Preparation method of isocyanate based on rare earth upconversion material

Abstract

The invention belongs to the technical field of preparation of isocyanate, and particularly discloses an isocyanate preparation method based on a rare earth upconversion material, which comprises the following steps: mixing and dissolving rare earth metal salt and ligand in absolute ethyl alcohol or anhydrous ethylene glycol, and performing solvothermal reaction to prepare rare earth nanoparticles; and calcining the prepared rare earth nanoparticles at 450-550 DEG C to obtain the rare earth up-conversion material. The preparation method comprises the following steps: adding the rare earth up-conversion material into a solution of an organic amine compound, and carrying out photocatalytic oxidation reaction under the irradiation of near-infrared light, so as to prepare the isocyanate, wherein the mass percent of the rare earth up-conversion material in the organic amine compound is 1-10%, and the mass percent of the rare earth up-conversion material in the organic amine compound is 1-10%. Through the light conversion characteristic of the rare earth upconversion material, the isocyanate reaction is smoothly carried out under the excitation of low-energy near-infrared light, and the method has the advantages of mild reaction, low equipment requirement, high efficiency and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of isocyanate preparation, and particularly relates to a method for preparing isocyanate based on rare earth up-conversion materials. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Isocyanate is an important organic intermediate, widely used in many industries such as polyurethane materials, coatings, adhesives, etc. The preparation of isocyanate mainly depends on phosgenation reaction, mainly including direct phosgenation of amines, phosgenation of amine hydrochlorides, phosgenation of carbamic acid and gas phase phosgenation, among which phosgene, also known as carbonyl chloride, is a very active electrophilic reagent, easily hydrolyzed, and is a severe asphyxiating gas. Inhalation of high concentrations can cause pulmonary edema. Therefore, the traditional preparation method of isocyanate that relies on phosgene is toxic, corrosive and has high operating risks. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for preparing isocyanate based on rare earth up-conversion materials. The method introduces the prepared rare earth up-conversion material, generates high-energy visible light or ultraviolet light under low-energy near-infrared light irradiation, thereby exciting the reactants to generate free radicals, and promotes the reaction of organic amines and chloroform compounds, and finally generates isocyanate.

[0005] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0006] A method for preparing isocyanate based on rare earth up-conversion materials comprises the following steps:

[0007] The rare earth metal salt and the ligand are mixed and dissolved in anhydrous ethanol or anhydrous ethylene glycol, and a solvent thermal reaction is performed to prepare rare earth nanoparticles;

[0008] The prepared rare earth nanoparticles are calcined at 450-550° C. to obtain a rare earth upconversion material;

[0009] The rare earth up-conversion material is added to a solution of an organic amine compound, wherein the mass percentage of the rare earth up-conversion material to the organic amine compound is 1%-10%. In an oxygen-containing environment, a photocatalytic oxidation reaction is carried out under near-infrared light irradiation to prepare isocyanate.

[0010] When rare earth nanoparticles are used as catalysts, the yield of isocyanate is higher and the experimental reproducibility is good.

[0011] In some embodiments, the organic amine compound is aniline, butylamine, ethylamine, propylamine or phenethylamine.

[0012] In some embodiments, the rare earth metal salt is a mixture of yttrium chloride, ytterbium chloride, and europium chloride.

[0013] Preferably, in the rare earth metal salt, the mass ratio of yttrium chloride, ytterbium chloride and europium chloride is 10-15:10-15:1.

[0014] In some embodiments, the ligand is citric acid or acetic acid.

[0015] In some embodiments, the temperature of the solvothermal reaction is 160-200° C., and the reaction time is 8-12 hours. During the solvothermal process, the rare earth ions interact with the ligands to form rare earth nanoparticles.

[0016] In some embodiments, before calcining, the step of washing and drying the prepared rare earth nanoparticles is also included. Impurities are removed by washing to improve the purity of the rare earth up-conversion material. Organic matter on the surface of the rare earth nanoparticles is removed by calcining to obtain a rare earth up-conversion material with good up-conversion performance.

