Method for preparing triphenylphosphine

Abstract

Provided is a method for preparing triphenylphosphine, comprising reacting triphenylphosphine oxide and triphenyl phosphite as follows. The method uses a one-step process to synthesize triphenylphosphine, and involves a simple process step, a high reaction yield, high product purity and low process cost, and does not need to use a solvent and therefore reduce emission of waste liquids. In addition, the method also synthesizes a high-value byproduct triphenyl phosphate that can be used in great quantity in the fields such as flame retardants, plasticizers and stabilizers, and said co-production greatly reduces the cost of raw materials and the cost of the production process, thereby achieving substantial cost advantages. The raw materials of the method do not involve high-risk chemicals; and since triphenyl phosphate is synthesized at the same time, the method achieves a remarkable flame retardant effect and high process safety.

Description

Process for preparing triphenylphosphine

[0001] This patent application claims priority to the following Chinese patent application:

[0002] Filing date: June 20, 2024; Application No. 2024108046401; Invention name: Process for preparing triphenylphosphine; The entire contents of the above application are incorporated herein by reference. TECHNICAL FIELD

[0003] The present invention relates to the field of organic chemistry, in particular to a process for preparing triphenylphosphine. BACKGROUND

[0004] Triphenylphosphine is an important fine chemical raw material with a wide range of applications. In petroleum and chemical industry, triphenylphosphine is used as a homogeneous catalyst ligand. In the fine chemical industry, it is widely used in various reactions such as Wittig reaction, Staudinger reaction, Mitsunobu reaction, Appel reaction, etc., for example, the production of intermediates for cephalosporin series drugs, vitamins, beta carotene and other products. After triphenylphosphine is applied in the above reactions, it is converted into triphenylphosphine oxide. Triphenylphosphine oxide has few uses and cannot be consumed. Triphenylphosphine oxide is very harmful to aquatic organisms, and as a byproduct of a series of important reactions, it brings great difficulties to the discharge of waste and the treatment of waste residues in the factory, seriously affecting the economic benefits.

[0005] Regenerating triphenylphosphine oxide into triphenylphosphine is the most important solution. The methods disclosed in the prior art for converting triphenylphosphine oxide into triphenylphosphine are almost reduction methods. For example, BASF uses phosgene to convert triphenylphosphine oxide into dichloride, and then reduces it to triphenylphosphine with elemental phosphorus. This process requires high-temperature reaction, and the reaction kettle needs special material. Horner and his colleagues reported in 1958 that triphenylphosphine oxide reacts with phosphorus pentachloride to form triphenylphosphine dichloride, and then reduces it with lithium aluminum hydride (LiAlH4) to obtain triphenylphosphine with a yield of 49%. Masaki and Fukui reported in 1959 that triphenylphosphine oxide can also react with oxalyl chloride or trichloromethyl formic acid to form Ph3PCl2, and then continue the subsequent reaction. Tanaka et al. further proposed a method to improve the yield by adding an aluminum salt as a catalyst to the Ph3PCl2 solution. However, the above methods either use high-cost reducing agents or high-cost chlorinating agents, and do not have industrial value.

[0006] Davis et al. reported in 1978 a co-reduction with hydride (e.g. sodium hydride) and trichlorosilane with a yield of 74.3%. Ethyl Corporation continued to adjust this method, using sodium aluminum hydride and aluminum trichloride as reducing agents, and the reaction was carried out at room temperature, with a yield of up to 80%. Schirmer et al. used trifluoromethylsulfonic acid as a catalyst, benzylsilane as a reducing agent, in toluene solution, at 70°C for 1h, to prepare triphenylphosphine with a yield of up to 99%. However, the cost of this method is still too high and does not have industrial value.

[0007] Chinese patent CN101747370A discloses the use of silicon powder as a reducing agent to regenerate triphenylphosphine oxide. Chinese patent CN101270132B discloses the use of trichlorosilane to reduce triphenylphosphine oxide in toluene solution with trimethylamine. Such methods generate a large amount of solid waste.

