Method for preparing triphenylphosphine by repeated heat treatment of chlorodiphenylphosphine and removal of dichlorophenylphosphine intermediate product

Abstract

The present invention relates to a method for preparing triphenylphosphine, comprising: 1) performing first heat treatment on a chlorodiphenylphosphine raw material at a temperature of 280-480ºC to obtain a first heat treatment mixture comprising dichlorophenylphosphine, chlorodiphenylphosphine and triphenylphosphine, wherein the content of dichlorophenylphosphine in the chlorodiphenylphosphine raw material does not exceed 35% by weight, based on the total weight of the chlorodiphenylphosphine raw material; 2) removing dichlorophenylphosphine from the first heat treatment mixture to obtain a dichlorophenylphosphine-lean mixture, wherein the content of dichlorophenylphosphine in the dichlorophenylphosphine-lean mixture does not exceed 8% by weight, based on the total weight of the dichlorophenylphosphine-lean mixture; and 3) at a temperature of 280-480ºC, performing second heat treatment on the mixture obtained in step 2) to obtain a second heat treatment mixture comprising dichlorophenylphosphine, chlorodiphenylphosphine and triphenylphosphine.

Description

Method for preparing triphenylphosphine by heat treating diphenylphosphine chloride multiple times and removing phenyldichlorophosphine intermediate product TECHNICAL FIELD

[0001] The present application relates to a method for preparing triphenylphosphine, wherein diphenylphosphine chloride is heat treated multiple times and phenyldichlorophosphine intermediate product is removed to prepare triphenylphosphine. TECHNICAL BACKGROUND

[0002] Triphenylphosphine has a wide range of uses in the chemical industry, and is an important fine chemical synthesis catalyst; a catalyst for petroleum processing; a new type of biocatalysis technology and catalyst; a new, efficient catalyst for environmental protection; a new catalyst for organic synthesis; a new, efficient catalyst for polyolefins; a new material for catalyst carriers and various new types of catalytic materials; it can also be used as a functional fine chemical; a new type of papermaking special chemical; a new oil field chemical suitable for protective exploitation and enhanced oil recovery; a new surfactant; a high-performance, water-based functional coating and additive; a new textile dyeing and finishing aid; a high-performance environmentally friendly adhesive; a new safe and environmentally friendly pigment and dye; and a high-performance environmentally friendly leather chemical. Triphenylphosphine can also be used as an intermediate for the synthesis of various important chemical products, such as β-carotene, cefprozil, and cefdinir.

[0003] The main synthesis methods for industrial production of triphenylphosphine include (1) the Grignard method (sodium method) using high-speed stirring to make metallic sodium and reacting it with chlorobenzene and phosphorus trichloride to produce triphenylphosphine. This method is technically demanding, especially the sodium sand making equipment, which needs to solve the problem of sodium dispersion and avoid the presence of water during operation, as highly active sodium can react violently with water and cause explosions. Therefore, there are significant safety hazards and high risks in the production process. (2) The Grignard reagent method (Grignard method), which uses phenylmagnesium halide and phosphorus trichloride as raw materials. By heating the reactants, triphenylphosphine can be generated, accompanied by a small amount of byproduct triphenylphosphine oxide. This method has the disadvantages of high cost, low yield, and poor economic benefits. (3) The Friedel-Crafts method, which produces triphenylphosphine sulfide by reacting phosphine sulfide chloride with benzene in the presence of excess aluminum trichloride, and then uses iron filings or sodium naphthalene for desulfurization (reduction) to obtain triphenylphosphine. However, the triphenylphosphine produced by iron powder reduction has poor quality and yellowish color, and the use of aluminum trichloride and iron powder as catalysts generates a large amount of solid waste, which is difficult to dispose and pollutes the environment. (4) The triphenylphosphine oxide reduction method, but the reducing agent used in this method is expensive.

[0004] In summary, there is an urgent need to develop a green and environmentally friendly, low-cost, high-yield, and simple method for synthesizing triphenylphosphine. SUMMARY

[0005] The present application aims to provide a method for preparing triphenylphosphine, which is green, safe, low in cost, high in yield, simple in operation, and does not need to use a solvent or a cosolvent and raw materials are easy to obtain.

[0006] The technical solution for achieving the above-mentioned purpose of the present application can be summarized as follows:

[0007] 1. A method for preparing triphenylphosphine, comprising:

[0008] 1) subjecting a diphenylphosphine chloride raw material to a first heat treatment at a temperature of 280-480°C to obtain a first heat treatment mixture comprising phenyldichlorophosphine, diphenylphosphine chloride and triphenylphosphine, wherein the content of phenyldichlorophosphine in the diphenylphosphine chloride raw material is not more than 35% by weight, based on the total weight of the diphenylphosphine chloride raw material;

[0009] 2) removing phenyldichlorophosphine from the first heat treatment mixture to obtain a mixture poor in phenyldichlorophosphine, wherein the content of phenyldichlorophosphine in the mixture poor in phenyldichlorophosphine is not more than 8% by weight, based on the total weight of the mixture poor in phenyldichlorophosphine; and

[0010] 3) subjecting the mixture obtained from step 2) to a second heat treatment at a temperature of 280-480°C to obtain a second heat treatment mixture comprising phenyldichlorophosphine, diphenylphosphine chloride and triphenylphosphine.

[0011] 2. The method according to embodiment 1, wherein the content of phenyldichlorophosphine in the diphenylphosphine chloride raw material is not more than 30% by weight, preferably not more than 28% by weight, more preferably not more than 22% by weight, still more preferably not more than 15% by weight, especially not more than 8% by weight, in particular not more than 3% by weight, most preferably not more than 1% by weight, for example not more than 0.5% by weight, based on the total weight of the diphenylphosphine chloride raw material.

[0012] 3. The method according to embodiment 1 or 2, wherein the content of phenyldichlorophosphine in the mixture poor in phenyldichlorophosphine in step 2) is not more than 5% by weight, preferably not more than 4% by weight, more preferably not more than 2% by weight, still more preferably not more than 1% by weight, based on the total weight of the mixture poor in phenyldichlorophosphine.

[0013] 4. The method according to any one of embodiments 1-3, wherein the content of diphenylphosphine chloride in the diphenylphosphine chloride raw material is at least 65% by weight, preferably at least 70% by weight, more preferably at least 80% by weight, even more preferably at least 88% by weight, still more preferably at least 95% by weight, for example at least 98% by weight, based on the total weight of the diphenylphosphine chloride raw material.

