阅读说明：本技术 共反应器制备n,n’-二环己基碳二亚胺的方法 (Method for preparing N, N' -dicyclohexylcarbodiimide by using co-reactor ) 是由 封小琴 陈小君 于 2019-09-25 设计创作，主要内容包括：本发明公开了一种共反应器制备N,N’-二环己基碳二亚胺的方法。所述方法包括在同一反应器内将环己胺的水溶液维持在强碱性环境,再向同一个反应器中加入二硫化碳,随后加入次氯酸钠进行氧化,进而得到N,N’-二环己基碳二亚胺。本发明的方法通过共反应器反应简化了工艺流程、避免剧毒有害气体的生成、降低生产的安全风险,从而实现绿色安全生产的目的。(The invention discloses a method for preparing N, N' -dicyclohexylcarbodiimide by using a co-reactor. The method comprises the steps of maintaining an aqueous solution of cyclohexylamine in a strongly alkaline environment in the same reactor, adding carbon disulfide into the same reactor, and then adding sodium hypochlorite for oxidation to obtain the N, N' -dicyclohexylcarbodiimide. The method simplifies the process flow through the reaction of the co-reactor, avoids the generation of highly toxic and harmful gases, and reduces the safety risk of production, thereby realizing the purpose of green and safe production.)

1. A method for preparing N, N' -dicyclohexylcarbodiimide, the method comprising the steps of:

1) obtaining an alkaline aqueous solution of cyclohexylamine;

2) adding carbon disulfide into the alkaline aqueous solution of cyclohexylamine obtained in the step 1) for reaction;

3) adding sodium hypochlorite into the reaction system obtained in the step 2) for oxidation reaction;

4) obtaining the N, N' -dicyclohexylcarbodiimide.

2. The process according to claim 1, characterized in that the basic aqueous solution of cyclohexylamine obtained in step 1) has a pH higher than 12; preferably the pH is above 13; more preferably the pH is above 14.

3. The process according to claim 1, wherein the concentration of hydroxide ions in the aqueous alkaline solution of cyclohexylamine obtained in step 1) is greater than 0.01mol/L, preferably greater than 0.1mol/L, more preferably greater than 0.2mol/L, greater than 0.3mol/L, greater than 0.4mol/L, greater than 0.5mol/L, greater than 0.6mol/L, greater than 0.7mol/L, greater than 0.8mol/L or greater than 0.9mol/L, most preferably greater than 1 mol/L.

4. The process according to claim 1, wherein in step 2), the reaction is carried out at 10 to 40 ℃, preferably 30 ℃.

5. The method of claim 1, wherein in step 2), the molar ratio of carbon disulfide to cyclohexylamine is from 1:1.6 to 1: 2.5; preferably 1:2.

6. The process of claim 1 wherein step 3) is performed directly after the carbon disulfide addition of step 2) is complete.

7. The process according to claim 1, wherein in step 3), the reaction is carried out at 40 to 80 ℃, preferably 45 ℃.

8. The method of claim 1, wherein in step 3), the molar ratio of sodium hypochlorite to cyclohexylamine is from 1.5:1 to 6: 1; preferably 2: 1.

9. The method of any one of claims 1-8, wherein all steps are performed in the same reactor.

10. The method of claim 1, further comprising step 5): rectifying the N, N '-dicyclohexylcarbodiimide obtained in the step 4) to obtain refined N, N' -dicyclohexylcarbodiimide.

Technical Field

The present invention relates to the field of chemical synthesis. In particular, the invention relates to a method for preparing N, N' -dicyclohexylcarbodiimide by using a co-reactor.

Background

N, N' -dicyclohexylcarbodiimide is a white to off-white solid or a colorless to yellowish liquid. It can be used for the synthesis and dehydration of amikacin and amino acid, is a good low-temperature biochemical dehydrating agent, can be prepared by short-time reaction at normal temperature, and can also be used for the synthesis of acid, anhydride, aldehyde, ketone and the like.

