CN112979569A - Method for preparing aromatic isocyanate trimer - Google Patents
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- CN112979569A CN112979569A CN202110258146.6A CN202110258146A CN112979569A CN 112979569 A CN112979569 A CN 112979569A CN 202110258146 A CN202110258146 A CN 202110258146A CN 112979569 A CN112979569 A CN 112979569A
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- 239000012948 isocyanate Substances 0.000 title claims abstract description 67
- 239000013638 trimer Substances 0.000 title claims abstract description 65
- -1 aromatic isocyanate Chemical class 0.000 title claims abstract description 64
- 238000000034 method Methods 0.000 title claims abstract description 13
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 74
- 239000012043 crude product Substances 0.000 claims abstract description 28
- KEAYESYHFKHZAL-UHFFFAOYSA-N Sodium Chemical compound [Na] KEAYESYHFKHZAL-UHFFFAOYSA-N 0.000 claims abstract description 27
- 238000006243 chemical reaction Methods 0.000 claims abstract description 27
- 229910000104 sodium hydride Inorganic materials 0.000 claims abstract description 27
- 239000012312 sodium hydride Substances 0.000 claims abstract description 27
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 claims abstract description 25
- 239000000203 mixture Substances 0.000 claims abstract description 21
- 239000002244 precipitate Substances 0.000 claims abstract description 20
- DZSGDHNHQAJZCO-UHFFFAOYSA-N 1-isocyanato-3,5-dimethylbenzene Chemical compound CC1=CC(C)=CC(N=C=O)=C1 DZSGDHNHQAJZCO-UHFFFAOYSA-N 0.000 claims abstract description 17
- 239000000047 product Substances 0.000 claims abstract description 14
- 239000002904 solvent Substances 0.000 claims abstract description 13
- 238000010438 heat treatment Methods 0.000 claims abstract description 12
- 238000003760 magnetic stirring Methods 0.000 claims abstract description 12
- 239000003054 catalyst Substances 0.000 claims abstract description 10
- 238000001816 cooling Methods 0.000 claims abstract description 10
- 238000001035 drying Methods 0.000 claims abstract description 10
- 238000001914 filtration Methods 0.000 claims abstract description 10
- 239000000758 substrate Substances 0.000 claims abstract description 10
- 229910021642 ultra pure water Inorganic materials 0.000 claims abstract description 10
- 239000012498 ultrapure water Substances 0.000 claims abstract description 10
- 238000005406 washing Methods 0.000 claims abstract description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 10
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 36
- 229940125904 compound 1 Drugs 0.000 claims description 25
- 150000001875 compounds Chemical class 0.000 claims description 24
- 229940126214 compound 3 Drugs 0.000 claims description 21
- 229940125782 compound 2 Drugs 0.000 claims description 19
- FMDGXCSMDZMDHZ-UHFFFAOYSA-N 1-isocyanato-4-methoxybenzene Chemical compound COC1=CC=C(N=C=O)C=C1 FMDGXCSMDZMDHZ-UHFFFAOYSA-N 0.000 claims description 11
- 239000013078 crystal Substances 0.000 claims description 11
- YDNLNVZZTACNJX-UHFFFAOYSA-N isocyanatomethylbenzene Chemical compound O=C=NCC1=CC=CC=C1 YDNLNVZZTACNJX-UHFFFAOYSA-N 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 10
- DGTNSSLYPYDJGL-UHFFFAOYSA-N phenyl isocyanate Chemical compound O=C=NC1=CC=CC=C1 DGTNSSLYPYDJGL-UHFFFAOYSA-N 0.000 claims description 9
- 230000035484 reaction time Effects 0.000 claims description 4
- YEACGXMAEGBJSM-UHFFFAOYSA-N 1,3,5-triphenyl-1,3,5-triazinane-2,4,6-trione Chemical compound O=C1N(C=2C=CC=CC=2)C(=O)N(C=2C=CC=CC=2)C(=O)N1C1=CC=CC=C1 YEACGXMAEGBJSM-UHFFFAOYSA-N 0.000 claims description 3
- 230000015572 biosynthetic process Effects 0.000 abstract description 8
- 238000003786 synthesis reaction Methods 0.000 abstract description 8
- 238000005815 base catalysis Methods 0.000 abstract description 3
- 230000009286 beneficial effect Effects 0.000 abstract description 3
- 239000002861 polymer material Substances 0.000 abstract description 2
- 239000002585 base Substances 0.000 description 6
- 230000003197 catalytic effect Effects 0.000 description 5
- 230000003247 decreasing effect Effects 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
- 239000013067 intermediate product Substances 0.000 description 4
- 238000002360 preparation method Methods 0.000 description 4
- 239000006227 byproduct Substances 0.000 description 3
- 150000002513 isocyanates Chemical class 0.000 description 3
- 238000006116 polymerization reaction Methods 0.000 description 3
