Preparation method of perfluoroalkenyl ether iodine-containing vulcanization point monomer

Abstract

The invention provides a preparation method of a perfluoroalkenyl ether iodine-containing vulcanization point monomer. Specifically, the invention provides a preparation method of a compound as shown in a formula I. The preparation method comprises the following steps: in an aprotic solvent, in the presence of a dehalogenating agent, a compound as shown in a formula II is subjected to a dehalogenating reaction to generate the compound as shown in the formula I, the dehalogenating agent is a metal or organic metal compound; the metal is mixed metal of two or three of zinc, copper and palladium; the organic metal compound is an organic metal zinc reagent or an organic metal magnesium reagent. The preparation method is low in cost, high in yield, convenient and fast.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for preparing a perfluoroalkenyl ether iodine-containing cure site monomer. BACKGROUND

[0002] Perfluoroether rubber has extremely superior chemical stability and thermal stability, and plays an irreplaceable role in the field of high-tech.

[0003] Perfluoroether rubber (FFKM) is known as "King of Rubber", which is a multi-copolymer polymerized by tetrafluoroethylene (CF2=CF2, TFE), perfluoroalkyl vinyl ether (CF2=CFOR F , PAVE), cure site (CSM) and other monomers, and the typical structure is as follows:

[0004]

[0005] Due to the complete absence of C-H bonds in the molecular structure, perfluoroether rubber has excellent high temperature resistance, chemical corrosion resistance and other properties, and the long-term use temperature can reach 300 ℃ or above, and the short-term use temperature can reach 350 ℃. Perfluoroether rubber is the best rubber sealing material in terms of high temperature resistance and medium resistance, and is the only optional material for sealing media above 300 ℃ in the field of high-tech.

[0006] Perfluoroalkenyl ether iodine-containing cure site monomer is an important raw material in the preparation of high-end fluorinated ether rubber field. By adding iodine-containing cure site monomer in the polymerization reaction, the efficiency of fluorine rubber post-curing can be greatly improved, the excessive mold dirt and high waste rate in the processing process can be effectively improved, the molding problem of iodine-containing fluorine elastomer obtained by the iodine-containing cure site monomer is relatively reduced, and more mature molding technology (such as injection molding) can be used. In addition, iodine-containing elastomer shows more excellent sealing performance. The fluorine elastomer produced by Dupont and Dakin Company using iodine-based curing system has excellent demolding properties, excellent compression permanent deformation resistance and heat resistance.

[0007] The preparation methods for iodine-containing sulfur point monomers are mainly prepared by the following methods: (1) The first method is to directly use sulfonyl fluoride / chlorine containing perfluorovinyl ether to undergo a substitution reaction in a solvent with iodine-containing salts such as NaI, and remove SO2 and NaF / NaCl to obtain the target product (WO089617) (CN 110759805A). Another method is to generate acyl fluoride by telomerization of ICF2COF with HFPO, and then react with alkali in an ether solvent to generate carboxylate, and then heat to decarboxylate to obtain the target product (US0185355A1). The raw materials used in the first method are very rare and are not commercially available. They are themselves high-value fluorine material raw materials and the preparation method is complicated and difficult to engineer. In the second method, the entire route is long, the raw material ICF2COF is not easy to obtain, and the product produced is not single, the yield is not ideal, and it has a certain degree of toxicity. Therefore, the synthesis of simple and direct iodine-containing sulfur point monomers has always been the focus of attention.

[0008] Currently, the method for constructing perfluoroalkenyl ethers via terminal iodine is only mentioned in patents (CN111072526A / DE2934194A1). These patents all use a substrate with a single-terminal sulfonyl fluoride, which is removed by metal powder under high-temperature conditions. However, when we repeated this reaction, we found that it could not proceed. Furthermore, we performed theoretical calculations, which showed that the reaction is theoretically impossible to carry out. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to overcome the defects of high raw material cost and low yield in the preparation of iodine-containing sulfur point monomers in the prior art, and to provide a low-cost, high-yield, convenient and quick method for preparing perfluoroalkenyl ether iodine-containing sulfur point monomers.

