Efficient preparation method of trioctyl phosphate

Abstract

The invention discloses an efficient preparation method of trioctyl phosphate, which specifically comprises the following steps: mixing a catalyst and isooctyl alcohol, dropwise adding phosphorus oxychloride under a low-temperature condition (5-15 DEG C), keeping the temperature at 15 DEG C for 0.5 hour after dropwise adding, starting vacuum, and keeping the temperature for 2-3 hours to remove a large amount of HCl generated by reaction; under the conditions that the temperature is 60-80 DEG C and the vacuum degree is 0.098 MPa or above, reaction liquid obtained after heat preservation is completed enters a film evaporator through a peristaltic pump, diester acyl chloride which does not completely react in the reaction liquid is rapidly reacted through a film scraper to generate trioctyl phosphate, meanwhile, generated HCl is rapidly taken out, integrated synthesis is achieved, side reactions are reduced, and crude trioctyl phosphate is obtained; and carrying out dealcoholization, neutralization, light component removal and molecular distillation on the crude product to obtain a trioctyl phosphate finished product. The method is simple in process, and in a crude product obtained after esterification synthesis, the byproduct dioctyl phosphate is less, the purity is high, and the reaction is rapid; and mass production can be carried out by using existing equipment.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical industry, and particularly relates to a method for efficiently preparing trioctyl phosphate. Background Art

[0002] Trioctyl phosphate is a phosphate compound. It is a colorless to light yellow liquid with low volatility. Trioctyl phosphate is mainly used as a solvent in the anthraquinone method of hydrogen peroxide production process. It has low volatility and high extraction distribution coefficient, making it an ideal solvent. Trioctyl phosphate can also be used as a cold-resistant flame-retardant plasticizer for vinyl resin, cellulose resin, polyurethane, and synthetic rubber. At the same time, trioctyl phosphate is also an efficient lubricant additive and an auxiliary agent for the production of agricultural chemical products.

[0003] At present, Guangxi Xingda Fine Chemicals has disclosed a method for synthesizing trioctyl phosphate (CN 115974914B). Ammonia is gradually introduced during the reaction, and the ammonia introduction rate and reaction rate must match so that the hydrogen chloride produced during the reaction is completely reacted by ammonia to form ammonium chloride. However, a large amount of water needs to be added to wash the material during the post-treatment process in this process, which results in a large cost loss. However, in the conventional process of removing HCl in the esterification reaction stage, the removal efficiency of the hydrogen chloride gas is low by using negative pressure, and only about 70% of the hydrogen chloride gas is removed. There is also a large amount of hydrogen chloride gas dissolved in octanol, which inhibits the main reaction of generating TOP, easily triggers more side reactions, and reduces the yield of trioctyl phosphate. The molecular formula of TOP is as follows:

[0004] Summary of the invention

[0005] In view of the above problems existing in the prior art, the object of the present invention is to provide an efficient preparation method of trioctyl phosphate. The present invention firstly reacts phosphorus oxychloride with isooctyl alcohol at low temperature to generate diisooctyl phosphate chloride, and then the reaction liquid is continuously and thoroughly reacted through a thin film evaporator, HCl can be completely removed, the reaction can be continuously and thoroughly reacted, and the yield of triester is increased.

[0006] The technical solution adopted by the present invention is as follows:

[0007] The highly efficient preparation method of trioctyl phosphate comprises the following steps:

[0008] Step 1: Under low temperature conditions and the catalysis of Lewis acid, phosphorus oxychloride reacts with excess isooctyl alcohol to obtain a mixture of diester chloride and a small amount of triester;

[0009] Step 2: pump the product of step 1 into a thin film evaporator under high vacuum, continue the reaction and remove HCl generated by the reaction to obtain a crude product of trioctyl phosphate;

[0010] Step 3: The crude product obtained in step 2 is subjected to vacuum distillation dealcoholization, alkali washing, vacuum distillation light removal, filtration, and molecular distillation to obtain the target product trioctyl phosphate (TOP).

[0011] The molecular formula of trioctyl phosphate is as follows:

[0012]

[0013] Furthermore, the Lewis acid in step 1 includes anhydrous magnesium chloride, anhydrous aluminum chloride, anhydrous zinc chloride, titanium tetrachloride or butyl titanate, preferably titanium tetrachloride; the amount of the Lewis acid added is 0.05%-1.1% of phosphorus oxychloride, preferably 0.7-0.9%.

[0014] Furthermore, the molar ratio of phosphorus oxychloride to isooctyl alcohol in step 1 is 1:3-7, and most preferably 1:4.5-5.5.