- 229920000858 Cyclodextrin Polymers 0.000 description 2
- 229940125898 compound 5 Drugs 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- HFHDHCJBZVLPGP-UHFFFAOYSA-N schardinger α-dextrin Chemical compound O1C(C(C2O)O)C(CO)OC2OC(C(C2O)O)C(CO)OC2OC(C(C2O)O)C(CO)OC2OC(C(O)C2O)C(CO)OC2OC(C(C2O)O)C(CO)OC2OC2C(O)C(O)C1OC2CO HFHDHCJBZVLPGP-UHFFFAOYSA-N 0.000 description 2
- UQBNGMRDYGPUOO-UHFFFAOYSA-N 1-n,3-n-dimethylbenzene-1,3-diamine Chemical compound CNC1=CC=CC(NC)=C1 UQBNGMRDYGPUOO-UHFFFAOYSA-N 0.000 description 1
- 239000004952 Polyamide Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229940124350 antibacterial drug Drugs 0.000 description 1
- 239000004202 carbamide Substances 0.000 description 1
- 238000007036 catalytic synthesis reaction Methods 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010812 external standard method Methods 0.000 description 1
- 150000002222 fluorine compounds Chemical class 0.000 description 1
- 239000004009 herbicide Substances 0.000 description 1
- 238000004128 high performance liquid chromatography Methods 0.000 description 1
- 239000000017 hydrogel Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000002329 infrared spectrum Methods 0.000 description 1
- 239000002917 insecticide Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000004811 liquid chromatography Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 150000007530 organic bases Chemical class 0.000 description 1
- 229920002647 polyamide Polymers 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- QDRKDTQENPPHOJ-UHFFFAOYSA-N sodium ethoxide Chemical compound [Na+].CC[O-] QDRKDTQENPPHOJ-UHFFFAOYSA-N 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000005829 trimerization reaction Methods 0.000 description 1
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D251/00—Heterocyclic compounds containing 1,3,5-triazine rings
- C07D251/02—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings
- C07D251/12—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members
- C07D251/26—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members with only hetero atoms directly attached to ring carbon atoms
- C07D251/30—Only oxygen atoms
- C07D251/34—Cyanuric or isocyanuric esters
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a method for preparing aromatic isocyanate trimer in the field of high polymer material synthesis, which comprises the following steps: s1: respectively taking dimethylacetamide, ethanol and sodium hydride, adding the dimethylacetamide as a solvent and the ethanol and the sodium hydride as catalysts into a flask to react at room temperature; s2: then dropwise adding aromatic isocyanate as a reaction substrate, and heating and reacting under magnetic stirring; s3: and (3) cooling the mixture to room temperature, pouring the mixture into ultrapure water to separate out a product, filtering, washing the precipitate with water and ethanol in sequence, and drying the precipitate in an oven to obtain a crude product. The invention takes dimethylacetamide as solvent, under the condition of no change of ethanol, a small amount of sodium hydride is used for carrying out base catalysis on aromatic isocyanates such as 3, 5-dimethylphenyl isocyanate and the like to synthesize the compound aromatic isocyanate trimer, the yield of the aromatic isocyanate trimer can be improved, the cost is reduced, and the invention is beneficial to the use of people.
Description
Technical Field
The invention relates to the field of synthesis of high polymer materials, in particular to a method for preparing an aromatic isocyanate trimer.
Background
The application of isocyanate oligomer in the construction of complex polymer frameworks dates back to 30 years in the 20 th century or even earlier, and is widely applied to the preparation of various new materials, including: aromatic isocyanate oligomer (AIS) is also widely applied to synthesis of hydrogel due to a unique cyclic polyamide structure, and phenyl-substituted isocyanate trimer is common in the preparation process of N-aryloxy oxazolone herbicides, wherein phenyl isocyanate trimer is also commonly applied to development of insecticides and antibacterial drugs containing urea bridge structures.
The inventors, in preparing a cyclodextrin macromolecular polymer modified with 3, 5-dimethylphenyl isocyanate (FIG. 1 (Compound 1)), occasionally obtained a colorless crystal, which was confirmed to be a trimer of 3, 5-dimethylphenyl isocyanate by X-ray single crystal diffraction test and analysis.
