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CN-122010743-A - O-chlorobenzylamine synthesis method

CN122010743ACN 122010743 ACN122010743 ACN 122010743ACN-122010743-A

Abstract

The application relates to the technical field of organic synthetic chemistry, and particularly discloses a synthesis method of o-chlorobenzylamine. The method takes o-chlorobenzyl chloride, liquid ammonia and liquid alkali as raw materials, and the preparation process mainly comprises the steps of amination reaction, liquid ammonia recovery, alkali treatment deamination and product purification. The method comprises the steps of reacting liquid ammonia serving as a reaction medium with o-chlorobenzyl chloride at a low temperature and under a specific pressure in a high-pressure reaction kettle, evaporating and recovering the liquid ammonia for recycling, dissolving in water, adding alkali for dissociation, removing residual ammonia under negative pressure, standing for layering, separating an organic phase, dehydrating and filtering to obtain a high-purity o-chlorobenzyl chloride product. The method remarkably inhibits the occurrence of side reaction by constructing a solvent-free system and cooperatively controlling the reaction temperature, the material proportion and the post-treatment parameters, thereby realizing high-selectivity synthesis. The whole process has the advantages of simple and convenient operation, environmental protection, high resource utilization rate and easy industrialized implementation.

Inventors

  • ZOU GUANGDONG
  • GAO QI

Assignees

  • 辽宁龙田化工科技有限公司

Dates

Publication Date
20260512
Application Date
20260203

Claims (10)

  1. 1. A synthesis method of o-chlorobenzylamine is characterized by comprising the following steps: s1, in a high-pressure reaction kettle, liquid ammonia is used as a reaction medium and is subjected to amination reaction with o-chlorobenzyl chloride, and after the reaction is finished, the liquid ammonia is distilled out and recovered; s2, adding water into the reaction product obtained in the step S1 for dissolution, then adding liquid alkali, and removing ammonia under the negative pressure condition; and S3, standing and layering the materials treated in the step S2, separating an organic phase, and carrying out dehydration and solid-liquid separation on the organic phase to obtain the o-chlorobenzylamine.
  2. 2. The method for synthesizing o-chlorobenzyl amine according to claim 1, wherein in the step S1, the reaction temperature of the amination reaction is-30 ℃ to-20 ℃, the molar ratio of the o-chlorobenzyl chloride to liquid ammonia is 1:50 to 1:100, the o-chlorobenzyl chloride is pumped by a metering pump, the pumping pressure is 3bar to 8bar, the charging time is 0.4h to 0.6h, and after the charging is completed, the reaction is carried out at the reaction temperature for 1h.
  3. 3. The method for synthesizing o-chlorobenzylamine according to claim 1, wherein in the step S1, the system is cooled by evaporating part of liquid ammonia before the reaction, the pressure in the reaction kettle is reduced from 5bar to 7bar to 1.5bar to 2bar during the cooling process, and the liquid ammonia is distilled off at a heating rate of 5 ℃ per hour to 10 ℃ per hour after the reaction is completed.
  4. 4. A method for synthesizing o-chlorobenzyl amine according to claim 1, wherein in the step S2, the water is added in an amount of 3L/kg to 5L/kg based on the mass of o-chlorobenzyl, and the liquid alkali is a 32% sodium hydroxide aqueous solution in an amount of 90kg to 100kg based on each 100kg of o-chlorobenzyl.
  5. 5. The method for synthesizing o-chlorobenzylamine according to claim 1, wherein in the step S2, the negative pressure condition means that the absolute pressure of the system is lower than the normal pressure, the operation temperature for removing ammonia gas is 35-45 ℃, and the deamination time is 0.8-1.2 h.
  6. 6. A process for synthesizing o-chlorobenzylamine according to claim 5, wherein in step S3, the organic phase is dehydrated using anhydrous sodium sulfate, the amount of the anhydrous sodium sulfate added is 2kg to 4kg, the particle size of the anhydrous sodium sulfate is 50 μm to 200 μm based on 100kg of o-chlorobenzyl chloride, and the dehydration stirring time is 0.5h.
  7. 7. A method for synthesizing o-chlorobenzylamine according to claim 1, wherein in step S3, the solid-liquid separation is performed by suction filtration using a filter medium having a pore diameter of 0.1 μm to 1 μm and a vacuum pressure of-0.05 MPa to-0.09 MPa.
  8. 8. The method for synthesizing o-chlorobenzylamine according to claim 7, wherein in step S1, the mass content of water in the recovered liquid ammonia is less than or equal to 0.6%.
  9. 9. A method for synthesizing o-chlorobenzylamine according to claim 1, wherein in step S2, the stirring dissolution rate after adding water is 100rpm to 300rpm, and after removing ammonia gas, the mixture is left for 0.8h to 1.2h to conduct delamination.
  10. 10. A synthesis method of o-chlorobenzylamine according to claim 1, wherein in step S2, the removed ammonia gas is treated by water absorption at a temperature of 10 ℃ to 25 ℃ and in step S3, the standing delamination is carried out at an ambient temperature of 20 ℃ to 30 ℃.

