Oxazole disubstituted compound and preparation method and application thereof

Abstract

The invention discloses an oxazole disubstituted compound and a preparation method and application thereof. The oxazole disubstituted compound has a structure as shown in a formula I. Most of the raw materials in the synthesis route of the oxazole diacid / ester can be synthesized through non-grain biomass, and the oxazole diacid / ester with a brand new structure is finally obtained through cyclization, deamination, carboxylation and nucleophilic substitution reaction by taking bromopyruvic acid / ester substances and urea as raw materials. The obtained oxazole diacid / ester can be used as a monomer to synthesize a novel green degradable polymer. The structural rigidity is large, and the mechanical property of polyester can be improved in the field of polymer synthesis; # imgabs0 #

Description

Technical Field

[0001] The present application relates to an oxazole disubstituted compound and a preparation method and application thereof, belonging to the technical field of organic chorus. Background Art

[0002] As a non-renewable resource, petrochemical resources have limited reserves and cannot meet people's growing demand for energy and chemicals. In addition, due to the large-scale exploitation of petrochemical resources, serious energy crises and environmental problems have been caused. Therefore, using renewable resources as raw materials to synthesize new bio-based chemicals to replace petroleum-based chemicals, and finding and developing new bio-based polymer materials have important practical significance for alleviating the energy crisis brought by petrochemical resources, solving environmental pollution problems, and high-value utilization of biomass resources. In the field of polymers, polyesters based on terephthalic acid series, such as polyethylene terephthalate (PET), polypropylene terephthalate (PTT), polybutylene terephthalate (PBT) and their derived series of copolyesters have good mechanical properties, thermal stability and processability. They are a class of bulk polymer materials with excellent comprehensive performance and are widely used in many fields such as fibers, films, plastic bottles, packaging, engineering plastics, etc. However, since terephthalic acid is a non-renewable raw material derived from petrochemicals, the sustainable development of its polyester materials is greatly limited. Therefore, the development of bio-based polyester monomers to replace petroleum-based raw materials has become an important research direction in the field of polyester materials.

[0003] At present, the main chains of bio-based polyesters commonly used in the market are mainly aliphatic chain structures, such as PBS, PLA and PHA, which leads to their poor barrier properties and heat resistance, making it difficult to compete with existing petroleum-based polyesters. Summary of the invention

[0004] In view of the current problems of few types of bio-based degradable polyester materials and poor comprehensive performance, this application will develop some new structures of oxazole disubstituted compounds for the synthesis of bio-based polyesters with excellent thermodynamic properties and degradability.

[0005] The purpose of this application is to provide a new type of green high-performance biodegradable polyester raw material.

[0006] The 2,4-oxazoledicarboxylic acid diethyl ester synthesized in the present application is a monomer derived from biomass resources, and can be used as a synthetic raw material for a novel green and degradable polyester.

[0007] According to one aspect of the present application, there is provided an oxazole disubstituted compound having a structure shown in Formula I:

[0008]

[0009] In formula I, R1 is selected from one of -H, -OH, -OCH3, -OCH2CH3;

[0010] R2 is selected from one of -H, -F, -Cl, -Br, -I, -OH, -OCH3, and -OCH2CH3.

[0011] According to another aspect of the present application, a method for preparing the above-mentioned disubstituted oxazole compound is provided, and the preparation method comprises the following steps:

[0012] S1: reacting a mixture I containing a pyruvate compound, urea and a solvent I to obtain a compound 2;

[0013] S2: Dissolve compound 2 in an acid solution, add solvent II, and react with II to obtain compound 3;

[0014] S3: Under a carbon dioxide atmosphere, a mixture containing compound 3, an organic strong base, and a solvent III is reacted with III to obtain compound 4;

[0015] S4: reacting a mixture containing compound 4 and alkyl halide with IV to obtain the oxazole disubstituted compound;

[0016] The pyruvate compound has the structure shown in Compound 1;

[0017]

[0018]

[0019] R1 in Compound 1, Compound 2, Compound 3 and Compound 4 is consistent with R1 described above.