[0014] 5. The process according to any one of embodiments 1 to 4, wherein the content of diphenylchlorophosphine in the phenyldichlorophosphine-lean mixture in step 2) is at least 45 wt.-%, preferably 50 to 85 wt.-%, more preferably 55 to 80 wt.-%, even more preferably 55 to 70 wt.-%, based on the total weight of the diphenylchlorophosphine feedstock.

[0015] 6. The process according to any one of embodiments 1 to 5, wherein the content of triphenylphosphine in the phenyldichlorophosphine-lean mixture in step 2) is 12 to 40 wt.-%, preferably 15 to 38 wt.-%, more preferably 20 to 35 wt.-%, based on the total weight of the phenyldichlorophosphine-lean mixture.

[0016] 7. The process according to any one of embodiments 1 to 6, wherein the first and second heat treatment temperatures are 300 to 450 °C, preferably 320 to 400 °C, more preferably 330 to 390 °C.

[0017] 8. The process according to embodiment 7, wherein the first and second heat treatment temperatures are especially 340 to 370 °C, in particular 345 to 360 °C, most preferably 345 to 355 °C, for example about 350 °C.

[0018] 9. The process according to any one of embodiments 1 to 8, wherein the maximum pressure (gauge pressure) during the first and second heat treatment is at least 0.05 MPa, preferably at least 0.08 MPa, for example 0.05 to 6 MPa, more preferably 0.08 to 5 MPa, still more preferably 0.1 to 2 MPa or 0.1 to 1 MPa.

[0019] 10. The process according to any one of embodiments 1 to 9, wherein the first and second heat treatment is carried out under autogenous pressure.

[0020] 11. The process according to any one of embodiments 1 to 10, wherein the time of the first and second heat treatment is at least 0.4 hours, preferably 0.4 to 12 hours, more preferably 0.6 to 8 hours, especially 0.8 to 8 hours, most preferably 1.5 to 2.5 hours, for example about 2 hours.

[0021] 12. The process according to any one of embodiments 1 to 11, wherein the phosphorus trichloride content in the diphenylchlorophosphine feedstock is not more than 5 wt.-%, preferably not more than 2 wt.-%, more preferably not more than 1 wt.-%, for example not more than 0.5 wt.-% or not more than 0.1 wt.-%, based on the total weight of the diphenylchlorophosphine feedstock.

[0022] 13. The process according to any one of embodiments 1 to 12, wherein the first and second heat treatment is carried out under stirring.

[0023] 14. The process according to any one of embodiments 1 to 13, wherein step 2) further comprises the additional addition of diphenylchlorophosphine to the phenyldichlorophosphine depleted mixture, preferably the amount of diphenylchlorophosphine added is at least 5 wt.%, preferably at least 10 wt.% or at least 20 wt.%, such as 10 to 80 wt.% based on the total weight of the phenyldichlorophosphine depleted mixture, in which case the mixture subjected to the second heat treatment in step 3) is the mixture to which diphenylchlorophosphine has been additionally added.

[0024] 15. The process according to any one of embodiments 1 to 14, wherein the removal of phenyldichlorophosphine in step 2) is carried out by flashing or distillation, preferably distillation, in particular rectification.

[0025] 16. The process according to any one of embodiments 1 to 15, further comprising repeating steps 2) and 3) one or more times.

[0026] 17. The process according to any one of embodiments 1 to 16, wherein the diphenylchlorophosphine starting material in step 1) is derived from a reaction mixture obtained by reacting chlorobenzene and yellow phosphorus, wherein chlorobenzene, phosphorus trichloride and most of the phenyldichlorophosphine are removed from the reaction mixture to obtain the diphenylchlorophosphine starting material.

[0027] 18. The process according to any one of embodiments 1 to 17, wherein the first and second heat treatment is carried out at a temperature of 300 to 450 °C, the maximum pressure (gauge pressure) during the first and second heat treatment is at least 0.05 MPa, the time of the first and second heat treatment is at least 0.4 hours,

[0028] the content of diphenylchlorophosphine in the diphenylchlorophosphine starting material is at least 65 wt.%, the content of phenyldichlorophosphine is not more than 30 wt.%, the content of phosphorus trichloride is not more than 5 wt.%, based on the total weight of the diphenylchlorophosphine starting material, and

[0029] the content of diphenylchlorophosphine in the phenyldichlorophosphine depleted mixture in step 2) is at least 45 wt.%, the content of phenyldichlorophosphine is not more than 5 wt.%, the content of triphenylphosphine is 12 to 40 wt.%, based on the total weight of the phenyldichlorophosphine depleted mixture.

[0030] 19. The process according to any one of embodiments 1 to 18, wherein the first and second heat treatment is carried out at a temperature of 345 to 355 °C, the maximum pressure (gauge pressure) during the first and second heat treatment is 0.15 to 1 MPa (preferably the first and second heat treatment is carried out at autogenous pressure), the time of the first and second heat treatment is 1.5 to 2.5 hours,

[0031] the content of diphenylchlorophosphine in the diphenylchlorophosphine raw material is at least 98% by weight, the content of phenyldichlorophosphine is not more than 1% by weight, and the content of phosphorus trichloride is not more than 0.1% by weight (preferably, the diphenylchlorophosphine raw material is free of phosphorus trichloride), based on the total weight of the diphenylchlorophosphine raw material,

[0032] the content of diphenylchlorophosphine in the phenyldichlorophosphine-lean mixture in step 2) is at least 55-80% by weight, the content of phenyldichlorophosphine is not more than 2% by weight, and the content of triphenylphosphine is 20-35% by weight, based on the total weight of the phenyldichlorophosphine-lean mixture, and

[0033] step 2) further comprises additional addition of diphenylchlorophosphine to the phenyldichlorophosphine-lean mixture, and the amount of added diphenylchlorophosphine is at least 20% by weight, based on the total weight of the phenyldichlorophosphine-lean mixture.

[0034] The beneficial effects of the present application are as follows:

[0035] (1) The method of the present application is green, safe, low in cost, high in quality, and simple to operate.

[0036] (2) The method of the present application uses diphenylchlorophosphine as a raw material, and does not need to add other cosolvents, and the raw material is simple and easy to obtain.

