397 results about "Phosgene" patented technology

Provided herein is a process for preparing compound A comprising (a) admixing 2-isopropyl-4-methylpyridin-3-amine (Compound B), or a salt thereof, a first base, and a reactive compound comprising phosgene or a phosgene equivalent in an organic solvent to form 3-isocyanato-2-isopropyl-4-methylpyridine (Compound C); (b) admixing Compound C and 2,6-dichloro-5-fluoronicotinamide (Compound D) to form 2,6-dichloro-5-fluoro-N-((2-isopropyl-4-methylpyridin-3-yl)carbamoyl)nicotinamide (Compound E); and (c) admixing Compound E and a second base to form a product mixture comprising Compound A and the second base. Also provided herein is a process for synthesizing AMG 510 comprising using Compound A prepared according to the disclosed processes

The invention relates to a preparation method and a preparation device of isocyanate, and the preparation method comprises the following steps: carrying out cold reaction on a phosgene solution and an amine solution in a cold reactor to obtain an intermediate mixed solution; separating the intermediate mixed solution by adopting a cyclone, obtaining a carbamoyl chloride mixed solution from an underflow port of the cyclone, and obtaining an amine hydrochloride mixed solution from an overflow port of the cyclone; the carbamyl chloride mixed solution enters a first thermal reactor for thermal reaction to obtain a first reaction product, and the amine hydrochloride mixed solution enters a second thermal reactor for thermal reaction to obtain a second reaction product; mixing the first reaction product and the second reaction product in a staying reactor to obtain an isocyanate reaction solution; and carrying out post-treatment on the isocyanate reaction liquid to obtain the isocyanate. The method can reduce the generation amount of urea by-products, further inhibits the generation of other subsequent by-products, reduces the chromaticity of the product, and improves the quality of isocyanate.

The invention provides a preparation method of polycarbonate, which comprises the following steps: firstly, obtaining a polycarbonate oligomer obtained by reacting bisphenol or polyphenol with phosgene, adding an end-capping reagent, continuing to react until the content of acyl chloride is specific, and adding a catalyst until the reaction end point. Wherein when the catalyst is controlled to be added, the reaction system meets the following conditions: (1) 0.1 < = [-COCl]: [-OH] < = N [-COCl]: N [-OH]; and (2) the ratio of the input molar weight of the catalyst to the molar weight of the terminal group acyl chloride in the system is 1: 5-5: 1 when the catalyst is added. By adopting the method, the polycarbonate with excellent quality can be prepared.

The invention relates to the technical field of chemical recovery, and particularly discloses a carbon tetrachloride removal system and process, the system comprises a washing tower and a carbon tetrachloride removal assembly, the washing tower is used for introducing a solvent and a phosgene material; the tower top of the washing tower is used for outputting treated substances; a tower kettle of the washing tower is communicated with the carbon tetrachloride removal assembly, and the carbon tetrachloride removal assembly is used for removing carbon tetrachloride in materials from the washing tower. The solvent is introduced into the washing tower to wash the phosgene material, and after the solvent is introduced, the washing tower is not pure phosgene equipment, so that the safety performance is improved; and compared with the prior art that carbon tetrachloride is removed by utilizing a phosgene rectifying tower and a solvent refining tower, the combination of the washing tower and the carbon tetrachloride removal assembly is beneficial to reducing the energy consumption.

The invention provides a method for preparing toluene diisocynate through a phosgene method, and belongs to the technical field of toluene diisocynate preparation. According to the method, liquid phosgene is atomized into atomized phosgene through a high-pressure spraying device, the atomized phosgene is in countercurrent contact with a toluenediamine solution sprayed into a phosgenation reactor, the contact area of the atomized phosgene and the toluenediamine solution is increased, and the phosgenation reaction process is accelerated. In addition, due to the arrangement of the liquid homogenizer, the contact area between the atomized phosgene and the toluenediamine solution is increased, the reaction rate between the atomized phosgene and the toluenediamine solution is increased, and side reactions are reduced. Meanwhile, the phosgene participates in the phosgenation reaction in the form of mist droplets and is not dissolved in the solvent, so that the use of the solvent is greatly reduced, the concentration of the phosgene in the phosgenation reactor is improved, and side reactions are reduced. The liquid phosgene is subjected to high-pressure spraying treatment, so that the use of a solvent is saved, and subsequent solvent separation is facilitated. After the decomposition reaction is finished, hydrogen chloride gas and unreacted phosgene are separated in a freezing mode, phosgene recovery is achieved, and the recovery mode is simple.