[0020] Optionally, in step S1, the pyruvate compound is selected from at least one of 3-bromopyruvic acid, 3-bromopyruvic acid methyl ester and 3-bromopyruvic acid ethyl ester.

[0021] Optionally, the solvent I is selected from at least one of methanol, ethanol, petroleum ether, dichloromethane and chloroform.

[0022] Optionally, the molar ratio of the pyruvate compound to the urea is 2:1 to 1:2.

[0023] Optionally, the molar volume ratio of the pyruvate compound to the solvent I is 1:1000 to 1:10 mol / L.

[0024] Optionally, in step S2, the acid in the acid solution is selected from at least one of sulfuric acid, hydrochloric acid, phosphoric acid, hypophosphorous acid, p-toluenesulfonic acid, and perchloric acid.

[0025] Optionally, the concentration of the acid solution is 1 to 10 mol / L.

[0026] Optionally, the concentration of the acid solution is independently selected from any value among 1mol / L, 2mol / L, 3mol / L, 4mol / L, 5mol / L, 6mol / L, 7mol / L, 8mol / L, 9mol / L, 10mol / L or a range between any two of the above.

[0027] Optionally, the solvent II is selected from at least one of sodium nitrite, isoamyl nitrite, tert-butyl nitrite, hypophosphorous acid, ethanol, acetic acid, and sodium bisulfate.

[0028] Optionally, the mass ratio of the compound 2 to the acid solution is 1:10 to 10:1.

[0029] Optionally, the molar volume ratio of the compound 2 to the solvent II is 1:1000 to 1:10 mol / L.

[0030] Optionally, in step S3, the organic strong base is selected from at least one of sodium ethoxide, potassium ethoxide, sodium tert-butoxide and potassium tert-butoxide.

[0031] Optionally, the solvent III is selected from at least one of ethanol, methanol, N,N-dimethylformamide, tetrahydrofuran, and dimethyl sulfoxide.

[0032] Optionally, the molar ratio of the compound 3 to the organic strong base is 1:10 to 10:1.

[0033] Optionally, the molar volume ratio of the compound 3 to the solvent III is 1:1000 to 1:10 mol / L.

[0034] Optionally, in step S4, the alkyl halide is selected from at least one of methyl bromide, ethyl bromide, methyl iodide and ethyl iodide.

[0035] Optionally, the molar ratio of the compound 4 to the alkyl halide is 1:10 to 10:1.

[0036] Optionally, in step S1, the temperature of reaction I is 40-200° C., and the time of reaction I is 1-5 h.

[0037] Optionally, in step S1, the temperature of the reaction I is independently selected from any value of 40°C, 60°C, 80°C, 100°C, 120°C, 140°C, 160°C, 180°C, 200°C or a range between any two of the above.

[0038] Optionally, the reaction time I is independently selected from any value among 1h, 2h, 3h, 4h, 5h or a range between any two of the above.

[0039] Optionally, in step S2, the temperature of reaction II is 40-200° C., and the time of reaction II is 0.5-4 h.

[0040] Optionally, in step S2, the temperature of reaction II is independently selected from any value of 40°C, 60°C, 80°C, 100°C, 120°C, 140°C, 160°C, 180°C, 200°C or a range between any two of the above.

[0041] Optionally, the time of the reaction II is independently selected from any value of 0.5h, 1h, 2h, 3h, 4h or a range between any two of the above.

[0042] Optionally, in step S3, the temperature of reaction III is 60-120° C., and the time of reaction III is 30-240 min.

[0043] Optionally, in step S3, the temperature of reaction III is independently selected from any value of 60°C, 80°C, 100°C, 120°C or a range between any two of the above values.

[0044] Optionally, the time of the reaction III is independently selected from any value of 30 min, 60 min, 90 min, 120 min, 150 min, 180 min, 210 min, 240 min, or a range between any two of the above.

[0045] Optionally, in step S4, the temperature of reaction IV is 30-90° C., and the time of reaction IV is 30-240 min.

[0046] Optionally, in step S4, the temperature of reaction IV is independently selected from any value of 30°C, 60°C, 90°C or a range between any two of the above values.

