阅读说明：本技术 一种制备1,6-六亚甲基二氨基甲酸乙酯的方法 (Method for preparing 1, 6-hexamethylene dicarbamate ) 是由 李会泉 袁浠焘 王利国 贺鹏 曹妍 于 2021-09-16 设计创作，主要内容包括：本发明提供了一种制备1,6-六亚甲基二氨基甲酸乙酯的方法,所述方法包括如下步骤：(1)混合碳酸二乙酯、1,6-己二胺和固体催化剂进行反应,所述反应后的物料经固液分离,得到反应后溶液；(2)步骤(1)所述反应后溶液经萃取和结晶,得到1,6-六亚甲基二氨基甲酸乙酯；步骤(1)所述固体催化剂包括锰基催化剂和/或水滑石基催化剂。本发明所述方法绿色安全,反应条件温和,操作简便,制备得到的1,6-六亚甲基二氨基甲酸乙酯最高质量收率可达99.5％以上,具有良好的工业化应用前景。(The invention provides a method for preparing 1, 6-hexamethylene dicarbamate, which comprises the following steps: (1) mixing diethyl carbonate, 1, 6-hexamethylenediamine and a solid catalyst to react, and performing solid-liquid separation on the reacted material to obtain a reacted solution; (2) extracting and crystallizing the solution obtained in the step (1) after the reaction to obtain 1, 6-hexamethylene dicarbamate; the solid catalyst in the step (1) comprises a manganese-based catalyst and/or a hydrotalcite-based catalyst. The method disclosed by the invention is green and safe, mild in reaction conditions and simple and convenient to operate, and the highest mass yield of the prepared 1, 6-hexamethylene dicarbamate can reach more than 99.5%, so that the method has a good industrial application prospect.)

1. A process for the preparation of ethyl 1, 6-hexamethylene dicarbamate comprising the steps of:

(1) mixing diethyl carbonate, 1, 6-hexamethylenediamine and a solid catalyst to react, and performing solid-liquid separation on the reacted material to obtain a reacted solution;

(2) extracting and crystallizing the solution obtained in the step (1) in sequence to obtain 1, 6-hexamethylene dicarbamate;

the solid catalyst in the step (1) comprises a manganese-based catalyst and/or a hydrotalcite-based catalyst.

2. The method of claim 1, wherein the manganese-based catalyst comprises MnO₂、Mn₂O₃、Mn(CH₃COO)₂Or Mn (CH)₃COO)₂·4H₂Any one or a combination of at least two of O, preferably Mn (CH)₃COO)₂And/or Mn (CH)₃COO)₂·4H₂O；

Preferably, the hydrotalcite-based catalyst comprises any one or a combination of at least two of Ce-modified Zn-Al hydrotalcite, Ce-modified Mg-Al hydrotalcite, La-modified Zn-Al hydrotalcite or La-modified Mg-Al hydrotalcite.

3. The process according to claim 1 or 2, wherein the diethyl carbonate of step (1) is subjected to molecular sieve separation of impurities before being mixed;

preferably, the pore diameter of the molecular sieve is 0.3-0.5 nm.

4. The process according to any one of claims 1 to 3, wherein the molar ratio of diethyl carbonate to 1, 6-hexanediamine in step (1) is (10-50): 1;

preferably, the amount of the solid catalyst is 5-24% of the mass fraction of 1, 6-hexanediamine, and preferably 5-20%.

5. The process according to any one of claims 1 to 4, wherein the temperature of the reaction in step (1) is 40 to 140 ℃, preferably 80 to 140 ℃;

preferably, the reaction time is 2-10 h, preferably 6-10 h.

6. The process according to any one of claims 1 to 5, wherein the reaction of step (1) is carried out under stirring;

preferably, the stirring speed is 400-800 r/min.

7. The method according to any one of claims 1 to 6, wherein a protective gas purge is performed during the reaction of step (1);

preferably, the shielding gas comprises any one of nitrogen, argon or helium or a combination of at least two thereof;

preferably, the purging rate is 100-600 mL/min.

8. The method according to any one of claims 1 to 7, wherein the extractant for the extraction in step (2) comprises any one or a combination of at least two of benzene, toluene, p-xylene, ethyl acetate, butyl acetate, dihexyl adipate, dihexyl azelate, dibutyl sebacate, or dioctyl sebacate;

preferably, the volume ratio of the extracting agent to the solution after reaction is (2-10): 1, and preferably (6-8): 1.

