阅读说明：本技术 一种利用高沸点极性溶剂分离甘氨酸与氯化铵混晶的方法 (Method for separating mixed crystals of glycine and ammonium chloride by using high-boiling-point polar solvent ) 是由 任丽君 武金丹 邴威瀚 赵文平 杨光 杨利强 刘新伟 王聪 杨克俭 霍瑜姝 梁秀 于 2019-12-11 设计创作，主要内容包括：本发明提供了一种利用高沸点极性溶剂分离甘氨酸与氯化铵混晶的方法,主要包括以下步骤：往甘氨酸与氯化铵混晶中加入水和高沸点极性溶剂,使得甘氨酸沉淀析出,氯化铵溶解在混合溶剂中,经过滤、干燥等步骤得到甘氨酸产品；析出甘氨酸后的剩余溶液为氯化铵、水、高沸点极性溶剂的混合液,将混合液中的水蒸发,使得氯化铵结晶析出,得到氯化铵产品。本发明所提供的分离方法,能够有效降低利用传统低沸点溶剂进行分离的复杂度,并且分离效果好,甘氨酸和氯化铵的回收率均可达95％以上,纯度均可达99％以上,同时能降低甘氨酸生产过程中混晶分离工段的设备投资,降低能耗,减少溶剂使用量以及降低对环境的危害。(The invention provides a method for separating mixed crystals of glycine and ammonium chloride by using a high-boiling-point polar solvent, which mainly comprises the following steps: adding water and a high-boiling-point polar solvent into the mixed crystal of glycine and ammonium chloride to precipitate glycine, dissolving ammonium chloride in the mixed solvent, and filtering, drying and the like to obtain a glycine product; and (3) the residual solution after the glycine is separated out is a mixed solution of ammonium chloride, water and a high-boiling-point polar solvent, and water in the mixed solution is evaporated to separate out ammonium chloride crystals, so that an ammonium chloride product is obtained. The separation method provided by the invention can effectively reduce the complexity of separation by using the traditional low-boiling point solvent, has good separation effect, can ensure that the recovery rates of the glycine and the ammonium chloride can reach more than 95 percent, and the purity can reach more than 99 percent, and can reduce the equipment investment of a mixed crystal separation section in the glycine production process, reduce the energy consumption, reduce the using amount of the solvent and reduce the harm to the environment.)

1. A method for separating mixed crystals of glycine and ammonium chloride by using a high-boiling-point polar solvent is characterized in that the high-boiling-point polar solvent is a polar solvent with a boiling point of above 130 ℃, and comprises the following steps:

(1) adding water and a high-boiling-point polar solvent into mixed crystal of glycine and ammonium chloride, wherein glycine is insoluble to obtain suspension, and separating glycine precipitate and solution by a solid-liquid separation method to obtain glycine;

(2) evaporating water in the solution to separate out ammonium chloride precipitate;

(3) separating the ammonium chloride precipitate and the high-boiling-point polar solvent by a solid-liquid separation method to obtain the ammonium chloride precipitate.

2. The method for separating the mixed crystal of glycine and ammonium chloride by using the high-boiling polar solvent as claimed in claim 1, wherein: the high-boiling-point polar solvent is a mixed solvent of one or more of N-methyl pyrrolidone (NMP), N, N '-Dimethylformamide (DMF), N, N' -dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), gamma-butyrolactone (GBL), hexamethyl phosphoramidite (HMPT), hexaethyl phosphoramidite (HEPT), ethylene glycol and glycerol.

3. The method for separating the mixed crystal of glycine and ammonium chloride by using the high-boiling polar solvent as claimed in claim 1, wherein: the mass sum of the water and the high-boiling-point polar solvent in the step (1) is 5-10 times of the mass sum of the mixed crystal of the glycine and the ammonium chloride.

4. The method for separating the mixed crystal of glycine and ammonium chloride by using the high-boiling polar solvent as claimed in claim 1, wherein: the mass of the high-boiling polar solvent in the step (1) is 50-95% of the total mass of the water and the high-boiling polar solvent.