[0010] The present invention solves the above-mentioned technical problems through the following technical solution:

[0011] The present invention provides a method for preparing a compound of formula I, which includes the following steps: in an aprotic solvent, in the presence of a dehalogenating agent, a compound of formula II undergoes a dehalogenation reaction to generate a compound of formula I;

[0012] ;

[0013] The dehalogenating agent is a metal or organometallic compound;

[0014] The metal is a mixture of two or three of zinc, copper and palladium;

[0015] The organometallic compound is an organometallic zinc reagent or an organometallic magnesium reagent.

[0016] In some embodiments, in the dehalogenation reaction, the aprotic solvent is selected from one or more of ketone solvents, ether solvents, nitrile solvents, amide solvents, aromatic hydrocarbon solvents, and ester solvents; more preferably, it is selected from one or more of acetonitrile, diethylene glycol dimethyl ether, diglyceride, toluene, N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), toluene, and 2-methyltetrahydrofuran (2-Me-THF), such as DMF, NMP, "a mixed solvent of diethylene glycol dimethyl ether and toluene", THF, or "a mixed solvent of 2-Me-THF and THF".

[0017] In some embodiments, the metal in the dehalogenation reaction is a powdered metal.

[0018] In some embodiments, the metal in the dehalogenation reaction is a mixture of zinc and copper in a mass ratio of (7-12):1 or a mixture of zinc and palladium in a mass ratio of 8:1-99:1; for example, a mixture of zinc and copper in a 9:1 ratio or a mixture of zinc and palladium in a 97:3 ratio. In this invention, all metal ratios in the metal mixture are mass ratios.

[0019] In some embodiments, the organometallic compound in the dehalogenation reaction is an alkyl metal zinc reagent or a magnesium Grignard reagent, such as diethylzinc, MeMgBr, or PhMgBr.

[0020] In some embodiments, the organometallic compound is used in the dehalogenation reaction in the form of a solution of the organometallic compound and the aprotic solvent; for example, a toluene solution of diethylzinc powder, a THF solution of MeMgBr, or a THF solution of PhMgBr.

[0021] In some embodiments, in the dehalogenation reaction, the molar ratio of compound of formula II to the dehalogenating agent is 1:(0.5-2.5), preferably 1:(0.7-2), further 1:(1.1-1.5), for example 1:1.1, 1:1.2, 1:1.4 or 1:1.5.

[0022] In some embodiments, when the dehalogenating agent is a metal in the dehalogenation reaction, the molar to volume ratio of the compound of formula II to the solvent is 1 mol / (0.2-1) L, preferably 1 mol / (0.3-0.5) L, for example 1 mol / 0.3 L or 1 mol / 0.5 L.

[0023] In some embodiments, when the dehalogenating agent is an organometallic compound in the dehalogenation reaction, the molar to volume ratio of the compound of formula II to the solvent is 1 mol / (0.5-3) L, preferably 1 mol / (0.8-3) L; for example, 1 mol / 1.5 L, 1 mol / 1.7 L, 1 mol / 0.8 L or 1 mol / 1.8 L.

[0024] In some embodiments, the progress of the dehalogenation reaction can be monitored using conventional detection methods in the art (e.g., HPLC, TLC or NMR), and the reaction endpoint is generally defined as the disappearance or cessation of reaction of the compound of formula II. The reaction time is generally 2-8 hours, preferably 4-8 hours (e.g., 6h, 8h, 5h, 4h).

[0025] In some embodiments, the dehalogenation reaction is carried out at a temperature of 20-200°C, preferably 50-150°C, such as 30°C, 55°C, 60°C, 65°C, 70°C or 80°C.

[0026] In some embodiments, when the dehalogenating agent is a mixture of zinc powder and copper powder in a mass ratio of 9:1, the reaction temperature is 80°C; and the aprotic solvent is DMF.

[0027] In some embodiments, the dehalogenation reaction is carried out at a temperature of 80°C when the dehalogenating agent is a mixture of zinc powder and palladium in a mass ratio of 97:3; and the aprotic solvent is NMP.

[0028] In some embodiments, during the dehalogenation reaction, when the dehalogenating agent is diethylzinc, the reaction temperature is 70°C; the aprotic solvent is a mixture of diethylene glycol dimethyl ether and toluene (e.g., a mixture of diethylene glycol dimethyl ether and toluene in a volume ratio of 1:4), and the diethylzinc and toluene are used in the form of a diethylzinc toluene solution.