9. The method according to any one of claims 1 to 8, wherein the temperature of the crystallization in step (2) is-30 to 10 ℃, preferably 0 to 10 ℃;

preferably, the crystallization time is 3-12 h, preferably 5-12 h;

preferably, the crystallization is followed by solid-liquid separation.

10. A method according to any one of claims 1 to 9, characterized in that the method comprises the steps of:

(1) separating impurities from diethyl carbonate through a molecular sieve with the aperture of 0.3-0.5 nm, mixing diethyl carbonate, 1, 6-hexamethylene diamine and a solid catalyst according to the molar ratio of diethyl carbonate to 1, 6-hexamethylene diamine (10-50): 1 and the use amount of the solid catalyst being 5-24% of the mass fraction of 1, 6-hexamethylene diamine, reacting for 2-10 h at the temperature of 40-140 ℃ and the stirring rate of 400-800 r/min, purging protective gas at the speed of 100-600 mL/min in the reaction process, and performing solid-liquid separation on the reacted materials to obtain a solution after reaction;

(2) extracting according to the volume ratio of the extracting agent to the reacted solution of (2-10): 1, crystallizing an extract phase for 3-12 h at the temperature of-30-10 ℃, and performing solid-liquid separation after crystallization to obtain the 1, 6-hexamethylene dicarbamate.

Technical Field

The invention belongs to the technical field of organic chemical industry, and particularly relates to a method for preparing 1, 6-hexamethylene dicarbamate.

Background

Hexamethylene diisocyanate is the most widely used aliphatic isocyanate in the polyurethane industry field at present, is a polyurethane coating produced by important raw materials for producing polyurethane coatings and polyurethane elastomers, has the characteristics of no yellowing, strong weather resistance and the like, and is widely used in the fields of aviation, automobiles, buildings, woodware, plastics, leather and the like. Hexamethylene diisocyanate is also used as a drying alkyd resin cross-linking agent and a raw material of synthetic fibers as a raw material for producing polyurethane coatings, and is also used as a drying alkyd resin cross-linking agent and a raw material of synthetic fibers.

There are two main methods for producing hexamethylene diisocyanate: phosgene and non-phosgene processes. Phosgene method using highly toxic COCl₂The raw material is a byproduct, contains a large amount of HCl, has high requirement on the corrosion resistance of equipment, and is not suitable for being popularized and used in a large range. Among the non-phosgene methods, the thermal decomposition method of N-carbamate is the most promising method, and the main steps are firstly synthesizing an intermediate of N-carbamate and then thermally decomposing the intermediate into isocyanate.

US5789614A discloses a process for producing an aliphatic diisocyanate compound by reacting dimethyl carbonate with an aliphatic diamine in the presence of a sodium methoxide catalyst to produce the corresponding urethane compound, and an aliphatic diisocyanate compound can be produced in high yield. Within 48 hours after the completion of the preparation of the urethane compound, the urethane compound is thermally decomposed under reduced pressure in the high boiling point solvent. However, this method produces a large amount of by-products, resulting in a low yield of methyl 1, 6-hexamethylenedicarbamate.

CN1424309A discloses a method for preparing corresponding carbamate by catalytic carbonylation of amine and dimethyl carbonate, which adopts ionic liquid as solvent and catalyst system to synthesize corresponding carbamate by carbonylation of amine and dimethyl carbonate. For general aliphatic amine, the yield is more than 98%, and the purity is more than 98%. The method has the main characteristics of high reaction activity and simple and convenient operation, but the by-product methanol and the excessive raw material dimethyl carbonate in the process have azeotropic phenomenon and are difficult to separate materials.

CN102391153A discloses a method for preparing n-butyl hexamethylene dicarbamate, which comprises the steps of taking hexamethylene diamine and butyl carbamate as raw materials, taking oxysalt of metal zirconium as a main catalyst, taking one of oxysalts of zinc, manganese and nickel as an auxiliary catalyst, reacting at the temperature of 150-180 ℃, filtering and recovering the catalyst when the reaction is finished, and carrying out reduced pressure rectification on the filtrate to obtain a target product. The process has lowered reaction temperature and shortened reaction time, but the yield of n-butyl hexamethylene dicarbamate is low.

