Method of producing o-methyl-n-phenyl carbamate
The reaction of diphenylurea with methanol at controlled temperatures and a two-stage rectification process addresses the inefficiencies of existing methods, achieving high yields and purity of O-methyl-N-phenylcarbamate, thus optimizing industrial production.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- ANDROSOV IGOR ALEKSEYEVICH
- Filing Date
- 2025-11-14
- Publication Date
- 2026-05-28
AI Technical Summary
Existing methods for producing O-methyl-N-phenylcarbamate face challenges such as high energy costs, low yields, and inefficient separation processes, particularly due to the use of phosgene, chlorine, and excessive methanol, leading to environmental contamination and low product purity.
A method involving the reaction of diphenylurea with methanol at a molar ratio of 1:6-15 at 120-190°C, followed by a two-stage rectification process to separate and isolate O-methyl-N-phenylcarbamate with high purity, achieving yields of 78-89% and a purity of 99.9%, using a metal autoclave and reduced pressure.
The method achieves high yields and purity of O-methyl-N-phenylcarbamate under optimized conditions, reducing energy consumption and environmental impact while ensuring efficient separation of process products.
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Figure RU2025000352_28052026_PF_FP_ABST
Abstract
Description
[0001] METHOD FOR PRODUCING O-METHYL-K-PHENYLCARBAMATE
[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, and more specifically to a method for producing O-methyl-K-phenylcarbamate formulas, hereinafter referred to as IFC.
[0004] MFC formulas can be used in the production of medicinal products, plant protection products and can be used as starting materials for the production of isocyanates (4,4-methylene diphenyl diisocyanate).
[0005] Prior art
[0006] Several methods for synthesizing N-aryl-O-alkyl carbamates are known. The main industrial method uses aromatic isocyanates (Arnold RG, Nelson JA, Verbanc JJ Recent Advances in Isocyanate Chemistry. / / Chem. Rev. - 1957. - V. 57, No. 1. - P. 47-76) or alkyl chloroformates (Matzner M., Kurkjy P., Cotter RJ The chemistry of Chlorformates. / / Chem. Rev. - 1964. - Vol. 64. - P. 645-687) as starting compounds. The use of these reagents ensures high yields of the target urethanes.
[0007] The main drawback is the use of phosgene for the industrial production of isocyanates and chloroformates, which leads to increased labor and environmental costs. Furthermore, the wasteful use of chlorine results in the generation of large quantities of waste contaminated with toxic phosgene.
[0008] A method for producing N-alkyl-O-alkyl carbamates of general formula I is known.
[0009] III
[0010] (patent RU 2359958, IPC S07S269 / 00; C07D307 / 42; S07S271 / 12; S07S271 / 16;
[0011] C07C271 / 26, published 06 / 27 / 2009), where R, R 1 mean alkyl groups of normal or branched structure with a number of carbon atoms from 1 to 8, arylalkyl or alkoxyalkyl, as well as heterylalkyl groups, which consists in the interaction of alcohol R'OH and symmetrical disubstituted urea II, where R, R 1 have the same meaning as in formula I, at elevated temperature, the process is carried out in a continuous or periodic mode and an organotin catalyst is additionally introduced in an amount of 0.01 to 1 mol.% at a reagent ratio of urea:aliphatic alcohol of 1:(1-60) mol. and a temperature of 140 to 220°C.
[0012] The disadvantage of this method is the use of a catalyst and low yield of the target product.
[0013] A known method for synthesizing the claimed N-alkyl-O-alkyl carbamates is the alcoholysis of symmetrical dialkyl ureas. In the cited patent (US Patent No. 2,677,698, IPC C07C271 / 06, published May 4, 1954), 1,3-dialkyl urea is obtained by continuously reacting urea and an alkyl amine. The urea is then fed into a column where it reacts with alcohol to form urethane.
[0014] This patent presents a block process flow diagram for the production of various N-alkyl-O-alkyl carbamates, and in particular, N,O-dimethylurethane. The main reaction units operate at temperatures ranging from 100°C to 200-250°C and pressures ranging from atmospheric to autogenous. The patent provides no examples of the final compounds, nor do the yields or properties of the target carbamates appear. A disadvantage of this method is the low yield of esters, which is unsuitable for producing the compounds on an industrial scale.
[0015] A method for producing N-aryl-O-alkyl carbamates (RU 2633358, IPC C07C269 / 00; C07C271 / 28, published 12.10.2017) of general formula I is known
[0016] I II where R denotes aryl groups, R 1 means alkyl groups of normal or branched structure with a number of carbon atoms from 1 to 4, which consists in the interaction of alcohol R*OH and symmetrical disubstituted urea II, where R denotes aryl groups, and R 1 means alkyl groups of normal or branched structure with the number of carbon atoms from 1 to 4, in continuous mode at atmospheric pressure in a carbamate I medium with a reagent ratio of urea: aliphatic alcohol = 1: (10-60) moles and a temperature from 140 to 250°C.