[0008] Chinese patent CN101659675B discloses the use of solid phosgene to chlorinate triphenylphosphine oxide, followed by the use of aluminum powder as a reducing agent to regenerate triphenylphosphine from Wittig reaction waste, with a yield of triphenylphosphine between 65.0% and 90.1%. This method has a lower cost, but uses high-risk chemicals and generates a large amount of aluminum trichloride wastewater after the reaction.

[0009] In addition to the above chemical reduction methods, there are electrochemical reduction methods. For example, Chinese patent CN109433203B discloses an electrochemical reduction of triphenylphosphine oxide after adding a catalyst. The catalyst used in the method is a platinum, tungsten, and zinc composite catalyst, which needs to be self-made, and sodium bromide or lithium chloride catalysts also need to be added. However, the service life or regeneration of the precious metal catalyst is not described in the method. At the same time, the industrial implementation of electrochemical reduction is difficult to achieve.

[0010] In summary, there is still a need in the art to find a low-cost, environmentally friendly, and more easily industrialized method for preparing triphenylphosphine.

[0011] SUMMARY

[0012] The purpose of the present application is to provide a method for preparing triphenylphosphine.

[0013] Another purpose of the present application is to provide a method for simultaneously preparing triphenylphosphine and triphenyl phosphate.

[0014] To solve the above technical problems, the first aspect of the present application provides a method for preparing triphenylphosphine, the method comprising the steps of:

[0015] reacting triphenylphosphine oxide and triphenylphosphite.

[0016] In some preferred embodiments, triphenylphosphine oxide and triphenylphosphite are reacted according to the following reaction formula I, i.e.

[0017] Reaction formula I

[0018] In some preferred embodiments, the reaction temperature is 250-380℃, most preferably 350℃.

[0019] In some preferred embodiments, the reaction time is 2-20 hours.

[0020] In some preferred embodiments, the molar ratio of the triphenyl phosphine oxide and the triphenyl phosphite is 1:1.5-0.95, most preferably 1:1.05.

[0021] In some preferred embodiments, the reaction is a solvent-free reaction.

[0022] In some preferred embodiments, the reaction of the triphenyl phosphine oxide and the triphenyl phosphite according to the reaction formula I comprises the steps of: mixing the triphenyl phosphine oxide and the triphenyl phosphite and reacting at 250-380℃ for 2-20 hours.

[0023] In some preferred embodiments, the reaction raw material moisture is ≤0.05%.

[0024] In some preferred embodiments, the reaction further comprises the step of separating the triphenyl phosphine.

[0025] In some preferred embodiments, the separation of the triphenyl phosphine comprises the steps of: subjecting the reaction product to rectification and collecting the corresponding fractions.

[0026] In some preferred embodiments, in the rectification device, the fraction with a top temperature ≤160℃ is collected.

[0027] In some preferred embodiments, in the rectification device, the fraction with a top temperature ≤160℃ and the fraction with a top temperature of 168-180℃ are collected separately, the fraction with a top temperature ≤160℃ is the triphenyl phosphine, and the fraction with a top temperature of 168-180℃ is the triphenyl phosphate.

[0028] In some preferred embodiments, the rectification device has a column height of 40 cm, an inner diameter of 2.4 cm, and is filled with glass packing.

[0029] In a second aspect, the present application provides a method for simultaneously preparing triphenyl phosphine and triphenyl phosphate, which comprises the steps of:

[0030] reacting triphenyl phosphine oxide and triphenyl phosphite according to the following reaction formula I to obtain triphenyl phosphine and triphenyl phosphate.

[0031] Reaction formula I

[0032] In some preferred embodiments, the reaction temperature is 250-380°C, most preferably 350°C.

[0033] In some preferred embodiments, the reaction time is 2-20 hours.