[0029] In some embodiments, during the dehalogenation reaction, when the dehalogenating agent is MeMgBr, the reaction temperature is 55°C; the aprotic solvent is THF, and MeMgBr is used in the form of a THF solution.

[0030] In some embodiments, during the dehalogenation reaction, when the dehalogenating agent is PhMgBr, the reaction temperature is 55°C; the aprotic solvent is a mixed solvent of 2-Me-THF and THF (e.g., a mixed solvent of 2-Me-THF and THF in a volume ratio of 3:5), wherein PhMgBr and THF are used in the form of a PhMgBr tetrahydrofuran solution.

[0031] In some embodiments, the starting materials for the dehalogenation reaction are the aprotic solvent, the compound of formula II, and the dehalogenating agent.

[0032] In some embodiments, the dehalogenation reaction includes the following post-processing step: after the reaction is complete, distillation is performed to obtain the compound of formula I.

[0033] In some embodiments, the dehalogenation reaction comprises the following steps: mixing the aprotic solvent and the metal, heating to 50-150°C, adding the compound of formula II to carry out the dehalogenation reaction, and after the reaction is completed, distilling to obtain the compound of formula I.

[0034] In some embodiments, the dehalogenation reaction comprises the following steps: mixing the aprotic solvent, the organometallic compound, and the compound of formula II at 50-150°C to carry out the dehalogenation reaction, and distilling after the reaction to obtain the compound of formula I.

[0035] In some embodiments, the preparation of the compound of formula I further includes the step of: in a solvent, the compound of formula III undergoes an iodination reaction with I2 to generate the compound of formula II;

[0036] .

[0037] In some embodiments, in the iodination reaction, the solvent is selected from one or more of nitrile solvents, ether solvents, amide solvents, sulfoxide solvents, and water, and is more preferably a mixed solvent of acetonitrile, tetrahydrofuran, DMF, and DMSO with H2O; for example, a mixed solvent of THF:H2O=1:1.

[0038] In the iodination reaction, the amount of solvent used can be the conventional amount used in this type of reaction in the art (e.g., the molar volume ratio of the compound of formula III to the solvent shown is (1-2) mol / L; preferably 1.2 mol / L) to ensure the normal progress of the reaction.

[0039] In some embodiments, the iodination reaction also incorporates K2S2O8, with the molar ratio of the Formula III compound to K2S2O8 being 1:(0.4-1); for example, 1:0.5.

[0040] In some embodiments, the molar ratio of the Formula III compound to the I2 in the iodination reaction is 1:(1-2.5), for example 1:2.

[0041] In some embodiments, after the iodination reaction is completed, a reducing agent is added to remove excess I2.

[0042] In some embodiments, the reducing agent is sodium thiosulfate.

[0043] In some embodiments, the molar ratio of the reducing agent to the compound of formula III is (1-3):1.

[0044] In some embodiments, the iodination reaction is carried out at a temperature of 20-80°C, preferably 30-80°C; for example, 50°C.

[0045] In some implementations, the iodination reaction uses a water bath to control the reaction temperature.

[0046] The progress of the iodination reaction can be measured using methods commonly used in the art (e.g., 19 The reaction is monitored by 1-3 hours (F-NMR), and the endpoint is generally taken as the disappearance of the raw material or the cessation of the reaction. For example, 2 hours.

[0047] In some embodiments, the iodination reaction further includes the following post-treatment step: after the reaction is completed, the reducing agent is added to quench the reaction, and water is added to precipitate the compound of formula II.

[0048] In some embodiments, the iodination reaction is carried out using a tail gas absorption or treatment device, such as using a sodium hydroxide solution to absorb the tail gas.

[0049] In some embodiments, the starting materials for the iodination reaction are the compound of formula III, the solvent, the I2, and the K2S2O8.

[0050] In some embodiments, the iodination reaction further includes the following specific steps: stirring the compound of formula III and the solvent until dissolved, adding K2S2O8; adding I2 in batches, absorbing the gas with sodium hydroxide solution, and controlling the reaction temperature to not exceed 80 degrees Celsius to obtain the compound of formula II.