[0037] (3) Diphenylchlorophosphine is a liquid, easy to operate, and does not need to use a solvent, avoiding solvent pollution.

[0038] (4) The present application can obtain triphenylphosphine at a higher yield and a higher triphenylphosphine / raw material weight ratio. The price of triphenylphosphine is much higher than that of diphenylchlorophosphine, and thus the method of the present application has a very high industrial value. DETAILED DESCRIPTION

[0039] The present application relates to a method for preparing triphenylphosphine, which comprises:

[0040] 1) subjecting a diphenylchlorophosphine raw material to a first heat treatment at a temperature of 280-480°C to obtain a first heat treatment mixture comprising phenyldichlorophosphine, diphenylchlorophosphine, and triphenylphosphine, wherein the content of phenyldichlorophosphine in the diphenylchlorophosphine raw material is not more than 35% by weight, based on the total weight of the diphenylchlorophosphine raw material;

[0041] 2) removing phenyldichlorophosphine from the first heat treatment mixture to obtain a phenyldichlorophosphine-lean mixture, wherein the content of phenyldichlorophosphine in the phenyldichlorophosphine-lean mixture is not more than 8% by weight, based on the total weight of the phenyldichlorophosphine-lean mixture; and

[0042] 3) subjecting the mixture obtained from step 2) to a second thermal treatment at a temperature of 280-480 °C to obtain a second thermal treatment mixture comprising phenyldichlorophosphine, diphenylchlorophosphine and triphenylphosphine.

[0043] In one embodiment, the content of phenyldichlorophosphine in the diphenylchlorophosphine starting material is not more than 30 wt.-% (e.g. 28 wt.-%, 26 wt.-%, 25 wt.-%, 22 wt.-%, 20 wt.-%, 18 wt.-%, 15 wt.-%, 12 wt.-%, 10 wt.-%, 8 wt.-%, 5 wt.-%, 3 wt.-%, 2 wt.-%, 1 wt.-%, 0.5 wt.-% or 0.1 wt.-%), preferably not more than 28 wt.-%, more preferably not more than 22 wt.-%, still more preferably not more than 15 wt.-%, especially not more than 8 wt.-%, in particular not more than 3 wt.-%, most preferably not more than 1 wt.-%, e.g. not more than 0.5 wt.-%, based on the total weight of the diphenylchlorophosphine starting material.

[0044] In one embodiment, the content of the diphenylchlorophosphine in the diphenylchlorophosphine starting material is at least 65 wt.-% (e.g. 68 wt.-%, 70 wt.-%, 75 wt.-%, 80 wt.-%, 85 wt.-%, 88 wt.-%, 90 wt.-%, 91 wt.-%, 92 wt.-%, 93 wt.-%, 95 wt.-%, 98 wt.-%, 99 wt.-%, 99.5 wt.-% or 99.9 wt.-%), preferably at least 70 wt.-%, more preferably at least 80 wt.-%, even more preferably at least 88 wt.-%, still more preferably at least 95 wt.-%, e.g. at least 98 wt.-%, based on the total weight of the diphenylchlorophosphine starting material. The content of the diphenylchlorophosphine in the diphenylchlorophosphine starting material is 65-99.5 wt.-%, 70-99.5 wt.-%, 80-99.5 wt.-%, 80-98 wt.-%, 85-95 wt.-% or 90-95 wt.-%.

[0045] According to the present application, the first and second thermal treatment temperatures are 280-480 °C, e.g. 280 °C, 290 °C, 300 °C, 310 °C, 320 °C, 330 °C, 340 °C, 345 °C, 350 °C, 355 °C, 360 °C, 370 °C, 380 °C, 390 °C, 400 °C, 410 °C, 420 °C, 430 °C, 440 °C or 450 °C. In one embodiment, the thermal treatment temperature is 290-450 °C, 300-450 °C, preferably 320-400 °C or 330-390 °C, more preferably 330-380 °C. In one preferred embodiment, the thermal treatment temperature is especially 340-370 °C, in particular 345-360 °C, most preferably 345-355 °C, e.g. about 350 °C. The first and second thermal treatment temperatures can be the same or different.

[0046] In one embodiment, the maximum pressure (gauge pressure) during the first and second heat treatment processes is at least 0.05 MPa (e.g. 0.08 MPa, 0.1 MPa, 0.15 MPa, 0.2 MPa, 0.25 MPa, 0.3 MPa, 0.5 MPa, 0.8 MPa, 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa), preferably at least 0.08 MPa, e.g. 0.05-6 MPa, more preferably 0.08-5 MPa, still more preferably 0.1-4 MPa, 0.1-3 MPa, 0.1-2 MPa, 0.1-1 MPa, 0.1-0.8 MPa, 0.15-0.8 MPa, 0.2-0.6 MPa. The maximum pressure during the first and second heat treatment processes can be the same or different.

[0047] The reactor can be evacuated, e.g. to -50 Kpa or less (i.e. 50 Kpa or less below atmospheric pressure), preferably -80 Kpa or less (i.e. 80 Kpa or less below atmospheric pressure), prior to charging, so that the maximum pressure during the heat treatment process can be reduced. Of course, the reactor can also be purged with an inert gas, e.g. nitrogen, prior to the heat treatment, so that the maximum pressure during the heat treatment process can be increased.

[0048] In one preferred embodiment, the first and second heat treatments are carried out at autogenous pressure.

[0049] In one embodiment, the first and second heat treatments are carried out for a time of at least 0.4 hours (e.g. 0.5 hours, 0.8 hours, 1 hour, 1.2 hours, 1.5 hours, 1.8 hours, 2 hours, 2.2 hours, 2.5 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours or 12 hours), preferably 0.4-12 hours, more preferably 0.6-8 hours, especially 0.8-8 hours, 1-7 hours, 1-5 hours, 1.5-4 hours, most preferably 1.5-2.5 hours, e.g. about 2 hours. The time of the first and second heat treatments can be the same or different.

[0050] In one embodiment, the content of phosphorus trichloride in the diphenylchlorophosphine starting material is no more than 5 wt% (e.g. 4 wt%, 3 wt%, 2 wt%, 1 wt%, 0.5 wt%, 0.2 wt%, 0.1 wt% or 0.05 wt%), preferably no more than 2 wt%, more preferably no more than 1 wt%, e.g. no more than 0.5 wt% or no more than 0.1 wt%, based on the total weight of the diphenylchlorophosphine starting material. In one embodiment, the diphenylchlorophosphine starting material is free of phosphorus trichloride.

