21results about "Preparation from carbamates" patented technology

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 relates to a novel method of producing 4,4'-methylene diphenyl diisocyanate (MDI). A phosgene-free method of producing 4,4'-methylene diphenyl diisocyanate is characterized in that diphenylurea is produced from urea and aniline in an aromatic hydrocarbon medium, and the resulting diphenylurea is reacted with an excess of methanol to produce O-methyl-N-phenyl carbamate; molten O-methyl-N-phenyl carbamate is reacted with anhydrous derivatives of formaldehyde in the presence of acidic catalysts to produce 4,4'-methylene diphenyl dicarbamate; 4,4'-methylene diphenyl dicarbamate in the form of a melt, or of a suspension in an inert carrier liquid, or of a powder is subjected to continuous thermal decomposition in a stream of inert gas, and 4,4'-methylene diphenyl diisocyanate is isolated by fractionation. The invention provides a novel phosgene-free method of synthesizing 4,4'-MDI, which is suitable for industrial-scale implementation.

The invention relates to organic synthesis techniques, and more particularly to a method of thermally decomposing 4,4'-methylene diphenyl dicarbamate (4,4'-MDC) to 4,4'-methylene diphenyl diisocyanate (4,4'-MDI), which is characterized in that 4,4'-MDC, in the form of a melt, or of a suspension in an inert carrier liquid, or of a powder, and an inert gas are fed into a column for conducting continuous thermal decomposition, the mixture is heated to 200-400°C inside the column for the gas-phase decomposition of 4,4'-MDC in the stream of inert gas at atmospheric pressure, then the mixture is separated in a fractionation column to isolate high-purity 4,4'-MDI. The technical result of the proposed invention is an improved method resulting in a high yield of high-purity 4,4'-MDI.

The application belongs to the technical field of fine chemical synthesis, and particularly relates to a device and method for continuously preparing 1,5-pentamethylene diisocyanate through thermal cracking. 1,5-pentamethylene diurethane and bismuth neodecanoate are mixed, preheated, and then pumped into a reaction kettle containing tetraethylene glycol dimethyl ether to perform a thermal cracking reaction. The obtained reaction liquid is subjected to primary purification, and then secondary purification is continuously performed to obtain 1,5-pentamethylene diisocyanate. The application provides a device and method for continuously preparing 1,5-pentamethylene diisocyanate through thermal cracking. The preparation process adopts a non-phosgene method, is green and environmentally friendly, has small safety hazards, has mild reaction conditions, and is simple in process. The yield of 1,5-pentamethylene diisocyanate reaches more than 80%, and the purity reaches 99%.

The invention relates to a method for preparing methyl cyclohexyl diisocyanate through liquid phase cracking of methyl cyclohexyl dicarbamate. The method comprises the following steps: dissolving methyl cyclohexyl dicarbamate in a mixture to form a raw material solution, then enabling the raw material solution and carrier gas to flow through a fixed bed reactor together, and reacting under the conditions that the vacuum degree is 0.06-0.1 MPa and the temperature is 150-300 DEG C and the liquid space velocity is 0.38-3.82 h <-1 > to obtain methyl cyclohexyl diisocyanate, the mixture is a hydrogen bond acceptor-containing ionic liquid and a solvent. The ionic liquid has the advantages of being high in catalytic activity and selectivity, good in reusability, environmentally friendly and the like.

The invention relates to a method for the preparation of isocyanates. Here it is provided that(i) a first organosilicon compound having at least one silicon atom Si1 and a unit of formula G-I bound theretois converted to a third organosilicon compound having a unit of formula G-IIby silylation of the NH group of the unit of formula G-I with a second organosilicon compound having one silicon atom Si2; and(ii) the third organosilicon compound is reacted to an isocyanate by thermolysis, whereby the unit of formula G-II is converted to an isocyanate group.

The application provides a method and system for green preparation of hexamethylene diisocyanate, which comprises a first thermal decomposition reaction device and a second thermal decomposition reaction device connected in series, a two-component heat carrier composed of a low-boiling heat carrier and a high-boiling heat carrier, a first partial condenser and a second partial condenser. The application has the beneficial effects that: the product hexamethylene diisocyanate is prevented from staying at high temperature for too long, thereby avoiding further polymerization reaction; the by-product methanol generated in the thermal decomposition reaction is continuously carried out of the reaction system by the low-boiling carrier, thereby promoting the continuous forward progress of the thermal decomposition reaction; the isocyanate concentration is prevented from rising due to the loss of a large amount of low-boiling heat carrier, thereby preventing the side reaction from intensifying; the isocyanate concentration is effectively reduced, thereby preventing the occurrence of the polymerization side reaction.

