阅读说明：本技术 一种2,2-双(4-氨基苯基)六氟丙烷的绿色制备方法 (Green preparation method of 2, 2-bis (4-aminophenyl) hexafluoropropane ) 是由 吴成英 江丽军 谢伟东 吕涛 王孟英 郭勇 于 2021-08-10 设计创作，主要内容包括：本发明涉及精细有机合成领域,尤其涉及一种2,2-双(4-氨基苯基)六氟丙烷的绿色制备方法,包括以下步骤：(a)在全氟化合物溶剂中,2,2-双(4-甲基苯基)六氟丙烷和氧气发生氧化反应,分离得到2,2-双(4-羧基苯基)六氟丙烷；(b)将步骤(a)得到的化合物与氨气在有机溶剂中回流反应,得到2,2-双(4-羧基苯基)六氟丙烷的铵盐；(c)将步骤(b)得到的化合物与有机溶剂混合加热,升温脱水,得到2,2-双(4-甲酰胺基苯基)六氟丙烷；(d)在氢氟醚溶剂中,将步骤(c)得到的化合物与次氯酸钠进行霍夫曼降解反应,纯化得到2,2-双(4-氨基苯基)六氟丙烷。本发明选用氧化剂经济绿色,氧化溶剂不燃不爆；霍夫曼反应选用氢氟醚溶剂减少产生高COD废水,有利于工业化生产。(The invention relates to the field of fine organic synthesis, in particular to a green preparation method of 2, 2-bis (4-aminophenyl) hexafluoropropane, which comprises the following steps: (a) in a perfluorinated compound solvent, 2, 2-bis (4-methylphenyl) hexafluoropropane and oxygen are subjected to oxidation reaction and separated to obtain 2, 2-bis (4-carboxyphenyl) hexafluoropropane; (b) refluxing and reacting the compound obtained in the step (a) and ammonia gas in an organic solvent to obtain ammonium salt of 2, 2-bis (4-carboxyphenyl) hexafluoropropane; (c) mixing the compound obtained in the step (b) with an organic solvent, heating, and dehydrating by heating to obtain 2, 2-bis (4-formamidophenyl) hexafluoropropane; (d) and (c) in a hydrofluoroether solvent, carrying out Hofmann degradation reaction on the compound obtained in the step (c) and sodium hypochlorite, and purifying to obtain the 2, 2-bis (4-aminophenyl) hexafluoropropane. The invention selects the oxidant to be economical and green, and the oxidation solvent is non-combustible and non-explosive; the hydrofluoroether solvent is selected for the Hofmann reaction to reduce the generation of high COD wastewater, which is beneficial to industrial production.)

1. A green preparation method of 2, 2-bis (4-aminophenyl) hexafluoropropane is characterized by comprising the following steps of:

(a) in a perfluorinated compound solvent, 2, 2-bis (4-methylphenyl) hexafluoropropane and oxygen are subjected to oxidation reaction and separated to obtain 2, 2-bis (4-carboxyphenyl) hexafluoropropane;

(b) refluxing and reacting the compound obtained in the step (a) and ammonia gas in an organic solvent to obtain ammonium salt of 2, 2-bis (4-carboxyphenyl) hexafluoropropane;

(c) mixing the compound obtained in the step (b) with an organic solvent, heating, and dehydrating by heating to obtain 2, 2-bis (4-formamidophenyl) hexafluoropropane;

(d) and (c) preparing the compound obtained in the step (c) and hydrofluoroether into a solution, dropwise adding sodium hypochlorite to perform Hofmann degradation reaction, and purifying to obtain a product 2, 2-bis (4-aminophenyl) hexafluoropropane.

2. The process for the green production of 2, 2-bis (4-aminophenyl) hexafluoropropane as claimed in claim 1, wherein the mass ratio of 2, 2-bis (4-methylphenyl) hexafluoropropane to the perfluoro compound solvent in the step (a) is 1 (2-6).

