A process for the synthesis of dibutyltin dibenzoate

Abstract

The application discloses a method for synthesizing dibutyl tin dibenzoate, and relates to the technical field of organic tin series chemicals preparation. The method comprises the following steps: (1) adding lye into a reactor, and then adding benzoic acid after starting stirring to perform preliminary constant-temperature reaction; (2) when the preliminary constant-temperature reaction reaches a requirement, dropwise adding dibutyl tin dichloride, and continuously performing constant-temperature reaction after the dropwise adding is completed; (3) after the reaction is completed, stopping stirring, standing and separating phases, removing a water phase rich in chlorine ions, and collecting colorless to light yellow oily liquid; and (4) washing, drying and filtering the collected oily liquid to obtain dibutyl tin dibenzoate product. The synthesis process does not need to use any organic solvent and catalyst, and can prepare dibutyl tin dibenzoate meeting the use requirements of high-molecular oil paint, ink and coating under mild reaction conditions, and has the characteristics of short process route, low equipment requirement, simple operation, high product purity and the like.

Description

Technical Field

[0001] This invention relates to the field of organotin chemical preparation technology, specifically to a method for synthesizing dibutyltin dibenzoate. Background Technology

[0002] Dibutyltin dibenzoate, chemical formula C 22 H 28 O4Sn is an important class of organotin compounds. Currently, the market demand for dibutyltin dibenzoate is growing, especially in the polymer paint, ink and coating industry, where its role as an esterification catalyst and drying agent is irreplaceable.

[0003] However, existing synthesis methods either suffer from environmental pollution problems caused by the use of organic solvents or face the dilemma of limited large-scale production due to high raw material costs.

[0004] Therefore, developing a green, environmentally friendly, and low-cost synthesis method can not only meet the market demand for dibutyltin dibenzoate, but also promote the sustainable development of related industries, reduce environmental impact, and is of great significance to the industrial production of dibutyltin dibenzoate. Summary of the Invention

[0005] In view of this, the present invention provides a method for synthesizing dibutyltin dibenzoate that is simple to operate, low in cost, and environmentally friendly.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A method for synthesizing dibutyltin dibenzoate includes the following steps: (1) Add the alkaline solution to the reactor, turn on the stirring and add benzoic acid to carry out a preliminary isothermal reaction; (2) When the initial isothermal reaction reaches the required level, add dibutyltin dichloride dropwise, and continue the isothermal reaction after the dropwise addition is completed; (3) After the reaction is complete, stop stirring, let stand and separate the phases, remove the aqueous phase rich in chloride ions, and collect the colorless to pale yellow oily liquid; (4) The collected oily liquid was washed with water, dried and filtered to obtain dibutyltin dibenzoate product.

[0008] Synthesis route:

[0009] Furthermore, the alkaline solution in step (1) is a sodium hydroxide solution, a potassium hydroxide solution, or ammonia water, and the mass concentration of the alkaline solution is 10%.

[0010] Further, in step (1), benzoic acid and alkaline solution are fed in a mass ratio of 1:(1.53~5.05).

[0011] Furthermore, the initial isothermal reaction temperature in step (1) is 50~60℃, the initial isothermal reaction time is 15~30 minutes, and the stirring speed is 400r / min.

[0012] Furthermore, in step (2), the dibutyltin dichloride is fed in a mass ratio of benzoic acid: dibutyltin dichloride = 1:1.25.

[0013] Furthermore, in step (2), the temperature for the continued constant temperature reaction is 75~80℃, the reaction time is 3 hours, and the dropping rate of dibutyltin dichloride is 20kg / min.

[0014] Furthermore, the settling time for phase separation in step (3) is 30 minutes.

[0015] Furthermore, in step (4), each wash lasts 60 minutes, followed by 30 minutes of standing. The washes are repeated 3 times, and the product is filtered while still hot after drying.

[0016] Furthermore, the drying in step (4) is vacuum drying, with a vacuum degree of -0.1 MPa, a drying temperature of 100°C, and a drying time of 2 hours.

[0017] Furthermore, the filtration in step (4) uses a filter with a pore size of 0.2 μm.

