A process for the preparation of 2,2'- (1,4-phenylene) bis-4H-3,1-benzoxazin-4-one

Abstract

This invention provides a method for preparing 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one, relating to the field of compounds. The preparation method of this invention includes the following steps: (1) reacting anthranilic acid with terephthaloyl chloride in an organic solvent to generate intermediate A; (2) centrifuging the reaction product of step (1) to separate the wet crystalline intermediate A and the centrifugal mother liquor; (3) performing a cyclization reaction between the wet crystalline intermediate A from step (2) and acetic anhydride; (4) centrifuging, washing, and drying the reaction product of step (3) to obtain the target 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one product. This invention prepares 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one with not only low yellowness values ​​and high purity, but also high yield. The preparation method of the present invention has significant industrial value, and is particularly applicable to the field of polymer material additives where strict requirements are placed on product purity and yellowness.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis, and in particular to a method for preparing 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one. Background Technology

[0002] Yellowness value is a quantitative indicator that measures the degree of yellowing of a substance. It is used to characterize the degree of deviation of the yellow tone of a material in the visible light range due to impurities in its own components.

[0003] 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one is an important class of heterocyclic compounds characterized by high molecular weight, low volatility, and colorlessness, making it widely used in optical materials (such as PET and PC lenses, and liquid crystal display diffusers). However, traditional preparation methods result in products with high yellowness (yellowness value > 5) due to side reactions or impurities, making it difficult to meet the requirements for light-colored or transparent materials. This compound also exhibits poor solubility in common organic solvents, and its yellowness cannot be improved through decolorization. Therefore, developing a method for preparing high-purity, low-yellowness 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one has significant industrial value. Summary of the Invention

[0004] In view of this, the present invention proposes a method for preparing 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazine-4-one, which solves the quality problems of high yellowness and inability to decolorize products in traditional methods, and provides a preparation process with a stable yellowness value of less than 1.

[0005] The technical solution of this invention is implemented as follows: A method for preparing 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one includes the following steps: (1) Angiobenzoic acid is reacted with terephthaloyl chloride in an organic solvent, and the general reaction formula is shown in (I) to generate intermediate A; General reaction formula (I): (I); Solvent (Chinese meaning: solvent) (2) The reaction product of step (1) is centrifuged to separate wet crystalline intermediate A and centrifuged mother liquor; (3) The wet crystalline intermediate A from step (2) undergoes a cyclization reaction with acetic anhydride, and the general reaction formula is shown in (II): (II); (4) The product of the cyclization reaction in step (4) is filtered, washed and dried to obtain the target 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazine-4-one product.

[0006] Further, in step (1), the organic solvent is N,N-dimethylformamide or N,N-dimethylacetamide.

[0007] Further, in step (1), the molar ratio of anthranilic acid to terephthaloyl chloride is 1 to 1.2:1, and the mass-volume ratio of terephthaloyl chloride to organic solvent (g / ml) is 1:8 to 15, preferably 1:10 to 12; Furthermore, in step (1), the reaction temperature is -15℃ to 20℃, and the reaction time is 2 to 3 hours.

[0008] Further, in step (2), the centrifugation is carried out under a nitrogen protective atmosphere, the centrifugation speed is 1000-1100 r / min, and the solvent content of the wet crystalline intermediate A is 10%-40%.

[0009] Further, in step (2), sodium hydroxide or sodium carbonate is added to the centrifuged mother liquor for neutralization and filtration. Toluene is added to the filtrate for azeotropic water separation. After water separation is completed, the organic solvent is recovered by vacuum distillation and recycled for step (1).

[0010] Furthermore, the amount of sodium hydroxide or sodium carbonate added is 1 to 1.5 times the molar amount of hydrogen chloride produced by terephthaloyl chloride; Furthermore, the volume of toluene added is between 10% and 40% v / v of the total (toluene + DMAC), preferably 25% to 30% v / v; here, the volume of DMAC is the amount of DMAC added in step (1).

[0011] Furthermore, the reaction temperature is 118–130°C, and the reaction time is 5–8 hours.

[0012] Furthermore, in step (3), the solid content of the suspension after the reaction is completed is controlled to be 10% to 50% before centrifugation.