3. The process for the green production of 2, 2-bis (4-aminophenyl) hexafluoropropane as claimed in claim 1, wherein in the step (a), the molar ratio of 2, 2-bis (4-methylphenyl) hexafluoropropane to oxygen is 1 (3-5), and the reaction temperature is 90-150 ℃.

4. The process according to claim 1, wherein in step (a), the perfluoro compound solvent is one of perfluoroalkane, perfluorocycloalkane, perfluorodialkyl ether, perfluoropolyether, a perfluoro-substituted aromatic compound and a perfluoroamine compound.

5. The process for the green production of 2, 2-bis (4-aminophenyl) hexafluoropropane as claimed in claim 1, wherein the molar ratio of 2, 2-bis (4-carboxyphenyl) hexafluoropropane to ammonia gas in step (b) is 1 (2-2.5).

6. The method for green production of 2, 2-bis (4-aminophenyl) hexafluoropropane as claimed in claim 1, wherein in the steps (b) and (c), said organic solvent is one of an aromatic hydrocarbon compound, a perfluoro compound and a hydrofluoroether compound; in the step (c), the temperature for temperature rise dehydration is 120-200 ℃.

7. The green preparation method of 2, 2-bis (4-aminophenyl) hexafluoropropane as claimed in claim 1, wherein in step (d), 2-bis (4-carboxamidophenyl) hexafluoropropane and hydrofluoroether are prepared into a solution, the temperature is reduced, a sodium hypochlorite solution is added dropwise, after the temperature is raised, a sodium hydroxide solution is added dropwise, layering is carried out, a lower layer solution is taken out, and 2, 2-bis (4-aminophenyl) hexafluoropropane is obtained through concentration, drying and purification.

8. The process for the green production of 2, 2-bis (4-aminophenyl) hexafluoropropane as claimed in claim 1, wherein in step (d), said hydrofluoroether is one or more of perfluorobutyl methyl ether, 3-methoxy-2-trifluoromethyl octafluorobutane, decafluoro-3-methoxy-2-trifluoromethyl pentane.

Technical Field

The invention relates to the technical field of fine organic synthesis, in particular to a green preparation method of 2, 2-bis (4-aminophenyl) hexafluoropropane.

Background

The polyimide is used as the special engineering plastic at the top end of the pyramid, has excellent thermal property, physical and mechanical properties and chemical stability, and is suitable for various fields. The fluorine-containing polyimide with fluorine introduced into the polyimide has the characteristics of high polymer materials besides the characteristics, and the performances enable the fluorine-containing polyimide to have important application prospects in the fields of electronic materials, aerospace materials, optical materials, separation membranes, liquid crystal materials and the like. In general, the fluorine-containing polyimide is prepared by reacting a fluorine-containing diamine compound with an aromatic dianhydride compound, or by reacting a fluorine-containing aromatic dianhydride compound with a diamine compound.

Among the various fluorine-containing polyimide intermediates, 2, 2-bis (4-aminophenyl) hexafluoropropane is a widely used intermediate. At present, there are two main methods for synthesizing 2, 2-bis (4-aminophenyl) hexafluoropropane which are publicly reported. One of the methods is a three-step synthesis method proposed by a Maruta research team, namely a)2, 2-bis (4-carboxylic acid phenyl) -hexafluoropropane is used as a raw material and reacts with thionyl chloride to generate 2, 2-bis (4-chloroformyl phenyl) -hexafluoropropane; b) reacting 2, 2-bis (4-chloroformylphenyl) -hexafluoropropane with an azide compound to generate 2, 2-bis (4-isocyanatophenyl) -hexafluoropropane; c) hydrolyzing the isocyanate group of the 2, 2-bis (4-isocyanatophenyl) -hexafluoropropane to obtain the 2, 2-bis (4-aminophenyl) -hexafluoropropane. Another synthesis method is disclosed in U.S. Pat. No. 4, 4370501A, which comprises converting 2, 2-bis (4-hydroxyphenyl) -hexafluoropropane potassium salt as a raw material into 4-chloro-2-phenylquinazoline under the condition of dimethyl sulfoxide, converting the 4-chloro-2-phenylquinazoline into bisquinazolinone at a high temperature of 320 ℃, and hydrolyzing the bisquinazolinone into 2, 2-bis (4-aminophenyl) -hexafluoropropane. Based on the two methods, the former method uses azide compounds, which has the problems of high operation danger and difficult separation of the formed isocyanic acid intermediate compound; the latter method requires expensive reagents and harsh reaction conditions, and is not suitable for industrial production.