In this experiment, yields of up to 90% of product have prompted us to systematically study trimerization reactions, even though aromatic isocyanate trimers have been synthesized catalyzed by catalytic fluorides and by N-heterocyclic olefins, but the synthesis of aromatic isocyanate trimers under organic base catalysis, such as sodium ethoxide, has never been reported in this experiment after excluding the possibility of cyclodextrin catalyzed polymerization, and the synthesis costs for base catalyzed preparation of aromatic isocyanate trimers are much simpler and less costly than several known catalytic synthesis methods. Accordingly, one skilled in the art provides a method for preparing aromatic isocyanate trimers.
Disclosure of Invention
The object of the present invention is to provide a method for preparing an aromatic isocyanate trimer, which solves the problems of the background art mentioned above.
In order to achieve the purpose, the invention provides the following technical scheme:
a process for preparing an aromatic isocyanate trimer comprising the steps of:
s1: respectively taking dimethylacetamide, ethanol and sodium hydride, adding the dimethylacetamide as a solvent and the ethanol and the sodium hydride as catalysts into a flask to react at room temperature;
s2: then dropwise adding aromatic isocyanate as a reaction substrate, and heating and reacting under magnetic stirring;
s3: cooling the mixture to room temperature, pouring the mixture into ultrapure water to separate out a product, filtering, washing the precipitate with water and ethanol in sequence, and drying the precipitate in an oven to obtain a crude product;
s4: the crude product was dissolved in acetone and recrystallized to obtain aromatic isocyanate trimer of compound 1, compound 2, compound 3 and compound 4, respectively.
As a further scheme of the invention: respectively taking dimethylacetamide in the S1: 5.0mL, ethanol: 200. mu.L, sodium hydride: 0.01g to 0.5 g.
As a still further scheme of the invention: the aromatic isocyanate in S2: 7.0mmol, magnetic stirring speed 200 rpm.
As a still further scheme of the invention: the heating reaction temperature in the S2 is 50-100 ℃.
As a still further scheme of the invention: the reaction time in the S1 and the S2 is 1-12 h.
As a still further scheme of the invention: in the S4, the compound 1 is a trimer of 3, 5-dimethylphenyl isocyanate, the compound 2 is phenyl isocyanate, the compound 3 is 4-methoxyphenyl isocyanate, and the compound 4 is benzyl isocyanate.
As a still further scheme of the invention: the crude product in S3 was recrystallized from acetone to obtain cubic aromatic isocyanate trimer crystals.
Characterization data of the product:
3, 5-dimethylphenyl isocyanate trimer (Compound 1).
Phenyl isocyanate trimer (compound 2).
4-methoxyphenyl isocyanate trimer (Compound 3).
Benzyl isocyanate trimer (compound 4).
Compared with the prior art, the invention has the beneficial effects that: the invention takes dimethylacetamide as solvent, under the condition of no change of ethanol, a small amount of sodium hydride is used for carrying out base catalysis on aromatic isocyanates such as 3, 5-dimethylphenyl isocyanate and the like to synthesize the compound aromatic isocyanate trimer, the yield of the aromatic isocyanate trimer can be improved, the cost is reduced, and the invention is beneficial to the use of people.
Drawings
FIG. 1 is a chart of the infrared spectrum of an aromatic isocyanate trimer according to the present invention;
FIG. 2 is a high performance liquid chromatogram of the present invention;
FIG. 3 is a schematic diagram of the synthesis scheme and X-ray structure of the aromatic isocyanate trimer according to the present invention;
FIG. 4 is a diagram showing the polymerization of another aromatic isocyanate according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1, a method of preparing an aromatic isocyanate trimer, comprising the steps of: s1: respectively taking 5.0mL of dimethylacetamide, 200 mu L of ethanol and 0.01g of sodium hydride, adding the dimethylacetamide serving as a solvent and the ethanol and the sodium hydride serving as catalysts into a flask to react for 1h at room temperature; s2: then 7.0mmol of aromatic isocyanate is added as a reaction substrate, and the reaction is carried out for 12 hours by heating at 100 ℃ under the magnetic stirring at 200 rpm; s3: cooling the mixture to room temperature, pouring the mixture into ultrapure water to separate out a product, filtering, washing the precipitate with water and ethanol in sequence, and drying the precipitate in an oven to obtain a crude product; recrystallizing the crude product in S3 by acetone to obtain cubic aromatic isocyanate trimer crystals; s4: dissolving the crude product by acetone and recrystallizing to obtain aromatic isocyanate trimer of compound 1, compound 2, compound 3 and compound 4; in S4, compound 1 is trimer of 3, 5-dimethylphenyl isocyanate, compound 2 is phenyl isocyanate, compound 3 is 4-methoxyphenyl isocyanate, and compound 4 is benzyl isocyanate.