[0051] In some embodiments, the preparation of the compound of formula I further includes the step of reducing the compound of formula IV and a reducing agent in the presence of a solvent to generate the compound of formula III.

[0052] .

[0053] In some embodiments, in the reduction reaction, the solvent is selected from one or more of nitrile solvents, ether solvents, amide solvents and water, more preferably a mixed solvent of acetonitrile, tetrahydrofuran, dioxane, DMF and water in a ratio of 10:1 to 1:10, more preferably 3:1 to 1:3; for example, a mixed solvent of dioxane:water = 3:2 (volume ratio).

[0054] In some embodiments, the molar to volume ratio of the compound of formula IV and the solvent in the reduction reaction is (0.5-1.5) mol / L; for example, 0.7 mol / L or 4.7 / 7 mol / L.

[0055] In some embodiments, the reducing agent in the reduction reaction is an alkali metal reducing agent; preferably Na2SO3, K2SO3, NaBH4 and KBH4, more preferably Na2SO3 or NaBH4; for example, Na2SO3.

[0056] In some embodiments, the molar ratio of the alkali metal reducing agent to the compound of formula IV in the reduction reaction is (2-8):1; preferably (2-5):1; for example, 2.5:1 or 11.7 / 4.7.

[0057] In some embodiments, the reduction reaction is carried out at a temperature of -30°C to 160°C; preferably 0-80°C; for example, 15-30°C.

[0058] In some embodiments, the reduction reaction is carried out under mechanical stirring, preferably at a stirring speed of 50-600 rpm; for example, at a stirring speed of 300 rpm.

[0059] The reaction process can be tested using methods commonly used in the field (such as...). 19 The reaction is monitored by 10-F-NMR. The endpoint of the reaction is generally the disappearance of the raw material or the cessation of the reaction. The reaction time of the reduction reaction is 8-24 hours, for example, 10 hours.

[0060] After the reaction is completed, the product is processed using conventional post-processing methods in the art (e.g., extraction using solvents such as MeCN or ethyl acetate).

[0061] In some embodiments, the reduction reaction is connected to a gas absorption or collection device; for example, the tail gas is absorbed using a sodium hydroxide solution.

[0062] In some embodiments, the starting materials for the reduction reaction are the compound of formula IV, the solvent, and the reducing agent.

[0063] In some embodiments, the reduction reaction further includes the following specific steps: the Formula IV compound and the reducing agent react at room temperature in the presence of the solvent, and the tail gas is absorbed by a sodium hydroxide solution.

[0064] The positive and progressive effects of this invention are as follows:

[0065] 1. The process is simple and easy to industrialize; the raw materials for this invention are readily available, making it valuable for industrialization.

[0066] 2. Green and environmentally friendly: This invention prepares the product through selective reduction and selective dehalogenation, which significantly reduces the amount of waste, has atom economy, and meets the requirements of green and environmental protection.

[0067] 3. High yield, with a yield of over 90%, and up to 96% in some cases. Detailed Implementation

[0068] The present invention is further illustrated below by way of examples, but the invention is not limited to the scope of the examples. The following examples are experimental methods with specific conditions specified, following conventional methods and conditions, or selected according to the product instructions.

[0069] The structure and purity of the compound were determined by nuclear magnetic resonance (NMR). 19 The determination was performed using nuclear magnetic resonance (NMR) technology, employing a Bruker AVANCE 300 instrument, with the solvent being the solvent used in the reaction.

[0070] Step 1: Synthesis of diiodine compounds:

[0071]

[0072] A mixed solvent of Dioxane:H₂O = 3:2 (7 L) was added to a 10 L flask equipped with a mechanical stirrer. 2 kg (4.7 mol) of the raw material shown in Formula IV was weighed and added to the reaction flask, at which point the reaction system separated into layers. 1492 g (11.7 mol) of reducing agent Na₂SO₃ was weighed and the reaction was carried out at room temperature with stirring at 300 rpm for 10 h. SO₂ gas was released during the reaction, and the gas was absorbed using sodium hydroxide solution. After the reaction was confirmed to be complete by fluorine spectroscopy, the reaction solvent was removed by distillation. Then, EA (4 L) was added and stirred for 1 h. The resulting white suspension was filtered, and the filtrate was concentrated using a diaphragm pump to obtain sodium sulfite salt shown in Formula III, a white foamy solid (2 kg) with a yield of 91%. 19 F NMR (376 MHz, Acetone) δ ppm -68.89 (q, 2F), -83.25 (q, 2F), -86.25 (m, 2F), -133.76 (d, 2F).