In addition, patent publication No. CN108358794A discloses a new method for synthesizing 2, 2-bis (4-aminophenyl) -hexafluoropropane, which uses heavy metal oxidants with high cost, and has serious environmental pollution and occupational health risks, and the complicated removal process of the residual heavy metals in the product increases the production cost, and is not suitable for industrial production.

In summary, the existing synthesis methods of 2, 2-bis (4-aminophenyl) -hexafluoropropane all have some technical problems, and it is urgent and necessary to develop a new synthesis method with high safety and low cost.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to overcome the problems of expensive heavy metal oxidant, high flammable and explosive risk of a solvent, harsh reaction conditions and the like in the existing preparation method of 2, 2-bis (4-aminophenyl) hexafluoropropane, and provides a green synthesis method of 2, 2-bis (4-aminophenyl) hexafluoropropane.

The invention adopts the following technical scheme:

a green preparation method of 2, 2-bis (4-aminophenyl) hexafluoropropane comprises the following steps:

(a) in a perfluorinated compound solvent, 2, 2-bis (4-methylphenyl) hexafluoropropane and oxygen are subjected to oxidation reaction and separated to obtain 2, 2-bis (4-carboxyphenyl) hexafluoropropane;

(b) refluxing and reacting the compound obtained in the step (a) and ammonia gas in an organic solvent to obtain ammonium salt of 2, 2-bis (4-carboxyphenyl) hexafluoropropane;

(c) mixing the compound obtained in the step (b) with an organic solvent, heating, and dehydrating by heating to obtain 2, 2-bis (4-formamidophenyl) hexafluoropropane;

(d) and (c) preparing the compound obtained in the step (c) and hydrofluoroether into a solution, dropwise adding sodium hypochlorite to perform Hofmann degradation reaction, and purifying to obtain a product 2, 2-bis (4-aminophenyl) hexafluoropropane.

Further, in the step (a), the mass ratio of the 2, 2-bis (4-methylphenyl) hexafluoropropane to the perfluorinated compound solvent is 1 (2-6), the molar ratio of the 2, 2-bis (4-methylphenyl) hexafluoropropane to oxygen is 1 (3-5), the reaction temperature is 90-150 ℃, the reaction time is 12-16h, and oxygen is bubbled from the liquid phase of the reactor. The appropriate mass ratio of 2, 2-bis (4-methylphenyl) hexafluoropropane to the perfluorinated solvent is selected to completely dissolve the reactant 2, 2-bis (4-methylphenyl) hexafluoropropane. When the dosage of the perfluorinated compound solvent is too small, the reactant can be incompletely dissolved; when the consumption of the perfluorinated compound solvent is too high, the system utilization rate is low and the productivity is low.

Preferably, step (a) is: adding 2, 2-bis (4-methylphenyl) hexafluoropropane into a perfluorinated compound solvent, stirring, heating to 90-120 ℃, continuously bubbling, introducing oxygen from a liquid phase of a reactor after the solid is completely dissolved, controlling the temperature in the reaction to be 90-150 ℃, reacting for 12-16h, cooling, precipitating, and filtering to obtain an intermediate product, namely 2, 2-bis (4-carboxyphenyl) hexafluoropropane.