Example 2, a method of preparing an aromatic isocyanate trimer, comprising the steps of: s1: respectively taking 5.0mL of dimethylacetamide, 200 mu L of ethanol and 0.02g of sodium hydride, adding the dimethylacetamide serving as a solvent and the ethanol and the sodium hydride serving as catalysts into a flask to react for 2 hours at room temperature; s2: then 7.0mmol of aromatic isocyanate is added as a reaction substrate, and the reaction is carried out for 5 hours by heating at 50 ℃ under the magnetic stirring at 200 rpm; s3: cooling the mixture to room temperature, pouring the mixture into ultrapure water to separate out a product, filtering, washing the precipitate with water and ethanol in sequence, and drying the precipitate in an oven to obtain a crude product; recrystallizing the crude product in S3 by acetone to obtain cubic aromatic isocyanate trimer crystals; s4: dissolving the crude product by acetone and recrystallizing to obtain aromatic isocyanate trimer of compound 1, compound 2, compound 3 and compound 4; in S4, compound 1 is trimer of 3, 5-dimethylphenyl isocyanate, compound 2 is phenyl isocyanate, compound 3 is 4-methoxyphenyl isocyanate, and compound 4 is benzyl isocyanate.
Example 3, a method of preparing an aromatic isocyanate trimer comprising the steps of: s1: respectively taking 5.0mL of dimethylacetamide, 200 mu L of ethanol and 0.5g of sodium hydride, adding the dimethylacetamide serving as a solvent and the ethanol and the sodium hydride serving as catalysts into a flask to react for 5 hours at room temperature; s2: then 7.0mmol of aromatic isocyanate is added as a reaction substrate, and heating reaction is carried out for 10 hours at 200rpm under magnetic stirring; s3: cooling the mixture to room temperature, pouring the mixture into ultrapure water to separate out a product, filtering, washing the precipitate with water and ethanol in sequence, and drying the precipitate in an oven to obtain a crude product; recrystallizing the crude product in S3 by acetone to obtain cubic aromatic isocyanate trimer crystals; s4: dissolving the crude product by acetone and recrystallizing to obtain aromatic isocyanate trimer of compound 1, compound 2, compound 3 and compound 4; in S4, compound 1 is trimer of 3, 5-dimethylphenyl isocyanate, compound 2 is phenyl isocyanate, compound 3 is 4-methoxyphenyl isocyanate, and compound 4 is benzyl isocyanate.
Example 4, a method of preparing an aromatic isocyanate trimer, comprising the steps of: s1: respectively taking 5.0mL of dimethylacetamide, 200 mu L of ethanol and 0.03g of sodium hydride, adding the dimethylacetamide serving as a solvent and the ethanol and the sodium hydride serving as catalysts into a flask to react for 1h at room temperature; s2: then 7.0mmol of aromatic isocyanate is added as a reaction substrate, and heating reaction is carried out for 1h at 60 ℃ under the magnetic stirring at 200 rpm; s3: cooling the mixture to room temperature, pouring the mixture into ultrapure water to separate out a product, filtering, washing the precipitate with water and ethanol in sequence, and drying the precipitate in an oven to obtain a crude product; recrystallizing the crude product in S3 by acetone to obtain cubic aromatic isocyanate trimer crystals; s4: dissolving the crude product by acetone and recrystallizing to obtain aromatic isocyanate trimer of compound 1, compound 2, compound 3 and compound 4; in S4, compound 1 is trimer of 3, 5-dimethylphenyl isocyanate, compound 2 is phenyl isocyanate, compound 3 is 4-methoxyphenyl isocyanate, and compound 4 is benzyl isocyanate.