Therefore, it is desired to develop a method for producing hexamethylene dicarbamate with high yield of the target product, which can efficiently separate and recover the excessive amount of the raw material.

Disclosure of Invention

In view of the problems in the prior art, the invention aims to provide a method for preparing 1, 6-hexamethylene dicarbamate, wherein diethyl carbonate and 1, 6-hexamethylene diamine are reacted under the action of a solid catalyst, ethanol serving as a reaction byproduct does not generate azeotropy with residual raw material diethyl carbonate after the reaction, and excessive diethyl carbonate can be effectively separated and recovered; in addition, the catalyst in the method has high catalytic activity, and the 1, 6-hexamethylene dicarbamate with high yield is prepared, so that the method is suitable for large-scale industrial application.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a method for preparing 1, 6-hexamethylene dicarbamate, which comprises the following steps:

(1) mixing diethyl carbonate, 1, 6-hexamethylenediamine and a solid catalyst to react, and performing solid-liquid separation on the reacted material to obtain a reacted solution;

(2) extracting and crystallizing the solution obtained in the step (1) in sequence to obtain 1, 6-hexamethylene dicarbamate;

the solid catalyst in the step (1) comprises a manganese-based catalyst and/or a hydrotalcite-based catalyst.

According to the invention, diethyl carbonate and 1, 6-hexamethylene diamine are reacted under the action of a solid catalyst, the generated byproduct is ethanol, and the ethanol does not azeotrope with the residual raw material diethyl carbonate after the reaction, so that the excessive diethyl carbonate can be effectively separated and recovered. The invention adopts manganese-based catalyst and/or hydrotalcite-based catalyst, has high catalytic activity and is easy to separate and recycle. The product 1, 6-hexamethylene dicarbamate has higher solubility in the extractant, and can enter an extraction phase from a solution after reaction, so that the product is effectively separated from excessive raw materials and byproducts, and the quality yield of the product is greatly improved; the invention adopts a crystallization method for separation, and can obviously improve the quality yield of the product 1, 6-hexamethylene dicarbamate.

Preferably, the manganese-based catalyst comprises MnO₂、Mn₂O₃、Mn(CH₃COO)₂Or Mn (CH)₃COO)₂·4H₂Any one or a combination of at least two of O, wherein a typical but non-limiting combination is MnO₂And Mn₂O₃Combination of (2), Mn₂O₃And Mn (CH)₃COO)₂Combination of (1), Mn (CH)₃COO)₂·4H₂O and MnO₂In combination with, MnO₂、Mn₂O₃And Mn (CH)₃COO)₂A combination of the three or Mn₂O₃、Mn(CH₃COO)₂And Mn (CH)₃COO)₂·4H₂O, preferably Mn (CH)₃COO)₂And/or Mn (CH)₃COO)₂·4H₂O。

Preferably, the hydrotalcite-based catalyst comprises any one or a combination of at least two of Ce-modified Zn-Al hydrotalcite, Ce-modified Mg-Al hydrotalcite, La-modified Zn-Al hydrotalcite or La-modified Mg-Al hydrotalcite, wherein typical but non-limiting combinations are a combination of Ce-modified Zn-Al hydrotalcite and Ce-modified Mg-Al hydrotalcite, a combination of Ce-modified Mg-Al hydrotalcite and La-modified Zn-Al hydrotalcite, a combination of La-modified Zn-Al hydrotalcite and La-modified Mg-Al hydrotalcite, a combination of Ce-modified Zn-Al hydrotalcite, Ce-modified Mg-Al hydrotalcite and La-modified Zn-Al hydrotalcite, or a combination of Ce-modified Mg-Al hydrotalcite, La-modified Zn-Al hydrotalcite and La-modified Mg-Al hydrotalcite.

Mn (CH) is preferred in the present invention₃COO)₂And/or Mn (CH)₃COO)₂·4H₂O is used as a catalyst becauseBoth diethyl carbonate and 1, 6-hexanediamine can be mixed with Mn (CH)₃COO)₂Or Mn (CH)₃COO)₂·4H₂The O interacts. Wherein, manganese atoms attack amino nitrogen atoms of 1, 6-hexamethylene diamine to generate a transition state with a tetrahedral structure, so that the 1, 6-hexamethylene diamine is rapidly activated and further attacks methoxyl groups of diethyl carbonate to realize intermolecular reaction, and the reaction path is obviously reduced compared with that of a non-catalytic process, so that the catalytic activity of the reaction is high.

