Method of producing 4,4'-methylene diphenyl dicarbamate

Abstract

The invention relates to a method of producing 4,4'-methylene diphenyl dicarbamate of formula I, characterized in that molten O-methyl-N-phenyl carbamate of formula II is reacted with anhydrous derivatives of formaldehyde in the presence of acidic catalysts, where the molar ratio of the reagents is (2-10):1:(0.25-2) and the reaction is carried out at a temperature of 50-150°C. The technical result is a novel and improved method of producing 4,4'-MDC by a regioselective reaction with a high yield.

Description

[0001] METHOD FOR PRODUCING 4,4'-METHYLENE DIPHENYLDICARBAMATE

[0002] Field of technology

[0003] The invention relates to the field of synthesis of organic compounds, in particular to the production of valuable compounds for use in organic synthesis, more specifically to a method for producing 4,4'-methylene diphenyl dicarbamate, hereinafter 4,4'-MDC of formula I

[0004] 4,4'-MDC of formula I can be used as starting materials for the production of isocyanates (4,4'-methylene diphenyl diisocyanate).

[0005] Prior art

[0006] A method for producing 4,4'-MDC is known (patent JPH01203358, IPC C07C239 / 00; C07C269 / 00; C07C269 / 06; C07C271 / 26; C07C67 / 00, published.

[0007] 16.08.1989), in which the yield of MDC is increased by treating the condensation product of N-phenylcarbamate with a methyleneating agent in an aromatic system, precipitating and separating 4,4'-MDC, and re-condensing the resulting mother liquor with the methyleneating agent. N-phenylcarbamate is condensed with a methyleneating agent (e.g., an aqueous solution of formaldehyde) in the presence of an aqueous solution of acid as a catalyst to obtain a reaction product, which is then treated with an aromatic solvent (preferably benzene, toluene, or xylene) to preferentially precipitate 4,4'-methylene diphenyl dicarbamate. The precipitated substance is then separated from the mother liquor by solid-liquid separation.The mother liquor containing unreacted N-phenylcarbamate, 2,4'- and 2,2'-MDC, and polynuclear compounds is recondensed with a methyleneating agent in the presence of an aqueous acid solution to convert the unreacted N-phenylcarbamate to MDC and the 2,4'- and 2,2'-MDC to polynuclear compounds. This process reduces the amount of 2,4'- and 2,2'-MDC formed, which have low availability. A disadvantage of this method is that 4,4'-MDC contains impurities of ortho isomers, which reduces the yield of 4,4'-MDC and requires purification from impurities.

[0008] A method for producing 4,4'-MDC is known (patent JPH01211558, IPC C07C239 / 00; C07C269 / 00; C07C67 / 00, published 08 / 24 / 1989). In order to simultaneously increase the conversion of the feedstock and the selectivity for 4,4'-MDC, a methyleneating agent is added in portions to the condensation reaction between N-phenylcarbamate and the methyleneating agent in the presence of aqueous acid. The condensation reaction between N-phenylcarbamate and formaldehyde is carried out in the presence of aqueous acid at 60-120 °C, preferably at 80-100 °C, first less than 85% of the formaldehyde that must be added (preferably 0.4-0.7 mol per mol of N-phenylcarbamate) is added at a molar ratio of 0.2-0.4 to carry out the reaction. The reaction mixture is then cooled and combined with the remaining formaldehyde at a temperature of at least 10°C below the reaction temperature (preferably 50-60°C) and heated to the reaction temperature to carry out the reaction, as a result of which the selectivity of 4,4'-methylene diphenyl dicarbamate increases.

[0009] The disadvantage of the method is the difficulty of carrying it out to increase the selectivity of the formation of 4,4'-MDC, which contains a significant amount of ortho-isomers of 2,4' and 2,2'-MDC.

[0010] The closest technical solution to the claimed one is the method for producing 4,4'-MDC (patent CN106565545, IPC C07C269 / 06; C07C271 / 28, published on 19.04.2017). The reaction is carried out under continuous conditions under tungstophosphoric acid catalysis, using a 10% aqueous solution of formaldehyde and dimethyl carbonate as a solvent, diethylene glycol dimethyl ether is continuously pumped into a filled reactor with a fixed catalyst bed, heated to 160°C, preheated with a 20% concentration of phenylcarbamate - diethylene glycol dimethyl ether solution and with a 30% concentration of formaldehyde solution to 160°C. According to the patent, in addition to the main product 4,4'-MDC, ortho-isomers 2,4' and 2,2'-MDC are formed.