[0015] Furthermore, in step 1, the Lewis acid is mixed with an excess of isooctyl alcohol and cooled to a low temperature of 5-10° C., phosphorus oxychloride is added dropwise, and the temperature of the reaction solution is controlled not to exceed 15° C. After the addition is completed, the mixture is kept warm at 10-15° C. for 2-4 hours.

[0016] Furthermore, the heat preservation time after the phosphorus oxychloride is dripped is 2.5-3h.

[0017] Furthermore, the reaction temperature of the thin film evaporator in step 2 is 60-100° C., preferably 60-80° C., and the vacuum degree is above 0.098 MPa.

[0018] Furthermore, in step 3, the vacuum distillation dealcoholization temperature is 120-200° C., preferably 140-150° C., the vacuum degree is above 0.099 MPa, and the vacuum distillation dealcoholization is performed until the isooctyl alcohol content is ≤0.1%.

[0019] Furthermore, in step 3, the alkaline washing is neutralized with a saturated sodium carbonate aqueous solution, the pH is adjusted to 7-9, and stirred at 50-70°C for 0.5-2h.

[0020] Furthermore, in step 3, the vacuum distillation for light removal is carried out under vacuum, and the heating temperature is adjusted so that the system temperature gradually rises from the alkali washing temperature, and the distillate is collected until the system temperature reaches 100-120°C, and the operation is carried out until no distillate flows out and the vacuum degree is above 0.099MPa.

[0021] Furthermore, step 3 further includes a filtration operation after vacuum distillation to remove light substances, and the crude product obtained after filtration is then subjected to molecular distillation, the molecular distillation temperature is 140-220°C, preferably 160-190°C, and the vacuum degree is above 0.099MPa.

[0022] By adopting the defined technology, compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1) In the preparation method of the present invention, phosphorus oxychloride and isooctyl alcohol are reacted to generate diisooctyl phosphate chloride, and a large amount of HCl produced by the reaction is first removed at a low temperature to avoid inhibition of the positive reaction when the temperature is raised in a thin film evaporator to reduce the occurrence of side reactions;

[0024] 2) The present invention reduces the steps of water washing, salt washing, etc. in the post-process, reduces the generation and treatment of waste water, saves costs, and simplifies the overall process.

[0025] The esterification in Chinese patent CN116284111A is carried out under the condition of "the vacuum degree is reduced to (-0.05-0.1) MPa, and the reaction is kept at 75-80℃ for 3-4h". Although the esterification process is accompanied by the rapid removal of HCl, the present application also conducted a small test experiment with low vacuum (vacuum degree 0.098MPa) and a temperature of 75-80℃. It takes at least 1-2 hours to completely remove HCl, and if the high temperature is kept for too long, HCl will react with triester to decompose triester into diester. In the present invention, the reaction liquid is in a high temperature state for a very short time when passing through the thin film evaporator, and the possibility of triester decomposition while removing HCl is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the NMR image of Example 1 of the present invention after the esterification reaction, wherein the content of phosphorus oxychloride converted into triester accounts for 97.82%, and the content of diester accounts for 2.18%. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0028] Detection instrument: Nuclear magnetic resonance; Gas chromatograph, model: Shimadzu GC-2010Pro.

[0029] Embodiment 1:

[0030] 1) In the reaction kettle, add 14.8 kg of isooctyl alcohol and 31.5 g of titanium tetrachloride. When the temperature drops to 5-10 °C, start to add 3.5 kg of phosphorus oxychloride dropwise. After the addition is complete, keep the mixture at 15 °C for 3 hours.

[0031] 2) The reaction liquid after low temperature insulation is fed into a thin film evaporator through a peristaltic pump, with a feed rate of 100 g / min, a vacuum degree of 0.098 MPa, and a temperature of 80° C. The HCl produced by the reaction is quickly taken away and absorbed by a buffer tank and a recovery tank. Finally, a crude product is obtained after the reaction, wherein the content of the diester is 2.18%, the content of the triester is 97.82%, and there is no obvious peak of dioctyl phosphate chloride intermediate by phosphorus spectrum detection.

[0032] 3) The crude product is placed under vacuum conditions (vacuum degree is 0.099 MPa), and after the reaction is completed, the heating temperature is adjusted so that the temperature of the reactor system gradually reaches 145° C., and a distillate begins to flow out at about 80° C. After the isooctyl alcohol content in the detection system reaches the index (isooctanol content ≤ 0.1%), the alcohol distillation is stopped to obtain a crude trioctyl phosphate product.

[0033] 4) After the alcohol is evaporated, a sample is taken to test the acid value of the crude trioctyl phosphate, and then a saturated sodium carbonate aqueous solution is added for neutralization, the pH is adjusted to 7-9, and stirred at 60° C. for 1 hour.