[0013] Further, in step (4), the washing process includes sequential acetone washing and water washing, wherein the amount of acetone used is 2 to 3 times the total solid content of the reaction product; the water washing is performed by using a filter to wash until the pH value is neutral. Specifically, the solvent in the acetone washing can be collected from the centrifuged product, and then the light phase acetone can be distilled back for reuse in washing, while the heavy phase acetic anhydride and DMAC mixed solvent can be further distilled back for cyclization. This reduces the amount of nitrogenous compounds entering the wastewater system and better controls ammonia nitrogen compounds in the wastewater.

[0014] Further, in step (4), the drying process is segmented vacuum drying. Specifically, the washed product is transferred to a double cone dryer and the segmented vacuum drying is started.

[0015] Furthermore, the segmented vacuum drying conditions are as follows: First stage: maintain vacuum level at -0.06 to -0.09 MPa, temperature at 40 to 45°C, and dry for 1.5 to 2 hours; Second stage: increase the vacuum degree to -0.09 to -0.1 MPa, the temperature is 95 to 100℃, and the drying time is 2.0 to 2.5 h; Third stage: Cool down to 30-40℃ and maintain for 0.5-1.0 hours.

[0016] Further, in step (4), the 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazine-4-one product has a volume average diameter of 19~22 μm, an area average diameter of 7~10 μm, a number average diameter of 0.4~0.7 μm, and a peak particle size of 15~17 μm.

[0017] Further, in step (4), the yellowness value of the 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one product is between -3 and -6. Even further, the yellowness value of the 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one product is between -3 and -5.

[0018] Compared with the prior art, the beneficial effects of the present invention are: (1) The 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazine-4-one prepared by the method of the present invention not only has a low yellowness value and high purity, but also has a high yield.

[0019] (2) The present invention develops a method for preparing 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazine-4-one with high purity and low yellowness, which has important industrial value and is particularly suitable for the field of polymer material additives with strict requirements on product purity and yellowness.

[0020] (3) Before the intermediate of the present invention is prepared, it is centrifuged and separated, and the impurities are dissolved by solvent to effectively improve the yellowness index.

[0021] (4) The washing process of the present invention first performs acetone washing to better collect the solvent in the centrifuged product, and then distills to recover the light phase acetone for reuse in washing, while the heavy phase acetic anhydride and DMAC mixed solvent are further distilled and recovered for cyclization; reducing nitrogen-containing compounds entering the wastewater system and better controlling ammonia nitrogen compounds in the wastewater.

[0022] (5) The segmented vacuum drying of the present invention further removes the solvent adsorbed on the surface of the product and effectively removes the trace amount of solvent wrapped inside the crystal, further reducing the yellowness value and improving the product quality. Attached Figure Description

[0023] Figure 1 The HPLC chromatogram for the preparation of the 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one product according to the present invention is shown.

[0024] Figure 2 The particle size distribution of the first batch of 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one products prepared according to this invention is shown in the figure.

[0025] Figure 3 The particle size distribution of the second batch of 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one prepared according to this invention is shown in the figure.

[0026] Figures 2-3 This is a particle size analysis report from a Bettersize2600 laser particle size analyzer (wet method). The test parameters are as follows: Material refractive index: 1.8; Material absorption rate: 0.5; Medium refractive index: 1.333; Optical mode: Mle; Analysis mode: Adaptive; Distribution type: Volume distribution; Cycle count: 1200; Ultrasonic dispersion: Always on; 35W; Medium name: Water; Dispersant: Water. Detailed Implementation

[0027] Unless otherwise specified, the experimental methods used in the embodiments of this invention are conventional methods; Unless otherwise specified, all materials and reagents used in the embodiments of this invention are commercially available.