[0011] Another disadvantage of the method is the formation of ortho-isomers 2,4' and 2,2'-MDC in the main product 4,4'-MDC. Disclosure of the invention

[0012] The objective of the invention is to obtain a new compound 4,4'-MDC without impurities of ortho-isomers and without losses in the form of by-products, and to develop an improved method for obtaining 4,4'-MDC by a regioselective reaction with a high yield.

[0013] The problem is solved using a method for obtaining 4,4'-methylene diphenyl dicarbamate of formula I

[0014] MeO. Н ' ^OMe

[0015] T / VY

[0016] , where Me denotes the alkyl group CH3, which consists in the fact that the interaction of the melt O-methyl-N- phenylcarbamate of formula II with anhydrous derivatives of formaldehyde using acid catalysts at a molar ratio of reagents equal to (2-10): 1: (0.25-2) and the reaction is carried out at a temperature of 50-150°C.

[0017] Preferably, sulfonic acids are used as acid catalysts.

[0018] Preferably, trifluoromethanesulfonic acid, p-sulfobenzoic acid, cysteine ​​acid, benzenesulfonic acid, methanesulfonic acid, toluenesulfonic acid, and sulfuric acid are used as sulfonic acids.

[0019] Preferably, the reaction is carried out in molten O-methyl-N-phenylcarbamate for 1-10 hours.

[0020] Preferably, after completion of the reaction, the reaction mass is diluted with an inert solvent, filtered, the precipitate is dried and 4,4'-methylene diphenyl dicarbamate is isolated.

[0021] Preferably, benzene, toluene, chloroform, dichloromethane, and ethyl acetate are used as inert solvents.

[0022] Preferably, the residue containing O-methyl-N-phenylcarbamate is separated from the filtrate for reuse.

[0023] Preferably, the reaction proceeds regioselectively and the yield of 4,4'-methylene diphenyl dicarbamate is 71.0-95.0%, without impurities of orthoisomers and oligomers. Synthesis of 4,4 '-methylene diphenyl dicarbamate (hereinafter 4,4 '-MDC) from O-methyl-N- phenylcarbamate (hereinafter referred to as MFC) is carried out according to the following scheme:

[0024] The synthesis is carried out in molten MFC, which is used as both a reactant and a solvent. Anhydrous formaldehyde derivatives are used as the second reactant. The reaction is catalyzed by sulfonic acids: trifluoromethanesulfonic acid, p-sulfobenzoic acid, cysteine ​​acid, benzenesulfonic acid, methanesulfonic acid, toluenesulfonic acid, and sulfuric acid. The molar ratio of MFC reactants, formaldehyde derivative, and catalyst varies within the range: (2-10) : 1 : (0.25-2).

[0025] The reaction temperature and time were 50-150°C and 1-10 hours, respectively. After the reaction, the reaction mixture was diluted with an inert solvent (benzene, toluene, chloroform, dichloromethane, or ethyl acetate), and the product was filtered and dried. The yield of 4,4'-MDA was 71-95%. According to NMR spectra show that the product does not contain any ortho-isomers. The filtrate is washed with aqueous sodium bicarbonate to remove the acid, and the solvent is distilled off. The aqueous sodium salt solution (the main production waste) is disposed of. The MFC remaining after solvent distillation is reused in the process. The solvents are recovered by distillation.

[0026] Known analogues lack methods for obtaining 4,4'-MDC by a regioselective reaction, which significantly complicates industrial use due to the need to separate ortho-isomers.

[0027] The technical result of the proposed invention is the production of a new compound 4,4'-MDC without impurities of ortho-isomers and without losses in the form of by-products, and the development of an improved method for producing 4,4'-MDC by a regioselective reaction with a high yield.

[0028] The main difference of the proposed method for producing 4,4'-MDC is that it is carried out without the use of solvents or aqueous acid solutions, using a melt of O-methyl-1H-phenylcarbamate (MPC). Anhydrous acid catalysts, such as sulfonic acids, are used as catalysts. Anhydrous formaldehyde derivatives are used as another reactant. The reaction is carried out at a temperature of 50-150°C.

