CN113831264B - Method for preparing 1, 6-hexamethylene dicarbamate - Google Patents
Method for preparing 1, 6-hexamethylene dicarbamate Download PDFInfo
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- CN113831264B CN113831264B CN202111087704.3A CN202111087704A CN113831264B CN 113831264 B CN113831264 B CN 113831264B CN 202111087704 A CN202111087704 A CN 202111087704A CN 113831264 B CN113831264 B CN 113831264B
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- C07—ORGANIC CHEMISTRY
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- C07C269/00—Preparation of derivatives of carbamic acid, i.e. compounds containing any of the groups, the nitrogen atom not being part of nitro or nitroso groups
- C07C269/04—Preparation of derivatives of carbamic acid, i.e. compounds containing any of the groups, the nitrogen atom not being part of nitro or nitroso groups from amines with formation of carbamate groups
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Abstract
The invention provides a method for preparing 1, 6-hexamethylene dicarbamate, which comprises the following steps: (1) Mixing diethyl carbonate, 1, 6-hexamethylene diamine and a solid catalyst to react, and performing solid-liquid separation on the reacted materials to obtain a reacted solution; (2) Extracting and crystallizing the solution after the reaction in the step (1) 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.
Description
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 processes and non-phosgene processes. Phosgene method using highly toxic COCl 2 The 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, in which ionic liquid is used as solvent and catalyst system to implement carbonylation of amine and dimethyl carbonate to synthesize corresponding carbamate. 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 preparation method of n-butyl hexamethylene dicarbamate, which takes hexamethylene diamine and butyl carbamate as raw materials, takes oxysalt of metal zirconium as a main catalyst, takes one of oxysalts of zinc, manganese and nickel as an auxiliary catalyst, reacts at the temperature of 150-180 ℃, and after the reaction is finished and the catalyst is filtered and recycled, filtrate is subjected to reduced pressure rectification 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 by-product of the reaction 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-hexamethylene diamine and a solid catalyst to react, and carrying out solid-liquid separation on the reacted materials 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, which can obviously improve the quality yield of the product 1, 6-hexamethylene dicarbamate.
Preferably, the manganese-based catalyst comprises MnO 2 、Mn 2 O 3 、Mn(CH 3 COO) 2 Or Mn (CH) 3 COO) 2 ·4H 2 Any one or a combination of at least two of O, wherein a typical but non-limiting combination is MnO 2 And Mn 2 O 3 Combination of (2), mn 2 O 3 And Mn (CH) 3 COO) 2 Combination of (1), mn (CH) 3 COO) 2 ·4H 2 O and MnO 2 In combination with, mnO 2 、Mn 2 O 3 And Mn (CH) 3 COO) 2 A combination of the three orMn 2 O 3 、Mn(CH 3 COO) 2 And Mn (CH) 3 COO) 2 ·4H 2 A combination of three elements of O, preferably Mn (CH) 3 COO) 2 And/or Mn (CH) 3 COO) 2 ·4H 2 O。
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 invention 3 COO) 2 And/or Mn (CH) 3 COO) 2 ·4H 2 O is used as a catalyst, because the raw materials of diethyl carbonate and 1, 6-hexamethylene diamine can be mixed with Mn (CH) 3 COO) 2 Or Mn (CH) 3 COO) 2 ·4H 2 The O interacts. Wherein, manganese atoms attack amino nitrogen atoms of the 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, which may be, for example, 0.3nm, 0.35nm, 0.4nm, 0.45nm or 0.5nm.
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, in the step (1), the molar ratio of diethyl carbonate to 1, 6-hexamethylenediamine is (10-50) 1, and may be, for example, 10.
Preferably, the solid catalyst is used in an amount of 5 to 24% by mass of 1, 6-hexamethylenediamine, for example 5%, 8%, 10%, 13%, 15%, 20%, 22% or 24%, preferably 5 to 20%.
Preferably, the reaction temperature in step (1) is 40 to 140 ℃, for example, 40 ℃, 45 ℃, 50 ℃, 55 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃ or 140 ℃, preferably 80 to 140 ℃.
Preferably, the reaction time is 2 to 10 hours, for example, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours, preferably 6 to 10 hours.
Preferably, the reaction of step (1) is carried out under stirring.
Preferably, the stirring rate is 400 to 800r/min, and may be, for example, 400r/min, 450r/min, 500r/min, 550r/min, 600r/min, 650r/min, 700r/min, 750r/min or 800r/min.
Preferably, 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, with typical but non-limiting combinations being a combination of nitrogen and argon, argon and helium, nitrogen and helium or a combination of three 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 600mL/min.