[0051] In one embodiment, the triphenylphosphine content of the diphenylchlorophosphine starting material is not more than 6 wt.-% (e.g. 5 wt.-%, 4 wt.-%, 3 wt.-%, 2 wt.-%, 1 wt.-%, 0.5 wt.-%, 0.2 wt.-% or 0.1 wt.-%), preferably not more than 5 wt.-%, more preferably not more than 1 wt.-%, e.g. not more than 0.5 wt.-% or not more than 0.1 wt.-%, based on the total weight of the diphenylchlorophosphine starting material.

[0052] In one embodiment, the diphenylchlorophosphine starting material in step 1) can be derived from a reaction mixture obtained by reacting chlorobenzene and yellow phosphorus. The reaction mixture typically comprises light components, such as chlorobenzene and phosphorus trichloride, and phenyldichlorophosphine, diphenylchlorophosphine and triphenylphosphine. The reaction is carried out at elevated temperature (e.g. 300-500°C or 300-400°C) and elevated pressure (e.g. 0.01-8.0 MPa or 0.01-6.0 MPa, preferably autogenous pressure). The diphenylchlorophosphine starting material of the present application can be prepared by removing chlorobenzene, phosphorus trichloride and most of the phenyldichlorophosphine from the reaction mixture, or can be prepared by additionally adding diphenylchlorophosphine to a product mixture enriched in diphenylchlorophosphine obtained after removing chlorobenzene, phosphorus trichloride and most of the phenyldichlorophosphine from the reaction mixture.

[0053] In this technical solution, purification costs are saved since the diphenylchlorophosphine does not have to be purified specifically.

[0054] According to the present application, the reaction mixture can comprise phenyldichlorophosphine, diphenylchlorophosphine, triphenylphosphine, chlorobenzene and phosphorus trichloride. In the reaction mixture, the amount of triphenylphosphine is typically not more than 6 wt.-%, e.g. 1-6 wt.-% or 2-6 wt.-%, based on the total weight of phenyldichlorophosphine, diphenylchlorophosphine and triphenylphosphine.

[0055] In step 2) of the present application, phenyldichlorophosphine is removed from the first heat treatment mixture to obtain a mixture depleted in phenyldichlorophosphine.

[0056] The removal of phenyldichlorophosphine in step 2) is carried out by flashing or distillation, preferably distillation, in particular rectification, e.g. atmospheric rectification or vacuum rectification.

[0057] In one embodiment, the content of phenyldichlorophosphine in the phenyldichlorophosphine-lean mixture in step 2) is not more than 5 wt.%, preferably not more than 4 wt.% or 3 wt.%, more preferably not more than 2 wt.%, still more preferably not more than 1 wt.%, based on the total weight of the phenyldichlorophosphine-lean mixture. In one embodiment, the content of phenyldichlorophosphine in the phenyldichlorophosphine-lean mixture in step 2) is 0.5-5 wt.%, preferably 1-4 wt.%, more preferably 2-3 wt.%, based on the total weight of the phenyldichlorophosphine-lean mixture.

[0058] In one embodiment, the content of diphenylchlorophosphine in the phenyldichlorophosphine-lean mixture in step 2) is at least 45 wt.% (e.g. 50 wt.%, 55 wt.%, 60 wt.%, 65 wt.%, 70 wt.%, 75 wt.% or 80 wt.%), preferably 50-85 wt.%, more preferably 55-80 wt.%, even more preferably 55-70 wt.%, based on the total weight of the diphenylchlorophosphine feedstock.

[0059] In one embodiment, the content of triphenylphosphine in the phenyldichlorophosphine-lean mixture in step 2) is 12-40 wt.% (e.g. 15 wt.%, 18 wt.%, 20 wt.%, 25 wt.%, 30 wt.% or 35 wt.%), preferably 15-38 wt.%, more preferably 20-35 wt.%, based on the total weight of the phenyldichlorophosphine-lean mixture.

[0060] In one embodiment, the content of phosphorus trichloride in the phenyldichlorophosphine-lean mixture in step 2) is not more than 1 wt.%, preferably not more than 0.5 wt.%, still more preferably not more than 0.1 wt.%, based on the total weight of the phenyldichlorophosphine-lean mixture. In one embodiment, the phenyldichlorophosphine-lean mixture is free of phosphorus trichloride.

[0061] In one embodiment, the first and second heat treatment is carried out under stirring. The stirring rate can for example be 50-700 r / min, e.g. 100-600 r / min, or 200-500 r / min or 300-450 r / min.

[0062] The diphenylchlorophosphine feedstock can be preheated before stirring, e.g. to 40-90 °C, preferably to 50-80 °C, e.g. 60-80 °C.

[0063] In one embodiment, step 2) further comprises additional addition of diphenylphosphine chloride to the mixture depleted in phenyldichlorophosphine, preferably the amount of diphenylphosphine chloride added is at least 5 wt% (e.g. 8 wt%, 10 wt%, 12 wt%, 15 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt% or 80 wt% or 100 wt%) based on the total weight of the mixture depleted in phenyldichlorophosphine, preferably at least 10 wt% or at least 20 wt%, in which case the mixture subjected to the second heat treatment in step 3) is the mixture to which diphenylphosphine chloride is additionally added. In one embodiment, the amount of diphenylphosphine chloride added is 5-100 wt%, preferably 10-80 wt%, or 20-50 wt% based on the total weight of the mixture depleted in phenyldichlorophosphine. The content of triphenylphosphine in the product can be further increased by adding diphenylphosphine chloride to the mixture depleted in phenyldichlorophosphine.

[0064] In one embodiment, the process further comprises repeating steps 2) and 3) one or more times, e.g. one or two times, after step 3). For example, if repeated once, the repeated step 2) can be named step 2'), and the repeated step 3) can be named step 3'), in which case the process of the application comprises steps 1), 2), 3), 2') and 3'). The conditions in step 2') are as described for step 2), and the conditions in step 3') are as described for step 3).