[0029] The use of MFC as a reagent and as a solvent in the proposed method allows the process to be carried out at a temperature of 50-150°C and a molar ratio of MFC, anhydrous formaldehyde derivative and catalyst in the range of: (2-10) : 1 : (0.25-2).

[0030] Table 1 presents data on the method for obtaining 4,4'-MDC.

[0031] The best embodiment of the invention

[0032] The invention is illustrated by the following examples, in which the structure of the obtained 4,4'-MDC compound without impurities of ortho-isomers is confirmed by the *H NMR spectroscopy method.

[0033] Example 1.

[0034] In a flask equipped with a stirrer, reflux condenser and thermometer, 70.0 g (464.0 mmol) of O-methyl-N-phenylcarbamate, 1.40 g (46.4 mmol) of anhydrous formaldehyde derivative and 4.45 g (46.4 mmol) of methanesulfonic acid are charged. The mixture is heated with stirring to a temperature of 150 °C and stirred at this temperature for 4 hours. After this, the reaction mass is cooled to room temperature, 200 ml of methylene chloride are added. The precipitate is filtered, washed with 50 ml of methylene chloride and dried. After drying, 12.1 g (82.5%) of 4,4'-MDC are obtained, ortho-isomers and by-products are absent. The chloromethylene fractions are combined, washed with a saturated solution of sodium bicarbonate until a neutral medium is obtained. The organic phase is separated and distilled under vacuum. The residue, 56.2 g of MFC, is reused.

[0035] Example 2.

[0036] In a flask equipped with a stirrer, reflux condenser and thermometer, 48.7 g (323 mmol) of O-methyl-N-phenylcarbamate, 2.42 g (80.7 mmol) of anhydrous formaldehyde derivative and 4.55 g (46.4 mmol) of hydroxysulfonic acid are charged. The mixture is heated with stirring to a temperature of 130 °C and stirred at this temperature for 2 hours. After this, 100 ml of toluene are added to the reaction mass. The precipitate is filtered, washed with 50 ml of toluene and dried. After drying, 18.2 g (71.4%) of 4,4'-MDC are obtained, ortho-isomers and by-products are absent. The toluene fractions are combined, washed with a saturated sodium bicarbonate solution until a neutral medium is obtained. The organic phase is separated and the toluene is distilled off under vacuum. The residue is 30.3 g of MFC and is reused.

[0037] Example 3.

[0038] In a flask equipped with a stirrer, reflux condenser and thermometer, 35.0 g (0.232 mol) of O-methyl-N-phenylcarbamate, 3.48 g (0.116 mol) of anhydrous formaldehyde derivative and 11.0 g (0.058 mol) of toluenesulfonic acid hydrate are charged. The mixture is heated with stirring to a temperature of 100 °C and stirred at this temperature for 4 hours. After this, the reaction mass is cooled to room temperature, 100 ml of ethyl acetate are added. The precipitate is filtered and dried. After drying, 29.3 g (80.0%) of 4,4'-MDC are obtained, ortho-isomers and by-products are absent. The organic phase is separated and distilled under vacuum. The residue containing MFC and toluenesulfonic acid is reused.

[0039] Example 4.

[0040] In a flask equipped with a stirrer, reflux condenser and thermometer, 70.0 g (464.0 mmol) of O-methyl-N-phenylcarbamate, 2.32 g (77.3 mmol) of anhydrous formaldehyde derivative and 14.8 g (154.4 mmol) of methanesulfonic acid are charged. The mixture is heated with stirring to a temperature of 50 °C and stirred at this temperature for 10 hours. After this, the reaction mass is cooled to room temperature, 300 ml of benzene are added. The precipitate is filtered and dried. After drying, 21.7 g (89.3%) of 4,4'-MDC are obtained, ortho-isomers and by-products are absent. The filtrate is washed with a saturated solution of sodium bicarbonate until the medium is neutral. The organic phase is separated and distilled under vacuum. The residue - 46.1 g of MFC - is reused.

[0041] Example 5.

[0042] In an autoclave equipped with a stirrer, 50.0 g (0.331 mol) of O-methyl-N-phenylcarbamate, 0.993 g (33.1 mmol) of anhydrous formaldehyde derivative and 1.58 g (8.3 mmol) of toluenesulfonic acid hydrate are charged. The mixture is heated with stirring to a temperature of 130 °C and stirred at this temperature for 1 hour. After this, the reaction mass is cooled to room temperature, diluted with 100 ml of chloroform. The precipitate is filtered and dried. After drying, 7.4 g (71.0%) of 4,4'-MDC are obtained, ortho-isomers and by-products are absent. The filtrate is washed with a saturated sodium bicarbonate solution until the medium is neutral. The organic phase is separated and distilled under vacuum. The residue - 41.1 g of MFC - is reused.