[0073]

[0074] In a 10 L glass reactor containing 4.7 mol of sodium sulfite (Formula III), 4 L of solvent THF:H₂O (1:1) was added. The mixture was mechanically stirred (300 rpm) to dissolve the sulfite. Then, 2.35 mol (0.5 eq) of K₂S₂O₈ was added, followed by 2387.6 g (9.4 mol) of I₂ in three batches. Bubbles were observed during the reaction, which were absorbed by sodium hydroxide solution. An exothermic reaction was also observed at 50 °C. After the addition was complete, the reaction was allowed to proceed at room temperature for 2 h. Fluorine spectroscopy analysis confirmed the reaction was complete. Then, 5 L of saturated sodium thiosulfate solution was added until the color of the reaction solution faded. A large amount of water was then added, causing the product (Formula II) to become a separate fluorine phase, concentrated at the bottom of the reaction solution. After separation, a total of 1787 g of a pale yellow oily product was obtained, with an overall yield of 78% and a purity of 95%. 19 F NMR (376 MHz, Chloroform-d) δ ppm -65.01 (s, 4F), -86.38 (s, 4F).

[0075] Process 2

[0076] Example 1:

[0077]

[0078] 78 g (1.2 mol) of a mixture of 300 mL DMF, zinc powder, and copper powder in a 9:1 mass ratio was added to a 2 L stainless steel reactor with a stirrer. The temperature was raised to 80 °C, and 526 g (1 mol) of ICF₂CF₂OCF₂CF₂I was slowly and continuously added to initiate the reaction. The feeding time was 1 h. After the feeding was completed, the reaction was continued for 6 h before being stopped. The product was cooled and discharged to obtain a crude product. The crude product was distilled to obtain 263.9 g of CF₂=CFOCF₂CF₂I product, with a yield of 81% and a purity of 99.6%. 19 F NMR (376 MHz, Chloroform-d) δppm -64.64 (t, J = 6.1 Hz, 2F), -87.84 (dtt, J = 8.5, 5.8, 2.7 Hz, 2F), -113.88 (ddd, J = 84.3, 65.5, 6.7 Hz, 1F), -121.82 (ddt, J = 111.9, 83.9, 5.5Hz, 1F), -135.14 (ddt, J = 112.2, 65.4, 5.3 Hz, 1F).

[0079] Example 2

[0080]

[0081] 94 g (1.4 mol) of a mixture of 300 mL NMP, zinc powder, and palladium in a mass ratio of 97:3 was added to a 2 L stainless steel reactor with a stirrer. The mixture was heated to 80 °C, and 526 g (1 mol) of ICF₂CF₂OCF₂CF₂I was slowly and continuously added to initiate the reaction. The feeding time was 1.5 h. After the feeding was completed, the reaction was continued for another 8 h before being stopped. The mixture was then cooled and discharged to obtain a crude product. The crude product was distilled to obtain 273.4 g of CF₂=CFOCF₂CF₂I product, with a yield of 84% and a purity of 99.3%.

[0082] Example 3

[0083]

[0084] 300 mL of diethylene glycol dimethyl ether (DG) and 526 g of ICF₂CF₂OCF₂CF₂I (1 mol) were added to a 5 L stainless steel reactor with a stirrer. 1.2 L (1.2 mol) of diethylzinc solution (1 M in tolene) was slowly and continuously added. The mixture was heated to 70 °C for 2.5 h of reaction. After the initial feeding, the reaction continued for another 5 h before being stopped. The mixture was then cooled and discharged to obtain a crude product. The crude product was distilled to obtain 300 g of CF₂=CFOCF₂CF₂I product, with a yield of 92% and a purity of 99.4%.

