A method for synthesizing dibutyl phosphite

Abstract

The application provides a synthesis method of dibutyl phosphite, comprising the following steps: feeding n-butanol added with a catalyst and phosphorus trichloride into a tubular reactor respectively to perform an esterification reaction, the esterification reaction temperature is less than or equal to 10 DEG C, the reaction residence time is less than or equal to 30 min, the reaction liquid flowing out after the reaction is neutralized, the neutralized reaction liquid is filtered to obtain a crude dibutyl phosphite product, and the crude dibutyl phosphite product is purified to obtain a dibutyl phosphite product; the catalyst comprises a quaternary ammonium base and / or an anion exchange resin; the functional groups of the anion exchange resin comprise quaternary ammonium groups. The application uses the tubular reactor to strengthen the mass transfer and heat transfer, shorten the dropping time and improve the reaction efficiency; in addition, the quaternary ammonium base / anion exchange resin is introduced as the catalyst, the catalyst has high catalytic activity and good selectivity, and the reaction product has high purity and high yield.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, and specifically to a method for synthesizing dibutyl phosphite. Background Technology

[0002] Dibutyl phosphite is an important organophosphorus compound with a significant role in fine chemicals. Industrially, it is mainly used as an extreme pressure anti-wear agent in lubricating oils. It can also be combined with appropriate amounts of alkaline rust inhibitors as an anti-rust and corrosion-inhibiting additive, and is used as an additive for gasoline fuel oils and a flame retardant for polymers.

[0003] There are many methods for synthesizing dibutyl phosphite, which can be summarized into two main types: (1) preparation by direct esterification of phosphoric acid with n-butanol. This method has a slow reaction rate and low product yield, so its development is limited and it has not yet been industrialized. (2) synthesis of dibutyl phosphite by direct esterification of phosphorus trichloride with anhydrous n-butanol. This method can be further divided into solvent method and non-solvent method: the solvent method is to directly react phosphorus trichloride with n-butanol in an organic medium at low temperature (generally below 10°C); the non-solvent method is to prepare it by two-step reaction of phosphorus trichloride with n-butanol under conditions such as solvent-free and negative pressure. The non-solvent method has a fast reaction rate, high product yield and good purity, but it requires high purity of phosphorus trichloride and has more complex operating conditions, which are not easy to control. The traditional synthesis process of dibutyl phosphite usually adopts a batch reactor, using phosphorus trichloride and n-butanol as raw materials for esterification reaction. However, batch reactors suffer from problems such as low mass and heat transfer efficiency, long reaction time, and numerous side reactions, making it difficult to improve product yield and purity.

[0004] Therefore, developing a synthesis method with high mass and heat transfer efficiency, easy process control, and the ability to effectively reduce side reactions and improve the yield and purity of dibutyl phosphite has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] In view of the technical problems existing in the background art, the present invention provides a method for synthesizing dibutyl phosphite, which aims to solve the problems of low mass and heat transfer efficiency, many side reactions, and difficulty in improving product yield and purity in traditional batch reaction processes.

[0006] In a first aspect, embodiments of the present invention provide a method for synthesizing dibutyl phosphite, comprising the following steps: Butanol with added catalyst and phosphorus trichloride are separately fed into tubular reactors for esterification reaction. The esterification reaction temperature is ≤10℃ and the reaction residence time is ≤30 min. The reaction liquid flowing out after the reaction is neutralized. The neutralized reaction liquid is filtered to obtain crude dibutyl phosphite. The crude dibutyl phosphite is purified to obtain dibutyl phosphite product. The catalyst includes quaternary ammonium bases and / or anion exchange resins; the functional groups of the anion exchange resins include quaternary ammonium groups.

[0007] Preferably, the amount of catalyst added is 0.1% to 1.5% of the mass of n-butanol.

[0008] Preferably, the quaternary ammonium base includes at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, and phenyltrimethylammonium hydroxide.

[0009] Preferably, the anion exchange resin is selected from at least one of 201×7, 717, D201, D202, D261, and D296.

[0010] Preferably, the molar ratio of n-butanol to phosphorus trichloride is (3.0~3.2):1.