Preferably, the diethyl carbonate of step (1) is subjected to molecular sieve separation of impurities before being mixed.

Preferably, the molecular sieve has a pore size of 0.3 to 0.5nm, such as 0.3nm, 0.35nm, 0.4nm, 0.45nm or 0.5 nm.

In the invention, the impurities such as water, methanol, ethanol and the like in the diethyl carbonate are separated by using a molecular sieve, so that the content of the byproduct ethanol in the 1, 6-hexamethylene dicarbamate can be obviously reduced.

Preferably, the molar ratio of diethyl carbonate to 1, 6-hexanediamine in step (1) is (10-50: 1), and may be, for example, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1 or 50: 1.

Preferably, the solid catalyst is used in an amount of 5 to 24% by mass of 1, 6-hexanediamine, for example, 5%, 8%, 10%, 13%, 15%, 20%, 22% or 24%, preferably 5 to 20%.

Preferably, the reaction temperature in step (1) is 40-140 ℃, for example, 40 ℃, 45 ℃, 50 ℃, 55 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃ or 140 ℃, preferably 80-140 ℃.

Preferably, the reaction time is 2-10 h, for example, 2h, 2.5h, 3h, 3.5h, 4h, 5h, 6h, 7h, 8h, 9h or 10h, preferably 6-10 h.

Preferably, the reaction of step (1) is carried out under stirring.

Preferably, the stirring rate is 400-800 r/min, such as 400r/min, 450r/min, 500r/min, 550r/min, 600r/min, 650r/min, 700r/min, 750r/min or 800 r/min.

Preferably, a protective gas purge is performed during the reaction of step (1).

Preferably, the shielding gas comprises any one or a combination of at least two of nitrogen, argon or helium, with typical but non-limiting combinations being a combination of nitrogen and argon, argon and helium, nitrogen and helium or a combination of nitrogen, argon and helium.

Preferably, the purge rate is 100 to 600mL/min, and may be, for example, 100mL/min, 150mL/min, 200mL/min, 300mL/min, 400mL/min, 500mL/min, 550mL/min, or 600 mL/min.

The function of the protective gas purging in the invention is to prevent the raw material 1, 6-hexamethylene diamine from deteriorating in the air.

Preferably, the extractant extracted in the step (2) comprises any one or a combination of at least two of benzene, toluene, p-xylene, ethyl acetate, butyl acetate, dihexyl adipate, dihexyl azelate, dibutyl sebacate and dioctyl sebacate, typical, but non-limiting combinations of these are combinations of benzene and toluene, toluene and para-xylene, a combination of para-xylene and ethyl acetate, a combination of butyl acetate and dihexyl adipate, a combination of dihexyl azelate and dibutyl sebacate, a combination of dibutyl sebacate and dioctyl sebacate, a combination of three of benzene, toluene and para-xylene, a combination of three of toluene, para-xylene and ethyl acetate, a combination of three of ethyl acetate, butyl acetate and dihexyl adipate, a combination of three of dihexyl azelate, dibutyl sebacate and dioctyl sebacate.

Preferably, the volume ratio of the extractant to the reacted solution is (2-10): 1, for example, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, preferably (6-8): 1.

Preferably, the crystallization temperature in step (2) is-30 to 10 ℃, for example, -30 ℃, -25 ℃, -20 ℃, -15 ℃, -10 ℃, -5 ℃, 0 ℃, 5 ℃, 8 ℃ or 10 ℃, preferably 0 to 10 ℃.

Preferably, the crystallization time is 3 to 12 hours, for example, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours or 12 hours, preferably 5 to 12 hours.

Preferably, the crystallization is followed by solid-liquid separation.

The solid-liquid separation in the invention mainly comprises any one of filtration, centrifugation or sedimentation, and the solution after the solid-liquid separation adopts a distillation mode to recover the excessive raw material diethyl carbonate.