[0085] Example 4

[0086]

[0087] 500 mL of THF and 526 g of ICF2CF2OCF2CF2I (1 mol) were added to a 5 L stainless steel reactor with a stirrer. 1.2 L (1.2 mol) of MeMgBr (1 M in THF) was slowly and continuously added. The temperature was raised to 55 °C for the reaction, with a feeding time of 3 h. After the feeding was completed, the reaction was continued for 4 h before stopping. The product was cooled and discharged to obtain a crude product. The crude product was distilled to obtain 312 g of CF2=CFO CF2CF2I product, with a yield of 96% and a purity of 99.5%.

[0088] Example 5

[0089]

[0090] In a 2 L stainless steel reactor with a stirrer, 300 mL of 2-Me-THF and 526 g of ICF2CF2OCF2CF2I (1 mol) were added. Then, 500 mL (1.5 mol) of PhMgBr (3 M in THF) was slowly and continuously added. The temperature was raised to 55 °C for the reaction, with a feeding time of 3 h. After the feeding was completed, the reaction was continued for 4 h before stopping. The product was cooled and discharged to obtain a crude product. The crude product was distilled to obtain 297 g of CF2=CFOCF2CF2I product, with a yield of 90% and a purity of 97.8%.

[0091] Comparative Example 1

[0092] Experiments were conducted using the same methods as in Example 3 of Step 2 for items 1-4, and the same methods as in Example 1 of Step 2 for items 5-8, using the reagents and conditions listed in the table below.

[0093]

[0095] Comparative Example 2

[0096] According to the method in Example 1 of CN111072526A, compound I was prepared using ICF2CF2OCF2CF2SO2F as the raw material, and experiments were conducted according to the reagents and conditions in the table below.

[0097]

[0099] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A process for the preparation of a compound of formula I, characterized in that, It comprises the following steps: The compound of formula II is subjected to dehalogenation reaction in the presence of a dehalogenating agent in an aprotic solvent to form the compound of formula I; ； The dehalogenating agent is a metal or an organometallic compound; The metal is a mixture of two or three of zinc, copper and palladium; The organometallic compound is an organometallic zinc reagent or an organometallic magnesium reagent.

2. The process for the preparation of a compound of formula I according to claim 1, characterized in that It satisfies one or more of the following conditions: (1) In the dehalogenation reaction, the aprotic solvent is selected from one or more of ketone solvents, ether solvents, nitrile solvents, amide solvents, aromatic hydrocarbon solvents and ester solvents; (2) In the dehalogenation reaction, the metal is in the form of a powder; (3) In the dehalogenation reaction, the metal is a mixture of zinc and copper (7-12): 1 or a mixture of zinc and palladium (8:1-99:1); (4) In the dehalogenation reaction, the organometallic compound is an alkyl metal zinc reagent or a Grignard reagent; (5) In the dehalogenation reaction, the organometallic compound is used in the form of a solution of organometallic and the aprotic solvent; (6) In the dehalogenation reaction, the molar ratio of the compound of formula II to the dehalogenating agent is 1: (0.5-2.5); (7) In the dehalogenation reaction, when the dehalogenating agent is a metal, the molar to volume ratio of the compound of formula II and the solvent is 1 mol / (0.2-1) L; (8) In the dehalogenation reaction, when the dehalogenating agent is an organometallic compound, the molar to volume ratio of the compound of formula II and the solvent is 1 mol / (0.5-3) L; (9) In the dehalogenation reaction, the reaction time is 2-8 hours; (10) In the dehalogenation reaction, the reaction temperature is 20-200℃; (11) The raw materials of the dehalogenation reaction are the aprotic solvent, the compound of formula II and the dehalogenating agent; (12) The dehalogenation reaction comprises the following post-treatment step: after the reaction is completed, distillation is performed to obtain the compound of formula I; (13) The dehalogenation reaction comprises the following steps: the aprotic solvent and the metal are mixed, heated to 50-150℃, the compound of formula II is added to perform dehalogenation reaction, after the reaction is completed, distillation is performed to obtain the compound of formula I; Alternatively, the dehalogenation reaction comprises the following steps: the aprotic solvent, the organometallic compound and the compound of formula II are mixed at 50-150℃ to perform dehalogenation reaction, after the reaction is completed, distillation is performed to obtain the compound of formula I.