5. The method for separating the mixed crystal of glycine and ammonium chloride by using the high-boiling polar solvent as claimed in claim 1, wherein: step (1) is to obtain suspension at the temperature of 20-90 ℃.

6. The method for separating the mixed crystal of glycine and ammonium chloride by using the high-boiling polar solvent as claimed in claim 1, wherein: the evaporation mode of the water in the step (2) is reduced pressure evaporation or normal pressure evaporation, and the evaporation temperature is 30-120 ℃.

7. The method for separating the mixed crystal of glycine and ammonium chloride by using the high-boiling polar solvent as claimed in claim 1, wherein: the solid-liquid separation means in the step (1) and the step (3) is filtration or centrifugation or suction filtration.

8. The method for separating the mixed crystal of glycine and ammonium chloride by using the high-boiling polar solvent as claimed in claim 1, wherein: the high boiling point polar solvent in the step (3) can be returned to the step (1) for recycling; after the solvent is circularly used for a plurality of times, the high boiling point polar solvent is recovered by a reduced pressure distillation mode, and the recovered high boiling point polar solvent can be reused for the mixed crystal separation of new glycine and ammonium chloride.

9. The method for separating the mixed crystal of glycine and ammonium chloride by using the high-boiling polar solvent as claimed in claim 8, wherein: the recycling frequency of the high-boiling polar solvent is 5 to 30 times.

10. The method for separating the mixed crystal of glycine and ammonium chloride by using the high-boiling polar solvent as claimed in claim 8, wherein: the reduced pressure distillation temperature is 60-150 ℃.

Technical Field

The invention belongs to the technical field of chemical separation, and particularly relates to a method for separating mixed crystals of glycine and ammonium chloride by using a high-boiling-point polar solvent.

Background

Glycine is an important fine chemical intermediate, and is widely applied to the fields of food, medicine, pesticide, feed additives and the like. At present, glycine produced in China is mainly used for synthesizing herbicide glyphosate. At present, the industrial production methods at home and abroad mainly comprise two routes of a chloroacetic acid ammonolysis method and a Scherrer's method. The Strand method using formaldehyde and sodium cyanide as main raw materials is also a method generally adopted abroad, although the cost is lower, the technology is not mature at home at present, and toxic cyanide is needed, and the requirements on transportation, storage and use are harsh, so that the chloroacetic acid ammonolysis method is mainly adopted at home at present, the process route is mature, the equipment is simple, the environmental pollution is less, but the defects of high energy consumption, low yield and the like exist, and the biggest problem is that the catalyst urotropine is difficult to recover, so that the cost is further increased.

Chinese patent CN 1340498A reports that glycine is prepared by performing ammonolysis reaction of chloroacetic acid in an alcohol solution to obtain a mixed crystal of ammonium chloride and glycine, referred to as mixed crystal for short. The mixed crystal is separated by using a water/alcohol mixed solvent, and in the process of separating ammonium chloride, the alcohol solvent is required to be evaporated firstly, then water is evaporated, and finally the ammonium chloride is obtained, so that the process is complex; meanwhile, a large amount of low-boiling-point alcohol solvent needs to be consumed in the process, a large amount of energy needs to be consumed for recovering the low-boiling-point solvent, and meanwhile, the low-boiling-point solvent is easy to volatilize in the treatment process and enter the environment, so that the ecological environment is harmed, and a plurality of defects exist.