[0034] In some preferred embodiments, the molar ratio of the triphenyl phosphine oxide and the triphenyl phosphite is 1:1.5-0.95, most preferably 1.05.

[0035] In some preferred embodiments, the reaction is a solvent-free reaction.

[0036] In some preferred embodiments, the reaction of the triphenyl phosphine oxide and the triphenyl phosphite according to the following reaction formula I comprises the step of mixing the triphenyl phosphine oxide and the triphenyl phosphite and reacting at 250-380°C for 2-20 hours.

[0037] In some preferred embodiments, the reaction raw material moisture is ≤0.05%.

[0038] In some preferred embodiments, the reaction further comprises the step of separating the triphenyl phosphine and the triphenyl phosphate.

[0039] In some preferred embodiments, the separation of the triphenyl phosphine and the triphenyl phosphate comprises the step of subjecting the reaction product to rectification and collecting the corresponding fractions.

[0040] In some preferred embodiments, in the rectification device, the fraction with a boiling point ≤160°C is collected as the triphenyl phosphine, and the fraction with a boiling point of 168-180°C is collected as the triphenyl phosphate.

[0041] In some preferred embodiments, the rectification device has a column height of 40 cm and an inner diameter of 2.4 cm, and is filled with glass packing.

[0042] Compared with the prior art, the present application has at least the following advantages:

[0043] (1) The method provided by the present application synthesizes triphenyl phosphine in one step, has simple process steps, high reaction yield, high product purity, low process cost, and does not require the use of solvents, thereby reducing waste liquid discharge.

[0044] (2) The method provided by the present application simultaneously synthesizes the high-value by-product triphenyl phosphate which can be widely used in the fields of flame retardants, plasticizers, stabilizers, etc., and the combined production greatly reduces the raw material cost and production process cost, and has great cost advantage.

[0045] (3) The method provided by the application does not involve high-risk chemicals, and the flame-retardant effect is obvious and the process safety is high due to the simultaneous synthesis of triphenyl phosphate.

[0046] It should be understood that, within the scope of the present application, each of the technical features described above and each of the technical features described in detail below (such as the examples) can be combined with each other to form a new or preferred technical solution. Due to the limited space, they will not be listed one by one here. BRIEF DESCRIPTION OF DRAWINGS

[0047] One or more embodiments are illustrated by pictures in the corresponding drawings, which do not constitute a limitation on the embodiments.

[0048] Figure 1 is a gas phase detection result of a reaction product according to Example 1 of the present application;

[0049] Figure 2 is a gas phase detection result of a reaction product according to Example 2 of the present application;

[0050] Figure 3 is a gas phase detection result of a reaction product according to Example 3 of the present application;

[0051] Figure 4 is a gas phase detection result of a reaction product according to Example 4 of the present application. DETAILED DESCRIPTION

[0052] The present inventors, aiming at the problems in the prior art process of regenerating triphenyl phosphine oxide into triphenyl phosphine, such as complex process, high cost, pollution from by-product regeneration, low production efficiency, high energy consumption, raw materials involving high-risk chemicals, or safety risks in production process, etc., have developed a new method for preparing triphenyl phosphine through extensive and in-depth research. The method directly and simultaneously prepares triphenyl phosphine and the by-product triphenyl phosphate with high industrial added value through the reaction of triphenyl phosphine oxide and triphenyl phosphite, which can greatly save process cost and has significant economic value.

[0053] Method for preparing triphenyl phosphine

[0054] The present application relates to a method for preparing triphenyl phosphine, comprising the step of: allowing triphenyl phosphine oxide and triphenyl phosphite to react.

[0055] The reaction formula of the foregoing reaction is shown in Reaction Formula I. Under the action of the reducing agent triphenyl phosphite, triphenyl phosphine oxide is reduced to directly obtain triphenyl phosphine and simultaneously obtain triphenyl phosphate.