[0047] Optionally, the reaction IV time is independently selected from any value of 30 min, 60 min, 90 min, 120 min, 150 min, 180 min, 210 min, 240 min or a range between any two of the above.

[0048] According to another aspect of the present application, there is provided a use of the above-mentioned disubstituted oxazole compound in a novel green biodegradable polyester.

[0049] As an optional implementation method, the present application is implemented through the following technical solutions:

[0050] A synthetic route for synthesizing diethyl 2,4-oxazoledicarboxylate comprises:

[0051] Step 1: Add a certain proportion of 3-bromopyruvic acid / pyruvic acid esters and urea to ethanol, heat and reflux, and react for a certain period of time. After the reaction, extract compound 2 with ethyl acetate;

[0052] Step 2: Dissolve the extracted compound 2 with a certain concentration of acid solution and place it in an ice water bath to fully cool it. After cooling, add a certain amount of substance c, and after a period of reaction, add hypophosphorous acid for reduction. After the reaction is completed, extract compound 3 with ethyl acetate;

[0053] Step 3: Carboxylation of compound 3 is performed as follows: the extracted compound 3 is mixed with a certain amount of organic strong base, dissolved with solvent d, placed in a CO2 atmosphere and heated to temperature I, and reacted for a period of time to generate compound 4;

[0054] Step 4: Compound 4 is subjected to a nucleophilic substitution reaction. The temperature of the system obtained in step 3 is changed to temperature II, a certain amount of alkyl halide is added and reacted for a certain time, and the product is extracted with ethyl acetate to obtain compound 5.

[0055] Optionally, in step 2, substance c is selected from one or a mixture of sodium nitrite, isopentyl nitrite, and tert-butyl nitrite.

[0056] Optionally, in step three, solvent d is selected from one or a mixture of anhydrous ethanol, anhydrous methanol, anhydrous dimethylformamide, anhydrous tetrahydrofuran, and anhydrous dimethyl sulfoxide.

[0057] Optionally, the reduction time is 30 to 180 minutes.

[0058] Optionally, the reduction time is independently selected from any value among 30 min, 60 min, 90 min, 120 min, 150 min, 180 min or a range between any two of the above.

[0059] The beneficial effects of this application include:

[0060] The present application provides a method for synthesizing a disubstituted oxazole compound and an oxazole diacid / ester with a completely new structure. Most of the raw materials in the oxazole diacid / ester synthesis route are synthesized from non-food biomass. The present application uses bromopyruvic acid / ester substances and urea as raw materials, and finally obtains an oxazole diacid / ester with a completely new structure through cyclization, deamination, carboxylation, and nucleophilic substitution reactions. The obtained oxazole diacid / ester can be used as a monomer to synthesize a new type of green degradable polymer. It has the characteristics of large structural rigidity and can improve the mechanical properties of polyester in the field of polymer synthesis. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of compound 5 in Example 1 of the present application.

[0062] Figure 2 This is the carbon NMR spectrum of compound 5 in Example 1 of the present application.

[0063] Figure 3 This is a comparison chart of the mechanical properties of ordinary PET and ethyl oxazole-2,4-dicarboxylate modified PET in Test Example 1 of this application. DETAILED DESCRIPTION

[0064] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0065] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0066] The present invention uses a JNM-ECZL400S nuclear magnetic resonance instrument for nuclear magnetic resonance characterization.

[0067] This application uses INSTRON electronic material universal testing machine to test mechanical properties.

[0068] The synthetic route of the disubstituted oxazole compound in the present application is as follows:

[0069]

[0070] R1 is selected from one of -H, -OH, -OCH3, -OCH2CH3;

[0071] R2 is selected from one of -H, -F, -Cl, -Br, -I, -OH, -OCH3, and -OCH2CH3.

[0072] Example 1

[0073] Step 1: Add 7.8 g of ethyl 3-bromopyruvate and 2.4 g of urea into a single-necked flask and then add 20 ml of anhydrous ethanol. Install a spherical condenser on the single-necked flask and heat the reaction system to reflux for 3 hours with a heating jacket. After the reaction is completed, extract with ethyl acetate and rotary evaporate to obtain ethyl 2-aminooxazole-4-carboxylate (Compound 2).