The function of the protective gas purging in the invention is to prevent the deterioration of the raw material 1, 6-hexamethylenediamine in the air.
Preferably, 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, wherein typical but non-limiting combinations are benzene and toluene, toluene and p-xylene, p-xylene and ethyl acetate, butyl acetate and dihexyl adipate, dihexyl azelate and dibutyl sebacate, dibutyl sebacate and dioctyl sebacate, benzene, toluene and p-xylene, toluene, p-xylene and ethyl acetate, butyl acetate and dihexyl adipate, dihexyl azelate, dibutyl sebacate and dioctyl sebacate.
Preferably, the volume ratio of the extractant to the post-reaction solution is (2 to 10): 1, and may be, for example, 2.
Preferably, the crystallization temperature in step (2) is-30 to 10 ℃, and may be, 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 a solid-liquid separation.
The solid-liquid separation 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 the diethyl carbonate, the 1, 6-hexamethylene diamine and a solid catalyst according to the molar ratio (10-50) of the diethyl carbonate to the 1, 6-hexamethylene diamine and the use amount of the solid catalyst being 5-24% of the mass fraction of the 1, 6-hexamethylene diamine, reacting for 2-10 h under the conditions that the temperature is 40-140 ℃ and the stirring rate is 400-800 r/min, carrying out protective gas purging at the rate of 100-600 mL/min in the reaction process, and carrying out solid-liquid separation on the reacted materials to obtain a solution after the reaction;
(2) Extracting according to the volume ratio of the extracting agent to the solution after reaction of (2-10) to 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 dicarbamic acid ethyl ester.
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 manganese-based catalyst and/or hydrotalcite-based catalyst, has higher catalytic activity to diethyl carbonate carbonylation system, realizes high quality yield of 1, 6-hexamethylene dicarbamic acid ethyl ester, the quality yield can reach more than 77.2%, the quality yield can reach more than 99.5% under better condition, and the catalyst can be recycled, and the catalytic activity reduction range 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 described below by way of specific 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.
1. Examples of the invention
Example 1
This example provides a process for preparing 1, 6-hexamethylene dicarbamate comprising the steps of:
(1) Separating impurities of water, methanol and ethanol from diethyl carbonate by using a 3A molecular sieve with the aperture of 0.3nm, and then adding MnO according to the molar ratio of 20 2 The dosage of the raw materials is 5 percent of the mass fraction of 1, 6-hexamethylene diamine, and the raw materials of diethyl carbonate, 1, 6-hexamethylene diamine and MnO are 2 Adding 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.
Example 2
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 mixing the diethyl carbonate and 1, 6-hexamethylene diamine according to the molar ratio of 1, mn 2 O 3 The dosage of the compound is 10 percent of the mass fraction of 1, 6-hexamethylene diamine, raw materials of diethyl carbonate, 1, 6-hexamethylene diamine and Mn 2 O 3 Adding the mixture into a three-neck flask, reacting for 10 hours at the temperature of 60 ℃ and the stirring rate of 500r/min, carrying out nitrogen purging at the rate 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.
Example 3
This example provides a process for preparing 1, 6-hexamethylene dicarbamate comprising the steps of:
(1) Separating impurity water and A from diethyl carbonate by 5A type molecular sieve with 0.5nm apertureAlcohol and ethanol, and according to a molar ratio of diethyl carbonate to 1, 6-hexanediamine of 10 3 COO) 2 The dosage of the raw materials is 15 percent of the mass fraction of 1, 6-hexamethylene diamine, and the raw materials of diethyl carbonate, 1, 6-hexamethylene diamine and Mn (CH) 3 COO) 2 Adding the mixture into a three-neck flask, reacting for 2 hours at the temperature of 90 ℃ and the stirring speed of 800r/min, carrying out 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.
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 mixing the diethyl carbonate and 1, 6-hexamethylene diamine according to the molar ratio of 1, mn 2 O 3 The dosage of the raw materials is 10 percent of the mass fraction of 1, 6-hexamethylene diamine, and the raw materials of diethyl carbonate, 1, 6-hexamethylene diamine and Mn 2 O 3 Adding 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.
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 mixing the diethyl carbonate and 1, 6-hexamethylene diamine according to the molar ratio of 20 3 COO) 2 The dosage of the raw materials is 15 percent of the mass fraction of 1, 6-hexamethylene diamine, and the raw materials of diethyl carbonate, 1, 6-hexamethylene diamine and Mn (CH) 3 COO) 2 Adding 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.