[0056] In some preferred embodiments of the present application, the reaction is a solvent-free reaction. The term "solvent-free reaction" refers to a reaction that does not require any liquid medium, which can be an organic solvent such as ethanol, glycerol, DMF, DMSO, etc., or water, or a mixture of an organic solvent and water. The "solvent-free reaction" preferably starts the reaction directly by mixing the reactants, which can reduce the discharge of industrial waste water.

[0057] In some preferred embodiments of the present application, the water content in the reaction raw materials is less than or equal to 0.05%. The inventors have found through experimental research that the introduction of water can cause the hydrolysis of triphenyl phosphite and triphenyl phosphate to produce a small amount of phenol.

[0058] In some preferred embodiments of the present application, the reaction temperature is 250-380°C, and most preferably 350°C. The inventors have found through experimental research that when the reaction temperature is less than 320°C, the reaction rate is very slow, and when the reaction temperature is higher than 350°C, impurities are generated, which can affect the yield.

[0059] In some preferred embodiments of the present application, the reaction time is 2-20 hours.

[0060] In some preferred embodiments of the present application, the molar ratio of triphenyl phosphine oxide to triphenyl phosphite is 1:1.5-0.95, and most preferably 1:1.05. The inventors have found that the molar ratio of triphenyl phosphine oxide to triphenyl phosphite does not affect the conversion of triphenyl phosphite, but can cause the residual of triphenyl phosphine oxide or triphenyl phosphite, which can make the product separation difficult.

[0061] In some preferred embodiments of the present application, the method comprises the step of mixing triphenyl phosphine oxide and triphenyl phosphite at 250-380°C for 2-20 hours.

[0062] After the reaction is completed, triphenyl phosphine and triphenyl phosphate can be separated by conventional separation means in the art. For example, the products can be separated by rectification. In some preferred embodiments of the present application, in the rectification device, a fraction with a top temperature of less than or equal to 160°C is collected, and a fraction with a top temperature of 168-180°C is collected, the fraction with a top temperature of less than or equal to 160°C is triphenyl phosphine, and the fraction with a top temperature of 168-180°C is triphenyl phosphate. A fraction with a top temperature of 160-168°C can also be collected and further separated.

[0063] As the rectification device, a rectification column with a column height of 40 cm, an inner diameter of 2.4 cm, and filled with glass packing can be used.

[0064] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the present application will be further described below with specific examples. It should be understood that these examples are only used to illustrate the present application but not to limit the scope of the present application. The experimental methods not specified in the following examples are usually carried out according to the conventional conditions or the conditions suggested by the manufacturers. Unless otherwise specified, the percentages and parts are weight percentages and weight parts. The experimental materials and reagents used in the following examples can be obtained from the market channels unless otherwise specified.

[0065] Unless otherwise indicated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should be noted that the terms used herein are only for the purpose of describing the specific embodiments of the present application and are not intended to limit the exemplary embodiments of the present application.

[0066] Unless otherwise indicated, the term "or" means the term "and / or" and can be used interchangeably with the term "and / or".

[0067] As used herein, including the appended claims, the singular forms "a," "an," and "the" include their respective plural referents unless the context clearly dictates otherwise.

[0068] Example 1

[0069] In a 250ml three-necked flask, triphenylphosphine oxide 83.4g and triphenyl phosphite 88.42g were added at one time; after the molten salt bath was heated to 350℃ for 3 hours, the sample was taken for gas phase detection until the content of triphenyl phosphite was ≤0.5%. The GC detection results are shown in Figure 1.

[0070] As shown in Figure 1, in the product, the content of phenol was 0.081%; the content of triphenyl phosphite was 0.4%; the content of triphenyl phosphate was 47.25%; the content of triphenylphosphine was 43.75%; and the content of triphenylphosphine oxide was 8.51%.