[0011] Preferably, the flow rate of n-butanol with added catalyst is 1-4 mL / min, and the flow rate of phosphorus trichloride is 5-10 mL / min.

[0012] Preferably, the esterification reaction temperature is 5~8℃ and the reaction residence time is 15~25 min.

[0013] Preferably, the neutralization of the reaction solution flowing out after the reaction is specifically carried out by: neutralizing the flowing reaction solution with solid sodium hydroxide in a neutralization reaction vessel, controlling the neutralization reaction temperature to be ≤35℃, the neutralization reaction time to be ≤60 min, and the pH value of the neutralized reaction solution to be 6.5~7.5.

[0014] Preferably, the neutralization reaction temperature is controlled at 20~30℃ and the neutralization reaction time is controlled at 20~30 min.

[0015] Preferably, the purification method includes: subjecting crude dibutyl phosphite to vacuum distillation, wherein the vacuum distillation conditions are: vacuum degree of -0.1 to -0.08 MPa, top temperature of 90 to 100°C, and bottom temperature of 105 to 115°C.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: The method for synthesizing dibutyl phosphite provided by this invention utilizes the excellent mass transfer and heat exchange performance of a tubular reactor, which significantly shortens the dropping time compared to traditional batch reactors. Compared to microchannel reactors, its equipment cost is greatly reduced, thus lowering the production cost of dibutyl phosphite. The method for synthesizing dibutyl phosphite provided by this invention has a small molar ratio of n-butanol to phosphorus trichloride, reducing the amount of n-butanol used in the reaction and reducing the cost of n-butanol recovery. Furthermore, the reaction uses a quaternary ammonium base / anion exchange resin as a catalyst, which has high catalytic activity, low catalyst dosage, good thermal stability, good selectivity, and high product purity and high yield. Detailed Implementation

[0017] The embodiments of the technical solution of the present invention will be described in detail below. These embodiments are only used to illustrate the technical solution of the present invention more clearly, and are therefore merely examples and should not be used to limit the scope of protection of the present invention.

[0018] To address the problems of low mass and heat transfer efficiency, numerous side reactions, and difficulty in improving product yield and purity in traditional batch reactor processes, this invention provides a method for synthesizing dibutyl phosphite. By using a tubular reactor, mass and heat transfer is enhanced, the dropping time is shortened, and reaction efficiency is improved. This solves the problem of long reaction times required in conventional reactors, avoids or reduces the probability of side reactions, and helps to increase the yield of dibutyl phosphite. Furthermore, the introduction of a quaternary ammonium base / anion exchange resin as a catalyst results in high catalytic activity, low catalyst dosage, good thermal stability, good selectivity, and high product purity and yield.

[0019] In a first aspect, embodiments of the present invention provide a method for synthesizing dibutyl phosphite, comprising the following steps: Butanol with added catalyst and phosphorus trichloride are separately fed into tubular reactors for esterification reaction. The esterification reaction temperature is ≤10℃ and the reaction residence time is ≤30 min. The reaction liquid flowing out after the reaction is neutralized. The neutralized reaction liquid is filtered to obtain crude dibutyl phosphite. The crude dibutyl phosphite is purified to obtain dibutyl phosphite product. The catalyst includes quaternary ammonium bases and / or anion exchange resins; the functional groups of the anion exchange resins include quaternary ammonium groups.

[0020] In the technical solution of this invention embodiment, the present invention enhances the mass and heat transfer of the reaction process by introducing n-butanol with added catalyst and phosphorus trichloride into a tubular reactor for esterification reaction, avoiding the problem of side reactions caused by excessively high local temperature in traditional batch reactors. The reaction temperature is easy to control, and the overall reaction time is shortened. The reaction conditions are mild and easy to operate, and the production cost is low. At the same time, the quaternary ammonium base and the anion exchange resin with quaternary ammonium group can effectively catalyze the esterification reaction and reduce the activation energy of the reaction. It can also act as an acid-binding agent to remove hydrogen chloride generated in the reaction in time, thereby inhibiting side reaction pathways, further improving the selectivity of the target product, and effectively improving the yield and purity of dibutyl phosphite.

[0021] Furthermore, in some embodiments, the amount of catalyst added is 0.1% to 1.5% of the mass of n-butanol.

