Method for synthesizing amino-methyl-phenyl methyl carbamate compound from p-toluidine

Abstract

The invention relates to a method for synthesizing an amino-methyl-phenyl methyl carbamate compound from p-toluidine. According to the method, p-toluidine is adopted as a raw material, an anhydrous zinc acetate catalyst and a green solvent-dimethyl carbonate are used, p-methylphenyl methyl carbamate is firstly prepared, then one-step direct amination is carried out on the p-methylphenyl methyl carbamate, and 2-amino-4-methylphenyl methyl carbamate and 3-amino-4-methylphenyl methyl carbamate are prepared. The method has the advantages that raw materials are easy to obtain, the reaction process is environment-friendly and the like, the atom utilization rate is high, the yield of the first-step reaction can reach 96%, and the yield of the second-step reaction can reach 35.7%.

Description

Technical Field

[0001] The invention belongs to the field of organic compound synthesis, and specifically is a method for synthesizing 2-amino-4-methylphenylcarbamate and 3-amino-4-methylphenylcarbamate by using p-toluidine as a raw material. Background Art

[0002] Methylaniline is a general term for amine compounds in which the hydrogen atoms at the ortho, para or meta positions on the benzene ring of the aniline molecule are substituted by methyl groups. It has three isomers, namely, o-methylaniline, m-methylaniline and p-methylaniline. Among them, p-toluidine is an important chemical raw material, which can be used as a dye intermediate, and is also an intermediate for products such as the pharmaceutical pyrimethamine and the pesticide cypermethrin, and can undergo a variety of chemical reactions. Methyl p-toluylcarbamate is an important intermediate. In the field of organic synthesis, it can be used for the non-phosgene preparation of monoisocyanates, the synthesis of non-toxic polyurethanes, and substances such as N-substituted pyrroles and N-substituted carbamates, and is often used as an excellent directing group and leaving group. In the field of medicine, it can be used as a sedative, insecticide, fungicide, etc. Methyl 2-amino-4-methylphenylcarbamate and methyl 3-amino-4-methylphenylcarbamate are also important organic intermediates, mainly used for the preparation of methyl toluene dicarbamate by methoxycarbonylation, which can be used as a precursor of toluene diisocyanate.

[0003] Traditional methods for synthesizing carbamates often use highly toxic phosgene or isocyanate derivatives as raw materials. Phosgene is a highly toxic gas that poses a huge safety hazard to operators and causes serious environmental pollution and safety issues. In recent years, dimethyl carbonate has been used as a widely used basic organic synthesis raw material with good reactivity and can be used as an ideal substitute for phosgene and dimethyl sulfate. Wang Yanji et al. (CN03156418) used zinc acetate as a catalyst to react 2,4-diaminotoluene and dimethyl carbonate to produce 2,4-toluene dicarbamate, in which the intermediate product 3-amino-4-methylphenylcarbamate is produced. Li Qun et al. (Fine Petrochemicals, 2013, 30(05):59-62.) used toluene as solvent, added 2,4-diaminotoluene and methyl chloroformate as raw materials, and zinc chloride as catalyst to react to produce 3-amino-4-methylphenylcarbamate, but the yield was low, the byproduct HCl produced needed to be neutralized by adding triethylamine, and the raw material 2,4-diaminotoluene was mostly prepared by reducing dinitrotoluene, which is a controlled product and has certain dangers. As for the preparation of 2-amino-4-methylphenylcarbamate, there is currently a lack of research in the academic community. Therefore, it is very important to explore a reaction route with high yield, environmental friendliness, and high atomic utilization. Summary of the invention

[0004] The purpose of the present invention is to provide a method for synthesizing amino-methyl-phenylcarbamate compounds from p-toluidine in view of the problems of low atom utilization, poor yield and environmental pollution in the current 3-amino-4-methylphenylcarbamate synthesis method. The method adopts p-toluidine as a raw material, uses anhydrous zinc acetate catalyst and green solvent-dimethyl carbonate, first prepares p-tolylcarbamate, and then directly aminates it in one step to prepare 2-amino-4-methylphenylcarbamate and 3-amino-4-methylphenylcarbamate. The present invention has the advantages of easy availability of raw materials, high atom utilization, and environmentally friendly reaction process.

