Preparation method of 3,3-bis(4-hydroxyphenyl)-3H-isobenzofuran-1-one

Abstract

The present invention discloses a preparation method of 3,3-bis(4-hydroxyphenyl)-3H-isobenzofuran-1-one (phenolphthalein), belonging to the technical field of fine chemical engineering. A mixed solution of phenol, phthalic anhydride and sulfolane is dropped into sulfolane, tris(pentafluorophenyl)borane and sulfonic acid-based ionic liquid heated to 70-110 °C; after the dropping is completed, the reaction is carried out until the conversion rate of the phthalic anhydride raw material > 98%; the temperature is lowered and added to a non-polar solvent, and the product is precipitated and filtered to obtain a phenolphthalein product. The present invention adopts a high-temperature reverse dropping method for synthesis, which is easy to operate and has a small amount of catalyst used; a unique tris(pentafluorophenyl)borane catalyst is selected, with a fast reaction rate and high efficiency; the use of sulfonic acid-based ionic liquid greatly avoids the corrosion of production pipelines, flanges and other components. The product yield finally obtained by the present invention is 92-96%, and the purity detected by liquid chromatography normalization > 99.5%.

Description

Technical Field

[0001] The present invention relates to a preparation method of 3,3-bis(4-hydroxyphenyl)-3H-isobenzofuranone (phenolphthalein), belonging to the technical field of fine chemical industry. Background Art

[0002] Phenolphthalein, with the chemical name 3,3-bis(4-hydroxyphenyl)-3H-isobenzofuranone (CAS No: 77-09-8), is colorless in acidic and neutral solutions and magenta in alkaline solutions. It is often used as an acid-base indicator. The structural formula is as follows:

[0003]

[0004] Phenolphthalein has a very wide range of uses. It can be used as a pharmaceutical raw material and a mild laxative in the pharmaceutical industry; it can also be used as an acid-base indicator; with the development of polymer materials, the amount of phenolphthalein used in the synthesis of high-performance polymer materials is increasing. Phenolphthalein is a typical bisphenol monomer with large side groups and a non-coplanar structure, and it is also an inexpensive industrial product. The side-group lactone ring structure can provide reaction sites, and various bisphenol monomers with different structures can be prepared. The two phenol rings of phenolphthalein are twisted and form an angle close to perpendicular to the phthalide side-group plane, which hinders the close packing of molecular chains. Therefore, polymers containing phenolphthalein structures not only have good thermal and mechanical properties but also have good solubility. Phenolphthalein is used in the synthesis of phenolphthalein-based polyaryletherketone (PEK-C). As an aromatic engineering plastic, PEK-C has the advantages of high modulus, high strength, low deformation, and high temperature resistance. It can not only be blended with polytetrafluoroethylene, polyetheretherketone, polyethersulfone, etc., but also be compounded with glass fiber, carbon fiber, etc. It can be used as materials such as membranes, plates, sheets, tubes, fibers, and coatings in the aerospace, electronics, nuclear industry, manufacturing industries, etc., and it is also one of the ideal materials for membrane materials. Phenolphthalein can also be used in the synthesis of various polymer materials such as phenolphthalein-based polyarylate, phenolphthalein-based polyarylether, and phenolphthalein-based polyarylethersulfone.

[0005] Currently, there are many reported processes for synthesizing phenolphthalein at home and abroad. For example, phthalic anhydride and phenol are used as raw materials and react under the action of a catalyst (methanesulfonic acid) (Tetrahedron Letters, 2009, 50, 6261-6263); phthalic anhydride and phenol are used as raw materials and react under the action of a catalyst (zinc chloride) (Russian Journal of Applied Chemistry, 2015, 88, 711-718); phthalic anhydride and phenol are used as raw materials, and phenolphthalein is synthesized under the catalysis of sulfuric acid and titanium tetrachloride or sulfuric acid and boron trifluoride diethyl ether solution (Chemical Reagents, 2006, 28, 697-698). All of the above reactions inevitably produce a large amount of acidic wastewater or inorganic salts.

[0006] Therefore, it is necessary to improve the existing process and develop a more convenient and environmentally friendly process method. Summary of the Invention

[0007] The object of the present invention is to provide an improved preparation method of phenolphthalein in view of the deficiencies of the above process methods. Using phthalic anhydride and phenol as raw materials, reacting and synthesizing phenolphthalein under the catalysis of tris(pentafluorophenyl)borane and sulfonic acid-based ionic liquid. The present invention adopts a high-temperature reverse dropping method for synthesis, which is easy to operate and has a small amount of catalyst used; selects a unique tris(pentafluorophenyl)borane catalyst, with a fast reaction rate and high efficiency; adopts a sulfonic acid-based ionic liquid to greatly avoid the corrosion of production pipelines, flanges and other components. The product yield finally obtained by the present invention is 92-96%, and the purity detected by liquid chromatography normalization is >99.5%.