[0022] Furthermore, in some embodiments, the quaternary ammonium base includes at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, and phenyltrimethylammonium hydroxide.

[0023] Furthermore, in some embodiments, the anion exchange resin is selected from at least one of 201×7, 717, D201, D202, D261, and D296.

[0024] Furthermore, in some embodiments, the molar ratio of n-butanol to phosphorus trichloride is (3.0~3.2):1.

[0025] Furthermore, in some embodiments, the flow rate of n-butanol with added catalyst is 1-4 mL / min, and the flow rate of phosphorus trichloride is 5-10 mL / min.

[0026] Furthermore, in some embodiments, the flow rate of n-butanol with added catalyst is 2-3 mL / min, and the flow rate of phosphorus trichloride is 6-8 mL / min.

[0027] Furthermore, in some embodiments, the esterification reaction temperature is 5~8°C, and the reaction residence time is 15~25 min.

[0028] In the technical solution of this invention embodiment, by adjusting the flow rate, ratio, reaction temperature and residence time of the reactants, the reactants are fully and uniformly mixed in the tubular reactor, which not only ensures that the reaction proceeds fully, but also avoids side reactions caused by excessively long reaction residence time, thereby further improving the yield and purity of the product.

[0029] Furthermore, in some embodiments, the neutralization of the reaction liquid flowing out after the reaction specifically involves: neutralizing the flowing reaction liquid with solid sodium hydroxide in a neutralization reaction vessel, controlling the neutralization reaction temperature to be ≤35°C, the neutralization reaction time to be ≤60 min, and the pH value of the neutralized reaction liquid to be 6.5~7.5.

[0030] Furthermore, in some embodiments, the neutralization reaction temperature is controlled at 20~30°C, and the neutralization reaction time is controlled at 20~30 min.

[0031] Furthermore, in some embodiments, the purification method includes: subjecting crude dibutyl phosphite to vacuum distillation, wherein the vacuum distillation conditions are: vacuum degree of -0.1 to -0.08 MPa, top temperature of 90 to 100°C, and bottom temperature of 105 to 115°C.

[0032] In the technical solution of this invention embodiment, by purifying under reduced pressure distillation under the above parameter conditions, low-boiling-point impurities and residual raw materials in the crude product can be effectively removed, and finally a high-purity dibutyl phosphite product is obtained.

[0033] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0034] Example 1 A method for synthesizing dibutyl phosphite, the specific steps of which are as follows: (1) Add 1 kg of n-butanol to the mixing tank, and add 5 g of anion exchange resin catalyst (model 201×7, belonging to strong basic type I, with quaternary ammonium functional group [-N-1]). + (CH3)3OH - (The amount of catalyst is 0.5% of the mass of n-butanol), and the mixture is stirred and dispersed evenly to obtain a n-butanol solution containing the catalyst.

[0035] (2) The n-butanol solution containing the catalyst and phosphorus trichloride (purity ≥99%) are respectively delivered to the tubular reactor at a constant flow rate through metering pumps. The flow rate of the n-butanol solution is 2 mL / min and the flow rate of phosphorus trichloride is 6 mL / min. The molar ratio of phosphorus trichloride to n-butanol is 1:3.05. The tubular reactor is made of PTFE lined steel with an inner diameter of 10 mm and a total length of 20 m, and is divided into 4 temperature control zones.

[0036] (3) The temperature of the first section (inlet section, 5m in length) of the tubular reactor is controlled at 3℃, the temperature of the second section (5m in length) is controlled at 5℃, the temperature of the third section (5m in length) is controlled at 8℃, and the temperature of the fourth section (outlet section, 5m in length) is controlled at 10℃; the reaction pressure is 20kPa; the total residence time of the reactants in the tubular reactor is about 15 minutes.

[0037] (4) The reaction liquid flowing out of the reactor continuously enters the neutralization reactor (volume 100L, equipped with a stirring device and temperature control system), and solid sodium hydroxide is added at the same time to carry out the neutralization reaction. The neutralization temperature is controlled at 25℃ and the neutralization reaction time is 25min. The amount of sodium hydroxide added is controlled by the pH online monitoring instrument so that the pH value after neutralization is stable at 7.0~7.5.