[0034] 5) After neutralization, distill and dehydrate, turn on the vacuum (vacuum degree 0.099 MPa), adjust the heating temperature, gradually increase the system temperature from the alkali washing temperature, collect the distillate until the system temperature reaches 120°C, and operate until no distillate flows out and the vacuum degree is above 0.099 MPa.

[0035] 6) After the dehydration is completed, the temperature is lowered to about 50° C. and filtered (the purpose of filtering is to filter most of the sodium diester salt and the catalyst). The crude product is treated by molecular distillation. The temperature of the molecular distillation device is initially set at 160° C., the vacuum degree is above 0.099 MPa, the feed rate and temperature are adjusted according to the actual situation, and the light phase is the trioctyl phosphate product. When there is no fraction in the light phase, 9.37 kg of trioctyl phosphate finished product is finally obtained with a purity of more than 99%.

[0036] Figure 1 This is the characterization result of the product of step 2 in Example 1 of the present invention. In the esterification stage, the position of the triester in the NMR was determined to be -0.48 ppm, and the position of the diester was 0.06 ppm. Figure 1 The results showed that the esterification stage had been completed and the diester content was low.

[0037] Embodiment 2:

[0038] 1) In the reaction kettle, add 18.7 kg of isooctyl alcohol and 32.0 g of titanium tetrachloride. When the temperature drops to 5-10 °C, start to add 4.0 kg of phosphorus oxychloride dropwise. After the addition is complete, keep the mixture at 15 °C for 3 hours.

[0039] 2) The reaction liquid after low temperature insulation is fed into a thin film evaporator through a peristaltic pump, with a feed rate of 100 g / min, a vacuum degree of 0.098 MPa, and a temperature of 70°C, and the HCl produced by the reaction is quickly taken away and absorbed by a buffer tank and a recovery tank. Finally, a crude product is obtained after the reaction, wherein the content of the diester is 2.90%, the content of the triester is 97.10%, and there is no obvious peak of dioctyl phosphate chloride intermediate by phosphorus spectrum detection.

[0040] 3) After the crude product is placed under vacuum conditions (vacuum degree is 0.099 MPa), the heating temperature is adjusted so that the temperature of the reactor system gradually reaches 145° C., and a fraction begins to flow out at 80° C. After the isooctyl alcohol content in the detection system reaches the index (isooctanol content ≤ 0.1%), the alcohol distillation is stopped to obtain a crude product of trioctyl phosphate.

[0041] 4) After the alcohol is evaporated, a sample is taken to test the acid value of the crude trioctyl phosphate, and then a saturated sodium carbonate aqueous solution is added for neutralization, the pH is adjusted to 7-9, and stirred at 60° C. for 1 hour.

[0042] 5) After neutralization, distill and dehydrate, turn on the vacuum (vacuum degree 0.099 MPa), adjust the heating temperature, gradually increase the system temperature from the alkali washing temperature, collect the distillate until the system temperature reaches 120°C, and operate until no distillate flows out and the vacuum degree is above 0.099 MPa.

[0043] 6) After the dehydration is completed, the temperature is lowered to about 50° C. and filtered. The crude product is treated by molecular distillation. The temperature of the molecular distillation device is initially set at 160° C., the vacuum degree is above 0.099 MPa, the feed rate and temperature are adjusted according to the actual situation, and the light phase is the trioctyl phosphate product. When there is no fraction in the light phase, 10.63 kg of trioctyl phosphate finished product is finally obtained with a purity of more than 99%.

[0044] Embodiment 3:

[0045] 1) In the reaction kettle, add 11.5 kg of isooctyl alcohol and 21.0 g of titanium tetrachloride. When the temperature drops to 5-10 °C, start to add 3.0 kg of phosphorus oxychloride dropwise. After the addition is complete, keep the mixture at 15 °C for 3 hours.

[0046] 2) The reaction liquid after low temperature insulation is fed into a thin film evaporator through a peristaltic pump, with a feed rate of 100 g / min, a vacuum degree of 0.098 MPa, and a temperature of 60° C. The HCl produced by the reaction is quickly taken away and absorbed by a buffer tank and a recovery tank. Finally, a crude product is obtained after the reaction, wherein the content of the diester is 3.11%, the content of the triester is 96.89%, and there is no obvious peak of dioctyl phosphate chloride intermediate by phosphorus spectrum detection.

[0047] 3) The crude product is placed under vacuum conditions (vacuum degree is 0.099 MPa), and after the reaction is completed, the heating temperature is adjusted so that the temperature of the reactor system gradually reaches 145° C., and a distillate begins to flow out at about 80° C. After the isooctyl alcohol content in the detection system reaches the index (isooctanol content ≤ 0.1%), the alcohol distillation is stopped to obtain a crude trioctyl phosphate product.