[0017] In some embodiments, the wavelength of the near infrared light is 808 nm or 980 nm.

[0018] Preferably, the optical power of the near-infrared light is 0.1-5 W / cm2.

[0019] Preferably, the photocatalytic oxidation reaction time is 1-12 hours.

[0020] In some embodiments, the organic solvent in the solution of the organic amine compound is chloroform or bromoform. These two types of solvents will generate free radicals under ultraviolet light, which then attack the organic amine to generate isocyanate, which cannot be achieved by other solvents.

[0021] In some embodiments, the method further includes purifying the prepared isocyanate by solvent evaporation, extraction or recrystallization.

[0022] The beneficial effects achieved by one or more embodiments of the present invention are as follows:

[0023] 1) The prepared rare earth upconversion material has excellent optical properties. It can convert low-energy light into high-energy ultraviolet light or visible light under near-infrared light irradiation, which enables it to effectively generate free radicals in the photocatalytic reaction and then oxidize organic amines to generate isocyanates.

[0024] 2) This method can effectively realize the efficient preparation of isocyanate under mild conditions by introducing rare earth up-conversion materials, reducing the use of phosgene, and solving the problems of equipment loss and complicated operation caused by the use of high-energy ultraviolet light in the traditional method. The present invention uses the light conversion characteristics of rare earth up-conversion materials to make the isocyanate reaction proceed smoothly under low-energy near-infrared light excitation, which has the advantages of mild reaction, low equipment requirements, and high efficiency. It avoids the high requirements of traditional ultraviolet light sources on equipment and operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0026] Figure 1 This is a TEM image of the rare earth up-conversion material prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0027] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0028] The present invention will be further described below in conjunction with the embodiments.

[0029] Example 1

[0030] 0.781 g (2 mmol) of yttrium chloride (YCl3·6H2O), 0.274 g (0.75 mmol) of ytterbium chloride (YbCl3·6H2O) and 0.061 g (0.15 mmol) of europium chloride (EuCl3·6H2O) were weighed and dissolved in 20 mL of anhydrous ethanol. 0.640 g (2 mmol) of citric acid was added to the solution as a ligand and stirred until completely dissolved.

[0031] The above solution was transferred into a 300 mL autoclave, and the autoclave was ensured to be well sealed. The autoclave was placed in an oven, the temperature was set at 180°C, and the solvothermal reaction was carried out for 12 hours.

[0032] After the reaction was completed, the reactor was taken out and naturally cooled to room temperature.

[0033] Transfer the reaction solution to a 50 mL centrifuge tube and centrifuge at 8000 rpm for 10 minutes to separate the precipitate. Wash the precipitate 3 times with deionized water, adding 30 mL of deionized water each time, and keep the centrifugation conditions unchanged. Wash the precipitate 2 times with anhydrous ethanol, adding 30 mL of anhydrous ethanol each time, and keep the centrifugation conditions unchanged.

[0034] The washed precipitate was dried in an oven at 60°C for 12 hours to obtain dry rare earth nanoparticles. The dried nanoparticles were transferred to a muffle furnace and calcined at 500°C in an air atmosphere for 4 hours to remove surface organic matter and obtain a rare earth upconversion material with good upconversion performance. The SEM electron microscope image of the obtained material is shown in the figure. Figure 1 shown.

[0035] Example 2

[0036] 10 g of aniline was mixed with 50 mL of chloroform, and 1 g of the rare earth up-conversion material (Yb 3+ / Er 3+ doped NaYF4 nanoparticles). Under 808nm near-infrared light irradiation (optical power density 0.1 W / cm2), the reaction was carried out in an open state for 1 hour. After the reaction was completed, 11.3 g of phenyl isocyanate was obtained by distillation separation with a yield of 89%. The molecular weight of the product was [M+H] verified by GCMS. + : 120.1, which is consistent with the theoretical molecular weight, proving that the obtained product is the target product.