As a preferred technical scheme of the method, the method comprises the following steps:

(1) separating impurities from diethyl carbonate through a molecular sieve with the aperture of 0.3-0.5 nm, mixing diethyl carbonate, 1, 6-hexamethylene diamine and a solid catalyst according to the molar ratio of diethyl carbonate to 1, 6-hexamethylene diamine (10-50): 1 and the use amount of the solid catalyst being 5-24% of the mass fraction of 1, 6-hexamethylene diamine, reacting for 2-10 h at the temperature of 40-140 ℃ and the stirring rate of 400-800 r/min, purging protective gas at the speed of 100-600 mL/min in the reaction process, and performing solid-liquid separation on the reacted materials to obtain a solution after reaction;

(2) extracting according to the volume ratio of the extracting agent to the reacted solution of (2-10): 1, crystallizing an extract phase for 3-12 h at the temperature of-30-10 ℃, and performing solid-liquid separation after crystallization to obtain the 1, 6-hexamethylene dicarbamate.

The recitation of numerical ranges herein includes not only the above-recited values, but also any values between any of the above-recited numerical ranges not recited, and for brevity and clarity, is not intended to be exhaustive of the specific values encompassed within the range.

Compared with the prior art, the invention has the beneficial effects that:

(1) according to the method for preparing 1, 6-hexamethylene dicarbamic acid ethyl ester, the by-product ethanol of the reaction does not azeotropy with the residual raw material diethyl carbonate after the reaction, so that the excessive diethyl carbonate can be effectively separated and recovered, and the production cost is reduced;

(2) the method for preparing 1, 6-hexamethylene dicarbamic acid ethyl ester uses a manganese-based catalyst and/or a hydrotalcite-based catalyst, has higher catalytic activity to a diethyl carbonate carbonylation system, realizes the high quality yield of the 1, 6-hexamethylene dicarbamic acid ethyl ester, and has the quality yield of more than 77.2 percent and the quality yield of more than 99.5 percent under better conditions, and the catalyst can be recycled, and the reduction range of the catalytic activity is small when the catalyst is reused;

(3) the method for preparing 1, 6-hexamethylene dicarbamic acid ethyl ester provided by the invention adopts diethyl carbonate to replace phosgene, is green and safe, has mild reaction conditions and is simple and convenient to operate; has good industrial application prospect.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.

First, an embodiment

Example 1

This example provides a process for preparing 1, 6-hexamethylene dicarbamate comprising the steps of:

(1) separating impurity water, methanol and ethanol from diethyl carbonate by using a 3A type molecular sieve with the aperture of 0.3nm, and MnO according to the molar ratio of 20:1 of diethyl carbonate to 1, 6-hexamethylene diamine₂The dosage of the raw materials is 5 percent of the mass fraction of the 1, 6-hexamethylene diamine, and the raw materials of diethyl carbonate, the 1, 6-hexamethylene diamine and MnO are₂Adding the mixture into a three-neck flask, reacting for 6 hours at the temperature of 40 ℃ and the stirring speed of 400r/min, performing nitrogen purging at the speed of 100mL/min in the reaction process, and filtering the reacted materials to obtain a reacted solution;

(2) extracting according to the volume ratio of benzene to the reacted solution of 10:1, crystallizing an extract phase for 3 hours at the temperature of minus 30 ℃, separating out white crystals, and filtering to obtain the 1, 6-hexamethylene dicarbamate.

Example 2

This example provides a process for preparing 1, 6-hexamethylene dicarbamate comprising the steps of:

(1) carbon (C)Separating impurity water, methanol and ethanol from diethyl carbonate by using a 4A type molecular sieve with the aperture of 0.4nm, and then adding Mn according to the molar ratio of diethyl carbonate to 1, 6-hexamethylene diamine of 30:1₂O₃The dosage of the raw materials is 10 percent of the mass fraction of the 1, 6-hexamethylene diamine, and the raw materials of diethyl carbonate, the 1, 6-hexamethylene diamine and Mn₂O₃Adding the mixture into a three-neck flask, reacting for 10 hours at the temperature of 60 ℃ and the stirring speed of 500r/min, performing nitrogen purging at the speed of 200mL/min in the reaction process, and filtering the reacted materials to obtain a reacted solution;

(2) extracting according to the volume ratio of toluene to the reacted solution of 5:1, crystallizing an extract phase for 4 hours at the temperature of minus 10 ℃, separating out white crystals, and filtering to obtain the 1, 6-hexamethylene dicarbamate.