The invention relates to a device for producing isocyanate by a light solvent method and a production method thereof, the device comprises a pre-fractionating tower and a main tower, the tower top of the pre-fractionating tower is communicated with the tower top of the main tower, and the tower kettle of the pre-fractionating tower is communicated with the tower kettle of the main tower; the method comprises the following steps: directly conveying an isocyanate photochemical reaction material prepared by a light solvent method into a pre-fractionating tower for primary separation, extracting phosgene and a solvent from the top of the pre-fractionating tower, and directly feeding the phosgene and the solvent into the top of a main tower; a solvent and isocyanate are extracted from a tower kettle of the pre-fractionating tower and then directly enter a tower kettle of the main tower, phosgene is separated from the tower top of the main tower, a liquid-phase solvent is extracted from a side line of the main tower, and an isocyanate crude product separated from the tower kettle of the main tower enters the next process; a phosgene removal tower for removing phosgene and a solvent in a photochemical reaction material and a first desolventizing tower are combined into a complex tower. Therefore, the process flow is optimized, the energy efficiency is improved, and the load and energy consumption for separating and purifying the isocyanate product are reduced.

The present invention relates to a process for preparing 2, 4-di substituted thiophene-3- sulfonyl isocyanate compound of Formula (I), by reacting with the compound of Formula (II) with phosgene in the presence of a catalyst, and a mixture of a non-polar solvent and an organosulfur co-solvent, and optionally in the presence of a base.

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 present application relates to a kind of equipment and method for preparing hexamethylene diisocyanate by hexamethylene diaminoformate intermediate pyrolysis, the present application uses continuous pyrolysis reaction device, HDI can be prepared in high-boiling solvent, can completely replace the existing phosgene and phosgene derivative method for preparing HDI, solve the safety and pollution problem of phosgene method;Compared with low-boiling solvent process, the present application can greatly reduce energy consumption in product separation stage, and the energy consumption required for separating solvent in high-boiling solvent method is 1 / 10 of low-boiling solvent process, it is a green environmental protection energy-saving process;The present application uses non-toxic high-boiling solvent, compared with low-boiling solvent method, production safety is guaranteed;Compared with ordinary high-boiling solvent, the present application can avoid multiple contact between isocyanate and alcohol, and the yield of HDI can be further improved;The process flow of the present application is simple, and the operating condition is mild, it is a process that can be rapidly industrialized.

The present invention relates to a method for preparing a diphenylmethane-based diisocyanate and polyisocyanate. The method comprises the following steps: S1. performing a phosgenation reaction on a diphenylmethane-based diamine and polyamine and phosgene in a solvent to obtain a first mixed solution; S2. performing phosgene removal treatment on the first mixed solution to obtain a second mixed solution; S3. performing stripping treatment on the second mixed solution by using HCl gas to obtain a third mixed solution; and S4. performing solvent removal treatment on the third mixed solution to obtain a crude diphenylmethane-based diisocyanate and polyisocyanate product. In the method for preparing a diphenylmethane-based diisocyanate and polyisocyanate as provided by an embodiment of the present invention, by optimizing process parameters of the stripping treatment step, a diphenylmethane-based diisocyanate and polyisocyanate product having a light color can be prepared.

The application relates to the technical field of organic synthesis, and discloses a synthesis method of benzthiazuron, which comprises the following steps: step 1, addition reaction of alpha-methyl styrene and hydrogen chloride gas, and degassing to obtain a first reaction liquid; step 2, substitution reaction of the first reaction liquid and cyanate in the presence of a zinc chloride catalyst, and filtration to obtain a second reaction liquid containing isocyanate; and step 3, construction of an inorganic salt aqueous solution system with a density of 1.05-1.10 g / ml and a pH of 9-10, dropwise addition of the second reaction liquid into the system for condensation reaction with o-chlorobenzylamine, and post-treatment and refinement to obtain a target product. The non-phosgene route of chloro-isocyanate substitution is adopted, and the use of the toxic phosgene is completely avoided; the salting-out effect and interface control generated by the specific high-density salt solution effectively inhibit the isocyanate hydrolysis side reaction, and the reaction yield and product purity are obviously improved.