Currently, in industrial production of N, N '-dicyclohexylcarbodiimide, cyclohexylamine and carbon disulfide are condensed in a solvent xylene, hydrogen sulfide is removed to obtain N, N' -dicyclohexylthiourea, the N, N '-dicyclohexylthiourea is oxidized in a solvent benzene with sodium hypochlorite and a phase transfer catalyst to obtain a crude product of the N, N' -dicyclohexylcarbodiimide, and the crude product of the N, N '-dicyclohexylcarbodiimide is rectified to obtain the N, N' -dicyclohexylcarbodiimide. Also, it is disclosed that the synthesis of N, N '-dicyclohexylcarbodiimide uses water as solvent, the cyclohexylamine and carbon disulfide are condensed and the hydrogen sulfide is removed under pressure, after cooling, the N, N' -dicyclohexylthiourea is obtained by filtration. Mixing N, N '-dicyclohexyl thiourea and an auxiliary agent, adding a sodium hypochlorite solution, heating for layering, adding a hot sodium sulfide solution into an organic phase, heating for layering while hot, washing the organic phase twice with the hot sodium hydroxide solution to obtain a crude product, and rectifying to obtain a finished product N, N' -dicyclohexyl carbodiimide.

In the existing synthesis method, an organic solvent is required to be used, or the synthesis is carried out under a pressure condition, and the generation of virulent hydrogen sulfide gas is inevitable, and the generated hydrogen sulfide gas needs to be absorbed by liquid caustic soda, so that dangerous waste, namely the sodium sulfide, is generated.

Therefore, a method for producing N, N' -dicyclohexylcarbodiimide, which has the advantages of simplified process flow, simple production equipment, reduced cost and environmental friendliness, is urgently needed in the field.

Disclosure of Invention

The invention aims to provide a method for producing N, N '-dicyclohexylcarbodiimide, which can produce N, N' -dicyclohexylcarbodiimide by simple process and equipment and is environment-friendly, thereby realizing the aim of green and safe production.

In order to achieve the above object, the present invention provides a method for preparing N, N' -dicyclohexylcarbodiimide, the method comprising the steps of:

1) obtaining an alkaline aqueous solution of cyclohexylamine;

2) adding carbon disulfide into the alkaline aqueous solution of cyclohexylamine obtained in the step 1) for reaction;

3) adding sodium hypochlorite into the reaction system obtained in the step 2) for oxidation reaction;

4) obtaining the N, N' -dicyclohexylcarbodiimide.

In a specific embodiment, the pH of the aqueous alkaline solution of cyclohexylamine obtained in step 1) is higher than 12; preferably the pH is above 13; more preferably the pH is above 14.

In a specific embodiment, the hydroxide ion concentration in the alkaline aqueous solution of cyclohexylamine obtained in step 1) is greater than 0.01mol/L, preferably greater than 0.1mol/L, more preferably greater than 0.2mol/L, greater than 0.3mol/L, greater than 0.4mol/L, greater than 0.5mol/L, greater than 0.6mol/L, greater than 0.7mol/L, greater than 0.8mol/L or greater than 0.9mol/L, most preferably greater than 1 mol/L.

In a preferred embodiment, the concentration of hydroxide ions in the alkaline aqueous solution of cyclohexylamine obtained in step 1) is from 0.01mol/L to 1mol/L, from 0.1mol/L to 1mol/L, from 0.2mol/L to 1mol/L, from 0.3mol/L to 1mol/L, from 0.4mol/L to 1mol/L, from 0.5mol/L to 1mol/L, from 0.6mol/L to 1mol/L, from 0.7mol/L to 1mol/L, from 0.8mol/L to 1mol/L, from 0.9mol/L to 1 mol/L.

In a preferred embodiment, in step 1), cyclohexylamine is mixed with an aqueous solution of sodium hydroxide, potassium hydroxide, thereby obtaining an alkaline aqueous solution of cyclohexylamine.

In a preferred embodiment, in step 1), cyclohexylamine is mixed with a 5% aqueous sodium hydroxide solution in a weight ratio of 1:4 to 1:8, preferably 1: 6.

In a particular embodiment, in step 2), the reaction is carried out at 10 to 40 ℃, preferably 30 ℃.

In a preferred embodiment, step 2) is carried out at about 1 atmosphere of pressure.

In a specific embodiment, in step 2), the molar ratio of carbon disulfide to cyclohexylamine is from 1:1.6 to 1: 2.5; preferably 1:2.