[0008] The improved preparation method of phenolphthalein according to the present invention comprises the following steps: dropping a mixed solution of phenol, phthalic anhydride and sulfolane into sulfolane, tris(pentafluorophenyl)borane and sulfonic acid-based ionic liquid heated to 70-110 °C; after dropping, reacting until the conversion rate of the phthalic anhydride raw material >98%; cooling and adding to a non-polar solvent, and filtering the precipitated product to obtain a phenolphthalein product.

[0009] Further, the specific reaction steps of the technical solution of the present invention are operated as follows:

[0010] 1) Adding phenol and phthalic anhydride to sulfolane to obtain a sulfolane solution of phenol and phthalic anhydride;

[0011] 2) Mixing sulfolane, tris(pentafluorophenyl)borane and sulfonic acid-based ionic liquid, and heating to 70-110 °C;

[0012] 3) Controlling the temperature at 70-110 °C, dropping the mixed solution in step 1) into the reaction system in step 2), and reacting after dropping until the conversion rate of the phthalic anhydride raw material >98%;

[0013] 4) Cooling the reaction solution, adding it to a non-polar solvent, and filtering the precipitated product to obtain a phenolphthalein product.

[0014] The improved preparation method of phenolphthalein according to the present invention is represented by the reaction equation as:

[0015]

[0016] Further, in the above step 1), the weight ratio of the total weight of phthalic anhydride and phenol to the weight of sulfolane is 1:1.

[0017] Further, in the above step 1), the molar ratio of phthalic anhydride to phenol is 1:2.00-2.05, and preferably the molar ratio of phthalic anhydride to phenol is 1:2.02.

[0018] Further, in the above step 2), the weight ratio of sulfolane to the total weight of phthalic anhydride and phenol in step 1) is 1.7 - 2.7:1, preferably 2.3:1.

[0019] Further, in the above step 2), the molar ratio of tris(pentafluorophenyl)borane to phthalic anhydride is 0.01 - 0.05:1, preferably the molar ratio of tris(pentafluorophenyl)borane to phthalic anhydride is 0.03:1.

[0020] Further, in the above step 2), the sulfonic acid-based ionic liquid is 1-sulfopropyl-3-methylimidazolium inner salt, 1-sulfopropyl-3-methylimidazolium trifluoromethanesulfonate or 1-sulfopropyl-3-methylimidazolium trifluoroacetate. Preferably it is 1-sulfopropyl-3-methylimidazolium inner salt.

[0021] Further, in the above step 2), the molar ratio of the sulfonic acid-based ionic liquid to phthalic anhydride is 0.001 - 0.003:1, preferably the molar ratio of the sulfonic acid-based ionic liquid to phthalic anhydride is 0.002:1.

[0022] Further, in the above step 3), the temperature-controlled reaction is at 85 - 95 °C; the reaction time is 1 - 4 h.

[0023] Further, in the above step 4), the non-polar solvent is n-hexane, n-heptane or cyclohexane, preferably n-heptane.

[0024] Further, in the above step 4), the weight ratio of the non-polar solvent to sulfolane is 1.0 - 1.5:1, preferably 1.2:1.

[0025] Further, in the above step 4), the yield of phenolphthalein prepared by the method of the present invention is 92 - 96%, and the purity of the product by liquid chromatography normalization > 99.5%.

[0026] Advantages of the present invention:

[0027] A. The technical route of the present invention is a high-temperature reverse dropping method for synthesis, which is easy to operate and has a small amount of catalyst used.

[0028] B. The present invention selects a unique tris(pentafluorophenyl)borane catalyst, with a fast reaction rate and high efficiency.

[0029] C. The present invention uses a sulfonic acid-based ionic liquid instead of a volatile acid as a catalyst, which can greatly avoid the corrosion of production pipelines, flanges and other components.

[0030] D. The final product yield of the present invention is 92 - 96%, and the purity detected by liquid chromatography normalization > 99.5%. Description of the drawings

[0031] Figure 1 For phenolphthalein in Example 11 H-NMR spectrum;

[0032] Figure 2 It is the HPLC normalization spectrum of phenolphthalein in Example 1. Detailed implementation manners

[0033] The present invention is illustrated by way of examples. The specific material ratios, process conditions and their results described in the examples only serve to illustrate the present invention, and the present invention should not and will not be limited by the examples.

