which do not react completely are returned to a reactor for continuous pyrolysis, a diisocyanate product and light components are subjected to extraction with the rectifying towers, a coarse product is high in purity, energy is saved, consumption is reduced, and the diisocyanate product is good in selectivity and high in yield.

The invention relates to novel carbodiimides having terminal urea and/or urethane groups, to processes for the production thereof and to the use thereof as a stabilizer in ester-based polymers especially in films for protection from hydrolytic degradation.

The invention provides application of an ionic liquid in preparing toluene diisocynate and a method for preparing the toluene diisocynate from urea under the catalysis of the ionic liquid. The method is used for preparing the toluene diisocynate by taking toluenediamine and urea as the raw materials, reacting the raw materials to generate toluene diurea under the catalytic action of the ionic liquid and then pyrolyzing the toluene diurea. The method does not need highly toxic phosgene and an extra solvent; the ionic liquid is adopted as a catalyst; on one hand, the ionic liquid is good in catalytic effect, easy to remove and environment-friendly, and on the other hand, a metal catalyst in the prior art is not used, so that the reaction of the method for preparing the toluene diisocynate from urea under the catalysis of the ionic liquid does not require harsh device materials and operating conditions, consequently, the production cost is greatly reduced, and the method is advantageous to industrial application.

The invention discloses a method for preparing p-phenylene diisocyanate by a non-phosgene method, one of the following methods is selected: (a) taking N, N''-(1, 4-phenylene) bis (N', N'-dialkyl) urea and protonic acid as raw materials, and carrying out protonation and pyrolysis to obtain p-phenylene diisocyanate; and (b) taking p-phenylenediamine, dialkyl carbamoyl chloride and an acid-binding agent as raw materials, carrying out nucleophilic substitution reaction to generate N, N''-(1, 4-phenylene) bis (N', N '-dialkyl) urea and ammonium hydrochloride corresponding to the acid-binding agent in situ, and then carrying out protonation and pyrolysis to obtain the p-phenylene diisocyanate. According to the preparation method, p-phenylene diisocyanate is synthesized in one step or continuously by using an intermittent tank reactor or a micro-channel continuous flow reactor under the action of protonic acid. The intermittent and continuous preparation process of the non-phosgene method has the advantages that the reaction time is short, the product is easy to separate, a hydrogen chloride byproduct is not generated and the like, the purity of the product is as high as 98%, and the yield is as high as 97%.