In a particular embodiment, step 3) is performed directly after the addition of carbon disulphide in step 2) is completed.

In a particular embodiment, in step 3), the reaction is carried out at 40 to 80 ℃, preferably 45 ℃.

In a specific embodiment, in step 3), the molar ratio of sodium hypochlorite to cyclohexylamine is from 1.5:1 to 6: 1; preferably 2: 1.

In a particular embodiment, all steps are performed in the same reactor.

In a particular embodiment, the method further comprises step 5): rectifying the N, N '-dicyclohexylcarbodiimide obtained in the step 4) to obtain refined N, N' -dicyclohexylcarbodiimide.

It is to be understood that within the scope of the present invention, the above-described features of the present invention and those specifically described below (e.g., in the examples) may be combined with each other to form new or preferred embodiments. Not to be reiterated herein, but to the extent of space.

Detailed Description

The inventors of the present invention have conducted extensive and intensive studies, and unexpectedly found that in the preparation process of N, N '-dicyclohexylcarbodiimide, by adding a base to a system of cyclohexylamine and water to maintain the system at a strong basicity, and then adding carbon disulfide, after the addition of carbon disulfide is completed, sodium hypochlorite can be directly added without heating to perform an oxidation reaction, thereby obtaining N, N' -dicyclohexylcarbodiimide. The preparation method of the invention simplifies the process flow, avoids the generation of highly toxic and harmful gases, reduces the safety risk of production and really realizes the purpose of green and safe production. In addition, the process of the invention improves the yield and purity of the final product. The present invention has been completed based on this finding.

In order to realize the aim of the invention, the invention discloses a method for preparing N, N-dicyclohexyl carbodiimide by using a co-reactor. Specifically, the process of the present invention mixes cyclohexylamine with an aqueous alkali solution, such as sodium hydroxide solution, to obtain an aqueous solution of cyclohexylamine having strong basicity; then adding carbon disulfide into the water solution of the strongly alkaline cyclohexylamine in the same reactor for reaction; after the carbon disulfide is dripped, the carbon disulfide is not required to be heated, and sodium hypochlorite is directly added into the same reactor for oxidation reaction; thereby obtaining N, N' -dicyclohexylcarbodiimide.

Based on the teachings of the present invention, those skilled in the art will recognize that the process of the present invention requires the initial addition of a base to maintain the alkalinity, especially the strong basicity, of the aqueous solution system of cyclohexylamine. Therefore, the strong basicity of the aqueous solution system of cyclohexylamine can be achieved by various technical means by those skilled in the art, and the present invention is not limited to the specific technical means for achieving the strong basicity of the aqueous solution system of cyclohexylamine. The person skilled in the art can adopt various technical means to make the pH value of the aqueous solution system of cyclohexylamine be higher than 12; preferably higher than 13; more preferably higher than 14. For example, a person skilled in the art can adopt various technical measures to make the concentration of hydroxide ions in the aqueous solution system of cyclohexylamine greater than 0.01mol/L, preferably greater than 0.1mol/L, more preferably greater than 0.2mol/L, greater than 0.3mol/L, greater than 0.4mol/L, greater than 0.5mol/L, greater than 0.6mol/L, greater than 0.7mol/L, greater than 0.8mol/L or greater than 0.9mol/L, and most preferably greater than 1 mol/L.

In a specific embodiment, the concentration of hydroxide ions in the alkaline aqueous solution of cyclohexylamine obtained in step 1) is 0.01mol/L-1mol/L, 0.1 mol/L-1mol/L, 0.2 mol/L-1mol/L, 0.3 mol/L-1mol/L, 0.4 mol/L-1mol/L, 0.5 mol/L-1mol/L, 0.6 mol/L-1mol/L, 0.7 mol/L-1mol/L, 0.8 mol/L-1mol/L, 0.9 mol/L-1mol/L, to ensure that the aqueous solution system of cyclohexylamine maintains strong alkalinity.

For example, in a specific embodiment, cyclohexylamine can be mixed with 5% aqueous sodium hydroxide at a weight ratio of 1:6 to maintain a proper alkaline environment. Of course, other means for maintaining the appropriate alkaline environment of the aqueous system of cyclohexylamine are known to those skilled in the art and need not be described in detail herein.