[0037] Example 3

[0038] 10 g of aniline was mixed with 50 mL of chloroform, and 0.1 g of the rare earth up-conversion material (Yb 3+ / Er 3+ doped NaYF4 nanoparticles). Under 808nm near-infrared light irradiation (optical power density 0.1 W / cm2), the reaction was carried out in an open state for 12 hours. After the reaction was completed, 10.1 g of phenyl isocyanate was obtained by distillation separation with a yield of 79%. The molecular weight of the product was [M+H] verified by GCMS. + : 120.3, which is consistent with the theoretical molecular weight, proving that the obtained product is the target product.

[0039] Example 4

[0040] 10 g of aniline was mixed with 50 mL of chloroform, and 1 g of the rare earth up-conversion material (Yb 3+ / Er 3+ doped NaYF4 nanoparticles). Under 808nm near-infrared light irradiation (optical power density 5 W / cm2), the reaction was carried out in an open state for 4 hours. After the reaction was completed, phenyl isocyanate 10.7 was obtained by distillation separation with a yield of 84%. The molecular weight of the product was [M+H] verified by GCMS. + : 120.3, which is consistent with the theoretical molecular weight, proving that the obtained product is the target product.

[0041] Example 5

[0042] 10 g of aniline was mixed with 50 mL of chloroform, and 0.1 g of the rare earth up-conversion material (Yb 3+ / Er 3+ doped NaYF4 nanoparticles). Under 980nm near-infrared light irradiation (optical power density 0.1 W / cm2), the reaction was carried out in an open state for 12 hours. After the reaction was completed, 10.5 g of phenyl isocyanate was obtained by distillation separation with a yield of 83%. The molecular weight of the product was [M+H] verified by GCMS. + : 120.2, which is consistent with the theoretical molecular weight, proving that the obtained product is the target product.

[0043] Example 6

[0044] 5 g of butylamine was mixed with 30 mL of chloroform, and 0.8 g of the rare earth up-conversion material prepared in Example 1 was added. The mixture was reacted for 3 hours under 980 nm near-infrared light in an open state. After the reaction, 5.9 g of butyl isocyanate was obtained by filtration and separation, with a yield of 88%. The molecular weight of the product was [M+H] as verified by GCMS. + : 100.2, which is consistent with the theoretical molecular weight, proving that the obtained product is the target product.

[0045] Comparative Example 1

[0046] The difference from Example 1 is that europium chloride is replaced by ytterbium chloride, that is, when preparing the rare earth up-conversion material, the rare earth metal salts used are: yttrium chloride (YCl3·6H2O) 0.781g and ytterbium chloride (YbCl3·6H2O) 0.335g, and the rest are the same as Example 1.

[0047] 10 g of aniline was mixed with 50 mL of chloroform, and 1 g of the rare earth up-conversion material prepared in Example 7 was added. The reaction was carried out for 1 hour under 808 nm near-infrared light irradiation (optical power density 0.1 W / cm2) in an open state. After the reaction was completed, an oily product was obtained by distillation separation, and the product was verified by GCMS to have no target product.

[0048] Comparative Example 2

[0049] The difference from Example 1 is that europium chloride is replaced by yttrium chloride, that is, when preparing the rare earth up-conversion material, the rare earth metal salts used are: 0.842g of yttrium chloride (YCl3·6H2O) and 0.274g of ytterbium chloride (YbCl3·6H2O), and the rest are the same as Example 1.

[0050] 10 g of aniline was mixed with 50 mL of chloroform, and 1 g of the rare earth up-conversion material prepared in Example 8 was added. The reaction was carried out for 1 hour under 808 nm near-infrared light irradiation (optical power density 0.1 W / cm2) in an open state. After the reaction was completed, an oily product was obtained by distillation separation, and the product was verified by GCMS to have no target product.