Example 3

This example provides a process for preparing 1, 6-hexamethylene dicarbamate comprising the steps of:

(1) separating impurity water, methanol and ethanol from diethyl carbonate by using a 5A type molecular sieve with the aperture of 0.5nm, and then adding Mn (CH) according to the molar ratio of the diethyl carbonate to the 1, 6-hexanediamine of 10:1₃COO)₂The dosage of the raw materials is 15 percent of the mass fraction of the 1, 6-hexamethylene diamine, and the raw materials of diethyl carbonate, the 1, 6-hexamethylene diamine and Mn (CH)₃COO)₂Adding the mixture into a three-neck flask, reacting for 2 hours at the temperature of 90 ℃ and the stirring speed of 800r/min, performing nitrogen purging at the speed of 200mL/min in the reaction process, and filtering the reacted materials to obtain a reacted solution;

(2) extracting according to the volume ratio of ethyl acetate to the reacted solution of 5:1, crystallizing an extract phase for 5 hours at the temperature of 0 ℃, separating out white crystals, and filtering to obtain the 1, 6-hexamethylene dicarbamate.

Example 4

This example provides a process for preparing 1, 6-hexamethylene dicarbamate comprising the steps of:

(1) separating impurity water, methanol and ethanol from diethyl carbonate by using a 3A type molecular sieve with the aperture of 0.3nm, and then separating the impurity water, the methanol and the ethanol according to the proportion of diethyl carbonate and 1, 6-hexanediThe molar ratio of amine is 40:1, Mn₂O₃The dosage of the raw materials is 10 percent of the mass fraction of the 1, 6-hexamethylene diamine, and the raw materials of diethyl carbonate, the 1, 6-hexamethylene diamine and Mn₂O₃Adding the mixture into a three-neck flask, reacting for 10 hours at the temperature of 80 ℃ and the stirring speed of 500r/min, performing nitrogen purging at the speed of 200mL/min in the reaction process, and filtering the reacted materials to obtain a reacted solution;

(2) extracting according to the volume ratio of ethyl acetate to the reacted solution of 2:1, crystallizing an extract phase for 6 hours at the temperature of 0 ℃, separating out white crystals, and filtering to obtain the 1, 6-hexamethylene dicarbamate.

Example 5

This example provides a process for preparing 1, 6-hexamethylene dicarbamate comprising the steps of:

(1) separating impurity water, methanol and ethanol from diethyl carbonate by using a 5A type molecular sieve with the aperture of 0.5nm, and then adding Mn (CH) according to the molar ratio of the diethyl carbonate to the 1, 6-hexanediamine of 20:1₃COO)₂The dosage of the raw materials is 15 percent of the mass fraction of the 1, 6-hexamethylene diamine, and the raw materials of diethyl carbonate, the 1, 6-hexamethylene diamine and Mn (CH)₃COO)₂Adding the mixture into a three-neck flask, reacting for 6 hours at the temperature of 120 ℃ and the stirring speed of 800r/min, performing nitrogen purging at the speed of 200mL/min in the reaction process, and filtering the reacted materials to obtain a reacted solution;

(2) extracting according to the volume ratio of dioctyl sebacate to the reacted solution of 6:1, crystallizing an extract phase for 12 hours at the temperature of 10 ℃, separating out white crystals, and filtering to obtain the 1, 6-hexamethylene dicarbamate.

Example 6

This example provides a process for preparing 1, 6-hexamethylene dicarbamate comprising the steps of:

(1) separating impurity water, methanol and ethanol from diethyl carbonate by using a 4A type molecular sieve with the aperture of 0.4nm, and then adding Mn (CH) according to the molar ratio of the diethyl carbonate to the 1, 6-hexanediamine of 10:1₃COO)₂·4H₂The dosage of O is the mass of 1, 6-hexanediamine20% of the total weight of the raw materials, diethyl carbonate, 1, 6-hexanediamine and Mn (CH)₃COO)₂·4H₂Adding O into a three-neck flask, reacting for 6 hours at the temperature of 140 ℃ and the stirring speed of 400r/min, performing nitrogen purging at the speed of 600mL/min in the reaction process, and filtering the reacted materials to obtain a reacted solution;

(2) extracting according to the volume ratio of dibutyl sebacate to the reacted solution of 8:1, crystallizing an extract phase at the temperature of 10 ℃ for 12 hours, separating out white crystals, and filtering to obtain the 1, 6-hexamethylene dicarbamate.