Further, the perfluorinated compound solvent is one of perfluoroalkane, perfluorocycloalkane, perfluorodialkyl ether, perfluoropolyether, a perfluorinated substituted aromatic compound, and a perfluorinated amine compound. In the prior art, the reaction solvent is mostly acetic acid or acetic anhydride when preparing the intermediate product 2, 2-bis (4-carboxyphenyl) hexafluoropropane, the oxidant is oxygen, and the catalyst is added at the same time. In the process, the explosion risk exists; the catalyst consumption is large, the 2, 2-bis (4-methylphenyl) hexafluoropropane is not completely oxidized, excessive oxygen is needed, and a preparation method which is not flammable and does not need to be added with the catalyst is needed to be developed in consideration of the safety of industrial production. The invention selects the perfluorinated solvent which has the characteristics of oxidation resistance, non-combustion and non-explosion; it can be used as safe solvent for oxidation reaction, and can be recycled, and is favorable for safe production. The perfluorinated compound solvent has high oxygen dissolving degree, can be directly contacted with oxygen, is non-combustible, has safe and stable reaction process, does not need to additionally add a catalyst, and is suitable for industrial production.

Preferably, in the step (a), the perfluorinated compound solvent is one of fluorocarbon cyclic ether, perfluoro (2-n-butyltetrahydropyrane) and perfluoropolyether.

Further, in the step (b), the molar ratio of the 2, 2-bis (4-carboxyphenyl) hexafluoropropane to the ammonia gas is 1 (2-2.5). Preferably, in the step (b), the molar ratio of the 2, 2-bis (4-carboxyphenyl) hexafluoropropane to the ammonia gas is 1 (2.2-2.5).

Further, in the steps (b) and (c), the organic solvent is one of aromatic hydrocarbon compound, perfluorinated compound and hydrofluoroether compound; in the step (c), the temperature for temperature rise dehydration is 120-200 ℃. Preferably, in the step (b), the aromatic hydrocarbon compound is one of xylene, o-xylene, p-xylene, trimethylbenzene and naphthalene. In the preparation process of the 2, 2-bis (4-formamidophenyl) hexafluoropropane, no chlorination reagent is needed, the process is simple, and the manufacturing cost is low.

Further, in the step (d), preparing the 2, 2-bis (4-formamidophenyl) hexafluoropropane and hydrofluoroether into a solution, cooling, dropwise adding a sodium hypochlorite solution, heating, dropwise adding a sodium hydroxide solution, layering, taking a lower layer solution, concentrating, drying and purifying to obtain the 2, 2-bis (4-aminophenyl) hexafluoropropane. Preferably, in the step (d), 2-bis (4-formamidophenyl) hexafluoropropane is dissolved in a hydrofluoroether solvent, and the temperature is reduced to 0-10 ℃. Dropping hydrofluoroether solvent dissolved with 2, 2-bis (4-formamidophenyl) hexafluoropropane into sodium hypochlorite solution cooled to 0 ℃, stirring for 1-2h, heating to 60 ℃, dropping sodium hydroxide solution, keeping stirring for 0.5-2h, taking reaction liquid to measure pH value, and taking the measured pH value as the base at the end point of the reaction. And (3) after the reaction is confirmed to be finished, layering, taking the lower layer solution, concentrating and drying to obtain the 2, 2-bis (4-aminophenyl) hexafluoropropane.

Further, in the step (d), the hydrofluoroether is one or more of perfluorobutyl methyl ether, 3-methoxy-2-trifluoromethyl octafluorobutane and decafluoro-3-methoxy-2-trifluoromethyl pentane.