[0034] Comparative Example 1

[0035] Under room temperature conditions, phthalic anhydride (148.1 g, 1.0 mol) and phenol (190.1 g, 2.02 mol) were added to sulfolane (338.2 g) and completely dissolved to obtain a sulfolane solution of phenol and phthalic anhydride. Then the mixture was added to a constant pressure dropping funnel. To another reaction kettle, sulfolane (777.9 g) was added, then tris(pentafluorophenyl)borane (15.36 g, 0.03 mol) was added, and then the reaction system was heated to 95°C. The mixture in the constant pressure dropping funnel was dropped into the reaction system, and the temperature of the reaction system was controlled at 95°C. After dropping, the reaction was carried out for 2 hours, and the conversion rate of the phthalic anhydride raw material was 80% (when the reaction time was extended to 8 hours, the conversion rate was 81.3%). The reaction solution was cooled to room temperature, and the reaction solution was dropped into n-heptane (1339.3 g) solvent with stirring, and the product precipitated. After filtration, phenolphthalein product was obtained, with a yield of 78% and the purity detected by HPLC normalization > 99.5%.

[0036] Example 1

[0037] Under room temperature conditions, phthalic anhydride (148.1 g, 1.0 mol) and phenol (190.1 g, 2.02 mol) were added to sulfolane (338.2 g) and completely dissolved to obtain a sulfolane solution of phenol and phthalic anhydride. Then the mixture was added to a constant pressure dropping funnel. To another reaction kettle, sulfolane (777.9 g) was added, then tris(pentafluorophenyl)borane (15.36 g, 0.03 mol) and 1-sulfopropyl-3-methylimidazolium inner salt (0.41 g, 0.002 mol) were added, and then the reaction system was heated to 95°C. The mixture in the constant pressure dropping funnel was dropped into the reaction system, and the temperature of the reaction system was controlled at 95°C. After dropping, the reaction was carried out for 2 hours until the conversion rate of the phthalic anhydride raw material > 98%. The reaction solution was cooled to room temperature, and the reaction solution was dropped into n-heptane (1339.3 g) solvent with stirring, and the product precipitated. After filtration, phenolphthalein product was obtained, with a yield of 96% and the purity detected by HPLC normalization > 99.5%. The 1 H-NMR spectrum, as Figure 1As shown; the liquid chromatography normalization detection spectrogram of the product, such as Figure 2 shown.

[0038] Example 2

[0039] At room temperature, phthalic anhydride (148.1 g, 1.0 mol) and phenol (188.2 g, 2.00 mol) were added to sulfolane (336.3 g) and completely dissolved to obtain a sulfolane solution of phenol and phthalic anhydride. Then the mixture was added to a constant-pressure dropping funnel. In another reaction kettle, sulfolane (571.7 g) was added, and then tris(pentafluorophenyl)borane (5.12 g, 0.01 mol) and 1-sulfopropyl-3-methylimidazolium inner salt (0.41 g, 0.002 mol) were added. Then the reaction system was heated to 110 °C. The mixture in the constant-pressure dropping funnel was added dropwise to the reaction system, and the temperature of the reaction system was controlled at 110 °C. After the addition was completed, the reaction was carried out for 4 hours until the conversion rate of the phthalic anhydride raw material > 98%. The reaction solution was cooled to room temperature, and the reaction solution was added dropwise to n-heptane (908 g) solvent with stirring, and the product precipitated. After filtration, the phenolphthalein product was obtained with a yield of 94% and the purity detected by liquid chromatography normalization > 99.5%.

[0040] Example 3

[0041] At room temperature, phthalic anhydride (148.1 g, 1.0 mol) and phenol (193.0 g, 2.05 mol) were added to sulfolane (341.0 g) and completely dissolved to obtain a sulfolane solution of phenol and phthalic anhydride. Then the mixture was added to a constant-pressure dropping funnel. In another reaction kettle, sulfolane (920.7 g) was added, and then tris(pentafluorophenyl)borane (25.6 g, 0.05 mol) and 1-sulfopropyl-3-methylimidazolium trifluoromethanesulfonate (0.71 g, 0.002 mol) were added. Then the reaction system was heated to 70 °C. The mixture in the constant-pressure dropping funnel was added dropwise to the reaction system, and the temperature of the reaction system was controlled at 70 °C. After the addition was completed, the reaction was carried out for 1 hour until the conversion rate of the phthalic anhydride raw material > 98%. The reaction solution was cooled to room temperature, and the reaction solution was added dropwise to n-heptane (1892.6 g) solvent with stirring, and the product precipitated. After filtration, the phenolphthalein product was obtained with a yield of 95% and the purity detected by liquid chromatography normalization > 99.5%.

