Method for preparing triphenylphosphine

Abstract

The invention discloses a method for preparing triphenylphosphine. The invention provides a method for preparing triphenylphosphine. The method comprises the step of enabling triphenylphosphine oxide and triphenyl phosphite to react. According to the method provided by the invention, triphenylphosphine is synthesized by adopting a one-step method, the process steps are simple, the reaction yield is high, the product purity is high, the process cost is low, no solvent is needed, and waste liquid discharge is reduced. Meanwhile, a high-value by-product triphenyl phosphate which can be widely applied to the fields of flame retardants, plasticizers, stabilizers and the like is synthesized, the raw material cost and the production process cost are greatly reduced through joint production, and the cost advantage is extremely high. According to the method, high-risk chemicals are not involved in raw materials, and triphenyl phosphate is synthesized at the same time, so that the flame-retardant effect is remarkable, and the process safety is high.

Description

Technical Field

[0001] The present invention relates to the field of organic chemistry, and particularly to a method for preparing triphenylphosphine. Background Art

[0002] Triphenylphosphine is an important fine chemical raw material with a wide range of uses. In petrochemical industry, triphenylphosphine is used as a ligand for homogeneous catalysts. In the fine chemical industry, it is widely applied in various reactions such as Wittig reaction, Staudinger reaction, Mitsunobu reaction, Appel reaction, etc., for example, in the production of intermediates for cephalosporin series drugs, vitamins, β-carotene and other products. After triphenylphosphine is applied in the above reactions, it is converted into triphenylphosphine oxide. However, triphenylphosphine oxide has few uses and cannot be consumed. Triphenylphosphine oxide is very harmful to aquatic organisms, and as a by-product generated by a series of important reactions, it brings great difficulties to the waste discharge and residue treatment of factories, seriously affecting economic benefits.

[0003] Regenerating triphenylphosphine oxide into triphenylphosphine is the main solution. Almost all the methods for converting triphenylphosphine oxide into triphenylphosphine disclosed in the prior art are reduction methods. For example, BASF company uses phosgene to convert triphenylphosphine oxide into dichloride, and then reduces it with elemental phosphorus to triphenylphosphine. This process requires high-temperature reaction and the reaction kettle needs special materials. Horner and his colleagues reported in 1958 that triphenylphosphine oxide reacts with phosphorus pentachloride to form triphenyldichlorophosphine, and then it is reduced with lithium aluminum hydride (LiAlH4) to obtain triphenylphosphine with a yield of 49%. Masaki and Fukui reported in 1959 on this basis that triphenylphosphine oxide can also react with oxalyl chloride or trichloromethyl formate to form Ph3PCl2, and then continue with the subsequent reactions. Tanaka et al. also proposed a method to improve the yield on this basis, by adding an aluminum salt as a catalyst to the Ph3PCl2 solution. However, the above methods either use expensive reducing agents or expensive chlorinating agents and do not have industrial value.

[0004] Davis et al. reported in 1978 that hydrides (such as sodium hydride) and trichlorosilane were used for co-reduction with a yield of 74.3%. Ethyl company further adjusted this method, using sodium aluminum hydride and aluminum trichloride as reducing agents, and reacting at room temperature, with a yield of up to 80%. Schirmers et al. used trifluoromethanesulfonic acid as a catalyst and benzylsilane as a reducing reagent, reacting in toluene solution at 70 °C for 1 h, and the yield of triphenylphosphine prepared could reach 99%. However, this method is still too costly and does not have industrial value.

[0005] Chinese Patent CN101747370A discloses the reduction and regeneration of triphenylphosphine oxide using silicon powder as a regeneration reagent. Chinese Patent CN101270132B discloses the reduction of triphenylphosphine oxide using trichlorosilane in toluene dissolved with trimethylamine. Such methods generate a large amount of solid waste.

[0006] Chinese Patent CN101659675B discloses first chlorinating triphenylphosphine oxide with solid phosgene, and then using aluminum powder as a reducing agent to regenerate triphenylphosphine from Wittig reaction waste residue, with the yield of triphenylphosphine between 65.0% and 90.1%. This method has a relatively low cost, but uses highly hazardous chemicals and generates a large amount of aluminum trichloride wastewater after the reaction.

[0007] In addition to the above chemical reduction methods, there is an electrochemical reduction method. For example, Chinese Patent CN 109433203 B discloses the electrochemical reduction of triphenylphosphine oxide after adding a catalyst. The catalyst used in the method is a platinum, tungsten, zinc composite catalyst, which needs to be prepared by oneself. In addition, a sodium bromide or lithium chloride co-catalyst needs to be added, but the service life or regeneration of the precious metal catalyst is not described in the method. At the same time, it is difficult to implement the electrochemical reduction industrially.