[0048] 4) After the alcohol is evaporated, a sample is taken to test the acid value of the crude trioctyl phosphate, and then a saturated sodium carbonate aqueous solution is added for neutralization, the pH is adjusted to 7-8, and stirred at 60° C. for 1 hour.

[0049] 5) After neutralization, distill and dehydrate, turn on the vacuum (vacuum degree 0.099 MPa), adjust the heating temperature, gradually increase the system temperature from the alkali washing temperature, collect the distillate until the system temperature reaches 120°C, and operate until no distillate flows out and the vacuum degree is above 0.099 MPa.

[0050] 6) After the dehydration is completed, the temperature is lowered to about 50° C. and filtered. The crude product is treated by molecular distillation. The temperature of the molecular distillation device is initially set at 160° C., the vacuum degree is above 0.099 MPa, the feed rate and temperature are adjusted according to the actual situation, and the light phase is the trioctyl phosphate product. When there is no fraction in the light phase, 7.95 kg of trioctyl phosphate finished product is finally obtained with a purity of more than 99%.

Claims

1. An efficient preparation method of trioctyl phosphate, characterized in that The following steps are involved: Step 1: Under low temperature conditions and the catalysis of Lewis acid, phosphorus oxychloride reacts with excess isooctyl alcohol to obtain a mixture of diester chloride and a small amount of triester; Step 2: pump the product of step 1 into a thin film evaporator under high vacuum, continue the reaction and remove HCl generated by the reaction to obtain a crude product of trioctyl phosphate; Step 3: The crude product obtained in step 2 is subjected to vacuum distillation dealcoholization, alkali washing, vacuum distillation light removal, and molecular distillation to obtain the target product trioctyl phosphate TOP. The molecular formula of trioctyl phosphate is as follows:

2. A highly efficient method for preparing trioctyl phosphate according to claim 1, characterized in that The Lewis acid in step 1 includes anhydrous magnesium chloride, anhydrous aluminum chloride, anhydrous zinc chloride, titanium tetrachloride or butyl titanate, preferably titanium tetrachloride; the feeding amount of the Lewis acid is 0.05%-1.1% of phosphorus oxychloride, preferably 0.7-0.9%.

3. A highly efficient method for preparing trioctyl phosphate according to claim 1, characterized in that The molar ratio of phosphorus oxychloride to isooctyl alcohol in step 1 is 1:3-7, and most preferably 1:4.5-5.

5.

4. A highly efficient method for preparing trioctyl phosphate according to claim 1, characterized in that In step 1, the Lewis acid is mixed with an excess of isooctyl alcohol and cooled to a low temperature of 5-10° C., phosphorus oxychloride is added dropwise, and the temperature of the reaction solution is controlled not to exceed 15° C. After the addition is completed, the mixture is kept warm at 10-15° C. for 2-4 hours.

5. A highly efficient method for preparing trioctyl phosphate according to claim 4, characterized in that The heat preservation time after the phosphorus oxychloride is dripped is 2.5-3h.

6. A highly efficient method for preparing trioctyl phosphate according to claim 1, characterized in that The reaction temperature of the thin film evaporator in step 2 is 60-100° C., preferably 60-80° C., and the vacuum degree is above 0.098 MPa.

7. A highly efficient method for preparing trioctyl phosphate according to claim 1, characterized in that In step 3, the vacuum distillation dealcoholization temperature is 120-200° C., preferably 140-150° C., the vacuum degree is above 0.099 MPa, and the vacuum film dealcoholization is carried out to an isooctyl alcohol content of ≤0.1%.

8. A highly efficient method for preparing trioctyl phosphate according to claim 1, characterized in that In step 3, the alkaline washing is carried out by neutralizing with a saturated sodium carbonate aqueous solution, adjusting the pH to 7-9, and stirring at 50-70° C. for 0.5-2 h.

9. A highly efficient method for preparing trioctyl phosphate according to claim 1, characterized in that In step 3, the vacuum distillation is carried out under vacuum, and the heating temperature is adjusted to gradually increase the system temperature from the alkali washing temperature, and the distillate is collected until the system temperature reaches 100-120°C. The operation is carried out until no distillate flows out and the vacuum degree is above 0.099MPa.

10. A highly efficient method for preparing trioctyl phosphate according to claim 1, characterized in that Step 3 includes a filtration operation after vacuum distillation to remove light, and the crude product obtained after filtration is then subjected to molecular distillation. The molecular distillation temperature is 140-220°C, preferably 160-190°C, and the vacuum degree is above 0.099MPa.

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