[0042] Example 4

[0043] At room temperature, phthalic anhydride (148.1 g, 1.0 mol) and phenol (191.0 g, 2.03 mol) were added to sulfolane (339.1 g) and completely dissolved to obtain a sulfolane solution of phenol and phthalic anhydride. Then the mixture was added to a constant-pressure dropping funnel. To another reaction kettle, sulfolane (847.9 g) was added, and then tris(pentafluorophenyl)borane (15.4 g, 0.03 mol) and 1-sulfopropyl-3-methylimidazolium trifluoroacetate (0.95 g, 0.003 mol) were added. Then the reaction system was heated to 85 °C. The mixture in the constant-pressure dropping funnel was dropped into the reaction system, and the temperature of the reaction system was controlled at 85 °C. After the dropping was completed, the reaction was carried out for 3 hours until the conversion rate of the phthalic anhydride raw material > 98%. The reaction solution was cooled to room temperature, and the reaction solution was dropped into n-heptane (1305.6 g) solvent with stirring, and the product precipitated. After filtration, the phenolphthalein product was obtained, with a yield of 92% and a purity > 99.5% detected by liquid chromatography normalization.

[0044] Example 5

[0045] At room temperature, phthalic anhydride (148.1 g, 1.0 mol) and phenol (192.0 g, 2.04 mol) were added to sulfolane (340.1 g) and completely dissolved to obtain a sulfolane solution of phenol and phthalic anhydride. Then the mixture was added to a constant-pressure dropping funnel. To another reaction kettle, sulfolane (918.2 g) was added, and then tris(pentafluorophenyl)borane (10.2 g, 0.02 mol) and 1-sulfopropyl-3-methylimidazolium inner salt (0.41 g, 0.002 mol) were added. Then the reaction system was heated to 90 °C. The mixture in the constant-pressure dropping funnel was dropped into the reaction system, and the temperature of the reaction system was controlled at 90 °C. After the dropping was completed, the reaction was carried out for 4 hours until the conversion rate of the phthalic anhydride raw material > 98%. The reaction solution was cooled to room temperature, and the reaction solution was dropped into n-heptane (1383.8 g) solvent with stirring, and the product precipitated. After filtration, the phenolphthalein product was obtained, with a yield of 93% and a purity > 99.5% detected by liquid chromatography normalization.

[0046] The above examples describe the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above examples. What is described in the above examples and the specification only illustrates the principles of the present invention. Without departing from the scope of the principles of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.

Claims

1. An improved preparation method of phenolphthalein, characterized in that, It includes the following steps: adding a mixed solution of phenol, phthalic anhydride and sulfolane dropwise into a mixed solution composed of sulfolane, tris(pentafluorophenyl)borane and a sulfonic acid-based ionic liquid preheated to 70 - 110 °C; after the dropping is completed, reacting until the conversion rate of the phthalic anhydride raw material > 98%; cooling and adding it into a non-polar solvent, filtering out the precipitated product to obtain the phenolphthalein product; the sulfonic acid-based ionic liquid is selected from 1-sulfopropyl-3-methylimidazolium inner salt, 1-sulfopropyl-3-methylimidazolium trifluoromethanesulfonate or 1-sulfopropyl-3-methylimidazolium trifluoroacetate.

2. The improved preparation method of phenolphthalein according to claim 1, characterized in that, The specific reaction steps are operated as follows: 1) Add phenol and phthalic anhydride into sulfolane to obtain a sulfolane solution of phenol and phthalic anhydride; 2) Mix sulfolane, tris(pentafluorophenyl)borane and the sulfonic acid-based ionic liquid, and heat to 70 - 110 °C; 3) Under the condition of controlling the temperature at 70 - 110 °C, drop the mixed solution in step 1) into the reaction system in step 2), and react after the dropping is completed until the conversion rate of the phthalic anhydride raw material > 98%; 4) Cool the reaction solution, add it into a non-polar solvent, filter out the precipitated product to obtain the phenolphthalein product.

3. The improved preparation method of phenolphthalein according to claim 2, wherein: In step 1), the weight ratio of the total weight of phthalic anhydride and phenol to the weight of sulfolane is 1:

1.

4. The preparation method of phenolphthalein according to claim 2, characterized in that: In step 1), the molar ratio of phthalic anhydride to phenol is 1:2.00 - 2.

05.

5. The improved preparation method of phenolphthalein according to claim 2, characterized in that: In step 2), the weight ratio of sulfolane to the total weight of phthalic anhydride and phenol in step 1) is 1.7 - 2.7:

1.

6. The improved preparation method of phenolphthalein according to claim 2, characterized in that: In step 2), the molar ratio of tris(pentafluorophenyl)borane to phthalic anhydride is 0.01 - 0.05:

1.

7. The improved preparation method of phenolphthalein according to claim 2, characterized in that: In step 2), the molar ratio of the sulfonic acid-based ionic liquid to phthalic anhydride is 0.001 - 0.003:

1.

8. The improved preparation method of phenolphthalein according to claim 2, characterized in that: In step 4), the non-polar solvent is selected from n-hexane, n-heptane or cyclohexane; the weight ratio of the non-polar solvent to sulfolane is 1.0 - 1.5:1.

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