[0008] In summary, there is still a need in the art to find a method for preparing triphenylphosphine that is low-cost, environmentally friendly and more easily industrialized. Summary of the Invention

[0009] The object of the present invention is to provide a method for preparing triphenylphosphine.

[0010] Another object of the present invention is to provide a method for simultaneously preparing triphenylphosphine and triphenyl phosphate.

[0011] To solve the above technical problems, in the first aspect of the present invention, a method for preparing triphenylphosphine is provided, and the method includes the steps of:

[0012] Reacting triphenylphosphine oxide with triphenyl phosphite.

[0013] In some preferred embodiments, reacting triphenylphosphine oxide with triphenyl phosphite according to the reaction formula I as shown below, and then obtaining.

[0014]

[0015] In some preferred embodiments, the temperature of the reaction is 250 - 380 °C, and most preferably 350 °C.

[0016] In some preferred embodiments, the time of the reaction is 2 - 20 hours.

[0017] In some preferred embodiments, the molar feeding ratio of triphenylphosphine oxide to triphenyl phosphite is 1:1.5 to 0.95, and most preferably 1:1.05.

[0018] In some preferred embodiments, the reaction is a solvent-free reaction.

[0019] In some preferred embodiments, the reaction of triphenylphosphine oxide and triphenyl phosphite to undergo the reaction shown in Reaction Scheme I includes the steps of: mixing triphenylphosphine oxide and triphenyl phosphite at 250-380 °C and reacting for 2-20 hours.

[0020] In some preferred embodiments, the water content of the reaction raw materials is ≤0.05%.

[0021] In some preferred embodiments, the steps after the reaction further include: separating triphenylphosphine.

[0022] In some preferred embodiments, the separation of triphenylphosphine includes the steps of: rectifying the reaction product and collecting the corresponding fractions.

[0023] In some preferred embodiments, in the rectifying device, the fractions with a top temperature ≤160 °C are collected.

[0024] In some preferred embodiments, in the rectifying device, the fractions with a top temperature ≤160 °C and the fractions with a top temperature of 168-180 °C are separately collected. The fractions with a top temperature ≤160 °C are triphenylphosphine, and the fractions with a top temperature of 168-180 °C are triphenyl phosphate.

[0025] In some preferred embodiments, the column height of the rectifying device is 40 cm; the inner diameter is 2.4 cm; and the rectifying device is filled with glass packing.

[0026] In the second aspect of the present invention, a method for simultaneously preparing triphenylphosphine and triphenyl phosphate is provided, and the method includes the steps of:

[0027] Subjecting triphenylphosphine oxide and triphenyl phosphite to the reaction shown in Reaction Scheme I below to obtain triphenylphosphine and triphenyl phosphate.

[0028]

[0029] In some preferred embodiments, the temperature of the reaction is 250-380 °C, and most preferably 350 °C.

[0030] In some preferred embodiments, the reaction time is 2-20 hours.

[0031] In some preferred embodiments, the molar feeding ratio of triphenylphosphine oxide to triphenyl phosphite is 1:1.5 to 0.95, and most preferably 1.05.

[0032] In some preferred embodiments, the reaction is a solvent-free reaction.

[0033] In some preferred embodiments, the reaction of triphenylphosphine oxide and triphenyl phosphite to produce the reaction shown in Reaction Scheme I includes the steps of: mixing triphenylphosphine oxide and triphenyl phosphite at 250-380 °C and reacting for 2-20 hours.

[0034] In some preferred embodiments, the water content of the reaction raw materials is ≤ 0.05%.

[0035] In some preferred embodiments, after the reaction, the steps further include: separating the triphenylphosphine and the triphenyl phosphate.

[0036] In some preferred embodiments, the separation of the triphenylphosphine and the triphenyl phosphate includes the steps of: rectifying the reaction product and collecting the corresponding fractions.

[0037] In some preferred embodiments, in the rectification device, the fraction with a temperature ≤ 160 °C is collected, which is the triphenylphosphine; the fraction with a top temperature of 168-180 °C is collected, which is the triphenyl phosphate.

[0038] In some preferred embodiments, the column height of the rectification device is 40 cm; the inner diameter is 2.4 cm; the rectification device is filled with glass packing.

[0039] The present invention has at least the following advantages over the prior art:

[0040] (1) The method provided by the present invention uses a one-step method to synthesize triphenylphosphine, with simple process steps, high reaction yield, high product purity, low process cost, and no need to use solvents, reducing waste liquid emissions.

[0041] (2) The method provided by the present invention simultaneously synthesizes the high-value by-product triphenyl phosphate that can be widely used in the fields of flame retardants, plasticizers, stabilizers, etc. The combined production greatly reduces the raw material cost and production process cost, and has great cost advantages.