3. The process according to claim 2 for the preparation of a compound of formula I, wherein It satisfies one or more of the following conditions: (1) In the dehalogenation reaction, the aprotic solvent is selected from one or more of acetonitrile, diethylene glycol dimethyl ether, glycerol diester, toluene, N, N-dimethylformamide, N-methyl-2-pyrrolidone, tetrahydrofuran, toluene and 2-methyltetrahydrofuran; (2) In the dehalogenation reaction, the metal is a mixture of zinc and copper (9:1) or a mixture of zinc and palladium (97:3); (3) In the dehalogenation reaction, the organometallic compound is diethyl zinc, MeMgBr or PhMgBr; (4) In the dehalogenation reaction, the molar ratio of the compound of formula II to the dehalogenating agent is 1: (0.7-2); (5) in the dehalogenation reaction, when the dehalogenation agent is a metal, the molar-to-volume ratio of the compound of formula II to the solvent is 1 mol / (0.3-0.5) L; (6) in the dehalogenation reaction, when the dehalogenation agent is an organometallic compound, the molar-to-volume ratio of the compound of formula II to the solvent is 1 mol / (0.8-3) L; (7) in the dehalogenation reaction, the reaction time is 4-8 hours; and (8) in the dehalogenation reaction, the reaction temperature is 50-150°C.

4. The process according to claim 3 for the preparation of a compound of formula I, wherein which satisfies one or more of the following conditions: (1) in the dehalogenation reaction, the aprotic solvent is DMF, NMP, "a mixed solvent of diglyme and toluene", THF or "a mixed solvent of 2-Me-THF and THF"; (2) the organometallic compound is used in the form of a toluene solution of diethyl zinc powder, a THF solution of MeMgBr or a THF solution of PhMgBr; (3) in the dehalogenation reaction, the molar ratio of the compound of formula II to the dehalogenation agent is 1:1.1, 1:1.2, 1:1.4 or 1:1.5; (4) in the dehalogenation reaction, when the dehalogenation agent is a metal, the molar-to-volume ratio of the compound of formula II to the solvent is 1 mol / 0.3 L or 1 mol / 0.5 L; (5) in the dehalogenation reaction, when the dehalogenation agent is an organometallic compound, the molar-to-volume ratio of the compound of formula II to the solvent is 1 mol / 1.5 L, 1 mol / 1.7 L, 1 mol / 0.8 L or 1 mol / 1.8 L; (6) in the dehalogenation reaction, the reaction time is 6 hours, 8 hours, 5 hours or 4 hours; and (7) in the dehalogenation reaction, the reaction temperature is 30°C, 55°C, 60°C, 65°C, 70°C or 80°C.

5. The process according to claim 3 for the preparation of the compounds of formula I, wherein which is any one of the following schemes: Scheme 1: in the dehalogenation reaction, the dehalogenation agent is a mixture of zinc powder and copper powder at a ratio of 9:1, and the reaction temperature is 80°C; the aprotic solvent is DMF; Scheme 2: in the dehalogenation reaction, the dehalogenation agent is a mixture of zinc powder and metallic palladium at a ratio of 97:3, and the reaction temperature is 80°C; the aprotic solvent is NMP; Scheme 3: in the dehalogenation reaction, the dehalogenation agent is diethyl zinc, and the reaction temperature is 70°C; the aprotic solvent is a mixed solvent of diglyme and toluene, and diethyl zinc and toluene are used in the form of a toluene solution of diethyl zinc; Scheme 4: in the dehalogenation reaction, the dehalogenation agent is MeMgBr, and the reaction temperature is 55°C; the aprotic solvent is THF, and MeMgBr is used in the form of a THF solution; Scheme 5: in the dehalogenation reaction, the dehalogenation agent is PhMgBr, and the reaction temperature is 55°C; the aprotic solvent is a mixed solvent of 2-Me-THF and THF, and PhMgBr and THF are used in the form of a THF solution of PhMgBr.