[0005] The technical solution of the present invention is: A method for synthesizing amino-methyl-phenylcarbamate compounds from p-toluidine, the method comprising the following steps: The first step is to prepare methyl p-toluene carbamate from p-toluidine Add p-toluidine, the first catalyst and dimethyl carbonate into a high-pressure reactor, seal it, and react it under an oxygen-free atmosphere at 110-180° C. for 2-10 hours with stirring to obtain methyl p-tolylcarbamate; The molar ratio is: dimethyl carbonate: p-toluidine = 5-30; the first catalyst is an organic salt catalyst, p-toluidine: first catalyst (in terms of metal atoms) = 10-200; The first catalyst is anhydrous zinc acetate, zinc acetate dihydrate or manganese acetate.

[0006] The material ratio is preferably dimethyl carbonate: p-toluidine = 10-25; p-toluidine: first catalyst (in terms of metal atoms) = 15-150; the preferred reaction temperature is 130-160° C.; and the preferred reaction time is 2-8 hours.

[0007] The second step is to prepare 2-amino-4-methylphenylcarbamate and 3-amino-4-methylphenylcarbamate from methyl p-tolylcarbamate Methyl p-tolylcarbamate, a second catalyst, hydroxylamine-O-sulfonic acid and an acidic medium are added to a reactor, and the mixture is stirred at a constant temperature of 40 to 90° C. under normal pressure for 0.25 to 3 hours, and then the organic phase in the reaction solution is separated to obtain the products methyl 2-amino-4-methylphenylcarbamate and methyl 3-amino-4-methylphenylcarbamate.

[0008] The material molar ratio is: methyl p-tolylcarbamate: hydroxylamine-O-sulfonic acid = 0.1-5, and the molar ratio is: the second catalyst (in terms of iron atoms or vanadium atoms): methyl p-tolylcarbamate = 0.01-0.6; Add 0.001-0.010 mol of methyl p-tolylcarbamate to every 15 mL of acidic medium; The second catalyst is ferrous sulfate, ferrous chloride, ferric chloride or ammonium metavanadate; the acidic medium is composed of lower fatty acid and water, or lower fatty acid, water and inorganic acid; the volume percentage of lower fatty acid is 17% to 83%, the volume percentage of water is 17% to 83%, and the volume percentage of inorganic acid is 0 to 15%; The lower fatty acid is formic acid, acetic acid or propionic acid; the inorganic acid is hydrochloric acid, sulfuric acid or phosphoric acid; The preferred reaction temperature is 50-80°C, and the reaction time is 0.5-1.5h. The preferred acidic medium composition is acetic acid: water = 5:15-16:4. The preferred molar ratio of the catalyst to methyl p-tolylcarbamate is 0.02-0.5, and the preferred molar ratio of methyl p-tolylcarbamate to hydroxylamine-O-sulfonic acid is 0.25-4.2.

[0009] The essential features of the present invention are: 2-amino-4-methylphenylcarbamate and 3-amino-4-methylphenylcarbamate are important raw materials for the synthesis of toluene dicarbamate, the latter of which is an important source for the synthesis of toluene diisocyanate. 3-amino-4-methylphenylcarbamate was initially discovered as an intermediate in the reaction of synthesizing 2,4-toluene dicarbamate, but the raw material used was 2,4-diaminotoluene, and its production was mostly obtained by reducing 2,4-dinitrotoluene, which is somewhat dangerous. There is no complete synthetic route for 2-amino-4-methylphenylcarbamate so far.

[0010] The invention uses p-toluidine as a raw material to synthesize 2-amino-4-methylphenylcarbamate and 3-amino-4-methylphenylcarbamate in two steps. p-toluidine itself can be prepared by one-step amination of toluene, avoiding the potential danger brought by nitrotoluene. The product of the first step methoxycarbonylation reaction, p-tolylcarbamate, can not only participate in the reaction in the second step, but also be used as a raw material for synthesizing monoisocyanate, and has the characteristics of high atomic utilization rate, sustainability and environmental friendliness. In the second step reaction, hydroxylamine-O-sulfonic acid is used to perform one-step amination, and the reaction conditions are mild, the time consumption is short, the equipment is simple and the operation is convenient.