[0042] (3) The method provided by the present invention does not involve high-risk chemicals in the raw materials, and due to the simultaneous synthesis of triphenyl phosphate, the flame retardant effect is significant and the process safety is high.

[0043] It should be understood that within the scope of the present invention, the above technical features of the present invention and the technical features specifically described below (such as in the examples) can be combined with each other to form new or preferred technical solutions. Due to space limitations, they will not be elaborated one by one here. Description of the Drawings

[0044] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings, and these exemplary illustrations do not constitute a limitation on the embodiments.

[0045] Figure 1 is the gas-phase detection result of the reaction product in Example 1 of the present invention;

[0046] Figure 2 is the gas-phase detection result of the reaction product in Example 2 of the present invention;

[0047] Figure 3 is the gas-phase detection result of the reaction product in Example 3 of the present invention;

[0048] Figure 4 is the gas-phase detection result of the reaction product in Example 4 of the present invention. Detailed implementation manners

[0049] In view of the problems existing in the prior art in the process of regenerating triphenylphosphine oxide into triphenylphosphine, such as complex process, high cost, pollution from regeneration by-products, low production efficiency, high energy consumption, raw materials involving high-risk chemicals, or safety risks in the production process, etc., the present inventors have conducted extensive and in-depth research and developed a new method for preparing triphenylphosphine. The method adopts the reaction of triphenylphosphine oxide and triphenyl phosphite to directly prepare triphenylphosphine and triphenyl phosphate with high industrial added value as by-products at the same time, which can greatly save the process cost and has significant economic value.

[0050] Method for preparing triphenylphosphine

[0051] The present invention relates to a method for preparing triphenylphosphine, which includes the step of reacting triphenylphosphine oxide and triphenyl phosphite.

[0052] The reaction formula of the aforementioned reaction is as shown in Reaction Formula I. Under the action of the reducing agent triphenyl phosphite, triphenylphosphine oxide undergoes a reduction reaction to directly obtain triphenylphosphine and triphenyl phosphate at the same time.

[0053]

[0054] In a preferred embodiment of the present invention, the reaction is a solvent-free reaction. The term "solvent-free reaction" means that no liquid medium is required for the reaction. Here, the liquid medium 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 directly mixes the reactants to start the reaction without any liquid medium, which can reduce the discharge of industrial wastewater.

[0055] In a preferred embodiment of the present invention, the water content in the reaction raw materials is ≤0.05%. Through experimental research, the inventors found that the introduction of water will cause the hydrolysis of triphenyl phosphite and triphenyl phosphate to produce a small amount of phenol.

[0056] In a preferred embodiment of the present invention, the reaction temperature is 250 - 380°C, and most preferably 350°C. Through experimental research, the inventors found 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 will be generated, thus affecting the yield.

[0057] In a preferred embodiment of the present invention, the reaction time is 2 - 20 hours.

[0058] In a preferred embodiment of the present invention, the molar feed ratio of triphenylphosphine oxide to triphenyl phosphite is 1:1.5 - 0.95, and most preferably 1:1.05. The inventors found that the molar ratio of triphenylphosphine oxide to triphenyl phosphite does not affect the conversion of triphenyl phosphite, but will cause the residue of triphenylphosphine oxide or triphenyl phosphite, resulting in difficult product separation.

[0059] In a preferred embodiment of the present invention, the method includes the steps of: mixing triphenylphosphine oxide and triphenyl phosphite at 250 - 380°C and reacting for 2 - 20 hours.

[0060] After the reaction is completed, triphenylphosphine and triphenyl phosphate can be separated by conventional separation means in the art. For example, the product is separated by distillation. In some preferred embodiments of the present invention, in the distillation device, the fractions with a top temperature ≤160°C and the fractions with a top temperature of 168 - 180°C are collected respectively. The fraction with a top temperature ≤160°C is triphenylphosphine, and the fraction with a top temperature of 168 - 180°C is triphenyl phosphate. The fraction at 160 - 168°C is used as the cross fraction, which can also be collected and further separated.

[0061] As the distillation device, a distillation column with a column height of 40 cm, an inner diameter of 2.4 cm, and filled with glass packing can be preferably selected.

[0062] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. The experimental methods without specific conditions noted in the following embodiments are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer. Unless otherwise specified, percentages and parts are weight percentages and weight parts. The experimental materials and reagents used in the following embodiments can be obtained from commercial channels without special instructions.

[0063] Unless otherwise specified, the technical and scientific terms used herein have the same meaning as commonly understood by ordinary technicians in the technical field to which the application belongs. It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments of the present application.

[0064] Unless otherwise indicated, the term "or" means and is used interchangeably with the term "and / or".

[0065] As used herein, including the appended claims, singular forms of words such as "a," "an," and "the" include their corresponding plural referents unless the context clearly dictates otherwise.