Disclosed in the present invention are a method for preparing a double-anion catalyst and the use thereof in the catalytic degradation of a polyurethane material. The method comprises: dissolving a metal salt in deionized water to prepare a metal salt solution; taking a nitrogen heterocyclic compound containing hydroxyl or amino as a substrate in a reactor, adding the metal salt solution in a dropwise manner into the reactor, and performing condensation reflux at 60°C-150°C for 1-8 h; adding an amine compound in a dropwise manner, reacting the mixture after the dropwise addition has finished, and performing a vacuum filtration treatment after the reaction has finished, so as to obtain a filtrate; and evaporating the filtrate and drying the product to obtain a double-anion catalyst. The basic physical properties, such as hydroxyl value, amine value and viscosity, of a recovered polyol obtained via degradation by means of the catalyst of the present invention are substantially equivalent to those of the raw material polyol, and the recovered polyol can partially replace the raw material polyol for preparing a flexible polyurethane foam.

The invention provides a method and a device for preparing isocyanate through thermal cracking of carbamate. The device comprises a reaction system and a separation system, and the reactor comprises four areas, namely a gas distribution area, a reaction and pre-separation area, a pyrolytic reaction area and a gas-solid separation area from bottom to top in sequence. The invention also provides a method for preparing isocyanate by adopting the device for thermal cracking. By adopting the reaction device, the reaction temperature of thermal decomposition of carbamate can be effectively reduced, the side reaction is reduced, the reaction yield is improved, the problems of coking and blockage caused by high-temperature polymerization of byproducts are reduced, and the operation period is prolonged.

The present invention provides a method for increasing the yield of isocyanate and a method for preparing isocyanate, which employs the method of the present invention to prepare isocyanate of general formula (II) to help increase the yield of the product. The method controls the acid content of an isocyanate intermediate having general formula (I) to be > 0 and < 3000 ppm, and thermally cracks the isocyanate intermediate to obtain the isocyanate; the acid content refers to the ability to release H + of the compound.

A preparation method of a dual-anion catalyst, and a use of the dual-anion catalyst in catalytic degradation of a polyurethane material are provided. The preparation method includes: dissolving a metal salt in deionized water to produce a metal salt solution; adding a nitrogen-containing heterocyclic compound with hydroxyl or amino as a substrate to a reactor, adding the metal salt solution dropwise to the reactor, and conducting condensation reflux at 60° C. to 150° C. for 1 h to 8 h; adding an amine compound dropwise, and conducting a reaction; after the reaction is completed, conducting vacuum filtration to produce a filtrate; and subjecting the filtrate to evaporation, and oven-drying a resulting product to produce the dual-anion catalyst. A recovered polyol obtained through the degradation with the catalyst exhibits basically the same fundamental physical properties such as hydroxyl value, amine value, and viscosity to a virgin polyol.

The invention relates to a method for decomposing polyurethane, wherein material containing polyurethane is heated to a temperature from 190° C. to 250° C. under overpressure in the presence of an aqueous solution containing 1 to 45 mass percent urea. It further relates to a liquid process medium obtainable thereby.

The invention belongs to the technical field of organic chemical synthesis, and provides a cyclohexyl isocyanate synthesis process, which comprises: 1, adding cyclohexylamine and a catalyst A into a solvent, controlling the temperature at 0-5 DEG C, slowly dropwise adding dimethyl carbonate, maintaining the temperature at less than 10 DEG C, removing the ice bath after completing the dropwise adding, slowly heating to a room temperature, continuously stirring for 14-20 h, and cooling to a room temperature to obtain a reaction product; adjusting the pH value to be neutral, then separating an organic phase, extracting a water phase by using an organic solvent, combining the organic phases, drying, filtering, and carrying out reduced pressure distillation to obtain N-cyclohexylmethyl carbamate; and step 2, carrying out thermal cracking reaction on the N-cyclohexylmethyl carbamate and a catalyst B, collecting, rectifying and purifying to obtain the cyclohexyl isocyanate. According to the method disclosed by the invention, the cyclohexyl isocyanate is synthesized by adopting a carbamate method, so that environmental hazards caused by phosgene are effectively avoided, and the cyclohexyl isocyanate with high yield and high purity is obtained.