The beneficial effects of the invention are mainly embodied as follows:

the 2, 2-bis (4-aminophenyl) hexafluoropropane prepared by the method selects a non-combustible and non-explosive perfluorinated solvent, and simultaneously adopts oxygen as an oxidant, so that the perfluorinated solvent has high oxygen dissolving degree, can be directly contacted with oxygen, can be recycled as a safe solvent for oxidation reaction, and is favorable for safe production; in the preparation process of the 2, 2-bis (4-formamidophenyl) hexafluoropropane, a chlorination reagent is not needed, the process is simple, and the manufacturing cost is low; in the final stage of preparing 2, 2-bis (4-aminophenyl) hexafluoropropane, hydrofluoroether is used to replace alcohol solvent, the hydrofluoroether has good solubility to 2, 2-bis (4-aminophenyl) hexafluoropropane and can be well layered with water, so that the extraction process is saved, meanwhile, an upper water system does not contain alcohol solvent, the COD (chemical oxygen demand) of wastewater is low, the treatment cost of wastewater is greatly reduced, and the hydrofluoroether realizes recycling through rotary evaporation and drying, so that the cost of a large amount of solvents is effectively saved, and the method is favorable for efficient green industrial production. According to the green preparation method of the 2, 2-bis (4-aminophenyl) hexafluoropropane, the green and economic oxygen oxidant is selected, the non-combustible and non-explosive perfluoro solvent is used as the oxidation solvent, the hydrofluoroether is used as the Hofmann reaction solvent, the high-COD wastewater is effectively reduced, the reaction speed is high, the reaction yield is high, the raw materials are cheap and easily available, the reaction condition is mild, the process safety is improved, the process cost is reduced, and the industrial large-scale production is easy.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all 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.

A green preparation method of 2, 2-bis (4-aminophenyl) hexafluoropropane comprises the following steps:

(a) adding 2, 2-bis (4-methylphenyl) hexafluoropropane into a perfluorinated compound solvent, stirring and heating to 90-120 ℃, continuously introducing oxygen after the solid is completely dissolved, controlling the reaction temperature to be 90-150 ℃ for reaction for 12-16h, finally cooling, separating out, and filtering to obtain an intermediate product, namely 2, 2-bis (4-carboxyphenyl) hexafluoropropane;

(b) carrying out reflux reaction on 2, 2-bis (4-carboxyphenyl) hexafluoropropane and ammonia gas in an organic solvent to obtain ammonium salt of the 2, 2-bis (4-carboxyphenyl) hexafluoropropane, wherein the molar ratio of the 2, 2-bis (4-carboxyphenyl) hexafluoropropane to the ammonia gas is 1 (2-2.5);

(c) mixing and heating the ammonium salt of the 2, 2-bis (4-carboxyphenyl) hexafluoropropane with an organic solvent, and heating for dehydration at the temperature of 120 ℃ and 200 ℃ to obtain the 2, 2-bis (4-formamidophenyl) hexafluoropropane;

(d) preparing 2, 2-bis (4-formamidophenyl) hexafluoropropane and hydrofluoroether into a solution, and cooling to 0-10 ℃. Dropping a hydrofluoroether solution dissolved with 2, 2-bis (4-formamidophenyl) hexafluoropropane into a sodium hypochlorite solution cooled to 0 ℃, stirring for 1-2h, heating to 60 ℃, continuing stirring for 0.5-2h after dropping a sodium hydroxide solution, taking a reaction solution to measure the pH value, and taking the measured pH value as the standard at the end point of the reaction. And (3) after the reaction is confirmed to be finished, layering, taking the lower layer solution, concentrating and drying to obtain the 2, 2-bis (4-aminophenyl) hexafluoropropane.

The specific reaction process of the invention is as follows:

the reaction formula of the step (a) is as follows:

the reaction formulas of the steps (b and c) are as follows:

the reaction formula of the step (d) is as follows:

the raw materials used in the invention are all common commercial products and AR pure unless specified otherwise.