[0066] Example 1

[0067] Add 83.4 g of triphenylphosphine oxide and 88.42 g of triphenyl phosphite into a 250 ml three-necked flask at once; heat the molten salt bath to 350°C and keep warm for 3 hours before sampling the gas phase for detection until triphenyl phosphite is ≤0.5%. The GC detection results are shown in Figure 1 .

[0068] like Figure 1 As shown, the product contains phenol: 0.081%; triphenyl phosphite: 0.4%; triphenyl phosphate: 47.25%; triphenyl phosphine: 43.75%; and triphenyl phosphine oxide: 8.51%.

[0069] Example 2

[0070] Add 83.4 g of triphenylphosphine oxide and 88.42 g of triphenyl phosphite into a 250 ml three-necked flask at once; heat the molten salt bath to 320°C for 12 hours, then take a sample for gas phase analysis. The GC test results are shown in Figure 2 .

[0071] like Figure 2 As shown, the product contains 0.79% phenol, 0.56% triphenyl phosphite, 53.33% triphenyl phosphate, 31.55% triphenyl phosphine and 12.13% triphenyl phosphine oxide.

[0072] Example 3

[0073] Add 83.4 g of triphenylphosphine oxide and 88.42 g of triphenyl phosphite into a 250 ml three-necked flask at once; heat the molten salt bath to 380°C and keep warm for 3 hours, then take a sample and analyze until the content of triphenyl phosphite is ≤0.5% and the reaction is terminated; GC is used to detect the components of the reaction solution. The GC detection results are shown in Figure 3 .

[0074] like Figure 3As shown, in the product, phenol: 1.24%; triphenyl phosphate: 42.24%; triphenylphosphine: 40.06%; triphenylphosphine oxide: 10.35%. Impurity at 9.381 min: 6.07%.

[0075] Example 4

[0076] 83.4 g of triphenylphosphine oxide and 79.2 g of triphenyl phosphite were added at once into a 250 ml three-necked flask; the molten salt bath was heated to 350 °C and kept warm for 3 hours, then samples were taken for analysis until the content of triphenyl phosphite was ≤ 0.5%. The HPLC detection results are shown in Figure 4 .

[0077] As Figure 4 shown, in the product, triphenyl phosphate: 45.3%, triphenyl phosphite: 0.16%; triphenylphosphine: 41.78%; triphenylphosphine oxide: 12.75%.

[0078] Example 5

[0079] 500 g of the reaction solution (prepared according to the method of Example 1) was transferred to a distillation device (1000 ml, column height 40 cm, inner diameter: 2.4 cm, filled with glass packing), and the vacuum was less than 10 Pa; the overhead temperature was ≤ 140 °C to collect the fore-run, the overhead temperature was 150 - 160 °C to collect the main fraction; the overhead temperature was 162 - 168 °C to collect the cross fraction; the overhead temperature was 168 - 180 °C to collect the after-run. The distillation data are shown in Table 1 below.

[0080] Table 1

[0081]

[0082] Those of ordinary skill in the art can understand that the above embodiments are specific examples for implementing the present invention, and in actual applications, various changes can be made in form and details without departing from the spirit and scope of the present invention.

Claims

1. A method for preparing triphenylphosphine, characterized in that: The method comprises the steps of: reacting triphenylphosphine oxide and triphenyl phosphite.

2. The method according to claim 1, characterized in that The reaction temperature is 250-380°C, most preferably 350°C.

3. The method according to claim 1, characterized in that The reaction time is 2 to 20 hours.

4. The method according to claim 1, characterized in that: The molar feed ratio of the triphenylphosphine oxide to the triphenyl phosphite is 1:1.5-0.95, and most preferably 1.

05.

5. The method according to claim 1, characterized in that The reaction is a solvent-free reaction.

6. The method according to claim 1, characterized in that The method of making triphenylphosphine oxide and triphenyl phosphite react as shown in the following reaction formula I comprises the following steps: mixing triphenylphosphine oxide and triphenyl phosphite for reaction at 250-380° C. for 2-20 hours.

7. The method according to claim 1, characterized in that The moisture content of the reaction raw materials in the reaction is ≤0.05%.

8. The method according to claim 1, characterized in that The reaction further comprises the step of separating triphenylphosphine.

9. The method according to claim 1, characterized in that: The separation of triphenylphosphine comprises the steps of: distilling the reaction product and collecting corresponding fractions; preferably, in the distillation device, collecting the fraction with a top temperature ≤ 160°C.

10. The method according to claim 1, characterized in that In the distillation device, the fraction with a top temperature of ≤160°C and the fraction with a top temperature of 168-180°C are collected respectively. The fraction with a top temperature of ≤160°C is triphenylphosphine, and the fraction with a top temperature of 168-180°C is triphenyl phosphate.

Images