Simple synthesis method of thermally crosslinkable monomer

Abstract

The invention relates to the technical field of organic chemistry, in particular to a simple synthesis method of a thermally crosslinkable monomer, which comprises the following steps: by taking methacrylic acid 2-(tert-butylamino) ethyl ester as a raw material, adding triphosgene into the methacrylic acid 2-(tert-butylamino) ethyl ester and a monomer containing an ester structure unit of active methylene in the presence of organic alkali and a first solvent, and reacting to obtain the thermally crosslinkable monomer. And after the reaction is finished, performing water-washing quenching, second solvent extraction and reduced-pressure concentration on the second solvent to obtain a target monomer. Compared with the existing monomer, the monomer only needs one step from the beginning to the end product (the synthesis of the existing monomer at least needs 6 steps), the material loss is greatly reduced, the reaction yield is improved, the material cost is greatly reduced, the monomer is more suitable for later-stage large-scale production, and compared with the existing monomer, the reaction activity of the monomer is not obviously reduced.

Description

Technical Field

[0001] The invention relates to the technical field of organic chemistry, and in particular to a simple synthesis method of a thermally crosslinkable monomer. Background Art

[0002] In recent years, with the development of flexible and wearable displays, display substrates that were originally made of glass as the main raw material have gradually been replaced by organic raw materials. As a substrate material, the resin obtained by polymerization of acrylate or epoxy groups alone has a low crosslinking density and usually cannot meet its performance requirements. Therefore, after the first polymerization, people hope that the initially polymerized resin still has active groups that can continue to react after heating. In early studies, people used glycidyl methacrylate (GMA) to achieve this goal. GMA is first copolymerized with other monomers by a free radical initiator (the epoxy group does not participate in the polymerization in this step). After film formation, the epoxy group continues to undergo thermal polymerization at a high temperature of 210 to 230°C, thereby further increasing the crosslinking density and enhancing the mechanical properties of the substrate. For example, the formation of color filters uses the above process. However, as an organic material, temperatures above 200°C often cause the material to turn yellow, affecting its optical properties. Therefore, researchers have developed a monomer that can be used for thermal crosslinking (CAS number: 2598192-92-6).

[0003]

[0004] Thanks to its special structure, the monomer can be cured at a temperature below 100°C (patent number: JP2014-62071A). Its synthesis method is as follows: ethanolamine and urea or ethanolamine and dimethyl carbonate are used as starting materials to prepare hydroxyethyl urea or 2-hydroxyethyl methyl carbamate, and then ammonia is removed under high temperature conditions to obtain oxazolidinone, which is then ring-opened with diethylamine, esterified with methyl acrylate, and removed at high temperature to obtain acrylate isocyanate, which is then reacted with diethyl malonate to obtain the target monomer.

[0005] The specific routes are as follows:

[0006]

[0007] The route of this monomer from the starting point to the final product has gone through 6 steps, which leads to the high price of this type of raw materials. In view of this, it is particularly important to develop a monomer with a simple synthesis method and considerable reactivity. Summary of the invention

[0008] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art: to provide a simple synthesis method of a thermally cross-linkable monomer, which has high yield, low cost, few steps and is suitable for industrial production.

[0009] In order to solve the above problems, the technical solution provided by the present invention is as follows:

[0010] A simple synthesis method of a heat-crosslinkable monomer comprises the following steps: using 2-(tert-butylamino)ethyl methacrylate as a raw material and a monomer having an ester structural unit containing an active methylene group, adding triphosgene to react in the presence of an organic base and a first solvent, washing and quenching after the reaction is completed, extracting with a second solvent, and concentrating the second solvent under reduced pressure to obtain the monomer.

[0011] Preferably, the monomer of the ester structural unit containing an active methylene group is any one of diethyl malonate, dimethyl malonate, ethyl acetoacetate and ethyl cyanoacetate.

[0012] Preferably, the organic base is one or more of TEA (triethylamine), DBU (dicyclic amidine), and DABCO (triethylenediamine).

[0013] Preferably, the first solvent is any one of MeCN (acetonitrile), DMF (N,N-dimethylformamide), and DMSO (dimethyl sulfoxide).

[0014] Preferably, the monomer molar ratio of the structural unit of the 2-(tert-butylamino)ethyl methacrylate to the ester containing an active methylene group is 1:1-1.1.