The invention discloses a synthetic carbamate compound based on 3-substituted dioxazolone as well as a preparation method and application of the synthetic carbamate compound, and belongs to the technical field of organic synthesis. The synthesis method comprises the following steps: (1) preparing 3-substituted dioxazolone from hydroximic acid with different substituent groups and phosgene under an ice bath condition; and (2) reacting the 3-substituted dioxazolone obtained in the step (1) with different phenols (alcohols) under an alkaline condition to obtain corresponding carbamate compounds. According to the method, the yield of carbamate is further improved by adjusting the conditions of alkali, equivalent weight, temperature and the like; the preparation method provided by the invention is novel and has the advantages of mild reaction conditions, few generated impurities, high yield, high safety, convenience in operation and the like; and the compound shows good cholinesterase activity in activity screening, and can be used in insecticides or pesticides.

The present invention relates to a method for using an optionally alkoxylated nitrogen-containing polymer in the capture of carbon dioxide, said optionally alkoxylated nitrogen-containing polymer comprising the following steps: a) a step of reacting (i) a di- or oligoamine (A) with (ii) a crosslinking compound (BC) to provide a nitrogen-containing polymer (NP), wherein the crosslinking compound (BC) is (I) phosgene; or (II) comprises at least two amine-reactive groups (ARG), the crosslinking compound (BC) being capable of binding to the amine groups of at least two di- or oligoamine (A) molecules, the nitrogen-containing polymer (NP) comprising the molecular components of the crosslinking compound (BC) that bind to at least two molecular components of the di- or oligoamine (A), the proportion of the crosslinking compound (BC) molecules bound to at least two di- or oligoamine (A) molecules being the crosslinking factor (BF) of the nitrogen-containing polymer (NP), the crosslinking factor (BF) exceeding 50%, the sum of the primary and secondary amine groups of the nitrogen-containing polymer (NP) being at least 600 mg KOH / g, the number average molecular weight (Mn) of the nitrogen-containing polymer (NP) exceeding 600 g / mol, and b) a step of reacting the nitrogen-containing polymer (NP) with an alkylene oxide (AO), wherein the molar ratio of the alkylene oxide (AO) to the NH functionality of the nitrogen-containing polymer (NP) is 0.25 or less, obtainable by a method comprising. The present invention further relates to a method for capturing carbon dioxide from a gas mixture using an optionally alkoxylated nitrogen-containing polymer.

The invention provides a continuous synthesis system and method of 2-chloro-5-methylpyridine, the system comprises a tower reactor, a clinker kettle, a condenser, a first flash tank, a spray absorption tower, a second flash tank and a circulating pump, the synthesis method comprises the following steps: phosgene and an intermediate solution enter the tower reactor for reaction from bottom to top, after discharging, introducing into a clinker kettle for reaction, discharging reaction tail gas out of a system after condensation, after a certain retention time, discharging reaction synthetic liquid, introducing into a first flash tank for gas-liquid separation, introducing a gas-phase material into a spray absorption tower, discharging after absorption treatment, introducing a liquid-phase material into a second flash tank for secondary gas-liquid separation, and discharging after secondary gas-liquid separation; a gas-phase material obtained after secondary gas-liquid separation enters a clinker kettle, and a liquid-phase material is subjected to a post-treatment step to obtain a 2-chloro-5-methylpyridine product. By adopting the synthesis system and the synthesis method, the yield of the 2-chloro-5-methylpyridine is high, and the discharge of a large amount of wastewater with complex components is reduced.

The present application discloses a non-fluorine polyaryletherketone (nitrile) resin, which adjusts the size and position of the long-chain side groups through the main chain structure design, further reduces the close stacking between the molecular chains, and can form a larger pore structure during the molding process, so that it has a lower dielectric constant and dielectric loss. At the same time, the material does not produce toxic and harmful substances such as fluorophosgene when treated at high temperatures, ensuring the safety of the material. The non-fluorine low-dielectric polyaryletherketone (nitrile) resin of the present application has the advantages of low dielectric constant and low dielectric loss, and is widely used in 5G and higher frequency communication fields.