6. The process according to claim 1 for the preparation of the compounds of formula I, wherein which further comprises the following step: in a solvent, the compound of formula III is subjected to an iodination reaction with I2 to generate the compound of formula II; 。 7. A process for the preparation of a compound of formula I according to claim 6, characterized in that which satisfies one or more of the following conditions: (1) In the iodination reaction, the solvent is selected from one or more of nitrile solvents, ether solvents, amide solvents, sulfoxide solvents and water; further preferably, it is a mixed solvent of one of acetonitrile, tetrahydrofuran, DMF and DMSO and H2O; for example, a mixed solvent of THF:H2O=1:1; (2) In the iodination reaction, the molar volume ratio of the compound of formula III to the solvent is (1-2) mol / L; for example, 1.2 mol / L; (3) In the iodination reaction, the molar ratio of the compound of formula III to I2 is 1:(1-2.5), for example, 1:2; (4) In the iodination reaction, K2S2O8 is also added, and the molar ratio of the compound of formula III to K2S2O8 can be 1:(0.4-1); for example, 1:0.5; (5) After the iodination reaction, a reducing agent is added to remove excess I2, preferably, the reducing agent is sodium thiosulfate; (6) The molar ratio of the reducing agent to the compound of formula III is (1-3):1; (7) The reaction temperature of the iodination reaction is 20-80°C, preferably 30-80°C; for example, 50°C; (8) The iodination reaction uses a water bath to control the reaction temperature; (9) The time of the iodination reaction is 1-3 hours; for example, 2 hours; (10) The iodination reaction further includes the following post-processing steps: after the reaction is completed, the reducing agent is added, quenched, water is added to precipitate to obtain the compound of formula II; (11) In the iodination reaction, a tail gas absorption or treatment device is used, for example, a sodium hydroxide solution is used to absorb the tail gas; and (12) The raw materials of the iodination reaction are the compound of formula III, the solvent, I2 and K2S2O8.

8. The process according to claim 7 for the preparation of a compound of formula I, wherein The iodination reaction further includes the following specific steps: the compound of formula III and the solvent are stirred to dissolve, K2S2O8 is added; I2 is added in batches, the gas is absorbed with a sodium hydroxide solution, the reaction temperature is controlled not to exceed 80°C, and the compound of formula II is obtained.

9. The process according to claim 6 for the preparation of the compounds of formula I, wherein It further includes the following steps: in the presence of a solvent, a compound of formula IV and a reducing agent undergo a reduction reaction to generate a compound of formula III; 。 10. A process for the preparation of a compound of formula I according to claim 9, characterized in that It meets one or more of the following conditions: (1) In the reduction reaction, the solvent is selected from one or more of nitrile solvents, ether solvents, amide solvents and water, further preferably, it is a mixed solvent of one of acetonitrile, tetrahydrofuran, dioxane, DMF and water, the ratio is 10:1-1:10, further preferably, 3:1-1:3; for example, a mixed solvent of dioxane and water in a volume ratio of 3:2; (2) In the reduction reaction, the molar and volume ratio of the compound of formula IV to the solvent is (0.5-1.5) mol / L; for example, 0.7 mol / L; (3) In the reduction reaction, the reducing agent is an alkali metal reducing agent; preferably, it is Na2SO3, K2SO3, NaBH4 and KBH4, further preferably, it is Na2SO3 or NaBH4; for example, Na2SO3; (4) In the reduction reaction, the molar ratio of the alkali metal reducing agent to the compound of formula IV is (2-8:1); preferably (2-5):1; for example 2.5:1; (5) In the reduction reaction, the temperature of the reduction reaction is -30°C to 160°C; preferably 0-80°C; for example 15-30°C; (6) In the reduction reaction, the reduction reaction is carried out under mechanical stirring, preferably under stirring at 50-600 rpm; for example under stirring at 300 rpm; (7) The reaction time of the reduction reaction is 8-24 hours, for example 10 hours; (8) After the completion of the reduction reaction, extraction is carried out using MeCN or ethyl acetate, and drying is performed; (9) In the reduction reaction, an absorption or collection device for the connecting gas is used; for example, the tail gas is absorbed by sodium hydroxide solution; and (10) In the reduction reaction, the raw materials of the reduction reaction are the compound of formula IV, the solvent and the reducing agent. Preferably, the reduction reaction further comprises the following specific steps: the compound of formula IV and the reducing agent are reacted at room temperature in the presence of the solvent, and the tail gas is absorbed by sodium hydroxide solution.

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