[0051] Comparative Example 3

[0052] The difference from Example 1 is that only yttrium chloride is used, that is, when preparing the rare earth up-conversion material, the rare earth metal salt used is: 1.116 g of yttrium chloride (YCl3·6H2O), and the rest is the same as Example 1.

[0053] 10 g of aniline was mixed with 50 mL of chloroform, and 1 g of the rare earth up-conversion material prepared in Example 9 was added. The reaction was carried out for 1 hour under 808 nm near-infrared light irradiation (optical power density 0.1 W / cm2) in an open state. After the reaction was completed, an oily product was obtained by distillation separation, and the product was verified by GCMS to have no target product.

[0054] Comparative Example 4

[0055] The difference from Example 1 is that only ytterbium chloride is used, that is, when preparing the rare earth up-conversion material, the rare earth metal salt used is: ytterbium chloride (YbCl3·6H2O) 1.116g, and the rest is the same as Example 1.

[0056] 10 g of aniline was mixed with 50 mL of chloroform, and 1 g of the rare earth up-conversion material prepared in Example 10 was added. The reaction was carried out for 1 hour under 808 nm near-infrared light irradiation (optical power density 0.1 W / cm2) in an open state. After the reaction was completed, an oily product was obtained by distillation separation, and the product was verified by GCMS to have no target product.

[0057] Comparative Example 5

[0058] 10 g of aniline was mixed with 50 mL of chloroform and reacted for 1 hour under 808 nm near-infrared light irradiation (optical power density 0.1 W / cm2). After the reaction was completed, an oily product was obtained by distillation separation, and the product was verified by GCMS to have no target product.

[0059] Comparative Example 6

[0060] 10 g of aniline was mixed with 50 mL of chloroform and reacted for 12 hours under 980 nm near-infrared light irradiation (optical power density 0.1 W / cm2). After the reaction was completed, an oily product was obtained by distillation separation, and the product was verified by GCMS to have no target product.

[0061] Comparative Example 7

[0062] 5 g of butylamine was mixed with 30 mL of chloroform and reacted under 980 nm near-infrared light for 3 hours. After the reaction, an oily product was obtained by distillation separation. GCMS confirmed that no target product was obtained.

[0063] Comparative Example 8

[0064] 10 g of aniline was mixed with 50 mL of chloroform, and 1 g of the rare earth up-conversion material (Yb 3+ / Er 3+ Doped NaYF4 nanoparticles). Under 500nm light irradiation (light power density 0.1 W / cm2), the reaction was carried out in an open state for 1 hour. After the reaction was completed, 1.4 g of phenyl isocyanate was obtained by distillation separation with a yield of 11%. The molecular weight of the product was verified by GCMS to be [M+H] + : 120.2, which is consistent with the theoretical molecular weight, proving that the obtained product is the target product.

[0065] The yield of phenyl isocyanate in this comparative example is very low, indicating that it is difficult to obtain the corresponding isocyanate under 500nm light irradiation, and the wavelength of light irradiation is a key factor.

[0066] Comparative Example 9

[0067] 10 g of aniline was mixed with 50 mL of acetonitrile, and 1 g of the rare earth up-conversion material (Yb 3+ / Er 3+ Doped NaYF4 nanoparticles). Under 808nm near-infrared light irradiation (optical power density 0.1 W / cm2), the reaction was carried out in an open state for 1 hour. After the reaction was completed, no target product was obtained by distillation. This indicates that when the solvent is acetonitrile, the corresponding isocyanate cannot be obtained, and the choice of solvent in the reaction system is a more critical factor.

[0068] Comparative Example 10

[0069] The difference from Example 1 is that the ligand used is porphyrin, and the rest is the same as Example 1.

[0070] 10 g of aniline was mixed with 50 mL of chloroform, and 1 g of the rare earth up-conversion material prepared in Comparative Example 6 was added. The reaction was carried out for 1 hour under 808 nm near-infrared light irradiation (optical power density 0.1 W / cm2) in an open state. After the reaction was completed, an oily product was obtained by distillation separation, and the product was verified by GCMS to have no target product.