[0011] The beneficial effects of the present invention are: (1) This method designed for the first time a relatively systematic synthesis route for 2-amino-4-methylphenylcarbamate and 3-amino-4-methylphenylcarbamate, with high atom utilization and mild reaction conditions. The yield of the first step reaction can reach 96%, and the yield of the second step reaction can reach 35.7%.

[0012] (2) This method realizes the reaction from monoaminotoluene to diaminotoluene-like compounds for the first time, and realizes a one-step amination reaction on monoaminocarbamate compounds, making them useful as raw materials for the synthesis of diaminocarbamates, which has good research and application prospects.

[0013] (3) The catalyst is easily available, has low cost, and has good catalytic performance (4) Using dimethyl carbonate as both reactant and solvent for methoxycarbonylation to replace toluene and methyl chloroformate.

[0014] (5) A new route for the direct synthesis of 2-amino-4-methylphenylcarbamate and 3-amino-4-methylphenylcarbamate using methylaniline as raw material has been opened up, breaking the previous production idea of ​​​​from dinitrotoluene to toluene diisocyanate, making the entire process route meet the characteristics of inherent safety and green environmental protection. DETAILED DESCRIPTION

[0015] (I) For the first step reaction, the reaction formula is:

[0016] Example 1: p-Toluidine (0.03 mol), dimethyl carbonate (50 mL, i.e., 0.5944 mol) and anhydrous zinc acetate catalyst (0.0005 mol) were added to a high-pressure reactor, which was sealed and N2 was introduced to replace the air in the high-pressure reactor to ensure an oxygen-free atmosphere in the reactor. The reaction was mechanically stirred at 140°C for 4 hours and then stopped. After the reaction solution was cooled to room temperature, the supernatant was centrifuged to allow the catalyst to sink to the bottom. The supernatant was filtered and analyzed on a high-performance liquid chromatography, and the remaining supernatant was subjected to reduced pressure distillation at a temperature of 50°C. The obtained solid was placed in a vacuum drying oven at 80°C overnight and used as a raw material for the second step reaction. The reaction results were: the conversion rate of p-toluidine was 98.1%, and the yield of p-tolylcarbamate was 96.2%.

[0017] The characterization method is: high performance liquid chromatography, using an ultraviolet detector, methanol-water solution as the mobile phase, a ratio of 7:3, a flow rate of 0.6 mL / min, a column temperature of 30°C, a detection wavelength of 232 nm, and external standard quantification.

[0018] Example 2: The other steps are the same as those of Example 1, except that the catalyst added is zinc acetate dihydrate. The conversion rate of p-toluidine is 0%, and the yield of p-tolylcarbamate is 87.5%.

[0019] Example 3: The other steps are the same as those of Example 1, except that manganese acetate is used as the catalyst. The conversion rate of p-toluidine is 12.1%, and the yield of p-tolylcarbamate is 3.6%.

[0020] Example 4: The other steps are the same as in Example 1, except that 0.0002 mol of anhydrous zinc acetate catalyst is added. The conversion rate of p-toluidine is 97.36%, and the yield of p-tolylcarbamate is 90.24%.

[0021] Example 5: The other steps are the same as those of Example 1, except that 0.001 mol of anhydrous zinc acetate catalyst is added. The conversion rate of p-toluidine is 97.05%, and the yield of p-tolylcarbamate is 88.98%.

[0022] Example 6: The other steps are the same as in Example 1, except that 0.002 mol of anhydrous zinc acetate catalyst is added. The conversion rate of p-toluidine is 95.63%, and the yield of p-tolylcarbamate is 82.53%.

[0023] Example 7: The other steps were the same as in Example 1, except that 25 mL (0.2967 mol) of dimethyl carbonate was added. The conversion rate of p-toluidine was 69.39%, and the yield of p-tolylcarbamate was 58.26%.