[0074] Step 2: Place 0.156 g of compound 2 in a single-necked flask and place the flask in an ice-water bath at 0-5°C to fully cool it, add 10 ml of 4 mol / L sulfuric acid solution and fully cool it. After cooling, add 0.0759 g of sodium nitrite powder and stir it thoroughly. After 10 minutes, add 0.099 g of hypophosphorous acid and place the system at room temperature to react for 2 hours; after the reaction is completed, extract with ethyl acetate and rotary evaporate to obtain oxazole-4-carboxylic acid ethyl ester (compound 3).

[0075] Step 3: Mix 0.141 g of compound 3 and 0.280 g of potassium tert-butoxide, add 5 ml of dry DMF to the system, react at 100 ° C for 3.5 hours in a CO2 atmosphere, then lower the system temperature to 60 ° C, add 0.468 g of iodoethane and react for another 60 minutes. After the reaction is completed, extract with ethyl acetate and rotary evaporate to obtain ethyl oxazole-2,4-dicarboxylate (Compound 5). Figure 1 is the H NMR spectrum of ethyl oxazole-2,4-dicarboxylate in deuterated chloroform, where H a (δ=8.36, one singlet, 1H), H b and H b’ (δ=4.52~4.40, two quartets, 4H), H c and H c’ (δ=1.46~1.38, two triplet peaks, 6H); Figure 2 is the carbon NMR spectrum of ethyl oxazole-2,4-dicarboxylate in deuterated chloroform, where C a δ=14.16Hz,C b δ=61.79Hz,C c δ=160.22Hz,C d δ=135.29Hz,C e δ=146.01Hz,C f δ=152.78Hz,C h δ=155.16Hz,C i δ=63.25Hz,C j δ=14.30Hz.

[0076] Example 2

[0077] Step 1: Add 7.8 g of methyl 3-bromopyruvate and 2.4 g of urea into a single-necked flask and then add 20 ml of anhydrous ethanol. Install a spherical condenser on the single-necked flask and heat the reaction system to reflux for 3 hours with a heating jacket. After the reaction, extract with ethyl acetate and rotary evaporate to obtain methyl 2-aminooxazole-4-carboxylate (Compound 2).

[0078] Step 2: Place 0.156 g of compound 2 in a single-necked flask and place the flask in an ice-water bath at 0-5°C to fully cool it, add 10 ml of 4 mol / L sulfuric acid solution and fully cool it. After cooling, add 0.0759 g of sodium nitrite powder and stir it thoroughly. After 10 minutes, add 0.099 g of hypophosphorous acid and place the system at room temperature to react for 2 hours; after the reaction is completed, extract with ethyl acetate and rotary evaporate to obtain oxazole-4-carboxylic acid methyl ester (compound 3).

[0079] Step 3: Mix 0.141 g of compound 3 and 0.280 g of potassium tert-butoxide, add 5 ml of dry DMF to the system, react at 100 ° C in a CO2 atmosphere for 3.5 hours, then lower the system temperature to 60 ° C, add 0.468 g of iodomethane and react for another 60 minutes. After the reaction is completed, extract with ethyl acetate and rotary evaporate to obtain methyl oxazole-2,4-dicarboxylate (compound 5).

[0080] Example 3

[0081] Step 1: Add 7.8 g of ethyl 3-bromopyruvate and 2.4 g of urea into a single-necked flask and then add 20 ml of anhydrous ethanol. Install a spherical condenser on the single-necked flask and heat the reaction system to reflux for 3 hours with a heating jacket. After the reaction is completed, extract with ethyl acetate and rotary evaporate to obtain ethyl 2-aminooxazole-4-carboxylate (Compound 2).