Example 1

A green preparation method of 2, 2-bis (4-aminophenyl) hexafluoropropane comprises the following steps:

(a) synthesis of 2, 2-bis (4-carboxyphenyl) hexafluoropropane

3320g (10mol) of 2, 2-bis (4-methylphenyl) hexafluoropropane and 9960g of fluorocarbon cyclic ether solvent were weighed into a 10 l (phi 10 cm. times.130 cm) stainless steel tubular reactor and heated to 90 ℃ while stirring to dissolve the solid. After the solid is completely dissolved, 739L (standard atmospheric pressure) of oxygen (33mol) is introduced through a liquid phase distributor, and the reaction temperature is controlled to be maintained at 90-120 ℃. After the reaction is finished, the temperature is reduced to room temperature, solid is separated out and filtered, and the obtained solid is dried in vacuum at 60 ℃ to obtain 3737g of white crystalline solid product. The molar yield based on 2, 2-bis (4-methylphenyl) hexafluoropropane was 95.3%. The product was characterized by H NMR (400MHz in DMSO) analysis as follows: 13.32(s,2H),8.08(d, j ═ 8Hz,4H),7.51(d, j ═ 8Hz,4H), indicating that the product is indeed 2, 2-bis (4-carboxyphenyl) hexafluoropropane with a purity of 99.5%.

(b) Synthesis of ammonium salt of 2, 2-bis (4-carboxyphenyl) hexafluoropropane

90g (0.23mol) of 2, 2-bis (4-carboxyphenyl) hexafluoropropane prepared in the step (a) is weighed and placed in a three-neck flask, 400mL of dichloromethane is added and heated to reflux to dissolve the solid (the solid is completely dissolved and the solution is clear), and 11.8L (0.53mol, standard atmospheric pressure) of ammonia gas is introduced to obtain the ammonium salt of 2, 2-bis (4-carboxyphenyl) hexafluoropropane.

(c) Synthesis of 2, 2-bis (4-formamidophenyl) hexafluoropropane compound

Mixing and heating the ammonium salt of the 2, 2-bis (4-carboxyphenyl) hexafluoropropane obtained in the step (b) and o-xylene, raising the temperature to be below the reflux temperature, keeping the internal temperature at 150 ℃ and 170 ℃, and dehydrating for 4 hours. After the completion of dehydration was confirmed by sampling and HPLC test, 2-bis (4-formamidophenyl) hexafluoropropane was precipitated by cooling and contained 99.7% by HPLC test.

(d) Synthesis of 2, 2-bis (4-aminophenyl) hexafluoropropane

A1 liter three-necked flask equipped with a reflux condenser was charged with 137.5g (0.24mol) of sodium hypochlorite having a mass fraction of 13%, and cooled to 0 ℃. 23.4g (0.06mol) of 2, 2-bis (4-carboxamidophenyl) hexafluoropropane obtained in step (c) was mixed with 93.6g of perfluorobutyl methyl ether to prepare a solution, and the solution was gradually dropped into a three-necked flask, and the internal temperature of the three-necked flask was maintained at not higher than 5 ℃. After the addition was completed, the resulting mixture was stirred at a temperature of not higher than 5 ℃ for 1 hour. The resulting reaction solution was diluted with 200g of water, heated to 60-62 ℃ under reflux and stirred for 1 hour, cooled to 20 ℃. After completion of the cooling, 25% sodium hydroxide solution was added to make the reaction solution pH 9, and the reaction solution was separated by a separatory funnel to obtain a lower layer solution of 2, 2-bis (4-aminophenyl) hexafluoropropane in perfluorobutyl methyl ether. Drying the lower layer solution by a rotary evaporator to recover perfluorobutyl methyl ether to obtain a solid which is the target compound 2, 2-bis (4-aminophenyl) hexafluoropropane, wherein the purity is 99.83% by HPLC (high performance liquid chromatography) test.

Example 1 step (a) the product yield, purity data are shown in table 1.

Example 2

As shown in Table 1, the procedure was as in example 1 except that in the step (a) of example 1, the solvent was changed to perfluoro (2-n-butyltetrahydropyran). The product yield and purity data of step (a) are shown in Table 1.