[0024] Example 8: The other steps were the same as in Example 1, except that 37 mL (0.4444 mol) of dimethyl carbonate was added. The conversion rate of p-toluidine was 80.38%, and the yield of p-tolylcarbamate was 71.86%.

[0025] Example 9: The other steps were the same as in Example 1, except that 63 mL (0.7444 mol) of dimethyl carbonate was added. The conversion rate of p-toluidine was 95.12%, and the yield of p-tolylcarbamate was 89.82%.

[0026] Example 10: The other steps are the same as in Example 1, except that the reaction time is 2 h. The conversion rate of p-toluidine is 97.46%, and the yield of methyl p-tolylcarbamate is 87.06%.

[0027] Example 11: The other steps are the same as those of Example 1, except that the reaction time is 6 h. The conversion rate of p-toluidine is 95.82%, and the yield of methyl p-tolylcarbamate is 85.31%.

[0028] Example 12: The other steps were the same as in Example 1, except that the reaction time was 8 h. The conversion rate of p-toluidine was 80.28%, and the yield of methyl p-tolylcarbamate was 76.1%.

[0029] Example 13: The other steps are the same as in Example 1, except that the reaction temperature is 130° C. The conversion rate of p-toluidine is 82.4%, and the yield of methyl p-tolylcarbamate is 81.57%.

[0030] Example 14: The other steps are the same as in Example 1, except that the reaction temperature is 150° C. The conversion rate of p-toluidine is 92.53%, and the yield of methyl p-tolylcarbamate is 87.23%.

[0031] Example 15: The other steps are the same as in Example 1, except that the reaction temperature is 160° C. The conversion rate of p-toluidine is 90.67%, and the yield of methyl p-tolylcarbamate is 85.44%.

[0032] It can be seen from the above examples that the catalytic system is simple to operate, the yield of methyl p-tolylcarbamate is high, the catalyst source is easily available, and the activity and selectivity are good, and it is easy to separate from the reaction system. By analyzing the data in the examples, the most active catalyst is anhydrous zinc acetate catalyst. At 140°C, the reaction conversion rate and yield under the experimental conditions of p-toluidine (0.03mmol), dimethyl carbonate (50mL, 0.5944mol) and anhydrous zinc acetate (0.0005mol) are both high.

[0033] (II) For the second step reaction

[0034] Example 16: Place p-tolylcarbamic acid methyl ester (0.002 mol), hydroxylamine-O-sulfonic acid (0.0036 mol), and ferrous sulfate (0.0003 mol) after vacuum drying in Example 1 in a 100 mL three-necked flask, add an acidic medium (15 mL), the volume ratio of glacial acetic acid to water in the acidic medium is 15:5, place in a 100 mL three-necked flask, heat to 60 ° C, reflux and react at normal pressure under constant temperature stirring for 1 hour. After the reaction is completed, the reaction solution is cooled to room temperature, and a sodium hydroxide solution with a mass fraction of 30% is gradually added dropwise until the pH of the reaction solution is neutral. After extraction, the organic phase is taken and analyzed by high performance liquid chromatography. The reaction results are that the conversion rate of p-tolylcarbamic acid methyl ester is 71.39%, the yield of 2-amino-4-methylphenylcarbamic acid methyl ester is 26.08%, and the yield of 3-amino-4-methylphenylcarbamic acid methyl ester is 9.67%.

[0035] The characterization method is the same as that of Example 1.

[0036] Example 17: The other steps are the same as those of Example 16, except that 0.001 mol of methyl p-tolylcarbamate is added. The conversion rate of methyl p-tolylcarbamate is 72.84%, the yield of methyl 2-amino-4-methylphenylcarbamate is 25.96%, and the yield of methyl 3-amino-4-methylphenylcarbamate is 7.43%.

[0037] Example 18: The other steps are the same as those of Example 16, except that 0.005 mol of methyl p-tolylcarbamate is added. The conversion rate of methyl p-tolylcarbamate is 63.64%, the yield of methyl 2-amino-4-methylphenylcarbamate is 21.54%, and the yield of methyl 3-amino-4-methylphenylcarbamate is 6.47%.