[0065] In one embodiment, the content of triphenylphosphine in the final product mixture obtained by the process of the application is at least 28 wt% (e.g. 30 wt%, 32 wt%, 35 wt%, 40 wt%, 50 wt%, 60 wt% or 70 wt%), preferably at least 30 wt% or at least 35 wt%, even at least 40 wt%, e.g. 28-70 wt%, 30-70 wt%, 35-60 wt%, 35-50 wt%, 40-50 wt%, based on the total weight of the final product mixture.

[0066] In one embodiment, the weight ratio of the amount of triphenylphosphine in the final product mixture to the total amount of diphenylphosphine chloride in all diphenylphosphine chloride starting materials can be at least 0.2 (e.g. 0.22, 0.25, 0.3, 0.35, 0.38, 0.4, 0.45, 0.5, 0.6 or 0.7), preferably at least 0.25 or at least 0.3, even at least 0.38, e.g. 0.2-0.7 or 0.2-0.6, preferably 0.25-0.7 or 0.25-0.6 or 0.25-0.5, more preferably 0.3-0.7 or 0.3-0.6 or 0.3-0.5, even 0.35-0.7 or 0.35-0.6 or 0.35-0.5 or 0.35-0.45.

[0067] The skilled person will understand that the final product mixture is the second heat treated mixture, or in case the process of the application further comprises repeating steps 2) and 3) one or more times, the final product mixture is the final product mixture obtained after repeating one or more times.

[0068] In one embodiment, the first and second heat treatments are carried out at a temperature of 300-450 °C, the maximum pressure (gauge pressure) during the first and second heat treatments is at least 0.05 MPa, and the first and second heat treatments are carried out for a time of at least 0.4 hours,

[0069] The content of diphenylchlorophosphine in the diphenylchlorophosphine starting material is at least 65 wt%, the content of phenyldichlorophosphine is not more than 30 wt%, the content of phosphorus trichloride is not more than 5 wt%, based on the total weight of the diphenylchlorophosphine starting material, and

[0070] The content of diphenylchlorophosphine in the phenyldichlorophosphine- depleted mixture in step 2) is at least 45 wt%, the content of phenyldichlorophosphine is not more than 5 wt%, the content of triphenylphosphine is 12-40 wt%, based on the total weight of the phenyldichlorophosphine-depleted mixture.

[0071] In one embodiment, the first and second heat treatments are carried out at a temperature of 320-400 °C, the maximum pressure (gauge pressure) during the first and second heat treatments is at least 0.05-6 MPa, and the first and second heat treatments are carried out for a time of 0.4-12 hours;

[0072] The content of diphenylchlorophosphine in the diphenylchlorophosphine starting material is at least 70 wt%, the content of phenyldichlorophosphine is not more than 28 wt%, the content of phosphorus trichloride is not more than 2 wt%, based on the total weight of the diphenylchlorophosphine starting material, and

[0073] The content of diphenylchlorophosphine in the phenyldichlorophosphine- depleted mixture in step 2) is 50-85 wt%, the content of phenyldichlorophosphine is not more than 4 wt%, the content of triphenylphosphine is 15-38 wt%, based on the total weight of the phenyldichlorophosphine-depleted mixture.

[0074] In one embodiment, the first and second heat treatments are carried out at a temperature of 330-390 °C, the maximum pressure (gauge pressure) during the first and second heat treatments is at least 0.08-5 MPa, and the first and second heat treatments are carried out for a time of 0.8-8 hours;

[0075] the content of diphenylchlorophosphine in the diphenylchlorophosphine starting material is at least 95 wt%, the content of phenyldichlorophosphine is not more than 1 wt%, the content of phosphorus trichloride is not more than 0.5 wt%, based on the total weight of the diphenylchlorophosphine starting material; and

[0076] the content of diphenylchlorophosphine in the phenyldichlorophosphine-lean mixture in step 2) is 55-80 wt%, the content of phenyldichlorophosphine is not more than 3 wt%, the content of triphenylphosphine is 20-35 wt%, based on the total weight of the phenyldichlorophosphine-lean mixture.

[0077] In one embodiment, the first and second heat treatments are carried out at a temperature of 340-370°C, the maximum pressure (gauge pressure) during the first and second heat treatments is at least 0.1-2 MPa, and the time of the first and second heat treatments is 0.8-8 hours.

[0078] the content of diphenylchlorophosphine in the diphenylchlorophosphine starting material is at least 95 wt%, the content of phenyldichlorophosphine is not more than 1 wt%, the content of phosphorus trichloride is not more than 0.5 wt%, based on the total weight of the diphenylchlorophosphine starting material; and

[0079] the content of diphenylchlorophosphine in the phenyldichlorophosphine-lean mixture in step 2) is 55-70 wt%, the content of phenyldichlorophosphine is not more than 2 wt%, the content of triphenylphosphine is 20-35 wt%, based on the total weight of the phenyldichlorophosphine-lean mixture.

[0080] In one embodiment, the first and second heat treatments are carried out at a temperature of 340-370°C, the maximum pressure (gauge pressure) during the first and second heat treatments is at least 0.1-2 MPa, and the time of the first and second heat treatments is 0.8-8 hours.

[0081] the content of diphenylchlorophosphine in the diphenylchlorophosphine starting material is at least 95 wt%, the content of phenyldichlorophosphine is not more than 1 wt%, the content of phosphorus trichloride is not more than 0.5 wt%, based on the total weight of the diphenylchlorophosphine starting material;

[0082] the content of diphenylchlorophosphine in the phenyldichlorophosphine-lean mixture in step 2) is 55-70 wt%, the content of phenyldichlorophosphine is not more than 2 wt%, the content of triphenylphosphine is 20-35 wt%, based on the total weight of the phenyldichlorophosphine-lean mixture; and

[0083] Step 2) further comprises additional addition of diphenylchlorophosphine to the phenyldichlorophosphine-lean mixture.

[0084] In one embodiment, the first and second heat treatments are carried out at a temperature of 345-360°C, the maximum pressure (gauge pressure) during the first and second heat treatments is at least 0.1-2 MPa (preferably the first and second heat treatments are carried out at autogenous pressure), and the first and second heat treatments are carried out for a time of 0.8-6 hours;

[0085] The content of diphenylchlorophosphine in the diphenylchlorophosphine starting material is at least 95 wt%, the content of phenyldichlorophosphine is not more than 1 wt%, and the content of phosphorus trichloride is not more than 0.1 wt%, based on the total weight of the diphenylchlorophosphine starting material;

[0086] The content of diphenylchlorophosphine in the phenyldichlorophosphine- depleted mixture in step 2) is 55-70 wt%, the content of phenyldichlorophosphine is not more than 2 wt%, and the content of triphenylphosphine is 20-35 wt%, based on the total weight of the phenyldichlorophosphine-depleted mixture; and

[0087] Step 2) further comprises the additional addition of diphenylchlorophosphine to the phenyldichlorophosphine-depleted mixture.