[0028] Table 1. Chinese meanings of the abbreviations

[0029] A method for preparing 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one includes the following steps: (1) Angiobenzoic acid (ABA) and terephthaloyl chloride (TPC) are reacted in N,N-dimethylacetamide (DMAC) at a temperature of -15℃ to 20℃ for 2 to 3 hours to generate amide intermediate A; the molar ratio of angiobenzoic acid to terephthaloyl chloride is 1 to 1.2:1, and the mass-volume ratio of terephthaloyl chloride to DMAC (g / ml) is 1:8 to 15, preferably 1:10 to 12; (2) The reaction product of step (1) is separated and purified by centrifugation. The centrifugation operation is carried out in a nitrogen protective atmosphere using a discharge centrifuge with a centrifugation speed of 1000-1100 r / min. The wet crystalline intermediate A and the centrifugation mother liquor are separated. The solvent content of the wet crystalline intermediate A is controlled to be 10%-40%wt. (3) The wet crystalline intermediate A from step (2) is reacted with acetic anhydride at a temperature of 117.9–130 °C for 5–8 h to form a cyclization reaction. (4) Centrifuge the cyclization reaction product of step (3) at 1000-1100 r / min, wash with acetone (the amount of acetone used is 2-3 times the total solid content of the reaction product), wash with water (wash with a filter until the pH value is neutral), and dry to obtain the target 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazine-4-one product.

[0030] Example 1 A method for preparing 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one includes the following steps: (1) Angiobenzoic acid (ABA) and terephthaloyl chloride (TPC) were reacted in N,N-dimethylacetamide (DMAC) at -10°C for 2 h to generate amide intermediate A; The molar ratio of anthranilic acid to terephthaloyl chloride is 1.1:1, and the mass-to-volume ratio of terephthaloyl chloride to DMAC (g / ml) is 1:11. (2) The reaction product of step (1) is separated and purified by centrifugation. The centrifugation operation is carried out in a nitrogen protective atmosphere using a bottom discharge centrifuge. The centrifugation speed is 1100 r / min and the centrifugation time is 60 min. Wet crystalline intermediate A and centrifugation mother liquor are obtained. The solvent content of the wet crystalline intermediate A is controlled to be 20% to 30% wt. (3) The wet crystalline intermediate A from step (2) was reacted with acetic anhydride at 125℃±5℃ for 6 hours to form a ring. (4) Before centrifugation, the solid content of the suspension after the reaction was completed was controlled at 25%. The reaction product was centrifuged (1100 r / min), washed with acetone (the amount of acetone used was 2.5 times the total solid content of the reaction product), washed with water (washed with a filter until the pH value was neutral), and dried to obtain the target 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazine-4-one product with a yield of 97% (based on terephthaloyl chloride).

[0031] The HPLC chromatogram of the preparation of the 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one product of this invention is shown below. Figure 1As shown, the results indicate that the 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one product obtained by this invention has a high purity of 99.96%.

[0032] The particle size distribution of different batches of the 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one product prepared by this invention is shown in the figure below. Figures 2-3 As shown in the figure. The results show that the particle size of the 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one product prepared by the present invention does not differ significantly between different batches, indicating that the particle size of the 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one product of the present invention has good controllability.

[0033] Table 2 Comparison of particle size of different batches of products

[0034] Example 2 A method for preparing 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one includes the following steps: (1) Angiobenzoic acid (ABA) and terephthaloyl chloride (TPC) were reacted in N,N-dimethylacetamide (DMAC) at -15°C for 2 h to generate amide intermediate A; The molar ratio of anthranilic acid to terephthaloyl chloride is 1:1, and the mass-volume ratio of terephthaloyl chloride to DMAC (g / ml) is 1:10. (2) The reaction product of step (1) is separated and purified by centrifugation. The centrifugation operation is carried out in a nitrogen protective atmosphere using a bottom discharge centrifuge. The centrifugation speed is 1100 r / min and the centrifugation time is 60 min. Wet crystalline intermediate A and centrifugation mother liquor are obtained. The solvent content of the wet crystalline intermediate A is controlled to be 20% to 30% wt. (3) The wet crystalline intermediate A from step (2) was reacted with acetic anhydride at 125℃±5℃ for 6 hours to form a ring. (4) When the suspension after the reaction is completed is centrifuged, the solid content is controlled to be 25%; the reaction product is centrifuged (1100 r / min), washed with acetone (the amount of acetone used is 3 times the total solid content of the reaction product), washed with water (washed with a filter until the pH value is neutral), and dried to obtain the target 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazine-4-one product.