[0038] Example 19: The other steps are the same as those of Example 16, except that 0.010 mol of methyl p-tolylcarbamate is added. The conversion rate of methyl p-tolylcarbamate is 58.35%, the yield of methyl 2-amino-4-methylphenylcarbamate is 17.43%, and the yield of methyl 3-amino-4-methylphenylcarbamate is 5.12%.

[0039] Example 20: The other steps are the same as those of Example 16, except that the catalyst added is ferrous chloride. The conversion rate of p-tolylcarbamate is 8.67%, the yield of 2-amino-4-methylphenylcarbamate is 3.3%, and the yield of 3-amino-4-methylphenylcarbamate is 1.75%.

[0040] Example 21: The other steps are the same as those of Example 16, except that the catalyst added is ferric chloride. The conversion rate of methyl p-tolylcarbamate is 5.63%, the yield of methyl 2-amino-4-methylphenylcarbamate is 2.27%, and the yield of methyl 3-amino-4-methylphenylcarbamate is 1.28%.

[0041] Example 22: The other steps are the same as those of Example 16, except that the catalyst added is ammonium metavanadate. The conversion rate of methyl p-tolylcarbamate is 15.28%, the yield of methyl 2-amino-4-methylphenylcarbamate is 8.72%, and the yield of methyl 3-amino-4-methylphenylcarbamate is 3.58%.

[0042] Example 23: The other steps are the same as those of Example 16, except that 0.0002 mol of ferrous sulfate catalyst is added. The conversion rate of methyl p-tolylcarbamate is 65.14%, the yield of methyl 2-amino-4-methylphenylcarbamate is 22.17%, and the yield of methyl 3-amino-4-methylphenylcarbamate is 8.52%.

[0043] Example 24: The other steps are the same as those of Example 16, except that 0.0004 mol of ferrous sulfate catalyst is added. The conversion rate of p-tolylcarbamate is 63.96%, the yield of 2-amino-4-methylphenylcarbamate is 21.1%, and the yield of 3-amino-4-methylphenylcarbamate is 7.91%.

[0044] Example 25: The other steps are the same as those of Example 16, except that 0.0005 mol of ferrous sulfate catalyst is added. The conversion rate of p-tolylcarbamate is 55.53%, the yield of 2-amino-4-methylphenylcarbamate is 20.7%, and the yield of 3-amino-4-methylphenylcarbamate is 7.87%.

[0045] Example 26: The other steps were the same as in Example 16, except that 0.0024 mol of hydroxylamine-O-sulfonic acid was added. The conversion rate of methyl p-tolylcarbamate was 45.49%, the yield of methyl 2-amino-4-methylphenylcarbamate was 21.1%, and the yield of methyl 3-amino-4-methylphenylcarbamate was 7.91%.

[0046] Example 27: The other steps are the same as those of Example 16, except that 0.003 mol of hydroxylamine-O-sulfonic acid is added. The conversion rate of methyl p-tolylcarbamate is 71.69%, the yield of methyl 2-amino-4-methylphenylcarbamate is 23.95%, and the yield of methyl 3-amino-4-methylphenylcarbamate is 9.37%.

[0047] Example 28: The other steps were the same as in Example 16, except that 0.004 mol of hydroxylamine-O-sulfonic acid was added. The conversion rate of methyl p-tolylcarbamate was 74.98%, the yield of methyl 2-amino-4-methylphenylcarbamate was 21.99%, and the yield of methyl 3-amino-4-methylphenylcarbamate was 7.65%.

[0048] Example 29: The other steps were the same as Example 16, except that the ratio of the added acidic medium was formic acid: water = 15:5. The conversion rate of methyl p-tolylcarbamate was 28.55%, the yield of methyl 2-amino-4-methylphenylcarbamate was 8.68%, and the yield of methyl 3-amino-4-methylphenylcarbamate was 4.44%.

[0049] Example 30: The other steps were the same as Example 16, except that the ratio of the added acidic medium was propionic acid: water = 15:5. The conversion rate of methyl p-tolylcarbamate was 23.72%, the yield of methyl 2-amino-4-methylphenylcarbamate was 12.25%, and the yield of methyl 3-amino-4-methylphenylcarbamate was 4.18%.