[0038] (5) The neutralized material is filtered through a plate and frame filter press to remove sodium chloride and other salt solids, and crude dibutyl phosphite is obtained.

[0039] (6) The crude product is transferred to a vacuum distillation apparatus (equipped with a distillation column with a theoretical plate number ≥10) and distilled under vacuum conditions of -0.09MPa, top temperature of 95℃ and bottom temperature of 110℃. The top fraction is collected to obtain colorless and transparent dibutyl phosphite product.

[0040] The dibutyl phosphite product was analyzed and tested, and the results are as follows: yield 96.8%, purity 99.3% (determined by gas chromatography).

[0041] Example 2 A method for synthesizing dibutyl phosphite, the specific steps of which are as follows: (1) Add 1 kg of n-butanol to the mixing tank, and add 2 g of anion exchange resin catalyst (model D202, which is a strong basic type II with functional groups [-N]). + (CH3)2(CH2CH2OH)OH - (The amount of catalyst is 0.2% of the mass of n-butanol), and the mixture is stirred and dispersed evenly to obtain a n-butanol solution containing the catalyst.

[0042] (2) The n-butanol solution containing the catalyst and phosphorus trichloride (purity ≥99%) are respectively delivered to the tubular reactor at a constant flow rate through metering pumps. The flow rate of the n-butanol solution is 3 mL / min and the flow rate of phosphorus trichloride is 8 mL / min. The molar ratio of phosphorus trichloride to n-butanol is 1:3.02. The tubular reactor is made of PTFE lined steel with an inner diameter of 8 mm and a total length of 15 m.

[0043] (3) The temperature of the tubular reactor is controlled at 5~8℃ throughout the process, the reaction pressure is 20kPa, and the reaction residence time is about 8 minutes.

[0044] (4) The reaction liquid flowing out of the reactor continuously enters the neutralization reactor (volume 100L, equipped with a stirring device and temperature control system), and solid sodium hydroxide is added at the same time to carry out the neutralization reaction. The neutralization temperature is controlled at 15℃ and the neutralization reaction time is 30min. The amount of sodium hydroxide added is controlled by the pH online monitoring instrument so that the pH value after neutralization is stable at 6.5~7.0.

[0045] (5) The neutralized material is filtered through a plate and frame filter press to remove sodium chloride and other salt solids, and crude dibutyl phosphite is obtained.

[0046] (6) The crude product is transferred to a vacuum distillation apparatus (equipped with a distillation column with ≥10 theoretical plates) and distilled under vacuum conditions of -0.09 MPa, top temperature of 90°C and bottom temperature of 105°C. The top fraction is collected to obtain colorless and transparent dibutyl phosphite product.

[0047] The dibutyl phosphite product was analyzed and tested, and the results are as follows: yield 95.2%, purity 99.1% (determined by gas chromatography).

[0048] The results of this example show that excellent product yield and purity can still be obtained under conditions of lower catalyst dosage and lower reaction temperature, and the reaction time is further shortened.

[0049] Example 3 A method for synthesizing dibutyl phosphite, the specific steps of which are as follows: (1) Add 10 kg of n-butanol to the mixing tank, add 150 g of tetraethylammonium hydroxide (TEAH) catalyst (the amount of catalyst is 1.5% of the mass of n-butanol), stir and mix evenly to obtain a n-butanol solution containing the catalyst.

[0050] (2) The n-butanol solution containing the catalyst and phosphorus trichloride (purity ≥99%) are respectively delivered to the tubular reactor at a constant flow rate through metering pumps. The flow rate of the n-butanol solution is 2 mL / min and the flow rate of phosphorus trichloride is 6 mL / min. The molar ratio of phosphorus trichloride to n-butanol is 1:3.1. The tubular reactor is made of PTFE lined steel with an inner diameter of 15 mm and a total length of 30 m, and is divided into 3 temperature control zones.

[0051] (3) The temperature of the first section (10m long) of the tubular reactor is controlled at 8℃, the temperature of the second section (10m long) is controlled at 10℃, and the temperature of the third section (10m long) is controlled at 8℃; the reaction pressure is 20kPa; the total residence time of the reactants in the tubular reactor is about 20 minutes.