[0035] Example 3 A method for preparing 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one includes the following steps: (1) Angiobenzoic acid (ABA) and terephthaloyl chloride (TPC) were reacted in N,N-dimethylacetamide (DMAC) at -10°C for 2 h to generate amide intermediate A; The molar ratio of anthranilic acid to terephthaloyl chloride is 1.2:1, and the mass-to-volume ratio of terephthaloyl chloride to DMAC (g / ml) is 1:12. (2) The reaction product of step (1) is separated and purified by centrifugation. The centrifugation operation is carried out in a nitrogen protective atmosphere using a bottom discharge centrifuge. The centrifugation speed is 1100 r / min and the centrifugation time is 60 min. Wet crystalline intermediate A and centrifugation mother liquor are obtained. The solvent content of the wet crystalline intermediate A is controlled to be 20% to 30% wt. (3) The wet crystalline intermediate A from step (2) was reacted with acetic anhydride at 125℃±5℃ for 6 hours to form a ring. (4) When centrifuging the suspension after the reaction is completed, the solid content is controlled to be 35%; the cyclization reaction product of step (3) is centrifuged (1100 r / min), washed with acetone (the amount of acetone used is twice the total solid content of the reaction product), washed with water (washed with a filter until the pH value is neutral), and dried to obtain the target 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazine-4-one product.

[0036] Example 4 Based on Example 1, sodium hydroxide or sodium carbonate is added to the centrifuged mother liquor in step (2) for neutralization and filtration. Toluene is added to the filtrate for azeotropic water separation. After water separation is completed, the organic solvent DMAC is recovered by vacuum distillation and used in step (1).

[0037] The amount of sodium hydroxide or sodium carbonate added is 1.1 times the molar amount of hydrogen chloride produced by terephthaloyl chloride; The volume of toluene added is 25% v / v of the total volume of (toluene + DMAC).

[0038] The volume of DMAC here is the amount of DMAC added in step (1).

[0039] This embodiment fully recovers DMAC and recycles it for the reaction in step (1), which not only reduces the amount of organic solvent used, but also makes the reaction preparation process more environmentally friendly.

[0040] Example 5 Based on Example 1, step (5) is a segmented vacuum drying process. The specific operation is as follows: the washed product is transferred to a double cone dryer, and the segmented vacuum drying is started. The segmented vacuum drying conditions are as follows: First stage: maintain vacuum at -0.06 MPa, temperature at 42℃, and dry for 1.5 hours; Second stage: Increase the vacuum to -0.09MPa, maintain the temperature at 95℃, and continue drying for 2.0h; Phase 3: Cool down to 35℃ and maintain for 0.8 hours.

[0041] The segmented vacuum drying method of this invention further removes the solvent adsorbed on the surface of the product and effectively removes trace amounts of solvent encapsulated inside the crystals, thereby further improving the product quality and stability.

[0042] Comparative Example 1 The difference from Example 1 is that intermediate A was not centrifuged and purified, but directly reacted with acetic anhydride to form a ring.

[0043] A method for preparing 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one includes the following steps: (1) Angiobenzoic acid (ABA) and terephthaloyl chloride (TPC) were reacted in N,N-dimethylacetamide (DMAC) at -10°C to generate amide intermediate A; The molar ratio of anthranilic acid to terephthaloyl chloride is 1.1:1, and the mass-to-volume ratio of terephthaloyl chloride to DMAC (g / ml) is 1:11. (2) The amide intermediate A from step (1) was reacted with acetic anhydride at 125℃±5℃ for 6 hours to form a cyclization reaction. (3) When the suspension after the reaction is completed is centrifuged, the solid content is controlled to be 25%; the reaction product is centrifuged (1100 r / min), washed with acetone (the amount of acetone used is 2.5 times the total solid content of the reaction product), washed with water (washed with a filter until the pH value is neutral), dried, and the target 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazine-4-one product is obtained.

[0044] Comparative Example 2 The difference from Example 1 is that the centrifugation speed for step (2) of centrifugation separation and purification is 600 r / min and the centrifugation time is 60 min.

[0045] (2) The reaction product of step (1) is separated and purified by centrifugation. The centrifugation operation is carried out in a nitrogen protective atmosphere using a discharge centrifuge with a centrifugation speed of 600 r / min. Wet crystalline intermediate A and centrifuged mother liquor are obtained. The solvent content of wet crystalline intermediate A is controlled to be 53% to 56% wt.

[0046] Comparative Example 3 The difference from Example 1 is that the centrifugation speed for step (2) of centrifugation separation and purification is 900 r / min and the centrifugation time is 60 min.