[0017] The disadvantage of this method is that the interaction of the reagents during the process is carried out in the environment of the molten reaction product, which significantly increases energy costs, but the product yield is 40-65% based on the loaded urea.
[0018] The closest technical solution to the claimed one is the synthesis of MFC (patent CN 106146353, IPC C07C269 / 04; C07C271 / 28, published 23.11.2016), which is carried out under the action of methanol on DFM for three hours at 140-200°C, with a molar ratio of DFM to methanol of 1:10-30. The patent further proposes separation of the components by stepwise film evaporation or molecular distillation.
[0019] The disadvantage of this method is the difficulty of separating MFC and aniline, as well as the use of a large excess of methanol, high process temperatures and the duration of the process.
[0020] Disclosure of invention
[0021] The objective of the proposed invention is to develop a new improved method for producing O-methyl-N-phenylcarbamate and efficient separation of the process products.
[0022] The problem is solved using a method for obtaining O-methyl-N-phenylcarbamate of the formula
[0023] , where Me denotes a methyl group - CH3, including the interaction of methanol with diphenylurea, which consists in the fact that the interaction of methanol with diphenylurea is carried out at a molar PC17RU2025 / 000352
[0024] 4 in a ratio of diphenylurea:methanol reagents equal to 1:(6-15), the process is carried out at a temperature of 120 to 190°C and O-methyl-N-phenylcarbamate with a purity of 99.9% is obtained, with subsequent isolation of the process products by rectification.
[0025] Preferably, the process is carried out in an autoclave for a period of 1 to 8 hours.
[0026] Preferably, after completion of the process, the autoclave is cooled and the process products are subjected to a two-stage rectification; in the first column, methanol is separated from high-boiling products: O-methyl-N-phenylcarbamate and aniline; in the second column, high-boiling products are separated.
[0027] Preferably, the separation of high-boiling products is carried out under reduced pressure.
[0028] Preferably, the separation of high-boiling products is carried out under a vacuum of 20-40 mm Hg.
[0029] Preferably, after completion of the process, the autoclave is cooled, then the process products are diluted with methanol and unreacted diphenylurea is filtered off.
[0030] The proposed invention is implemented in the following manner.
[0031] From diphenylurea (DFU) and methanol (MeOH) O-methyl-N-phenylcarbamate (MPC) is obtained according to the scheme:
[0032] The reaction is carried out in a metal autoclave at a methanol to DFU molar ratio of 6-15:1. The best yields are achieved at temperatures of 120-190°C and reaction times of 1-8 hours. The target MFU is isolated by a two-stage distillation method. In the first distillation column, methanol is distilled off, and in the second, MFU and aniline are distilled under reduced pressure. The MFU yield is 78-89%. The recovered aniline is returned to the diphenylurea production stage.
[0033] The technical result of the proposed invention is the development of an improved method for obtaining O-methyl-M-phenylcarbamate under optimal process conditions with a yield of up to 78-89% and the isolation of the process products by rectification.
[0034] Patent CN 106146353 uses an energy-intensive and time-consuming method of separating components using film evaporation or molecular distillation.
[0035] In the proposed invention, a fairly simple and widely used in the chemical industry rectification method is used to separate O-methyl-N-phenylcarbamate and the process products.
[0036] In the proposed invention, in contrast to known methods, the production of MFC is carried out with a slight excess of methanol, at reduced process temperatures, the process products are isolated by rectification and O-methyl-N-phenyl is obtained with a fairly high yield of 78-89% in terms of diphenylurea and a purity of 99.9%, the structure of which is confirmed by *H NMR spectroscopy.
[0037] Table 1 presents data on the process of obtaining MFC.
[0038] The best embodiment of the invention
[0039] The invention is illustrated by the following examples.
[0040] Example 1.
[0041] A steel autoclave is charged with 45.00 g (0.21 mol) of DFM and 71.3 g (2.38 mol) of methanol. The autoclave is hermetically sealed and heated at 140°C for 8 hours. After the specified time, the autoclave is cooled and opened. The residue is subjected to two-stage distillation. In the first column, methanol and high-boiling products - MFC and aniline - are distilled. Methanol is returned to the process. In the second column, MFC and aniline are distilled under vacuum (30 mm Hg). 28.5 g (89.0%) of MFC and 18.7 g of aniline are obtained, which are sent to the DFM synthesis stage. The purity of MFC is 99.9%.
[0042] Example 2.
[0043] A steel autoclave is charged with 45.00 g (0.21 mol) of DFM and 40.3 g (1.26 mol) of methanol. The autoclave is hermetically sealed and heated at 180°C for 2 hours. After the specified time, the autoclave is cooled and opened. 10 ml of methanol are diluted and unreacted DFM (5.2 g) is filtered off. The residue is subjected to two-stage distillation. In the first column, methanol and high-boiling products - MFC and aniline - are distilled. Methanol is recycled to the process. In the second column, MFC and aniline are distilled under vacuum (30 mm Hg). 22.6 g (78.0% of the reacted DFM) of MFC and 18.7 g of aniline are obtained, which are sent to the DFM synthesis stage. The purity of MFC is 99.9%.