The method for preparing N, N' -dicyclohexylcarbodiimide of the present invention may be carried out at normal temperature and pressure, for example, at 10 to 40 deg.C, preferably 30 deg.C, at about one atmosphere pressure.

Based on the teachings of the present invention and the common general knowledge in the art, those skilled in the art know that the N, N '-dicyclohexylcarbodiimide obtained by the process of the present invention can be rectified to give a refined N, N' -dicyclohexylcarbodiimide.

The method of the invention can obtain high-quality N, N '-dicyclohexylcarbodiimide, for example, the molar yield of the N, N' -dicyclohexylcarbodiimide obtained by the method of the invention can reach 94%, and the purity is more than 99.0%.

The invention has the advantages that:

1. the method of the invention prepares the N, N' -dicyclohexylcarbodiimide in the same reactor, thereby simplifying the process flow and reducing the potential safety hazard in the replacement process of the reactor;

2. the method avoids the generation of highly toxic and harmful gas and hydrogen sulfide, and improves the safety in the production process;

3. the method of the invention avoids the generation of highly toxic hydrogen sulfide, does not need high temperature reaction, does not need filtration and drying steps;

4. the method can be carried out at normal temperature and normal pressure, so that the safety risk generated by the pressure container is reduced;

5. the method avoids the generation of dangerous chemical sodium sulfide, and converts the dangerous chemical sodium sulfide into the common sodium chloride and sodium sulfate, thereby really achieving the purpose of green and safe production.

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The experimental procedures, in which specific conditions are not noted in the following examples, are generally carried out under conventional conditions or conditions recommended by the manufacturers. Unless otherwise indicated, percentages and parts are percentages and parts by weight. The test materials and reagents used in the following examples are commercially available without specific reference.

Example 1.

Mixing 25g of cyclohexylamine with 150g of 5% alkaline water; and then 9.6g of carbon disulfide is added, the reaction is carried out at the temperature of 30 ℃, after the reaction is completed, 300g of 12 percent sodium hypochlorite is added for oxidation, the temperature is controlled to be 40-80 ℃, layering is carried out to obtain a crude product of the N, N '-dicyclohexylcarbodiimide, and the crude product of the N, N' -dicyclohexylcarbodiimide is obtained by rectification.

Comparative example 1 preparation of N, N' -dicyclohexylcarbodiimide by conventional method

The present inventors also prepared N, N' -dicyclohexylcarbodiimide using conventional methods in the art.

Mixing water and cyclohexylamine; then dropwise adding carbon disulfide into the aqueous solution of cyclohexylamine; after the carbon disulfide is dripped, heating and pressurizing (100 ℃ and 160 ℃, and the pressure is 0.1-0.6Mpa) to remove hydrogen sulfide; absorbing the generated hydrogen sulfide by using liquid alkali, and filtering to obtain N, N' -dicyclohexyl thiourea solid; adding an auxiliary agent into the N, N' -dicyclohexyl thiourea solid, and adding sodium hypochlorite to react to obtain a crude product of a final product containing sulfur; adding a sodium sulfide solution into the crude product containing sulfur to remove sulfur (the sulfur and the sodium sulfide generate sodium polysulfide); and adding sodium hydroxide solution to further remove sulfur and sodium polysulfide to obtain an organic layer, namely a crude product of the final product, and rectifying the crude product to obtain the product.

As can be seen from the conventional method for preparing the N, N' -dicyclohexylcarbodiimide in the field, the method does not need to use an organic solvent, can react at normal temperature and normal pressure, does not generate highly toxic hydrogen sulfide gas in the production process, and does not generate sodium sulfide which belongs to hazardous waste, thereby greatly reducing the safety risk of production. Only produce the salt waste water that contains sodium chloride and sodium sulfate in whole production process, whole reaction can go on in same reation kettle, and reaction condition is mild, and production facility simplifies, and the flow shortens, and manufacturing cost reduces, and waste gas absorption system is simpler, stink greatly reduced to realize simple, swift, green production.

All documents referred to herein are incorporated by reference into this application as if each were individually incorporated by reference. Furthermore, it should be understood that various changes and modifications of the present invention can be made by those skilled in the art after reading the above teachings of the present invention, and these equivalents also fall within the scope of the present invention as defined by the appended claims.