Description

O-chlorobenzylamine synthesis method Technical Field The application relates to the technical field of organic synthetic chemistry, in particular to a synthesis method of o-chlorobenzylamine. Background The o-chlorobenzylamine is used as an important organic synthesis intermediate, is widely applied to the fields of medicines, pesticides, dyes and the like, and the rationality and environmental friendliness of the synthesis process directly influence the quality and production cost of related downstream products, so that the development of an efficient and clean o-chlorobenzylamine synthesis method has important industrial application value. At present, the method for synthesizing o-chlorobenzylamine by using halogenated hydrocarbon as a raw material mainly comprises a Gabriel synthesis method, a Delapine synthesis method and a method for directly reacting with ammonia water, and the methods are applied to certain industrial production. The existing synthesis method has obvious technical limitations, the Gabriel synthesis method needs to use polar organic solvents such as DMF (dimethyl formamide), so that VOCs are high in emission, the raw material cost is high, the separation and purification are complex, the Delapine synthesis method can generate a large amount of byproducts with low recovery value, so that the resource waste is caused, the operation procedure is complex, and the direct reaction with ammonia water is difficult to control due to side reaction, so that the method is easy to cause multi-amination reaction to generate impurities such as secondary amine and tertiary amine, so that the selectivity of target products is low, and the utilization efficiency of recovered ammonia gas is low. Among the problems, the most core technical pain point is that the existing method is difficult to inhibit the multi-amination side reaction, improve the reaction selectivity, simultaneously reduce the environment-friendly pressure brought by the use of an organic solvent, realize the efficient recycling of resources and limit the greenization and industrialization upgrading of the o-chlorobenzylamine synthesis process. Disclosure of Invention The application provides a method for synthesizing o-chlorobenzylamine, which aims to solve the problems that in the prior art, the synthesis of o-chlorobenzylamine is difficult to achieve the effects of multi-amination side reaction inhibition, reaction selectivity improvement, environmental protection and resource recycling. A synthesis method of o-chlorobenzylamine comprises the following steps: s1, in a high-pressure reaction kettle, liquid ammonia is used as a reaction medium and is subjected to amination reaction with o-chlorobenzyl chloride, and after the reaction is finished, the liquid ammonia is distilled out and recovered; s2, adding water into the reaction product obtained in the step S1 for dissolution, then adding liquid alkali, and removing ammonia under the negative pressure condition; and S3, standing and layering the materials treated in the step S2, separating an organic phase, and carrying out dehydration and solid-liquid separation on the organic phase to obtain the o-chlorobenzylamine. By adopting the technical scheme, liquid ammonia is selected as a reaction medium and an amination reagent at the same time, an organic solvent in the traditional synthesis is abandoned, and a proper environment is constructed for the amination reaction by means of the physical and chemical characteristics of the liquid ammonia. The liquid ammonia evaporation can quickly cool the system to a target interval, and the high molar ratio is matched, so that sufficient amino sites can be provided to ensure sufficient reaction, primary amine generated by low-temperature inhibition can be further condensed with raw materials, and the multi-amination side reaction is reduced. The metering pump is adopted to stably convey raw materials, abnormal reaction caused by overhigh local concentration can be avoided, and the uniformity of the system is improved. And adding a certain amount of water into the reaction product to fully dissolve salts, subsequently adding liquid alkali to neutralize acidic substances and promote the dissociation of o-chlorobenzylamine, and absorbing ammonia gas removed by negative pressure heating to prepare ammonia water for secondary use. After standing and layering, dehydration is carried out by anhydrous sodium sulfate, impurities are removed by pumping filtration by a filter material with specific precision, the technical means of each step are closely cooperated, a simple and efficient synthesis system is constructed, and the smooth reaction and effective separation of products are ensured. Preferably, in the step S1, the reaction temperature of the amination reaction is between-30 ℃ and-20 ℃, the molar ratio of the o-chlorobenzyl chloride to the liquid ammonia is between 1:50 and 1:100, the o-chlorobenzyl chloride is pumped by a metering pump, the pump