Disclosure of Invention

In order to solve the defects of the prior art, the invention provides a production process for separating mixed crystals of glycine and ammonium chloride by using a high-boiling-point polar solvent, so that the separation efficiency is improved, the separation difficulty is reduced, the energy consumption in the separation process is reduced, and the harm to the environment is reduced.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

a method for separating mixed crystals of glycine and ammonium chloride by using a high-boiling-point polar solvent, wherein the high-boiling-point polar solvent refers to a polar solvent with a boiling point of above 130 ℃, and comprises the following steps:

(1) water and high boiling polar solvent are added into mixed crystal of glycine and ammonium chloride, and the mixture is stirred to assist dissolution at 20-90 deg.c, preferably 40-90 deg.c. Preferably, water is added into the mixed crystal of glycine and ammonium chloride to dissolve the mixed crystal of glycine and ammonium chloride, and then the high-boiling-point polar solvent is added. In a mixed solvent composed of water and a high-boiling polar solvent, the solubility of glycine is different from that of ammonium chloride, the ammonium chloride is dissolved, and the glycine is insoluble or slightly soluble to form a suspension, thereby obtaining the glycine.

(2) Separating glycine precipitate and solution by solid-liquid separation, and drying glycine to obtain glycine product.

(3) The water in the solution is removed by adopting a method of reduced pressure evaporation or normal pressure evaporation, and the evaporation temperature is 30-120 ℃, and preferably 50-120 ℃.

(4) Along with the evaporation of water, because the ammonium chloride is insoluble in the high-boiling polar solvent, the ammonium chloride gradually precipitates out, the ammonium chloride precipitate and the high-boiling polar solvent are separated by a solid-liquid separation method to obtain the ammonium chloride precipitate, and the ammonium chloride product is obtained after drying.

Further, the high boiling polar solvent used in step (1) is a mixed solvent of one or more components selected from the group consisting of N-methylpyrrolidone (NMP), N '-Dimethylformamide (DMF), N' -dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), γ -butyrolactone (GBL), Hexamethylphosphoramide (HMPT), Hexaethylphosphonotriamide (HEPT), ethylene glycol, and glycerol. Preferred high boiling polar solvents are mixed solvents of one or more of N-methylpyrrolidone (NMP), N, N' -Dimethylformamide (DMF), dimethyl sulfoxide (DMSO), gamma-butyrolactone (GBL), Hexamethylphosphoramidite (HMPT), ethylene glycol.

Further, glycine and ammonium chloride mixed crystals adopted in the step (1) are mixed, and the molar ratio of glycine to ammonium chloride is 1: 1.

Further, the mass sum of the water and the high-boiling polar solvent in the step (1) is 5 to 10 times, preferably 6 to 10 times of the mass sum of the mixed crystal of the glycine and the ammonium chloride.

Further, the mass of the high-boiling polar solvent in the step (1) is 50 to 95%, preferably 70 to 90% of the total mass of the water and the high-boiling polar solvent.

Further, the solid-liquid separation means in the step (1) and the step (3) is any means capable of separating a solid from a liquid, such as filtration, centrifugation, suction filtration, or the like.

Further, the high-boiling-point polar solvent in the step (3) can be returned to the step (1) for cyclic application, the number of cyclic application is 5 to 30, a good separation effect can be achieved, and the preferable number of application is 5 to 20.

Further, after the high-boiling-point polar solvent in the step (3) is recycled for several times, the high-boiling-point polar solvent is recovered in a reduced pressure distillation mode, the reduced pressure distillation temperature is 60-150 ℃, and the recovered high-boiling-point polar solvent can be reused for new mixed crystal separation of glycine and ammonium chloride.

Compared with the prior art, the method for separating the mixed crystal of glycine and ammonium chloride by using the high-boiling-point polar solvent has the following advantages:

1. compared with the prior art, when the ammonium chloride is recovered, the ammonium chloride precipitate can be obtained only by evaporating water, and a high-boiling-point polar solvent is not required to be evaporated, so that the process is saved, and the process difficulty and the energy consumption are reduced;

2. the recovery rate and the purity of the glycine and the ammonium chloride are high, the product loss is reduced, and the product quality is improved;

3. the polar solvent with high boiling point is difficult to volatilize, thus reducing the harm to the environment on one hand, reducing the loss of the solvent on the other hand and saving the cost.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention.

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.