The invention provides a preparation method of 2-chloro-5-methylpyridine, in the preparation method, by controlling the reaction pressure when pyridone chloride and phosgene react to generate 2-chloro-5-methylpyridine to be 0.15-1.1 MPa, the solubility of phosgene in a reaction liquid phase can be effectively improved, and the molar ratio of phosgene in a reaction liquid phase system is increased. According to the method, the pyridone chloride and the phosgene can fully react to generate the 2-chloro-5-methylpyridine, so that the utilization rate of the phosgene is increased; and the phenomenon that the pyrolytic intermediate pyridol of pyridone chloride is converted into other impurities due to insufficient phosgene content in a reaction liquid phase and delayed reaction can be effectively avoided. By adopting the continuous preparation operation of the overflow reaction kettle, the yield of the 2-chloro-5-methylpyridine can be further improved, the production cost can be further reduced, and the production efficiency is improved. The method has obvious progressive significance especially for improving the industrial large-scale production efficiency.

The invention discloses a triphosgene continuous synthesis method and device, and belongs to the technical field of fine chemical production. The triphosgene continuous synthesis method comprises the following steps: S1, continuously conveying dimethyl carbonate to the lower part of a reactor, and continuously inputting chlorine from the bottom of the reactor; s2, after dimethyl carbonate and chlorine are mixed in a reactor, a reaction is initiated by irradiation of an ultraviolet light source with the wavelength of 295-395 nm, and molten triphosgene and hydrogen chloride gas are generated; wherein the temperature in the reactor is gradually increased from bottom to top to present a temperature gradient; and S3, continuously overflowing the molten-state triphosgene into a degassing tower to remove residual hydrogen chloride in vacuum, and enabling the degassed molten-state triphosgene product to enter a flaking section. According to the method, by optimizing reaction conditions and equipment design, the cost can be reduced, the utilization rate of raw materials can be increased, generation of byproducts can be reduced, meanwhile, the safety and efficiency of the reaction are guaranteed, and efficient, safe and continuous production of triphosgene is achieved.

The present invention relates to a method for preparing 4,4'-difluorobenzophenone from 4-chlorofluorobenzene, which comprises the following steps: (1) Using 4-chlorofluorobenzene as the starting material, reacting with magnesium chips in a solvent to prepare a 4-fluorophenylmagnesium chloride solution; (2) Adding the 4-fluorophenylmagnesium chloride solution to a triphosgene solution, and reacting to obtain the target product 4,4'-difluorobenzophenone. In the present invention, the ketone carbonyl group is introduced through triphosgene, the reaction conditions are mild, the Friedel-Crafts reaction or diazotization reaction can be avoided, the use of aluminum trichloride or the generation of diazonium salts with explosion hazards can be avoided, the environmental pollution is small, the operation is safe and simple, and there is no corrosion to the equipment; the starting material 4-chlorofluorobenzene used has a wide source and low cost; the present invention has high yield and repeatability and is easy to be industrially produced.

The invention relates to the field of organic synthesis, in particular to a method for preparing aliphatic diisocyanate by a non-phosgene method. According to the method for preparing the aliphatic diisocyanate through the non-phosgene method, firstly, aliphatic diamine reacts with a carbonic acid diester compound to form an aliphatic dicarbamate compound, and then the aliphatic dicarbamate compound is subjected to a thermal cracking reaction to obtain the aliphatic diisocyanate. According to the method, aliphatic diamine can be converted into aliphatic diisocyanate under the condition that phosgene is not used, the preparation process is simple, a noble metal catalyst does not need to be used, the atom utilization rate is high, the product does not contain chlorine residues, the purity is high, and industrial large-scale application is facilitated.