[0088] In one embodiment, the first and second heat treatments are carried out at a temperature of 345-360°C, the maximum pressure (gauge pressure) during the first and second heat treatments is at least 0.15-1 MPa (preferably the first and second heat treatments are carried out at autogenous pressure), and the first and second heat treatments are carried out for a time of 1-4 hours;

[0089] The content of diphenylchlorophosphine in the diphenylchlorophosphine starting material is at least 95 wt%, the content of phenyldichlorophosphine is not more than 1 wt%, and the content of phosphorus trichloride is not more than 0.1 wt%, based on the total weight of the diphenylchlorophosphine starting material;

[0090] The content of diphenylchlorophosphine in the phenyldichlorophosphine- depleted mixture in step 2) is 55-70 wt%, the content of phenyldichlorophosphine is not more than 2 wt%, and the content of triphenylphosphine is 20-35 wt%, based on the total weight of the phenyldichlorophosphine-depleted mixture; and

[0091] Step 2) further comprises the additional addition of diphenylchlorophosphine to the phenyldichlorophosphine-depleted mixture, and the amount of diphenylchlorophosphine added is at least 10 wt% based on the total weight of the phenyldichlorophosphine-depleted mixture.

[0092] In one embodiment, the first and second heat treatments are carried out at a temperature of 345-355°C, the maximum pressure (gauge pressure) during the first and second heat treatments is 0.15-1 MPa (preferably the first and second heat treatments are carried out at autogenous pressure), the time of the first and second heat treatments is 1.5-2.5 hours,

[0093] The content of diphenylchlorophosphine in the diphenylchlorophosphine starting material is at least 98 wt.%, the content of phenyldichlorophosphine is not more than 1 wt.%, the content of phosphorus trichloride is not more than 0.1 wt.% (preferably the diphenylchlorophosphine starting material is free of phosphorus trichloride), based on the total weight of the diphenylchlorophosphine starting material,

[0094] The content of diphenylchlorophosphine in the phenyldichlorophosphine-lean mixture in step 2) is at least 55-80 wt.%, the content of phenyldichlorophosphine is not more than 2 wt.%, the content of triphenylphosphine is 20-35 wt.%, based on the total weight of the phenyldichlorophosphine-lean mixture, and

[0095] Step 2) further comprises the additional addition of diphenylchlorophosphine to the phenyldichlorophosphine-lean mixture, and the amount of added diphenylchlorophosphine is at least 20 wt.% based on the total weight of the phenyldichlorophosphine-lean mixture.

[0096] In one embodiment, the first and second heat treatments are carried out at a temperature of 345-355°C, the maximum pressure (gauge pressure) during the first and second heat treatments is 0.15-1 MPa (preferably the first and second heat treatments are carried out at autogenous pressure), the time of the first and second heat treatments is 1.5-2.5 hours,

[0097] The content of diphenylchlorophosphine in the diphenylchlorophosphine starting material is at least 98 wt.%, the content of phenyldichlorophosphine is not more than 1 wt.%, the content of phosphorus trichloride is not more than 0.1 wt.% (preferably the diphenylchlorophosphine starting material is free of phosphorus trichloride), based on the total weight of the diphenylchlorophosphine starting material,

[0098] The content of diphenylchlorophosphine in the phenyldichlorophosphine-lean mixture in step 2) is at least 55-80 wt.%, the content of phenyldichlorophosphine is not more than 2 wt.%, the content of triphenylphosphine is 20-35 wt.%, based on the total weight of the phenyldichlorophosphine-lean mixture, and

[0099] Step 2) further comprises the additional addition of diphenylchlorophosphine to the phenyldichlorophosphine-lean mixture, and the amount of added diphenylchlorophosphine is at least 20 wt.% based on the total weight of the phenyldichlorophosphine-lean mixture; and

[0100] The method further comprises repeating steps 2) and 3) once after step 3).

[0101] In one embodiment, the method comprises preheating the diphenylchlorophosphine starting material to 50-90°C, then starting the stirring, and subsequently heat treating the diphenylchlorophosphine starting material at a first heat treatment temperature.

[0102] The method of the present application is carried out under inert gas, for example nitrogen protection. Before carrying out the method of the present application, the reactor is replaced with inert gas (for example nitrogen), for example 2-5 times, preferably 3-5 times.

[0103] The product mixture of the method of the present application can be separated by post-treatment, for example rectification.

[0104] Examples

[0105] The features of the present application are further illustrated by the following examples, but are not limited to them. In the examples, the specific conditions not indicated are carried out under conventional conditions. The reagents or instruments used are not indicated by the manufacturer, but are conventional products available on the market. In the examples, the pressure is indicated as gauge pressure

[0106] Starting materials:

[0107] Diphenylchlorophosphine: Hubei Guron Technology Co., Ltd., purity ≥ 99.5%, triphenylphosphine content 0.1%-0.3%, without phosphorus trichloride.

[0108] Content determination:

[0109] The components are analyzed by gas chromatography, and quantified by correction normalization method.

[0110] Example 1:

[0111] The 1865g reaction liquid (the reaction liquid contains light components (phosphorus trichloride and chlorobenzene), phenyldichlorophosphine, diphenylchlorophosphine and triphenylphosphine) prepared by reaction of chlorobenzene and yellow phosphorus is subjected to vacuum rectification (vacuum degree is -0.1 MPa, rectification is collected to a tower top temperature of about 120°C) to remove light components and most of phenyldichlorophosphine, to obtain 830g of a bottom material containing 25g of phenyldichlorophosphine, 705g of diphenylchlorophosphine, 65g of triphenylphosphine and 35g of impurities.

[0112] The 830g of the bottom material is added to a synthesis reactor, the reactor valve is closed, the stirring is started, the stirring rate is 350-400r / min, and then the temperature is raised to a maximum of 350°C for 2.0h, the maximum pressure during the reaction is 0.5MPa, and 803g of reaction liquid is produced.