[0015] Preferably, the molar ratio of 2-(tert-butylamino)ethyl methacrylate to the organic base and triphosgene is 1:1-1.3:1-1.3.

[0016] Preferably, the second solvent is ethyl acetate or methyl tert-ether.

[0017] Preferably, the reaction conditions are heating under reflux in an oil bath at 75° C.-85° C. for 6 hours.

[0018] The present invention also includes the use of the monomer prepared by any of the above methods in thermal crosslinking.

[0019] The beneficial effect of the present invention is that, compared with the prior art, the present invention designs and synthesizes a thermally cross-linkable monomer, which only needs one step from the start to the final product compared with the existing monomer (the synthesis of the existing monomer requires at least 6 steps), which greatly reduces material loss, improves the reaction yield, greatly reduces material costs, and is more suitable for later large-scale production. Compared with the existing monomer, the reaction activity of the monomer does not decrease significantly. Therefore, it is of great significance to develop a synthetic method for the monomer. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the NMR spectrum of monomer Ⅰ in Example 1; DETAILED DESCRIPTION

[0021] The present invention is described below with reference to examples, but the present invention is not limited thereto. In the art, simple replacement or improvement made by technicians in the field to the present invention belongs to the technical solution protected by the present invention.

[0022] Embodiment 1:

[0023] The synthetic reaction formula of monomer I is as follows:

[0024]

[0025] The synthesis process of monomer I is as follows:

[0026] In a three-necked flask equipped with a stirring paddle and a thermometer, 2-(tert-butylamino)ethyl methacrylate (0.27 mol), diethyl malonate (0.297 mol) and reaction solvent MeCN (250 mL, 5 v) were added in sequence, and then TEA (0.324 mol) and a catalytic amount of DMAP (0.0135 mol) were added to the mixed solution. After the addition was completed, the mixed solution was stirred for 10 min, and triphosgene (0.297 mol) was slowly added under ice bath conditions. After the addition was completed, the ice bath was kept stirring for 20 min, and then the reaction bottle was placed in an oil bath at 80 degrees and heated to reflux for 6 h. TLC showed that the raw material disappeared; the reaction solution was slowly quenched in 500 mL of aqueous solution, and then 300 mL of ethyl acetate was added each time, extracted twice, and the combined organic phase was washed once with saturated brine, dried over anhydrous sodium sulfate, filtered and concentrated to remove the solvent to obtain a colorless oily monomer I (95 g, yield: 94.9%, HPLC purity: 97%).

[0027] Embodiment 2:

[0028] The synthetic reaction formula of monomer II is as follows:

[0029]

[0030] The synthesis process of monomer II is as follows:

[0031] In a three-necked flask equipped with a stirring paddle and a thermometer, 2-(tert-butylamino)ethyl methacrylate (50 g, 0.27 mol, 1 eq), dimethyl malonate (0.297 mol) and the reaction solvent DMF (250 mL, 5 v) were added in sequence, and then DBU (0.324 mol) and a catalytic amount of DMAP (1.65 g, 0.0135 mol) were added to the mixed solution. After the addition was completed, the mixed solution was stirred for 10 min, and then Sanguang was slowly added under ice bath conditions. Gas (0.297 mol), after addition, keep stirring in an ice bath for 20 min, then place the reaction bottle in an 80-degree oil bath and heat under reflux for 6 h, TLC shows that the raw material disappears; the reaction solution is slowly quenched in 500 mL of aqueous solution, and then 300 mL of tert-methyl ether is added each time, extracted twice, the combined organic phase is washed once with saturated brine, dried over anhydrous sodium sulfate, filtered and concentrated to remove the solvent to obtain colorless oily monomer II (95 g, yield: 94.9%, HPLC purity: 97%).

[0032] Embodiment 3:

[0033] The synthetic reaction formula of monomer III is as follows:

[0034]

[0035] Among them, the synthesis process of monomer III is as follows:

[0036] In a three-necked flask equipped with a stirring paddle and a thermometer, 2-(tert-butylamino)ethyl methacrylate (50 g, 0.27 mol, 1 eq), ethyl acetoacetate (0.297 mol) and reaction solvent DMSO (250 mL, 5 v) were added in sequence, and then DABCO (0.324 mol) and a catalytic amount of DMAP (0.0135 mol) were added to the mixed solution. After the addition was completed, the mixed solution was stirred for 10 min, and triphosgene (0.297 mol) was slowly added under ice bath conditions. After the addition was completed, the ice bath was kept stirring for 20 min, and then the reaction bottle was placed in an oil bath at 80 degrees and heated to reflux for 6 h. TLC showed that the raw material disappeared; the reaction solution was slowly quenched in 500 mL of aqueous solution, and then 300 mL of ethyl acetate was added each time, extracted twice, and the combined organic phase was washed once with saturated brine, dried over anhydrous sodium sulfate, filtered and concentrated to remove the solvent to obtain a colorless oily monomer III (95 g, yield: 94.9%, HPLC purity: 97%).