The invention provides a synthesis method of L-acetoxypropionyl chloride, and belongs to the field of medical intermediates and fine chemical engineering. The preparation method comprises the following steps: mixing L-lactic acid and acetyl chloride for first reaction; then adding trichlorotoluene and a catalyst to carry out a second reaction; and then rectifying and separating to obtain the product L-acetoxypropionyl chloride. According to the method, two raw materials react to generate two products, no sulfur dioxide or acidic mixed waste gas is generated, the utilization rate of the raw materials reaches 100% theoretically, and the method completely conforms to an environment-friendly and pollution-free green process. The safety of the used trichlorotoluene is far higher than that of thionyl chloride and phosgene, the reaction is mild, the reaction speed can be controlled by controlling the temperature and the input amount of the catalyst, the production operation is relatively safe, and the purity of the prepared L-acetoxypropionyl chloride product is greater than 99%, and the yield is greater than 90%.

The invention discloses a preparation method and application of a high-selectivity chemical warfare agent fluorescent probe based on free radicals, and belongs to the field of fluorescent probe materials. The invention aims to solve the problem that the existing fluorescent probe is seriously interfered by protonic acid. The method comprises the following steps: 1, preparing CZ-DTE-C1; and 2, preparing a filter paper strip membrane by using CZ-DTE-Cl doped polyoxyethylene. The high-selectivity chemical warfare agent fluorescent probe based on the free radicals is used for detecting mustard gas, phosgene or sarin and has high selectivity. Compared with the traditional fluorescent probes, such as an organic metal compound probe, a nitrogen-oxygen bifunctional nucleophilic reagent probe, a nitrogen-based nucleophilic reagent probe and an oxygen-based nucleophilic reagent probe, the fluorescent probe provided by the invention is a novel free radical-based sensing reaction, and can simultaneously realize visual-fluorescent dual-mode detection of mustard gas, phosgene and sarin simulants; the selectivity is high.

The invention discloses a 2-hydroxy-benzonitril solution and a production method thereof, the production method comprises the step of preparing a wet 2-hydroxy-benzonitril product through reaction of salicylamide and phosgene, and is characterized in that the wet 2-hydroxy-benzonitril product is directly added into a sodium hydroxide aqueous solution to obtain the 2-hydroxy-benzonitril solution. The sodium salt solution can be directly produced without taking out the 2-hydroxy-benzonitril, so that exposure of the 2-hydroxy-benzonitril is avoided, personal injury is reduced, investment of drying equipment is reduced, and direct feeding of downstream products is facilitated.

The present invention relates to a method for preparing 2,4-disubstituted thiophene-3-sulfonyl isocyanate compounds having formula (I), wherein the method comprises reacting a compound having formula (II) with phosgene in the presence of a catalyst and a mixture of a nonpolar solvent and an organosulfur cosolvent, and optionally in the presence of a base.

The present application belongs to the technical field of phosgene reaction tail gas treatment, and particularly relates to a phosgene tail gas alkali destruction device and method, which comprises the following steps: an operator passes the tail gas into a falling film absorber, the falling film absorber absorbs hydrochloric acid in the tail gas to obtain treated gas one; the treated gas one is passed into a catalytic hydrolysis box, a catalytic hydrolysis method is used to destroy phosgene in the treated gas one to obtain treated gas two; the treated gas two is passed into a multi-stage alkali destruction tower, 1% to 10% of a dilute alkali solution is sent into the top of the alkali destruction tower through a delivery pump, inorganic salt solution and treated gas three are generated through an acid-base reaction; the inorganic salt solution is sent to a high-salt wastewater treatment device for treatment, the treated gas three is sent to a burning device for treatment to remove unreacted carbon monoxide, organic matter and other combustible gases to obtain final gas which is discharged to the outside. The scheme solves the problem of waste caused by a large amount of generated high-salt wastewater.

The invention relates to a polymer dispersant, a preparation method thereof and a synthesis method of isocyanate using the polymer dispersant. The polymer dispersant has a structure shown in a general formula (I), wherein [Core] is a residue of a polyfunctional group initiator, A is an aliphatic polyester chain segment, B is an aromatic compatible chain segment, L is a residue formed by diisocyanate, and D is an anchoring group. The polymer dispersant disclosed by the invention is specially used for stabilizing amine hydrochloride particles in a process of synthesizing isocyanate by a salifying phosgene method and preventing agglomeration among the particles. The reaction system can form stable and low-viscosity slurry consisting of fine and discrete particles, and amine can be completely converted into hydrochloride, so that the yield of isocyanate is increased.