[0113] The 803 g reaction liquid was subjected to vacuum distillation (vacuum degree -0.1 MPa, distillation collected to a column top temperature of about 120°C) to remove light components and most of the phenyldichlorophosphine, and the remaining 638 g of the residue (containing 5 g of phenyldichlorophosphine, 417 g of diphenylchlorophosphine, 158 g of triphenylphosphine, and 58 g of impurities) was added to a synthesis reactor, the reactor valve was closed, stirring was started at a rate of 350-400 r / min, and the temperature was then raised to a maximum of 350°C over 70-80 min and maintained for 2.0 h, with the maximum pressure during the reaction being 0.4 MPa. The reaction produced 586 g of reaction liquid, containing 62 g of phenyldichlorophosphine, 254 g of diphenylchlorophosphine, 202 g of triphenylphosphine (34.5%), and 68 g of impurities.

[0114] Example 2:

[0115] The 1974 g reaction liquid prepared using chlorobenzene and yellow phosphorus as raw materials (containing light components (phosphorus trichloride and chlorobenzene), phenyldichlorophosphine, diphenylchlorophosphine, and triphenylphosphine) was subjected to vacuum distillation (vacuum degree -0.1 MPa, distillation collected to a column top temperature of about 120°C) to remove light components and most of the phenyldichlorophosphine, and 874 g of the residue was obtained, containing 13 g of phenyldichlorophosphine, 743 g of diphenylchlorophosphine, 87 g of triphenylphosphine, and 31 g of impurities.

[0116] The 874 g residue and 126 g of diphenylchlorophosphine were added to a 5 L synthesis reactor, the reactor valve was closed, stirring was started at a rate of 350-400 r / min, and the temperature was then raised to a maximum of 350°C over 70-80 min and maintained for 2.0 h, with the maximum pressure during the reaction being 0.4 MPa. The reaction produced 995 g of reaction liquid.

[0117] The 995 g reaction liquid was subjected to vacuum distillation (vacuum degree -0.1 MPa, distillation collected to a column top temperature of about 120°C) to remove light components and most of the monophenyl phosphine, and the remaining 803 g of the residue (containing 10 g of phenyldichlorophosphine, 531 g of diphenylchlorophosphine, 250 g of triphenylphosphine, and 12 g of impurities) and 197 g of diphenylchlorophosphine were added to a synthesis reactor, the reactor valve was closed, stirring was started at a rate of 350-400 r / min, and the temperature was then raised to a maximum of 350°C over 70-80 min and maintained for 2.0 h, with the maximum pressure during the reaction being 0.4 MPa. The reaction produced 980 g of reaction liquid, containing 111 g of phenyldichlorophosphine, 436 g of diphenylchlorophosphine, 427 g of triphenylphosphine (43.6 wt%), and 6 g of impurities.

[0118] Example 3:

[0119] The 5L synthesis reactor was replaced with nitrogen for three times, 1000g of diphenyl phosphine chloride was added into the synthesis reactor, the valve of the reactor was closed, the stirring was started with a stirring rate of 350-400r / min, the temperature was increased to 350℃ for 2.0h after 70-80min, the highest pressure during the reaction was 0.3MPa, and 970g of reaction liquid was obtained.

[0120] The above 970g of reaction liquid was subjected to vacuum distillation (the vacuum degree was-0.1MPa, the distillation was collected to the top temperature of about 120℃) to remove light components and most of the phenyl dichlorophosphine, 800g of the remaining bottom material (which contained 21g of phenyl dichlorophosphine, 492g of diphenyl phosphine chloride, 278g of triphenyl phosphine and 9g of impurities) was added into the synthesis reactor together with 200g of diphenyl phosphine chloride, the valve of the reactor was closed, the stirring was started with a stirring rate of 350-400r / min, the temperature was increased to 350℃ for 2.0h after 70-80min, the highest pressure during the reaction was 0.3MPa, and 978g of reaction liquid was obtained.

[0121] The above 978g of reaction liquid was subjected to vacuum distillation (the vacuum degree was-0.1MPa, the distillation was collected to the top temperature of about 120℃) to remove light components and phenyl dichlorophosphine, 880g of the remaining bottom material (which contained 457g of diphenyl phosphine chloride, 414g of triphenyl phosphine and 9g of impurities) was added into the synthesis reactor together with 120g of diphenyl phosphine chloride, the valve of the reactor was closed, the stirring was started with a stirring rate of 350-400r / min, the temperature was increased to 350℃ for 2.0h after 70-80min, the highest pressure during the reaction was 0.3MPa, and 980g of reaction liquid was obtained, which contained 38g of phenyl dichlorophosphine, 461g of diphenyl phosphine chloride and 446g of triphenyl phosphine, and the content of triphenyl phosphine was 45.5wt%.

[0122] Finally, it should be noted that the above content is only used to illustrate the technical solutions of the present application, and is not a limitation on the protection scope of the present application. Simple modifications or equivalent replacements of the technical solutions of the present application made by those skilled in the art do not deviate from the essence and scope of the technical solutions of the present application.

Claims

1. A process for the preparation of triphenylphosphine comprising: 1 ) subjecting a diphenylphosphine chloride starting material to a first thermal treatment at a temperature in the range of from 280 to 480°C to obtain a first thermal treatment mixture comprising phenyldichlorophosphine, diphenylphosphine chloride and triphenylphosphine, wherein the content of phenyldichlorophosphine in the diphenylphosphine chloride starting material is not more than 35% by weight, based on the total weight of the diphenylphosphine chloride starting material; 2) removing phenyldichlorophosphine from the first thermal treatment mixture to obtain a phenyldichlorophosphine depleted mixture, wherein the content of phenyldichlorophosphine in the phenyldichlorophosphine depleted mixture is not more than 8% by weight, based on the total weight of the phenyldichlorophosphine depleted mixture; and 3) subjecting the mixture obtained from step 2) to a second thermal treatment at a temperature in the range of from 280 to 480°C to obtain a second thermal treatment mixture comprising phenyldichlorophosphine, diphenylphosphine chloride and triphenylphosphine.

2. The process according to claim 1, wherein the content of phenyldichlorophosphine in the diphenylphosphine chloride starting material is not more than 30% by weight, preferably not more than 28% by weight, more preferably not more than 22% by weight, still more preferably not more than 15% by weight, especially not more than 8% by weight, in particular not more than 3% by weight, most preferably not more than 1 % by weight, such as not more than 0.5% by weight, based on the total weight of the diphenylphosphine chloride starting material.