Example 3

As shown in Table 1, the procedure was as in example 1 except that the solvent in step (a) of example 1 was changed to perfluoropolyether. The product yield and purity data of step (a) are shown in Table 1.

Comparative example 1

Synthesis of 2, 2-bis (4-carboxyphenyl) hexafluoropropane

1992g (6mol) of 2, 2-bis (4-methylphenyl) hexafluoropropane and 5976g of acetic acid were weighed into a 10 liter (. phi. sup.10 cm. times.130 cm) stainless steel tubular reactor, followed by addition of catalyst 12g of cobalt bromide and 6g of manganese acetate, and stirred to form a uniform solution. After the temperature is raised to 120 ℃, 444L (standard atmospheric pressure) of oxygen (19.8mol) is introduced through a liquid phase distributor, and the reaction temperature is controlled to be maintained at 90-120 ℃. After the reaction is finished, washing, extracting and drying are carried out, and the obtained solid is dried in vacuum at 60 ℃ to obtain the 2, 2-bis (4-carboxyphenyl) hexafluoropropane. The yield and purity data are shown in Table 1.

TABLE 1

According to the test results of examples 1-3 and comparative example 1, the perfluoro compound solvent is selected in step (a) of the present invention, and the examples 1-3 can successfully synthesize 2, 2-bis (4-carboxyphenyl) hexafluoropropane by adding different kinds of perfluoro compound solvents without adding additional catalyst, and the yield and purity are high, and the finally obtained 2, 2-bis (4-aminophenyl) hexafluoropropane also has high yield and purity. The perfluorinated compound solvents of different types of the invention have high oxygen dissolving degree, can be directly contacted with oxygen, are non-combustible, and have safe and stable reaction process. The reaction can be only reflected under the condition of simultaneously adding the catalyst by selecting acetic acid to replace fluorocarbon cyclic ether in the comparative example 1, and the yield and the purity of the 2, 2-bis (4-carboxyphenyl) hexafluoropropane prepared in the comparative example 1 are greatly different from those of the examples 1 to 3.

Example 4

Synthesis of 2, 2-bis (4-carboxyphenyl) hexafluoropropane

1660g (5mol) of 2, 2-bis (4-methylphenyl) hexafluoropropane and 4980g of fluorocarbon ether solvent were weighed into a 10 l (phi 10 cm. times.130 cm) stainless steel tubular reactor and heated to 90 ℃ with stirring to dissolve the solid. After the solid is completely dissolved, 370 liters (standard atmospheric pressure) of oxygen (16.5mol) is introduced through a liquid phase distributor, and the reaction temperature is controlled to be maintained at 90-120 ℃. After the reaction is finished, cooling to room temperature, separating out and filtering solid, and drying the obtained solid in vacuum at 60 ℃ to obtain the product 2, 2-bis (4-carboxyphenyl) hexafluoropropane. The product was characterized by H NMR (400MHz in DMSO) analysis as follows: 13.32(s,2H),8.08(d, j ═ 8Hz,4H),7.51(d, j ═ 8Hz,4H), indicating that the product is indeed 2, 2-bis (4-carboxyphenyl) hexafluoropropane. The product yield and purity data are shown in table 2.

Example 5

As shown in Table 2, the conditions were the same as those in example 4 except that the amount of the fluorocarbon cyclic ether charged in example 4 was changed to 3320 g. The product yield and purity data are shown in table 2.

Example 6

As shown in Table 2, the conditions were the same as those in example 4 except that the amount of the fluorocarbon cyclic ether charged in example 4 was 6640 g. The product yield and purity data are shown in table 2.

Example 7

As shown in Table 2, the conditions were the same as those in example 4 except that the amount of the fluorocarbon cyclic ether charged in example 4 was 8300 g. The product yield and purity data are shown in table 2.