Example 7

This example provides a process for preparing 1, 6-hexamethylene dicarbamate comprising the steps of:

(1) separating impurity water, methanol and ethanol from diethyl carbonate by using a 3A type molecular sieve with an aperture of 0.3nm, adding raw materials of diethyl carbonate, 1, 6-hexamethylenediamine and Ce modified Zn-Al hydrotalcite into a three-neck flask according to the molar ratio of the diethyl carbonate to the 1, 6-hexamethylenediamine being 40:1 and the dosage of the Ce modified Zn-Al hydrotalcite being 20% of the mass fraction of the 1, 6-hexamethylenediamine, reacting for 5 hours at 1600 ℃ and the stirring rate of 800r/min, carrying out nitrogen purging at the rate of 600mL/min in the reaction process, and filtering the reacted materials to obtain a solution after reaction;

(2) extracting according to the volume ratio of the dihexyl adipate to the reacted solution of 7:1, crystallizing an extract phase at the temperature of-20 ℃ for 4 hours, separating out white crystals, and filtering to obtain the 1, 6-hexamethylene dicarbamate.

Example 8

This example provides a process for preparing 1, 6-hexamethylene dicarbamate comprising the steps of:

(1) separating impurity water, methanol and ethanol from diethyl carbonate by using a 5A type molecular sieve with an aperture of 0.5nm, adding raw materials of diethyl carbonate, 1, 6-hexamethylenediamine and Ce modified Mg-Al hydrotalcite into a three-neck flask according to the molar ratio of the diethyl carbonate to the 1, 6-hexamethylenediamine being 40:1 and the dosage of the Ce modified Mg-Al hydrotalcite being 20% of the mass fraction of the 1, 6-hexamethylenediamine, reacting for 5 hours at the temperature of 180 ℃ and the stirring rate of 800r/min, carrying out nitrogen purging at the speed of 600mL/min in the reaction process, and filtering the reacted materials to obtain a solution after reaction;

(2) extracting according to the volume ratio of the dihexyl azelate to the reacted solution of 6:1, crystallizing an extract phase at 10 ℃ for 12 hours, separating out white crystals, and filtering to obtain the 1, 6-hexamethylene dicarbamate.

Example 9

This example provides a process for preparing 1, 6-hexamethylene dicarbamate comprising the steps of:

(1) separating impurity water, methanol and ethanol from diethyl carbonate by using a 5A type molecular sieve with an aperture of 0.5nm, adding raw materials of diethyl carbonate, 1, 6-hexamethylenediamine and La modified Zn-Al hydrotalcite into a three-neck flask according to the molar ratio of the diethyl carbonate to the 1, 6-hexamethylenediamine being 40:1 and the dosage of the La modified Zn-Al hydrotalcite being 25% of the mass fraction of the 1, 6-hexamethylenediamine, reacting for 3 hours at the temperature of 140 ℃ and the stirring rate of 600r/min, carrying out nitrogen purging at the rate of 200mL/min in the reaction process, and filtering the reacted materials to obtain a solution after reaction;

(2) extracting according to the volume ratio of p-xylene to the reacted solution of 10:1, crystallizing an extract phase for 4 hours at the temperature of minus 20 ℃, separating out white crystals, and filtering to obtain the 1, 6-hexamethylene dicarbamate.

Example 10

This example provides a process for preparing 1, 6-hexamethylene dicarbamate comprising the steps of:

(1) separating impurity water, methanol and ethanol from diethyl carbonate by using a 5A type molecular sieve with an aperture of 0.5nm, adding raw materials of diethyl carbonate, 1, 6-hexamethylenediamine and La modified Mg-Al hydrotalcite into a three-neck flask according to the molar ratio of the diethyl carbonate to the 1, 6-hexamethylenediamine being 40:1 and the dosage of the La modified Mg-Al hydrotalcite being 25% of the mass fraction of the 1, 6-hexamethylenediamine, reacting for 3 hours at the temperature of 180 ℃ and the stirring rate of 600r/min, carrying out nitrogen purging at the rate of 200mL/min in the reaction process, and filtering the reacted materials to obtain a solution after reaction;

(2) extracting according to the volume ratio of p-xylene to the reacted solution of 10:1, crystallizing an extract phase for 4 hours at the temperature of minus 20 ℃, separating out white crystals, and filtering to obtain the 1, 6-hexamethylene dicarbamate.