[0071] Example 2

[0072] In a 250ml three-necked flask, triphenylphosphine oxide 83.4g and triphenyl phosphite 88.42g were added at one time; after the molten salt bath was heated to 320℃ for 12 hours, the sample was taken for gas phase detection. The GC detection results are shown in Figure 2.

[0073] As shown in Figure 2, in the product, the content of phenol was 0.79%; the content of triphenyl phosphite was 0.56%; the content of triphenyl phosphate was 53.33%; the content of triphenylphosphine was 31.55%; and the content of triphenylphosphine oxide was 12.13%.

[0074] Example 3

[0075] 250ml three-port bottle, one time adding triphenyl phosphine oxide 83.4g, triphenyl phosphite 88.42g; melt salt bath heating 380℃ for 3 hours, sampling analysis to triphenyl phosphite ≤0.5% to end the reaction, GC detection of reaction liquid components, GC detection results are shown in Figure 3.

[0076] As shown in Figure 3, phenol in the product: 1.24%; triphenyl phosphate: 42.24%; triphenyl phosphine: 40.06%; triphenyl phosphine oxide: 10.35%. Impurities 9.381 min: 6.07%.

[0077] Example 4

[0078] 250ml three-port bottle, one time adding triphenyl phosphine oxide 83.4g, triphenyl phosphite 79.2g; melt salt bath heating 350℃ for 3 hours, sampling analysis to triphenyl phosphite ≤0.5%, HPLC detection results are shown in Figure 4.

[0079] As shown in Figure 4, triphenyl phosphate in the product: 45.3%, triphenyl phosphite: 0.16%; triphenyl phosphine: 41.78%; triphenyl phosphine oxide: 12.75%.

[0080] Example 5

[0081] Reaction liquid 500g (reactants prepared according to the method of Example 1) was transferred to a rectification device (1000ml, column height 40cm, inner diameter: 2.4cm, filled with glass packing), vacuum degree less than 10Pa; top temperature ≤140℃ to collect the front distillation, top temperature 150-160 to collect the normal distillation; top temperature 162-168 to collect the cross; top temperature 168-180 to collect the back distillation. Distillation data are shown in Table 1 below.

[0082] Table 1

[0083] Those skilled in the art can understand that the above embodiments are specific examples for implementing the present application, and in actual application, various changes can be made in form and details without departing from the spirit and scope of the present application.

Claims

1. A process for the preparation of triphenylphosphine, characterized in that, The method comprises the step of reacting triphenyl phosphine oxide and triphenyl phosphite.

2. The method of claim 1, wherein, The reaction temperature is 250-380℃, most preferably 350℃.

3. The method of claim 1, wherein, The reaction time is 2-20 hours.

4. The method of claim 1, wherein, The molar ratio of triphenyl phosphine oxide to triphenyl phosphite is 1:1.5-0.95, most preferably 1.

05.

5. The method of claim 1, wherein, The reaction is a solvent-free reaction.

6. The method of claim 1, wherein, The reaction of triphenyl phosphine oxide and triphenyl phosphite according to the following reaction formula I comprises the step of mixing triphenyl phosphine oxide and triphenyl phosphite at 250-380℃ for 2-20 hours.

7. The method of claim 1, wherein, The reaction raw material water content is ≤0.05%.

8. The method of claim 1, wherein, The reaction further comprises the step of separating triphenyl phosphine.

9. The method of claim 1, wherein, The separation of triphenyl phosphine comprises the steps of subjecting the reaction product to rectification and collecting the corresponding fraction; preferably, in the rectification device, the fraction with a top temperature ≤160℃ is collected.

10. The method of claim 1, wherein, In the rectification device, the fraction with a top temperature ≤160℃ is collected, and the fraction with a top temperature of 168-180℃ is collected, wherein the fraction with a top temperature ≤160℃ is triphenyl phosphine, and the fraction with a top temperature of 168-180℃ is triphenyl phosphate.

Images