[0050] Example 31: The other steps were the same as Example 16, except that the ratio of the added acidic medium was hydrochloric acid: acetic acid: water = 3:12:5. The conversion rate of methyl p-tolylcarbamate was 32.94%, the yield of methyl 2-amino-4-methylphenylcarbamate was 1.55%, and the yield of methyl 3-amino-4-methylphenylcarbamate was 0.75%.

[0051] Example 32: The other steps were the same as Example 16, except that the ratio of the added acidic medium was sulfuric acid: acetic acid: water = 3:12:5. The conversion rate of methyl p-tolylcarbamate was 66.87%, the yield of methyl 2-amino-4-methylphenylcarbamate was 0.85%, and the yield of methyl 3-amino-4-methylphenylcarbamate was 0.32%.

[0052] Example 33: The other steps were the same as Example 16, except that the ratio of the added acidic medium was phosphoric acid: acetic acid: water = 3:12:5. The conversion rate of methyl p-tolylcarbamate was 40.42%, the yield of methyl 2-amino-4-methylphenylcarbamate was 21.05%, and the yield of methyl 3-amino-4-methylphenylcarbamate was 10.72%.

[0053] Example 34: The other steps were the same as Example 16, except that the ratio of the added acidic medium was acetic acid: water = 5:15. The conversion rate of methyl p-tolylcarbamate was 30.28%, the yield of methyl 2-amino-4-methylphenylcarbamate was 14.32%, and the yield of methyl 3-amino-4-methylphenylcarbamate was 7.18%.

[0054] Example 35: The other steps were the same as Example 16, except that the ratio of the added acidic medium was acetic acid: water = 10:10. The conversion rate of methyl p-tolylcarbamate was 52.65%, the yield of methyl 2-amino-4-methylphenylcarbamate was 18.62%, and the yield of methyl 3-amino-4-methylphenylcarbamate was 8.61%.

[0055] Example 36: The other steps were the same as Example 16, except that the ratio of the added acidic medium was acetic acid: water = 16:4. The conversion rate of methyl p-tolylcarbamate was 52.65%, the yield of methyl 2-amino-4-methylphenylcarbamate was 22.94%, and the yield of methyl 3-amino-4-methylphenylcarbamate was 7.81%.

[0056] Example 37: The other steps were the same as those of Example 16, except that the reaction time was 0.5 h. The conversion rate of methyl p-tolylcarbamate was 81.67%, the yield of methyl 2-amino-4-methylphenylcarbamate was 15.99%, and the yield of methyl 3-amino-4-methylphenylcarbamate was 6.37%.

[0057] Example 38: The other steps were the same as those of Example 16, except that the reaction time was 0.75 h. The conversion rate of methyl p-tolylcarbamate was 78.59%, the yield of methyl 2-amino-4-methylphenylcarbamate was 16.34%, and the yield of methyl 3-amino-4-methylphenylcarbamate was 8.32%.

[0058] Example 39: The other steps were the same as Example 16, except that the reaction time was 1.5 h. The conversion rate of methyl p-tolylcarbamate was 78.59%, the yield of methyl 2-amino-4-methylphenylcarbamate was 14.38%, and the yield of methyl 3-amino-4-methylphenylcarbamate was 7.18%.

[0059] Example 40: The other steps were the same as in Example 16, except that the reaction temperature was 50° C. The conversion rate of methyl p-tolylcarbamate was 77.55%, the yield of methyl 2-amino-4-methylphenylcarbamate was 8.55%, and the yield of methyl 3-amino-4-methylphenylcarbamate was 3.69%.

[0060] Example 41: The other steps were the same as in Example 16, except that the reaction temperature was 70° C. The conversion rate of methyl p-tolylcarbamate was 73.56%, the yield of methyl 2-amino-4-methylphenylcarbamate was 14.56%, and the yield of methyl 3-amino-4-methylphenylcarbamate was 5.26%.