[0071] Comparative Example 11

[0072] The difference from Example 1 is that the rare earth metal salt used is erbium chloride, and the rest is the same as Example 1.

[0073] 10 g of aniline was mixed with 50 mL of chloroform, and 1 g of the rare earth up-conversion material prepared in Comparative Example 7 was added. The reaction was carried out for 1 hour under 808 nm near-infrared light irradiation (optical power density 0.1 W / cm2) in an open state. After the reaction was completed, an oily product was obtained by distillation separation, and the product was verified by GCMS to have no target product.

[0074] Comparative Example 12

[0075] The difference from Example 1 is that the rare earth metal salt used is thulium chloride, and the rest is the same as Example 1.

[0076] 10 g of aniline was mixed with 50 mL of chloroform, and 1 g of the rare earth up-conversion material prepared in Comparative Example 8 was added. The reaction was carried out for 1 hour under 808 nm near-infrared light irradiation (optical power density 0.1 W / cm2) in an open state. After the reaction was completed, an oily product was obtained by distillation separation, and the product was verified by GCMS to have no target product.

[0077] The present invention introduces rare earth upconversion materials to realize a preparation method for generating isocyanate by oxidizing organic amines under mild conditions by catalyzing near-infrared light sources. Compared with the traditional method, the preparation process of the present invention is more environmentally friendly, the reaction conditions are mild, and the rare earth upconversion materials have good photocatalytic properties, which effectively improves the reaction efficiency and yield.

[0078] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing isocyanate based on rare earth upconversion materials, characterized in that: The steps include: The rare earth metal salt and the ligand are mixed and dissolved in anhydrous ethanol or anhydrous ethylene glycol, and a solvent thermal reaction is performed to prepare rare earth nanoparticles; The prepared rare earth nanoparticles are calcined at 450-550° C. to obtain a rare earth upconversion material; The rare earth up-conversion material is added to a solution of an organic amine compound, wherein the mass percentage of the rare earth up-conversion material to the organic amine compound is 1%-10%. In an oxygen-containing environment, a photocatalytic oxidation reaction is carried out under near-infrared light irradiation to prepare isocyanate.

2. The method for preparing isocyanate based on rare earth up-conversion materials according to claim 1, characterized in that: The organic amine compound is aniline, butylamine, ethylamine, phenethylamine or propylamine.

3. The method for preparing isocyanate based on rare earth up-conversion materials according to claim 1, characterized in that: The rare earth metal salt is a mixture of yttrium chloride, ytterbium chloride and europium chloride.

4. The method for preparing isocyanate based on rare earth up-conversion materials according to claim 3, characterized in that: In the rare earth metal salt, the mass ratio of yttrium chloride, ytterbium chloride and europium chloride is 10-15:10-15:

1.

5. The method for preparing isocyanate based on rare earth up-conversion materials according to claim 1, characterized in that: The ligand is citric acid or acetic acid.

6. The method for preparing isocyanate based on rare earth up-conversion materials according to claim 1, characterized in that: The temperature of the solvent thermal reaction is 160-200° C., and the reaction time is 8-12 hours.

7. The method for preparing isocyanate based on rare earth up-conversion materials according to claim 1, characterized in that: Before calcination, the method further includes the steps of washing and drying the prepared rare earth nanoparticles.

8. The method for preparing isocyanate based on rare earth up-conversion materials according to claim 1, characterized in that: The wavelength of the near infrared light is 808nm or 980nm.

9. The method for preparing isocyanate based on rare earth up-conversion materials according to claim 8, characterized in that: The optical power of the near-infrared light is 0.1-5 W / cm2; and the time of the photocatalytic oxidation reaction is 1-12 hours.

10. The method for preparing isocyanate based on rare earth up-conversion materials according to claim 1, characterized in that: The organic solvent in the solution of the organic amine compound is chloroform or bromoform.

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