[0052] (4) The reaction liquid flowing out of the reactor continuously enters the neutralization reactor, and solid sodium hydroxide is added at the same time to carry out the neutralization reaction. The neutralization temperature is controlled at 30℃ and the neutralization reaction time is 20min. The amount of sodium hydroxide added is controlled by the pH online monitoring instrument so that the pH value after neutralization is stable at 7.0~7.5.

[0053] (5) The neutralized material is filtered through a plate and frame filter press to remove sodium chloride and other salt solids, and crude dibutyl phosphite is obtained.

[0054] (6) The crude product is transferred to a vacuum distillation apparatus (equipped with a distillation column with a theoretical plate number ≥10) and distilled under vacuum conditions of -0.085MPa, top temperature of 98℃ and bottom temperature of 115℃. The top fraction is collected to obtain colorless and transparent dibutyl phosphite product.

[0055] The dibutyl phosphite product was analyzed and tested, and the results are as follows: yield 97.5%, purity 99.5% (determined by gas chromatography).

[0056] The results of this embodiment show that the process of the present invention maintains excellent performance under scale-up production conditions and is suitable for large-scale industrial production.

[0057] Comparative Example 1 A traditional batch reactor (50L capacity, equipped with a stirring and cooling system) was used under nitrogen protection to mix 1kg of n-butanol and 5g of anion exchange resin catalyst (model 201×7, a strongly basic type I catalyst with quaternary ammonium functional groups [-N]). + (CH3)3OH - The catalyst (0.5% of the mass of n-butanol) was added to the reactor and cooled to 5°C. Then, phosphorus trichloride (molar ratio 1:3.05) was slowly added dropwise over 2 hours, maintaining the temperature at 5-10°C during the addition. After the addition was complete, the reaction continued for 1 hour. The subsequent neutralization, filtration, and distillation steps were the same as in Example 1.

[0058] Product analysis results: yield 88.5%, purity 97.2%, total reaction time over 3 hours. Compared with Example 1 of this invention, the traditional batch reactor process has a yield 8.3 percentage points lower, purity 2.1 percentage points lower, and reaction time 12 times longer, fully demonstrating the significant superiority of the technical solution of this invention.

[0059] Comparative Example 2 The difference between this comparative example and Example 1 is that the anion exchange resin catalyst is replaced with the traditional base catalyst triethylamine, and the amount of catalyst used is 5g. The remaining reaction conditions and post-treatment steps are the same as in Example 1.

[0060] Product analysis results: yield 90.2%, purity 98.3%. Compared with Example 1, the yield decreased by 6.6 percentage points and the purity decreased by 1.0 percentage point. It can be seen that the quaternary ammonium base / anion exchange resin catalyst used in this invention has superior catalytic performance compared with traditional base catalysts, and can significantly improve the yield and purity of the product.

[0061] The working principle of the quaternary ammonium base / anion exchange resin catalyst in this invention is as follows: The esterification reaction of phosphorus trichloride with n-butanol continuously releases hydrogen chloride (HCl). The presence of HCl can destroy the already formed dibutyl phosphite, causing it to decompose and undergo side reactions, resulting in a decrease in product yield and purity. Therefore, an acid-binding agent must be used to fix the HCl in a timely manner during the reaction.

[0062] Traditional alkaline catalysts (such as triethylamine, pyridine and other organic amines) can be used as acid-binding agents, but their acid-binding ability is limited. Moreover, they exist in a homogeneous form in the reaction system and are difficult to separate and recover after the reaction. They need to be removed by post-treatment processes such as water washing, which not only increases the emission of waste gas, wastewater, and solid waste, but may also take away some of the products.