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 mixing the diethyl carbonate and 1, 6-hexamethylene diamine according to the molar ratio of 10 3 COO) 2 ·4H 2 The dosage of O is 20 percent of the mass fraction of 1, 6-hexamethylene diamine, and the raw materials of diethyl carbonate, 1, 6-hexamethylene diamine and Mn (CH) 3 COO) 2 ·4H 2 Adding 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.
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-hexamethylene diamine and Ce modified Zn-Al hydrotalcite into a three-neck flask according to the molar ratio of the diethyl carbonate to the 1, 6-hexamethylene diamine being 40 and the using amount of the Ce modified Zn-Al hydrotalcite being 20% of the mass fraction of the 1, 6-hexamethylene diamine, 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.
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-hexamethylene diamine and Ce modified Mg-Al hydrotalcite into a three-neck flask according to the molar ratio of the diethyl carbonate to the 1, 6-hexamethylene diamine being 40 and the using amount of the Ce modified Mg-Al hydrotalcite being 20% of the mass fraction of the 1, 6-hexamethylene diamine, reacting for 5 hours at the temperature of 180 ℃ 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 the reaction;
(2) Extracting according to the volume ratio of the dihexyl azelate to the reacted solution of 6.
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-hexamethylene diamine and La modified Zn-Al hydrotalcite into a three-neck flask according to the molar ratio of the diethyl carbonate to the 1, 6-hexamethylene diamine being 40, the using amount of the La modified Zn-Al hydrotalcite being 25% of the mass fraction of the 1, 6-hexamethylene diamine, 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.
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-hexamethylene diamine and La modified Mg-Al hydrotalcite into a three-neck flask according to the molar ratio of diethyl carbonate to 1, 6-hexamethylene diamine being 40, the using amount of the La modified Mg-Al hydrotalcite being 25% of the mass fraction of 1, 6-hexamethylene diamine, reacting for 3 hours under the conditions that the temperature is 180 ℃ and the stirring rate is 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.
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) 3 COO) 2 Otherwise, 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) 3 COO) 2 ·4H 2 Except for O, the rest was the same as example 1.
Example 13
This example provides a process for preparing 1, 6-hexamethylene dicarbamate which was identical to example 6 except that the catalyst in step (1) was replaced with the catalyst obtained by filtration after the reaction of example 6.
2. 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 a combination of example 1 and examples 11 to 12, the catalyst used in example 1 is MnO 2 The catalysts used in examples 11 to 12 were each Mn (CH) 3 COO) 2 And Mn (CH) 3 COO) 2 ·4H 2 O, the mass yield of ethyl 1, 6-hexamethylene dicarbamate in example 1 was 77.2%, whereas the mass yields of ethyl 1, 6-hexamethylene dicarbamate in examples 11 to 12 were 93.3% and 94.6%, respectively, which were much higher than in example 1; thus, it is shown that Mn (CH) is preferred in the present invention 3 COO) 2 And Mn (CH) 3 COO) 2 ·4H 2 When O is used as a catalyst, the mass of 1, 6-hexamethylene dicarbamate is preparedThe yield is high;
(3) As can be seen by combining examples 6 and 13, the catalyst used in example 6 is Mn (CH) 3 COO) 2 ·4H 2 O, mn (CH) as a catalyst obtained by the reaction of example 6 and filtration, compared with the catalyst used in example 13 3 COO) 2 ·4H 2 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 6 2 The 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) As can be seen by combining example 6 with comparative example 1, example 6 employs catalyst Mn (CH) 3 COO) 2 ·4H 2 The 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; therefore, the manganese-based catalyst is adopted to participate in the reaction, the catalytic activity is high, and the quality yield of the 1, 6-hexamethylene dicarbamate can be greatly improved.
In conclusion, the method for preparing 1, 6-hexamethylene dicarbamate provided by the invention uses the manganese-based catalyst and/or the 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.
Claims (1)
1. A process for the preparation of ethyl 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 mixing the diethyl carbonate and 1, 6-hexamethylene diamine according to the molar ratio of 10 3 COO) 2 The dosage of the raw materials is 15 percent of the mass fraction of 1, 6-hexamethylene diamine, and the raw materials of diethyl carbonate, 1, 6-hexamethylene diamine and Mn (CH) 3 COO) 2 Adding 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; or
(1) Separating impurities of water, methanol and ethanol from diethyl carbonate by using a 5A molecular sieve with the aperture of 0.5nm, and then mixing the diethyl carbonate and 1, 6-hexamethylene diamine according to the molar ratio of 20 3 COO) 2 The dosage of the compound is 15 percent of the mass fraction of 1, 6-hexamethylene diamine, raw materials of diethyl carbonate, 1, 6-hexamethylene diamine and Mn (CH) 3 COO) 2 Adding 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.
Priority Applications (1)
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