[0061] Example 42: The other steps were the same as in Example 16, except that the reaction temperature was 80° C. The conversion rate of methyl p-tolylcarbamate was 70.82%, the yield of methyl 2-amino-4-methylphenylcarbamate was 8.51%, and the yield of methyl 3-amino-4-methylphenylcarbamate was 3.26%.

[0062] It can be seen from the above examples that the catalytic system is simple to operate, the catalyst is easily available and has good catalytic effect, and is easy to separate from the reaction system. By analyzing the data in the examples, the most active catalyst is ferrous sulfate, and the reaction conversion rate and yield are high under the experimental conditions of 60°C, methyl p-tolylcarbamate (0.002mmol), hydroxylamine-O-sulfonic acid (0.0036mol), ferrous sulfate (0.0003mol), acetic acid and water in a volume ratio of 15:5.

[0063] Matters not covered by the present invention are known technologies.

Claims

1. A method for synthesizing amino-methyl-phenylcarbamate compounds from p-toluidine, characterized in that the method comprises the following steps: The first step is to prepare methyl p-toluene carbamate from p-toluidine Add p-toluidine, the first catalyst and dimethyl carbonate into a high-pressure reactor, seal it, and react it under an oxygen-free atmosphere at 110-180° C. for 2-10 hours with stirring to obtain methyl p-tolylcarbamate; in, The molar ratio is: dimethyl carbonate: p-toluidine = 5-30; the first catalyst is an organic salt catalyst, p-toluidine: first catalyst (calculated as metal atoms) = 10-200; The first catalyst is anhydrous zinc acetate, zinc acetate dihydrate or manganese acetate; The second step is to prepare 2-amino-4-methylphenylcarbamate and 3-amino-4-methylphenylcarbamate from methyl p-tolylcarbamate Adding methyl p-tolylcarbamate, a second catalyst, hydroxylamine-O-sulfonic acid and an acidic medium into a reactor, reacting at 40-90° C. under normal pressure with constant temperature stirring for 0.25-3 hours, separating the organic phase in the reaction solution to obtain products methyl 2-amino-4-methylphenylcarbamate and methyl 3-amino-4-methylphenylcarbamate; The material molar ratio is: methyl p-tolylcarbamate: hydroxylamine-O-sulfonic acid = 0.1-5, and the molar ratio is: the second catalyst (in terms of iron atoms or vanadium atoms): methyl p-tolylcarbamate = 0.01-0.6; Add 0.001-0.010 mol of methyl p-tolylcarbamate to every 15 mL of acidic medium; The second catalyst is ferrous sulfate, ferrous chloride, ferric chloride or ammonium metavanadate; The acidic medium consists of lower fatty acids and water, or lower fatty acids, water and inorganic acids; the volume percentage of lower fatty acids is 17% to 83%, the volume percentage of water is 17% to 83%, and the volume percentage of inorganic acids is 0 to 15%.

2. The method for synthesizing amino-methyl-phenylcarbamate compounds from p-toluidine as claimed in claim 1, characterized in that in the first step, the material ratio is dimethyl carbonate: p-toluidine = 10-25; p-toluidine: first catalyst (in terms of metal atoms) = 15-150; the reaction temperature is 130-160°C; and the reaction time is 2-8h.

3. The method for synthesizing amino-methyl-phenylcarbamate compounds from p-toluidine as claimed in claim 1, characterized in that in the second step, the reaction temperature is 50-80° C. and the reaction time is 0.5-1.5 h; the acidic medium consists of acetic acid: water = 5:15-16:4; the molar ratio of the catalyst to methyl p-tolylcarbamate is 0.02-0.5; and the ratio of methyl p-tolylcarbamate to hydroxylamine-O-sulfonic acid is 0.25-4.

2.

4. The method for synthesizing amino-methyl-phenylcarbamate compounds from p-toluidine as claimed in claim 1, wherein in the second step, the lower fatty acids are formic acid, acetic acid or propionic acid.

5. The method for synthesizing amino-methyl-phenylcarbamate compounds from p-toluidine as claimed in claim 1, characterized in that The inorganic acid is hydrochloric acid, sulfuric acid or phosphoric acid.

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