[0047] (2) The reaction product of step (1) is separated and purified by centrifugation. The centrifugation operation is carried out in a nitrogen protective atmosphere using a discharge centrifuge with a centrifugation speed of 900 r / min. The wet crystalline intermediate A and the centrifuged mother liquor are separated. The solvent content of the wet crystalline intermediate A is controlled to be 44% to 48% wt.

[0048] The yellowness value of the 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one products prepared in the above examples and comparative examples was tested. The method for testing the yellowness value was as follows: 2.0 g of sample (accurate to 0.0002 g) was weighed and the yellowness value of the sample was measured using a spectrophotometer. A yellowness value between -3 and -6 is preferred. The results are shown in Table 3 below. Table 3 Yellowness of the Products

[0049] The results showed that the 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazine-4-one products prepared in Examples 1-5 of the present invention had lower yellowness values, which were significantly better than those of Comparative Example 1.

[0050] In Comparative Example 1, intermediate A was not centrifuged and purified, but directly reacted with acetic anhydride to form a ring. The final product had a significantly higher yellowness value.

[0051] In Comparative Examples 2 and 3, the centrifugation speed for purification after intermediate A was too slow, resulting in higher yellowness values ​​for the final products.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the scope of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one, characterized in that, Includes the following steps: (1) Angiobenzoic acid is reacted with terephthaloyl chloride in an organic solvent to generate intermediate A; (2) The reaction product of step (1) is centrifuged to separate wet crystalline intermediate A and centrifuged mother liquor; (3) The wet crystalline intermediate A from step (2) undergoes a cyclization reaction with acetic anhydride; (4) The reaction product of step (3) is centrifuged, washed and dried to obtain the target 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazine-4-one product.

2. The preparation method according to claim 1, characterized in that, In step (1), the organic solvent is N,N-dimethylformamide or N,N-dimethylacetamide; the molar ratio of o-aminobenzoic acid to terephthaloyl chloride is 1 to 1.2:1, and the mass-volume ratio of terephthaloyl chloride to organic solvent is 1:8 to 15 g / ml.

3. The preparation method according to claim 1 or 2, characterized in that, Step (1): The reaction temperature is -15℃ to 20℃, and the reaction time is 2 to 3 hours.

4. The preparation method according to claim 1, characterized in that, In step (2), the centrifugation is carried out under a nitrogen protective atmosphere at a speed of 1000-1100 r / min, and the solvent content of the wet crystalline intermediate A is 10%-40%.

5. The preparation method according to claim 1 or 4, characterized in that, In step (2), sodium hydroxide or sodium carbonate is added to the centrifuged mother liquor for neutralization and filtration. Toluene is added to the filtrate for azeotropic water separation. After water separation, the organic solvent is recovered by vacuum distillation. The organic solvent is used in step (1). The amount of sodium hydroxide or sodium carbonate added is 1 to 1.5 times the molar amount of hydrogen chloride produced by terephthaloyl chloride. The volume of toluene added is 10% to 40% v / v of the total amount of toluene and organic solvent in step (1).

6. The preparation method according to claim 1, characterized in that, Step (3): The reaction temperature is 118-130℃ and the reaction time is 5-8 hours; the solid content of the suspension before centrifugation is controlled at 10%-50%.

7. The preparation method according to claim 1, characterized in that, Step (4), the washing process includes sequential washing with acetone and washing with water, wherein the amount of acetone used is 2 to 3 times the total solid content of the reaction product; the water washing is performed by using a filter to wash until the pH value is neutral.

8. The preparation method according to claim 1, characterized in that, Step (4), the drying process is segmented vacuum drying, and the segmented vacuum drying conditions are: First stage: maintain vacuum level at -0.06 to -0.09 MPa, temperature at 40 to 45°C, and dry for 1.5 to 2 hours; Second stage: increase the vacuum degree to -0.09 to -0.1 MPa, the temperature is 95 to 100℃, and the drying time is 2.0 to 2.5 h; Third stage: Cool down to 30-40℃ and maintain for 0.5-1.0 hours.

9. The preparation method according to claim 1, characterized in that, In step (4), the 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazine-4-one product has a volume average diameter of 19~22 μm, an area average diameter of 7~10 μm, a number average diameter of 0.4~0.7 μm, and a peak particle size of 15~17 μm.

10. The preparation method according to claim 1, characterized in that, In step (4), the yellowness value of the 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazine-4-one product is between -3 and -6.

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