[0082] Step 2: Place 0.156 g of compound 2 in a single-necked flask and place the flask in an ice-water bath at 0-5°C to fully cool it, add 10 ml of 50 wt% hypophosphorous acid aqueous solution to dissolve compound 2, add 0.0759 g of sodium nitrite after 10 minutes and place the system at room temperature to react for 2 hours. After the reaction is completed, extract with ethyl acetate and rotary evaporate to obtain ethyl oxazole-4-carboxylate (compound 3).

[0083] Step 3: Mix 0.141 g of compound 3 and 0.280 g of potassium tert-butoxide, add 5 ml of dry DMF to the system, react at 100 ° C in a CO2 atmosphere for 3.5 hours, then lower the system temperature to 60 ° C, add 0.426 g of iodomethane and react for another 60 minutes. After the reaction is completed, extract with ethyl acetate and rotary evaporate to obtain oxazole-2-carboxylic acid methyl ester-4-carboxylic acid ethyl ester (compound 5).

[0084] Example 4

[0085] Step 1: Add 7.8 g of methyl 3-bromopyruvate and 2.4 g of urea into a single-necked flask and then add 20 ml of anhydrous ethanol. Install a spherical condenser on the single-necked flask and heat the reaction system to reflux for 3 hours with a heating jacket. After the reaction, extract with ethyl acetate and rotary evaporate to obtain methyl 2-aminooxazole-4-carboxylate (Compound 2).

[0086] Step 2: Place 0.156 g of compound 2 in a single-necked flask and place the flask in an ice-water bath at 0-5°C to fully cool it, add 10 ml of 50 wt% hypophosphorous acid aqueous solution to dissolve compound 2, add 0.0759 g of sodium nitrite after 10 minutes and place the system at room temperature to react for 2 hours; after the reaction is completed, extract with ethyl acetate and rotary evaporate to obtain oxazole-4-carboxylic acid methyl ester (compound 3).

[0087] Step 3: Mix 0.141 g of compound 3 and 0.280 g of potassium tert-butoxide, add 5 ml of dry DMF to the system, react at 100 ° C in a CO2 atmosphere for 3.5 hours, then lower the system temperature to 60 ° C, add 0.468 g of iodoethane and react for another 60 minutes. After the reaction is completed, extract with ethyl acetate and rotary evaporate to obtain oxazole-4-carboxylic acid methyl ester-2-carboxylic acid ethyl ester (compound 5).

[0088] Example 5

[0089] Step 1: Add 7.8 g of methyl 3-bromopyruvate and 2.4 g of urea into a single-necked flask and then add 20 ml of anhydrous ethanol. Install a spherical condenser on the single-necked flask and heat the reaction system to reflux for 3 hours with a heating jacket. After the reaction, extract with ethyl acetate and rotary evaporate to obtain methyl 2-aminooxazole-4-carboxylate (Compound 2).

[0090] Step 2: Place 0.156 g of compound 2 in a single-necked flask and place the flask in an ice-water bath at 0-5°C to fully cool it, add 10 ml of 50 wt% hypophosphorous acid aqueous solution to dissolve compound 2, add 0.0759 g of sodium nitrite after 10 minutes and place the system at room temperature to react for 2 hours; after the reaction is completed, extract with ethyl acetate and rotary evaporate to obtain oxazole-4-carboxylic acid methyl ester (compound 3).

[0091] Step 3: Mix 0.141 g of compound 3 and 0.280 g of potassium tert-butoxide, add 5 ml of dry DMF to the system, react at 100 ° C in a CO2 atmosphere for 3.5 hours, then lower the system temperature to 60 ° C, add 0.468 g of ethyl bromide and react for another 60 minutes. After the reaction is completed, extract with ethyl acetate and rotary evaporate to obtain oxazole-4-carboxylic acid methyl ester-2-carboxylic acid ethyl ester (compound 5).

[0092] Test Example 1

[0093] In the process of synthesizing PET, 5% of terephthalic acid was replaced by ethyl oxazole-2,4-dicarboxylate. The mechanical properties of PET synthesized by the conventional method and PET with ethyl oxazole-2,4-dicarboxylate added were compared. The mechanical properties graph is as follows Figure 3 ,from Figure 3 It can be seen that the tensile strength of PET synthesized by ordinary methods is 21MPa, while the tensile strength of PET with the addition of ethyl oxazole-2,4-dicarboxylate is 36MPa, which has a significant improvement in mechanical strength compared to ordinary PET.