Example 11

This example provides a process for the preparation of 1, 6-hexamethylene dicarbamate except that the catalyst in step (1) was replaced with Mn (CH)₃COO)₂Otherwise, the same procedure as in example 1 was repeated.

Example 12

This example provides a process for the preparation of 1, 6-hexamethylene dicarbamate except that the catalyst in step (1) was replaced with Mn (CH)₃COO)₂·4H₂Except for O, the same procedure as in example 1 was repeated.

Example 13

This example provides a process for preparing 1, 6-hexamethylene dicarbamate which is the same as in example 6 except that the catalyst in step (1) is replaced with the catalyst obtained by filtration after the reaction of example 6.

Second, comparative example

Comparative example 1

This comparative example provides a process for producing ethyl 1, 6-hexamethylenedicarbamate which is the same as in example 6 except that the catalyst in step (1) is replaced with silicotungstic acid.

The mass of 1, 6-hexamethylene dicarbamate before and after the reaction in examples 1 to 13 and comparative example 1 was measured and the mass yield thereof was calculated, and the results are shown in table 1.

TABLE 1

From table 1, the following points can be seen:

(1) it can be seen from the comprehensive examples 1 to 13 that the mass yield of the 1, 6-hexamethylene dicarbamate in the method for preparing the 1, 6-hexamethylene dicarbamate provided by the invention can reach more than 77.2%;

(2) as can be seen from the combination of example 1 and examples 11 to 12, the catalyst used in example 1 is MnO₂The catalysts used in examples 11 to 12 were each Mn (CH)₃COO)₂And Mn (CH)₃COO)₂·4H₂O, the mass yield of 1, 6-hexamethylene dicarbamate in example 1 was 77.2%, while the mass yields of 1, 6-hexamethylene dicarbamate in examples 11 to 12 were 93.3% and 94.6%, respectively, which were much higher than that in example 1; thus, it is shown that Mn (CH) is preferred in the present invention₃COO)₂And Mn (CH)₃COO)₂·4H₂When O is used as a catalyst, the prepared 1, 6-hexamethylene dicarbamate has higher mass yield;

(3) combining example 6 with example 13, it can be seen that the catalyst used in example 6 is Mn (CH)₃COO)₂·4H₂O, Mn (CH) as a catalyst obtained by the reaction of example 6 and filtration, compared with the catalyst used in example 13₃COO)₂·4H₂As for O, the mass yield of ethyl 1, 6-hexamethylene dicarbamate prepared in example 13 was 86.6%, compared with MnO as a reaction catalyst used in example 6₂The mass yield of 1, 6-hexamethylene dicarbamate obtained was only slightly reduced by 93.3%; therefore, the catalyst can be recycled, and the reduction range of the catalytic activity is small when the catalyst is secondarily utilized;

(4) by combining example 6 with comparative example 1, it can be seen that example 6 employs catalyst Mn (CH)₃COO)₂·4H₂The reaction is carried out, compared with the silicotungstic acid adopted in the comparative example 1, the mass yield of the 1, 6-hexamethylene dicarbamate prepared in the example 6 is far greater than that of the comparative example 1; it is thus shown that the present invention employsThe manganese-based catalyst participates in the reaction, has high catalytic activity, and can greatly improve the quality yield of the 1, 6-hexamethylene dicarbamate.

In conclusion, the method for preparing 1, 6-hexamethylene dicarbamate provided by the invention uses a manganese-based catalyst and/or a hydrotalcite-based catalyst, has higher catalytic activity on a diethyl carbonate carbonylation system, realizes high yield of 1, 6-hexamethylene dicarbamate, can recycle the catalyst, and has small reduction amplitude of the catalytic activity during secondary utilization; the reaction condition is mild, the operation process is simple and convenient, and the method has good industrial application prospect.

The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.