[0044] Example 3.
[0045] A steel autoclave is charged with 45.00 g (0.21 mol) of DFM and 100.8 g (3.15 mol) of methanol. The autoclave is hermetically sealed and heated at 120°C for 8 hours. After the specified time, the autoclave is cooled and opened. The residue is subjected to two-stage distillation. In the first column, methanol and high-boiling products - MFC and aniline - are distilled. Methanol is returned to the process. In the second column, MFC and aniline are distilled under vacuum (30 mm Hg). 26.7 g (84.3%) of MFC and 18.8 g of aniline are obtained, which are sent to the DFM synthesis stage. The purity of MFC is 99.9%.
[0046] Example 4.
[0047] A steel autoclave is charged with 45.00 g (0.21 mol) of DFM and 50.4 g (1.57 mol) of methanol. The autoclave is hermetically sealed and heated at 190°C for 2 hours. After the specified time, the autoclave is cooled and opened. The residue is subjected to two-stage distillation. In the first column, methanol and high-boiling products - MFC and aniline - are distilled. Methanol is recycled. In the second column, MFC and aniline are distilled under vacuum (20 mm Hg). 25.8 g (81.4%) of MFC and 17.2 g of aniline are obtained, which are sent to the DFM synthesis stage. The purity of MFC is 99.9%.
[0048] Example 5. According to the prototype.
[0049] Diphenylurea is further purified using an evaporative crystallizer, and then the solid feedstock is fed through an outlet valve into a mixing kettle while stirring and adding methanol. The feed ratio is 1:18, mixed to form a slurry, and then pumped into the alcoholysis reactor using a slurry pump and maintained at 160°C for 2 hours. The reaction solution feed ratio to methanol molar ratio is 1:18, passed through an overflow port into the second-stage alcoholysis reactor, and the temperature is maintained at 170-200°C for 1 hour. A portion of the methanol and aniline are separated using an evaporator. Residual methanol and most of the aniline are distilled off in a falling-film evaporator, and the bottom of the column yields a crude methyl phenyl carbamate product containing a trace amount of aniline.The crude product enters the molecular distillation film at the bottom of the tower, where it is scraped into a very thin liquid film using a scraper. The molecular distillation heating temperature is 120°C, the rotor speed is 150 rpm, and the pressure is 0.5 kPa. After the low-boiling aniline evaporates, it enters the aniline outlet tube from the top of the molecular distillation film and is recovered after condensation. After leaving the heating surface, methyl phenyl carbamate quickly condenses into liquid on an internal condenser and enters the phenylurethane outlet at the bottom via the molecular distillation condenser tube. The heavy component of the raffinate passes through an annular passage at the bottom of the heating zone and is discharged from the high-boiling side outlet tube. After natural cooling and crystallization of the methyl phenyl carbamate, a white product is obtained.The purity of methyl phenylcarbamate is not less than 99.9%, the aniline content is not more than 0.06%.
[0050] Table 1.
[0051] Example 5* according to patent No. CN 106146353.
[0052] From the examples given, it follows that the proposed method allows increasing the yield of MFC to 78-89% under optimal conditions at a temperature of 120 to 190°C, with a molar ratio of diphenylurea to methanol equal to 1: (6-15). The production method is economical on an industrial scale. Industrial applicability
[0053] The invention can be used in the production of O-methyl-N-phenylcarbamate for use in the production of medicinal preparations, plant protection products, and can also be used as a starting material for the production of isocyanates (4,4-methylene diphenyl diisocyanate).
Claims
CLAUSES OF THE INVENTION 1. A method for obtaining O-methyl-M-phenylcarbamate of the formula , which includes the interaction of methanol with diphenylurea, characterized by the fact that the interaction of methanol with diphenylurea is carried out at a molar ratio of the reagents diphenylurea:methanol equal to 1:(6-15), the process is carried out at a temperature of 120 to 190°C and O-methyl-N-phenylcarbamate is obtained with a purity of 99.9%, with subsequent isolation of the process products by rectification.
2. The method according to paragraph 1, characterized in that the process is carried out in an autoclave for a period of time from 1 to 8 hours.
3. The method according to paragraph 2, characterized in that after completion of the process, the autoclave is cooled and the process products are subjected to two-stage rectification, in the first column methanol is separated from high-boiling products: O-methyl-N-phenylcarbamate and aniline, in the second column the high-boiling products are separated.
4. The method according to paragraph 3, characterized in that the separation of high-boiling products is carried out at reduced pressure.
5. The method according to paragraph 4, characterized in that the separation of high-boiling products is carried out under a vacuum of 20-40 mm Hg.
6. The method according to paragraph 2, characterized in that after completion of the process, the autoclave is cooled, then the process products are diluted with methanol and unreacted diphenylurea is filtered off.