Example 5, a process for preparing an aromatic isocyanate trimer comprising the steps of: s1: respectively taking 5.0mL of dimethylacetamide, 200 mu L of ethanol and 0.04g of sodium hydride, adding the dimethylacetamide serving as a solvent and the ethanol and the sodium hydride serving as catalysts into a flask to react for 12 hours at room temperature; s2: then 7.0mmol of aromatic isocyanate is added as a reaction substrate, and heating reaction is carried out for 12 hours under the magnetic stirring at 200 rpm; s3: cooling the mixture to room temperature, pouring the mixture into ultrapure water to separate out a product, filtering, washing the precipitate with water and ethanol in sequence, and drying the precipitate in an oven to obtain a crude product; recrystallizing the crude product in S3 by acetone to obtain cubic aromatic isocyanate trimer crystals; s4: dissolving the crude product by acetone and recrystallizing to obtain aromatic isocyanate trimer of compound 1, compound 2, compound 3 and compound 4; in S4, compound 1 is trimer of 3, 5-dimethylphenyl isocyanate, compound 2 is phenyl isocyanate, compound 3 is 4-methoxyphenyl isocyanate, and compound 4 is benzyl isocyanate.
Example 6, a method of preparing an aromatic isocyanate trimer, comprising the steps of: s1: respectively taking 5.0mL of dimethylacetamide, 200 mu L of ethanol and 0.01g of sodium hydride, adding the dimethylacetamide serving as a solvent and the ethanol and the sodium hydride serving as catalysts into a flask to react for 3 hours at room temperature; s2: then 7.0mmol of aromatic isocyanate is added as a reaction substrate, and the reaction is carried out for 3 hours by heating at 50 ℃ under the magnetic stirring at 200 rpm; s3: cooling the mixture to room temperature, pouring the mixture into ultrapure water to separate out a product, filtering, washing the precipitate with water and ethanol in sequence, and drying the precipitate in an oven to obtain a crude product; recrystallizing the crude product in S3 by acetone to obtain cubic aromatic isocyanate trimer crystals; s4: dissolving the crude product by acetone and recrystallizing to obtain aromatic isocyanate trimer of compound 1, compound 2, compound 3 and compound 4; in S4, compound 1 is trimer of 3, 5-dimethylphenyl isocyanate, compound 2 is phenyl isocyanate, compound 3 is 4-methoxyphenyl isocyanate, and compound 4 is benzyl isocyanate.
Example 7, a process for preparing an aromatic isocyanate trimer comprising the steps of: s1: respectively taking 5.0mL of dimethylacetamide, 200 mu L of ethanol and 0.05g of sodium hydride, adding the dimethylacetamide serving as a solvent and the ethanol and the sodium hydride serving as catalysts into a flask to react for 5 hours at room temperature; s2: then 7.0mmol of aromatic isocyanate is added as a reaction substrate, and heating reaction is carried out for 5 hours at 80 ℃ under magnetic stirring; s3: cooling the mixture to room temperature, pouring the mixture into ultrapure water to separate out a product, filtering, washing the precipitate with water and ethanol in sequence, and drying the precipitate in an oven to obtain a crude product; recrystallizing the crude product in S3 by acetone to obtain cubic aromatic isocyanate trimer crystals; s4: dissolving the crude product by acetone and recrystallizing to obtain aromatic isocyanate trimer of compound 1, compound 2, compound 3 and compound 4; in S4, compound 1 is trimer of 3, 5-dimethylphenyl isocyanate, compound 2 is phenyl isocyanate, compound 3 is 4-methoxyphenyl isocyanate, and compound 4 is benzyl isocyanate.
In order to explore the optimal conditions for the reaction. We respectively investigate the influence of the concentration of catalytic base and the reaction temperature on the synthesis of the compound under a single factor. We then designed a three-factor complete orthogonal experiment. The influence of three variables, namely reaction temperature, catalytic base concentration and reaction time, on the synthesis of the compound is examined. In the orthogonal experiment, the reaction temperature is respectively selected to react under the conditions of 50 ℃, 75 ℃ and 100 ℃; the alkali concentration is respectively selected to be 0.01, 0.05, 0.1 and 0.5g (by mass of sodium hydride) in 0.2mL of ethanol; the reaction time is selected from the reaction under the conditions of 1, 2, 4, 8 and 12 hours respectively. The content in the sample was then measured using HPLC external standard method.
Influence of catalytic base concentration on the reaction. As shown in fig. 2A, as the amount of base was increased from 0.01g/0.2mL to 0.5g/0.2mL, the peak area percentages of the main product (compound 1, tr ═ 5.486min (tr is the "retention time" of the substance in liquid chromatography)) decreased gradually, being 95% (fig. 2A-a), 89% (fig. 2A-b), 75% (fig. 2A-c) and 15% (fig. 2A-d), respectively. Meanwhile, the peak area percentage of the intermediate product (compound 3, tr 4.536min) gradually decreased, and the peak of another intermediate product (compound 4, tr 8.430min) gradually became clear. In addition, the amount of a by-product (3, 5-dimethylaminobenzene (compound 6), tr: 18.210min) produced by decomposition of the raw material also gradually increased. In addition, some new impurity peaks were also observed in the high-strength alkaline catalyzed mixture during the stepwise increase of the decreasing concentration to 0.5g sodium hydride/0.2 mL ethanol. However, in the separation process, the purity of the intermediate compound 5 is still not separated, so that whether the intermediate compound 5 is represented in the chromatogram is not determined.