The invention discloses a preparation method of Linzagolix, which comprises the following steps: taking 2, 3-difluoro-6-methoxybenzyl alcohol as a raw material, under the action of alkali and phosphine ligand, carrying out Mitsunobu reaction on 2, 3-difluoro-6-methoxybenzyl alcohol and 2-methoxy-4-fluorophenol to obtain a compound A, sequentially carrying out nitration reaction and reduction reaction on the compound A to obtain a compound C, and carrying out recrystallization on the compound C to obtain the Linzagolix. Under the alkaline condition and the action of triphosgene, the compound C and 4-aminothiophene-2, 3-dimethyl dicarboxylate hydrochloride are subjected to a one-pot condensation reaction to obtain a compound D, and the compound D reacts under the alkaline condition to generate Linzaolix. According to the invention, the synthesis process of Linazagolix is shortened to five steps, the reaction condition is mild, the operation is simpler and more convenient, and the method is suitable for industrial production.

The invention discloses a preparation method of medical polycarbonate with high biocompatibility, and belongs to the technical field of polycarbonate preparation. The preparation method of the medical polycarbonate with high biocompatibility comprises the following steps: step 1, adding bisphenol A into dichloromethane, introducing phosgene, adding triethylamine, and continuously stirring and reacting at low temperature to obtain a prepolymer; step 2, adding modified polycaprolactone into dichloromethane, slowly adding into the prepolymer, and continuously stirring to react, so as to obtain a modified prepolymer; and 3, adding an auxiliary agent into deionized water, stirring, adding into the modified prepolymer, adding triethylamine, continuously reacting, adding ethanol, washing, drying, dissolving, precipitating, filtering and drying to obtain the medical polycarbonate with high biocompatibility. The polycarbonate prepared by the method has excellent biocompatibility, mechanical property and hydrophilic property.

The invention relates to a process for producing phosgene by gas-phase reaction of carbon monoxide and chlorine in the presence of a catalyst in a reactor which comprises a plurality of parallel catalyst tubes which are filled with the catalyst and around which at least one fluid heat transfer medium flows, where a feed stream of a mixture of a chlorine input stream and a carbon monoxide input stream is fed into the catalyst tubes and is allowed to react to give a phosgene-comprising product gas mixture, wherein the reaction is carried out at an area load of more than 2.75 kg of phosgene / m2s. The invention also provides a reactor for carrying out the process.

The application belongs to the technical field of bioreactors, and specifically discloses a microalgae bioreactor cooperating with phosgene, which comprises a barrel body, a gas collecting hopper fixedly connected to the bottom of the barrel body, a Venturi nano-bubble generator connected to the lower part of the gas collecting hopper, a liquid delivery pump connected to the Venturi nano-bubble generator, a bubble remover and a light guide structure and a thermometer detachably connected to the barrel body, wherein the light guide structure comprises optical fibers equally spaced and inserted into the barrel body, the optical fibers comprise outer sleeves inserted into the barrel body, and the inner part of the outer sleeves is fixedly connected with light guide cores. In actual use, the Venturi nano-bubble generator can deliver bubbles into the barrel body, the bubbles can drive the microalgae in the barrel body to float, and the light projected by the light guide cores can be refracted, so that the light can uniformly cover the inside of the barrel body, thereby realizing efficient cultivation of the microalgae.

The invention discloses a preparation method of 4, 6-dichloropyrimidine, and belongs to the field of organic synthesis, and the preparation method comprises the following steps: in the presence of an organic solvent or no solvent, mixing 4-chloro-6-methoxypyrimidine with DMF (Dimethyl Formamide), dropwise adding a chlorination reagent under a certain temperature condition, carrying out a heat preservation reaction, and then carrying out post-treatment to obtain the 4, 6-dichloropyrimidine. The preparation method is simple to operate, mild in condition and simple in post-treatment, and 4, 6-dichloropyrimidine can be prepared without using a phosphorus-containing reagent and a highly toxic reagent phosgene or triphosgene.