3. The process according to claim 1 or 2, wherein the content of phenyldichlorophosphine in the phenyldichlorophosphine depleted mixture in step 2) is not more than 5% by weight, preferably not more than 4% by weight, more preferably not more than 2% by weight, still more preferably not more than 1 % by weight, based on the total weight of the phenyldichlorophosphine depleted mixture.

4. The process according to any one of claims 1 to 3, wherein the content of diphenylphosphine chloride in the diphenylphosphine chloride starting material is at least 65% by weight, preferably at least 70% by weight, more preferably at least 80% by weight, even more preferably at least 88% by weight, still more preferably at least 95% by weight, such as at least 98% by weight, based on the total weight of the diphenylphosphine chloride starting material.

5. The process according to any one of claims 1 to 4, wherein the content of diphenylphosphine chloride in the phenyldichlorophosphine depleted mixture in step 2) is at least 45% by weight, preferably in the range of from 50 to 85% by weight, more preferably in the range of from 55 to 80% by weight, even more preferably in the range of from 55 to 70% by weight, based on the total weight of the diphenylphosphine chloride starting material.

6. The process according to any one of claims 1 to 5, wherein the content of triphenylphosphine in the phenyldichlorophosphine depleted mixture in step 2) is in the range of from 12 to 40% by weight, preferably in the range of from 15 to 38% by weight, more preferably in the range of from 20 to 35% by weight, based on the total weight of the phenyldichlorophosphine depleted mixture.

7. The process according to any one of claims 1 to 6, wherein the first and second thermal treatment temperatures are in the range of from 300 to 450°C, preferably in the range of from 320 to 400°C, more preferably in the range of from 330 to 390°C.

8. The process according to claim 7, wherein the first and second heat treatment temperatures are especially 340-370 °C, in particular 345-360 °C, most preferably 345-355 °C, such as about 350 °C.

9. The process according to any one of claims 1-8, wherein the maximum pressure (gauge) during the first and second heat treatment is at least 0.05 MPa, preferably at least 0.08 MPa, such as 0.05-6 MPa, more preferably 0.08-5 MPa, still more preferably 0.1-2 MPa or 0.1-1 MPa.

10. The process according to any one of claims 1-9, wherein the first and second heat treatment is carried out at autogenous pressure.

11. The process according to any one of claims 1-10, wherein the time of the first and second heat treatment is at least 0.4 hours, preferably 0.4-12 hours, more preferably 0.6-8 hours, especially 0.8-8 hours, most preferably 1.5-2.5 hours, such as about 2 hours.

12. The process according to any one of claims 1-11, wherein the content of phosphorus trichloride in the diphenylchlorophosphine starting material is not more than 5% by weight, preferably not more than 2% by weight, more preferably not more than 1% by weight, such as not more than 0.5% by weight or not more than 0.1% by weight, based on the total weight of the diphenylchlorophosphine starting material.

13. The process according to any one of claims 1-12, wherein the first and second heat treatment is carried out with stirring.

14. The process according to any one of claims 1-13, wherein step 2) further comprises additional addition of diphenylchlorophosphine to the mixture depleted in phenyldichlorophosphine, preferably the amount of diphenylchlorophosphine added is at least 5% by weight, preferably at least 10% by weight or at least 20% by weight, such as 10-80% by weight, based on the total weight of the mixture depleted in phenyldichlorophosphine, in which case the mixture subjected to the second heat treatment in step 3) is the mixture to which diphenylchlorophosphine is additionally added.

15. The process according to any one of claims 1-14, wherein the removal of phenyldichlorophosphine in step 2) is carried out by flashing or distillation, preferably distillation, in particular rectification.

16. The process according to any one of claims 1-15, further comprising repeating steps 2) and 3) one or more times.

17. The process according to any one of claims 1-16, wherein the diphenylchlorophosphine starting material in step 1) is derived from a reaction mixture obtained by reacting chlorobenzene and yellow phosphorus, wherein chlorobenzene, phosphorus trichloride and most of the phenyldichlorophosphine are removed from the reaction mixture to obtain the diphenylchlorophosphine starting material.

18. The process according to any one of claims 1-17, wherein the first and second heat treatment is carried out at a temperature of 300-450 °C, the maximum pressure (gauge) during the first and second heat treatment is at least 0.05 MPa, and the time of the first and second heat treatment is at least 0.4 hours, the content of diphenylchlorophosphine in the diphenylchlorophosphine starting material is at least 65 wt.%, the content of phenyldichlorophosphine is not more than 30 wt.%, the content of phosphorus trichloride is not more than 5 wt.%, based on the total weight of the diphenylchlorophosphine starting material, and the content of diphenylchlorophosphine in the phenyldichlorophosphine- depleted mixture in step 2) is at least 45 wt.%, the content of phenyldichlorophosphine is not more than 5 wt.%, the content of triphenylphosphine is 12 to 40 wt.%, based on the total weight of the phenyldichlorophosphine-depleted mixture.

19. The process according to any one of claims 1 to 18, wherein the first and second heat treatment is carried out at a temperature of 345 to 355 °C, the maximum pressure (gauge pressure) during the first and second heat treatment is 0.15 to 1 MPa (preferably the first and second heat treatment is carried out at autogenous pressure), the time of the first and second heat treatment is 1.5 to 2.5 hours, the content of diphenylchlorophosphine in the diphenylchlorophosphine starting material is at least 98 wt.%, the content of phenyldichlorophosphine is not more than 1 wt.%, the content of phosphorus trichloride is not more than 0.1 wt.% (preferably the diphenylchlorophosphine starting material is free of phosphorus trichloride), based on the total weight of the diphenylchlorophosphine starting material, the content of diphenylchlorophosphine in the phenyldichlorophosphine- depleted mixture in step 2) is at least 55 to 80 wt.%, the content of phenyldichlorophosphine is not more than 2 wt.%, the content of triphenylphosphine is 20 to 35 wt.%, based on the total weight of the phenyldichlorophosphine-depleted mixture, and step 2) further comprises the additional addition of diphenylchlorophosphine to the phenyldichlorophosphine-depleted mixture, and the amount of diphenylchlorophosphine added is at least 20 wt.%, based on the total weight of the phenyldichlorophosphine-depleted mixture.