[0043] Example 6.

[0044] In an autoclave equipped with a stirrer, 50.0 g (0.331 mol) of O-methyl-N-phenylcarbamate, 0.993 g (33.1 mmol) of anhydrous formaldehyde derivative and 12.5 g (66.2 mmol) of toluenesulfonic acid hydrate are charged. The mixture is heated with stirring to a temperature of 105 °C and stirred at this temperature for 10 hours. After this, the reaction mass is cooled to room temperature, diluted with 150 ml of chloroform. The precipitate is filtered and dried. After drying, 9.9 g (95.1%) of 4,4'-MDC are obtained, ortho-isomers and by-products are absent. The filtrate is washed with a saturated sodium bicarbonate solution until the medium is neutral. The organic phase is separated and distilled under vacuum. The residue - 39.1 g of MFC - is reused.

[0045] Example 7. According to the prototype.

[0046] Tungstophosphoric acid containing 2% of a heteropolyacid catalyst on a carrier is added to a fixed bed reactor, diethylene glycol dimethyl ether is continuously pumped into the filled fixed bed reactor, heated to 160°C, a 20% concentration solution of phenylcarbamate - diethylene glycol dimethyl ether and a 30% concentration solution of formaldehyde are preheated to 160°C, and simultaneously pumped into the fixed bed reactor, adjusting the flow rate of the phenylcarbamate - diethylene glycol dimethyl ether solution to 0.28 ml / min, the flow rate of the formaldehyde solution to 0.05 ml / min, a continuous condensation reaction under normal pressure conditions, the analysis time of the sample material sample, the selectivity of 4,4'-MDK was 82.0%, in addition to the main product, ortho isomers are formed. Table 1.

[0047] Example 7* according to patent No. CN106565545.

[0048] From the given examples it follows that the proposed invention has produced 4,4'-MDC without containing ortho-isomers and has proposed a new method for producing it.

[0049] The development of such a method will significantly simplify the industrial technology for producing 4,4'-MDC, which is widely used in the field of synthesis of organic compounds.

[0050] The method for producing 4,4'-MDC is economical on an industrial scale.

[0051] Industrial applicability

[0052] The invention can be used in the production of valuable compounds for use in organic synthesis, namely for the production of 4,4'-methylene diphenyl dicarbamate, which can be used as starting materials for the production of isocyanates (4,4'-methylene diphenyl diisocyanate).

Claims

CLAUSES OF THE INVENTION 1. A method for producing 4,4'-methylene diphenyl dicarbamate of formula I characterized by the fact that they carry out the interaction of a melt of O-methyl-I-phenylcarbamate of formula II with anhydrous derivatives of formaldehyde using acid catalysts at a molar ratio of reagents equal to (2-10): 1: (0.25-2) and the reaction is carried out at a temperature of 50-150°C.

2. The method according to paragraph 1, characterized in that sulfonic acids are used as acid catalysts.

3. The method according to paragraph 2, characterized in that the sulfonic acids used are trifluoromethanesulfonic acid, p-sulfobenzoic acid, cysteine ​​acid, benzenesulfonic acid, methanesulfonic acid, toluenesulfonic acid, and sulfuric acid.

4. The method according to claim 1, characterized in that the reaction is carried out in molten O-methyl-N-phenylcarbamate for 1-10 hours.

5. The method according to claim 1, characterized in that after completion of the reaction, the reaction mass is diluted with an inert solvent, filtered, the precipitate is dried and 4,4'-methylene diphenyl dicarbamate is isolated.

6. The method according to paragraph 5, characterized in that benzene, toluene, chloroform, dichloromethane, and ethyl acetate are used as inert solvents.

7. The method according to claim 5, characterized in that the residue containing O-methyl-I-phenylcarbamate is separated from the filtrate for reuse.

8. The method according to any one of paragraphs 1-7, characterized in that the reaction occurs regioselectively and the yield of 4,4'-methylene diphenyl dicarbamate is 71.0-95.0%, without containing impurities of ortho-isomers and oligomers.

Images