[0094] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. An oxazole disubstituted compound, characterized in that: The oxazole disubstituted compound has a structure shown in Formula I: In formula I, R1 is selected from one of -H, -OH, -OCH3, -OCH2CH3; R2 is selected from one of -H, -F, -Cl, -Br, -I, -OH, -OCH3, and -OCH2CH3.

2. The method for preparing the disubstituted oxazole compound according to claim 1, characterized in that: The preparation method comprises the following steps: S1: reacting a mixture I containing a pyruvate compound, urea and a solvent I to obtain a compound 2; S2: Dissolve compound 2 in an acid solution, add solvent II, and react with II to obtain compound 3; S3: Under a carbon dioxide atmosphere, a mixture containing compound 3, an organic strong base, and a solvent III is reacted with III to obtain compound 4; S4: reacting a mixture containing compound 4 and alkyl halide with IV to obtain the oxazole disubstituted compound; The pyruvate compound has the structure shown in Compound 1; R1 in Compound 1, Compound 2, Compound 3 and Compound 4 is consistent with R1 described in Claim 1.

3. The preparation method according to claim 2, characterized in that: In the step S1, the pyruvate compound is selected from at least one of 3-bromopyruvic acid, 3-bromopyruvic acid methyl ester, and 3-bromopyruvic acid ethyl ester; Preferably, the solvent I is selected from at least one of methanol, ethanol, petroleum ether, dichloromethane and chloroform; Preferably, the molar ratio of the pyruvate compound to the urea is 2:1 to 1:2; Preferably, the molar volume ratio of the pyruvate compound to the solvent I is 1:1000 to 1:10 mol / L.

4. The preparation method according to claim 2, characterized in that: In step S2, the acid in the acid solution is selected from at least one of sulfuric acid, hydrochloric acid, phosphoric acid, hypophosphorous acid, p-toluenesulfonic acid, and perchloric acid; Preferably, the concentration of the acid solution is 1 to 10 mol / L; Preferably, the solvent II is selected from at least one of sodium nitrite, isoamyl nitrite, tert-butyl nitrite, hypophosphorous acid, ethanol, acetic acid, and sodium bisulfate; Preferably, the mass ratio of the compound 2 to the acid solution is 1:10 to 10:1; Preferably, the molar volume ratio of the compound 2 to the solvent II is 1:1000 to 1:10 mol / L.

5. The preparation method according to claim 2, characterized in that: In step S3, the organic strong base is selected from at least one of sodium ethoxide, potassium ethoxide, sodium tert-butoxide, and potassium tert-butoxide; Preferably, the solvent III is selected from at least one of ethanol, methanol, N,N-dimethylformamide, tetrahydrofuran, and dimethyl sulfoxide; Preferably, the molar ratio of the compound 3 to the organic strong base is 1:10 to 10:1; Preferably, the molar volume ratio of the compound 3 to the solvent III is 1:1000 to 1:10 mol / L.

6. The preparation method according to claim 2, characterized in that: In step S4, the alkyl halide is selected from at least one of methyl bromide, ethyl bromide, methyl iodide and ethyl iodide; Preferably, the molar ratio of the compound 4 to the alkyl halide is 1:10 to 10:

1.

7. The preparation method according to claim 2, characterized in that: In the step S1, the temperature of the reaction I is 40 to 200° C., and the time of the reaction I is 1 to 5 hours; Preferably, in step S2, the temperature of reaction II is 40-200° C., and the time of reaction II is 0.5-4 h.

8. The preparation method according to claim 2, characterized in that: In the step S3, the temperature of the reaction III is 60-120° C., and the time of the reaction III is 30-240 min.

9. The preparation method according to claim 2, characterized in that: In the step S4, the temperature of the reaction IV is 30-90° C., and the time of the reaction IV is 30-240 min.

10. Use of the disubstituted oxazole compound according to claim 1 in novel green degradable polyester.

Images