Influence of temperature on the reaction. As shown in fig. 2B, the peak area of the main product (compound 1, tr ═ 5.486min) gradually decreased as the temperature increased from 50 ℃ to 100 ℃. Meanwhile, the peak area of the intermediate product (compound 3, tr ═ 4.536min) shows a tendency to increase first and then decrease, while the peak of another intermediate product (compound 4, tr ═ 8.430min) is still less pronounced.
In summary, we have found that the preparation of isocyanate trimerisation is favored by lower catalytic base concentrations and lower temperatures when 3, 5-dimethylphenyl isocyanate (2mL) is synthesized by base-catalysing the polymerization of 3, 5-dimethylphenyl isocyanate with a small amount of sodium hydride in dimethylacetamide as a solvent without the addition of ethanol (0.20 mL).
Table 1 yields of compound 1, by-product 1 of compound 1, and by-product 2 of compound 1 under different reaction conditions
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (7)
1. A process for preparing an aromatic isocyanate trimer characterized by: the method comprises the following steps:
s1: respectively taking dimethylacetamide, ethanol and sodium hydride, adding the dimethylacetamide as a solvent and the ethanol and the sodium hydride as catalysts into a flask to react at room temperature;
s2: then dropwise adding aromatic isocyanate as a reaction substrate, and heating and reacting under magnetic stirring;
s3: cooling the mixture to room temperature, pouring the mixture into ultrapure water to separate out a product, filtering, washing the precipitate with water and ethanol in sequence, and drying the precipitate in an oven to obtain a crude product;
s4: the crude product was dissolved in acetone and recrystallized to obtain a total of four aromatic isocyanate trimers, 3, 5-dimethylphenyl isocyanate trimer (compound 1), phenyl isocyanate trimer (compound 2), p-methoxyphenyl isocyanate trimer (compound 3) and benzyl isocyanate trimer (compound 4), respectively.
2. A process for preparing an aromatic isocyanate trimer according to claim 1, wherein: respectively taking dimethylacetamide in the S1: 5.0mL, ethanol: 200. mu.L, sodium hydride: 0.01g to 0.5 g.
3. A process for preparing an aromatic isocyanate trimer according to claim 1, wherein: the aromatic isocyanate in S2: 7.0mmol, magnetic stirring speed 200 rpm.
4. A process for preparing an aromatic isocyanate trimer according to claim 1, wherein: the heating reaction temperature in the S2 is 50-100 ℃.
5. A process for preparing an aromatic isocyanate trimer according to claim 1, wherein: the reaction time in the S1 and the S2 is 1-12 h.
6. A process for preparing an aromatic isocyanate trimer according to claim 1, wherein: in the S4, the compound 1 is a trimer of 3, 5-dimethylphenyl isocyanate, the compound 2 is phenyl isocyanate, the compound 3 is 4-methoxyphenyl isocyanate, and the compound 4 is benzyl isocyanate.
7. A process for preparing an aromatic isocyanate trimer according to claim 1, wherein: the crude product in S3 was recrystallized from acetone to obtain cubic aromatic isocyanate trimer crystals.
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|---|---|---|---|---|
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| US3962239A (en) * | 1974-02-28 | 1976-06-08 | Ceskoslovenska Akademie Ved | Method for producing cyclic trimers of organic isocyanates |
| US4632785A (en) * | 1983-08-11 | 1986-12-30 | The Dow Chemical Company | Thermally activable trimerization catalyst |
| WO2015133496A1 (en) * | 2014-03-04 | 2015-09-11 | 三井化学株式会社 | Laminate adhesive, method for manufacturing laminate film, laminate film, and retort pouch material |
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2021
- 2021-03-09 CN CN202110258146.6A patent/CN112979569A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB837120A (en) * | 1957-06-12 | 1960-06-09 | Ici Ltd | Trimerisation of organic isocyanates |
| US3716535A (en) * | 1968-02-27 | 1973-02-13 | Ici America Inc | Trimerization of isocyanates |
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