The invention relates to a process for the depolymerisation of a polyurethane material comprising the following steps: a) reacting the polyurethane material with a dialkylcarbonate or a diarylcarbonate or an alkylarylcarboante to produce i) at least one polyol and / or at least one carbonate-functionalised polyol, and ii) at least one polycarbamate; b) separating i) the at least one polyol and / or at least one carbonate-functionalised polyol, and ii) the at least one polycarbamate; and c) converting the at least one polycarbamate into at least one polyisocyanate. The resultant constituents of the depolymerised polyurethane material may subsequently be recycled for the purpose of making new polyurethanes or other useful materials.

The invention provides a preparation method of tetramethyl m-xylylene diisocyanate, which comprises the following steps: mixing tetramethyl xylylene dicarbamate with a catalyst, and carrying out thermal cracking reaction in a microchannel reactor. According to the preparation method provided by the invention, by designing the structure of the micro-channel reactor and optimizing the selection of a reaction catalyst and reaction parameters, the preparation of tetramethyl m-xylylene diisocyanate with the total yield of 90% or above and the high purity of 99% is realized.

The present invention relates to a method for decomposing polyurethanes, in which a polyurethane-containing material is heated to 190°C to 250°C under superatmospheric pressure in the presence of an aqueous solution containing 1 to 45% by weight of urea. The present invention also relates to a liquid treatment medium obtained by such a method.

The application discloses a zinc-aluminum composite oxide catalyst and a preparation method and application thereof, and belongs to the technical field of catalytic materials and non-phosgene isocyanate preparation. The application solves the problems of high reaction temperature, low raw material concentration, many side reactions and insufficient catalyst stability in the process of preparing isocyanate by pyrolysis of carbamic acid ester. The zinc-aluminum composite oxide catalyst comprises a composite oxide of zinc and aluminum, and has a dual-phase heterogeneous structure of ZnO and ZnAl2O4 spinel. When the catalyst is applied to the preparation of 4-(4'-phenylaminomethylcarbamate) diphenyl methane isocyanate (MMI) and diphenyl methane diisocyanate (MDI) by vacuum thermal decomposition of diphenyl methane diamino methylcarbamate (MDC), the self-polymerization and condensation side reactions in the reaction process can be effectively inhibited by the synergistic effect of the ZnO phase and the spinel phase, the selectivity and yield of the target product are improved, and the catalyst has good mechanical stability and is easy to recycle and cyclically used.

Disclosed herein are an isocyanate composition, and a preparation method therefor and the use thereof. The effective factor of the isocyanate composition is 3.70-4.70. The isocyanate composition has good reaction activity and can be used for preparing a high-performance polyurethane product.

Disclosed is a polyisocyanate composition containing at least one or more compounds represented by any one of general formulas (I), (II), and (III), and a polyisocyanate compound. Also disclosed is a method for producing an isocyanate compound, the method including a reaction step of decomposing a blocked isocyanate compound into a blocking agent and an isocyanate compound by heat treatment in the presence of a compound having a structure represented by either one or both of general formulas (I) and (II), thereby obtaining the isocyanate compound.

The present invention relates to a method for recovering raw materials from polyester-polyurethane-elastomer-containing polymer compositions, comprising the steps of (A) providing a polymer composition containing a polyester-polyurethane-elastomer based on (i) a polyester component, (ii) an isocyanate component and optionally (iii) a chain extender and / or crosslinker with hydroxy and / or amine functionality, wherein the polymer composition contains a first polyester-polyurethane-elastomer, the isocyanate component of which comprises naphthylene-1,5-diisocyanate; (B) reacting the polymer composition with a linear primary mono-alcohol with 1 to 4 carbon atoms thereby obtaining a product mixture comprising a liquid alcohol phase and a solid carbamate phase; and (C) isolating the carbamate from the product mixture.

This application describes an improved method for preparing 1,5-pentamethylene diisocyanate (PDI) from 1,5-pentanediamine salts. The method generally includes: providing a solution containing a 1,5-pentanediamine salt dissolved in an inert solvent in the presence of a tertiary amine; and subjecting the solution to a liquid-phase phosgenation reaction to convert 1,5-pentanediamine to PDI. The phosgenation reaction includes the step of maintaining the reaction at a temperature of 100°C to 120°C for a sufficient time to achieve the desired threshold yield of PDI. The method described in this application enables a reduction in the amount of reactants consumed, a lower reaction temperature, and / or a shorter total reaction time compared to conventional phosgenation reactions. It has been found advantageous to use bio-based 1,5-pentanediamine salts that have not been previously distilled, as subjecting 1,5-pentanediamine to high temperatures leads to the formation of certain cyclic compounds that may remain in the resulting PDI.