Comparative example 2

As shown in Table 2, the conditions were the same as those in example 4 except that the amount of the fluorocarbon cyclic ether charged in example 4 was changed to 2490 g. The product yield and purity data are shown in table 2.

Comparative example 3

As shown in Table 2, the conditions were the same as those in example 4 except that the amount of the fluorocarbon cyclic ether used in example 4 was changed to 11620 g. The product yield and purity data are shown in table 2.

TABLE 2

As can be seen from the results of the tests of examples 4 to 7 and comparative examples 2 to 3, 2, 2-bis (4-carboxyphenyl) hexafluoropropane was successfully synthesized in examples 4 to 7 according to the present invention using 2, 2-bis (4-methylphenyl) hexafluoropropane and a perfluoro compound solvent in an amount within the range of 1 (2 to 6) with high yield and purity. When the amount of the perfluoro-compound solvent is small, as shown in comparative example 2, the reactant may be incompletely dissolved, resulting in low yield and purity; when the amount of the perfluoro compound solvent is too high, as shown in comparative example 3, the yield and purity of the obtained 2, 2-bis (4-carboxyphenyl) hexafluoropropane are not far from each other, but the problems of excessive solvent, low system utilization rate and low productivity are caused.

Example 8

As shown in Table 3, the conditions were the same as those in example 1 except that the volume of oxygen in example 1 was changed to 806L. The product yield and purity data of step (a) are shown in Table 3.

Example 9

As shown in table 3, the conditions were the same as in example 1 except that the volume of oxygen in example 1 was changed to 896L. The product yield and purity data of step (a) are shown in Table 3.

Comparative example 4

As shown in Table 3, the conditions were the same as those in example 1 except that the volume of oxygen in example 1 was changed to 448L. The product yield and purity data of step (a) are shown in Table 3.

TABLE 3

According to the test results of the examples 1, 8-9 and the comparative example 4, the 2, 2-bis (4-carboxyphenyl) hexafluoropropane is successfully synthesized in the examples 1, 8-9 by changing the amount of the oxidant oxygen and controlling the molar ratio of the 2, 2-bis (4-methylphenyl) hexafluoropropane to the oxygen to be 1 (3-5), and the yield and the purity are high. When the oxygen content was low, as shown in comparative example 4, the purity and yield of 2, 2-bis (4-carboxyphenyl) hexafluoropropane obtained were low as compared with example 1. When the oxygen content is too high, the excess oxygen increases the reaction cost, and does not greatly contribute to the improvement of the yield and purity of the product. The invention selects oxygen as the oxidant, not only saves the cost of the heavy metal oxidant, but also solves the environmental protection problem caused by heavy metal, and is suitable for industrial production.

In conclusion, the 2, 2-bis (4-aminophenyl) hexafluoropropane prepared by the method selects a perfluorinated solvent as a safe solvent for oxidation reaction, can be recycled, is beneficial to safe production, and can be prepared into 2, 2-bis (4-carboxyphenyl) hexafluoropropane with higher purity and yield; in the preparation process of the 2, 2-bis (4-formamidophenyl) hexafluoropropane, a chlorination reagent is not needed, the process is simple, and the manufacturing cost is low; the method adopts hydrofluoroether as a solvent of a raw material to carry out Hofmann degradation reaction to obtain the 2, 2-bis (4-aminophenyl) hexafluoropropane, can greatly reduce the generation of COD in wastewater, can realize the cyclic utilization of the solvent, saves the cost and is beneficial to green production. The green preparation method of the 2, 2-bis (4-aminophenyl) hexafluoropropane has the advantages of cheap and easily obtained raw materials, mild reaction conditions and easy industrial large-scale production.

The present invention has been further described with reference to specific embodiments, but it should be understood that the detailed description should not be construed as limiting the spirit and scope of the present invention, and various modifications made to the above-described embodiments by those of ordinary skill in the art after reading this specification are within the scope of the present invention.