[0063] The present invention utilizes quaternary ammonium bases (such as tetramethylammonium hydroxide) and bases containing quaternary ammonium groups (e.g., [-N]). + (CH3)3OH - 〕、〔-N +(CH3)2(CH2CH2OH)OH - The strongly basic anion exchange resin has the following advantages: (1) Strong alkalinity: The quaternary ammonium group can completely dissociate into OH groups in aqueous solution. - Its alkalinity is close to that of NaOH / KOH, and its ability to capture HCl is stronger than that of traditional organic amine acid-binding agents. (2) In-situ binding of acid and inhibition of side reactions: Quaternary ammonium base or quaternary ammonium group on resin can combine with HCl generated in the reaction in time, fix HCl in the form of quaternary ammonium hydrochloride, and inhibit the decomposition of dibutyl phosphite by HCl. (3) Good selectivity: The alkalinity of the quaternary ammonium base / quaternary ammonium salt resin is moderate and controllable, which is conducive to the selective generation of diester (dibutyl phosphite) and reduces the byproducts of complete esterification into triester. (4) Recyclable and reusable: Anion exchange resin is a heterogeneous catalyst. After the reaction, it can be separated and regenerated by simple filtration, which significantly reduces the cost of catalyst and the emission of waste. (5) Good thermal stability: Quaternary ammonium anion exchange resin has good thermal and chemical stability and is suitable for continuous tubular reaction processes.

[0064] In summary, the method for synthesizing dibutyl phosphite provided by this invention employs a tubular reactor combined with a quaternary ammonium base / anion exchange resin catalyst. Compared with the traditional batch synthesis process, this method significantly improves mass and heat transfer efficiency, reduces reaction time from several hours to just over ten minutes, effectively suppresses side reactions, and significantly improves product yield and purity. Furthermore, the process exhibits good stability, maintaining high yield and purity even during scale-up production, making it suitable for large-scale industrial production and possessing promising industrial application prospects.

[0065] It should be noted that the present invention is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments that have the same structure and perform the same effects as the technical concept within the scope of the present invention are included within the scope of the present invention. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of the present invention, are also included within the scope of the present invention.

Claims

1. A method for synthesizing dibutyl phosphite, characterized in that, Includes the following steps: Butanol with added catalyst and phosphorus trichloride are separately fed into a tubular reactor for esterification reaction. The esterification reaction temperature is ≤10℃ and the reaction residence time is ≤30 min. The reaction liquid flowing out after the reaction is neutralized. The neutralized reaction liquid is filtered to obtain crude dibutyl phosphite. The crude dibutyl phosphite is purified to obtain dibutyl phosphite product. The catalyst comprises a quaternary ammonium base and / or anion exchange resin; the functional groups of the anion exchange resin include quaternary ammonium groups.

2. The method for synthesizing dibutyl phosphite according to claim 1, characterized in that, The amount of catalyst added is 0.1% to 1.5% of the mass of the n-butanol.

3. The method for synthesizing dibutyl phosphite according to claim 1, characterized in that, The quaternary ammonium base includes at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, and phenyltrimethylammonium hydroxide.

4. The method for synthesizing dibutyl phosphite according to claim 1, characterized in that, The anion exchange resin is selected from at least one of 201×7, 717, D201, D202, D261, and D296.

5. The method for synthesizing dibutyl phosphite according to claim 1, characterized in that, The molar ratio of n-butanol to phosphorus trichloride is (3.0~3.2):

1.

6. The method for synthesizing dibutyl phosphite according to claim 1, characterized in that, The flow rate of the catalyst-added n-butanol is 1~4 mL / min; And / or, the flow rate of the phosphorus trichloride is 5-10 mL / min.

7. The method for synthesizing dibutyl phosphite according to claim 1, characterized in that, The esterification reaction temperature is 5~8℃, and the reaction residence time is 15~25 min.

8. The method for synthesizing dibutyl phosphite according to claim 1, characterized in that, The neutralization of the reaction solution flowing out after the reaction is specifically carried out by: neutralizing the flowing reaction solution with solid sodium hydroxide in a neutralization reaction vessel, controlling the neutralization reaction temperature to be ≤35℃, the neutralization reaction time to be ≤60 min, and the pH value of the neutralized reaction solution to be 6.5~7.

5.

9. The method for synthesizing dibutyl phosphite according to claim 8, characterized in that, The neutralization reaction temperature was controlled at 20~30℃, and the neutralization reaction time was 20~30 min.

10. The method for synthesizing dibutyl phosphite according to claim 1, characterized in that, The purification method includes: vacuum distillation of crude dibutyl phosphite, wherein the vacuum distillation conditions are: vacuum degree of -0.1 to -0.08 MPa, top temperature of 90 to 100°C, and bottom temperature of 105 to 115°C.