[0037] Embodiment 4:

[0038] The synthetic reaction formula of monomer IV is as follows:

[0039]

[0040] Among them, the synthesis process of monomer IV is as follows:

[0041] In a three-necked flask equipped with a stirring paddle and a thermometer, 2-(tert-butylamino)ethyl methacrylate (0.27 mol), ethyl cyanoacetate (0.297 mol) and reaction solvent MeCN (250 mL, 5 v) were added in sequence, and then TEA (0.324 mol) and a catalytic amount of DMAP (0.0135 mol) were added to the mixed solution. After the addition was completed, the mixed solution was stirred for 10 min, and triphosgene (0.297 mol) was slowly added under ice bath conditions. After the addition was completed, the ice bath was kept stirring for 20 min, and then the reaction bottle was placed in an oil bath at 80 degrees and heated to reflux for 6 h. TLC showed that the raw material disappeared; the reaction solution was slowly quenched in 500 mL of aqueous solution, and then 300 mL of ethyl acetate was added each time, extracted twice, and the combined organic phase was washed once with saturated brine, dried over anhydrous sodium sulfate, filtered and concentrated to remove the solvent to obtain a colorless oily monomer IV (95 g, yield: 94.9%, HPLC purity: 97%).

[0042] Embodiment 5:

[0043] Dissolve 5g of each of the 6 monomer groups of monomers I to IV and the existing monomer (diethyl 2-((2-(acryloyloxy)ethyl)carbamoyl)malonate) in 6 parts of 5g of HEA (hydroxyethyl acrylate), and then heat and stir each group in a 95°C oil bath for 5h. HPLC monitoring shows that the reaction conversion rates of monomers I to IV are 90%, 91%, 91%, 90%, and 91%, respectively. The reaction conversion rate of the existing monomer is 91%.

[0044] Reaction mechanism: The structural unit monomers of esters containing active methylene groups, such as diethyl malonate, dimethyl malonate, ethyl acetoacetate, and ethyl cyanoacetate, undergo ester exchange with monomers containing hydroxyl structural units at a suitable temperature to achieve thermal crosslinking.

[0045] From the above comparison, it can be seen that compared with the existing monomers, the reaction activity of the monomers obtained by the present application has no obvious decrease.

[0046] The above is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several modifications and improvements without departing from the inventive concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A simple method for synthesizing a thermally crosslinkable monomer, characterized in that: The method comprises the following steps: using 2-(tert-butylamino)ethyl methacrylate as a raw material and a monomer of an ester structural unit containing an active methylene group, adding triphosgene to react in the presence of an organic base and a first solvent, washing and quenching the reaction after the reaction is completed, extracting with a second solvent, and concentrating the second solvent under reduced pressure to obtain a target monomer.

2. The method according to claim 1, characterized in that The monomer of the ester structural unit containing an active methylene group is any one of diethyl malonate, dimethyl malonate, ethyl acetoacetate and ethyl cyanoacetate.

3. The method according to claim 1, characterized in that The organic base is one or more of TEA, DBU and DABCO.

4. The method according to claim 1, characterized in that The first solvent is any one of MeCN, DMF and DMSO.

5. The method according to claim 1, characterized in that The monomer molar ratio of the structural unit of 2-(tert-butylamino)ethyl methacrylate to the ester containing active methylene is 1:1-1.

1.

6. The method according to claim 1, characterized in that The molar ratio of 2-(tert-butylamino)ethyl methacrylate to the organic base and triphosgene is 1:1-1.3:1-1.

3.

7. The method according to claim 1, characterized in that The second solvent is ethyl acetate or methyl tert-ether.

8. The method according to claim 1, characterized in that The reaction conditions are heating under reflux in an oil bath at 75° C.-85° C. for 6 hours.

9. Use of the monomer prepared by the method according to any one of claims 1 to 8 in thermal crosslinking.

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