[0018] The beneficial effects of adopting the above-mentioned further technical solutions are as follows: Compared with the prior art, the present invention has the following beneficial technical effects: (1) After the reaction is completed, both the organic phase and the brine phase are liquid and immiscible. The static phase separation desalination is adopted to make the chloride-rich brine phase more thoroughly separated, thereby effectively reducing the chloride content in the organic phase. The product has high purity, and the purity is ≥99% as determined by GC.

[0019] (2) The synthesis method provided by the present invention does not require the use of organic solvents and catalysts, thus avoiding the environmental pollution problems caused by the use of organic solvents in traditional methods, which is in line with the development concept of green chemistry.

[0020] (3) This synthesis process can prepare dibutyltin dibenzoate that meets the requirements of polymer paints, inks and coatings under mild reaction conditions. The raw materials used in this invention are relatively inexpensive, and the process route is short, the equipment requirements are low, and the operation is simple, which is conducive to large-scale industrial production, can significantly reduce production costs and improve production efficiency. The prepared dibutyltin dibenzoate product has stable quality and excellent performance, meeting the requirements of polymer paints, inks and coatings and other industries. Attached Figure Description

[0021] Figure 1 This is a process flow diagram for the synthesis of dibutyltin dibenzoate.

[0022] Figure 2 The image shows the C-NMR spectrum of dibutyltin dibenzoate in Example 1.

[0023] Figure 3 The NMR spectrum of dibutyltin dibenzoate in Example 1 is shown in H-ray.

[0024] Figure 4 This is a GC detection image of dibutyltin dibenzoate from Example 1. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1 The method for synthesizing dibutyltin dibenzoate involves adding 720 kg of a 10% sodium hydroxide solution to a reaction vessel, starting the stirrer, adding 200 kg of benzoic acid, and heating the mixture with steam. The stirring speed is 400 r / min, raising the temperature inside the vessel to 50°C, and maintaining this constant temperature for 30 minutes. Subsequently, 249 kg of dibutyltin dichloride is added dropwise from a feeding vessel to the reaction vessel at a rate of 20 kg / min. After the addition is complete, the temperature of the reaction vessel is raised to 75-80°C and maintained for 3 hours. After the reaction is complete, stirring is stopped, and the mixture is allowed to stand for 30 minutes for phase separation. The lower organic phase is separated and transferred to a washing vessel for washing, while the upper aqueous phase is discharged into the wastewater system. 1200 kg of pure water was transferred into the washing vessel to wash the organic phase (the washing water volume was approximately 3 times the mass of the organic phase). Washing lasted 60 minutes, followed by 30 minutes of settling and phase separation. This washing process was repeated 3 times. The first wash water phase was directly discharged into the wastewater treatment system, while the second and third wash water phases were discharged into a storage tank for the next batch of product washing. The washed organic phase was transferred into a drying vessel, and the vacuum chamber was used to evacuate the drying vessel to a negative pressure (-0.1 MPa). Drying was carried out at 100°C for 2 hours. After drying, the product was filtered while still hot through a precision filter with a pore size of 0.2 μm, yielding 384.89 kg of a pale yellow oily liquid product. The tin content was 25.02%, the chlorine content was 0.18%, the sodium content was 0.04%, the Pt-Co content was 62, and the purity was 99.07%. Figure 4 The yield was 98.8%.

[0027] Example 2 The method for synthesizing dibutyltin dibenzoate involves adding 2527 kg of a 10% potassium hydroxide solution to a reaction vessel, starting the stirrer, adding 500 kg of benzoic acid, and heating the mixture with steam. The stirring speed is 400 r / min, raising the temperature inside the vessel to 50°C, and maintaining this constant temperature for 30 minutes. Subsequently, 623 kg of dibutyltin dichloride is added dropwise from a feeding vessel to the reaction vessel at a rate of 20 kg / min. After the addition is complete, the temperature of the reaction vessel is raised to 75-80°C and maintained for 3 hours. After the reaction is complete, stirring is stopped, and the mixture is allowed to stand for 30 minutes for phase separation. The lower organic phase is separated and transferred to a washing vessel for washing, while the upper aqueous phase is discharged into the wastewater system. 3000 kg of pure water was transferred into the washing vessel to wash the organic phase (the washing water volume was approximately 3 times the mass of the organic phase). Washing was performed for 60 minutes, followed by 30 minutes of settling and phase separation. This washing process was repeated three times. The first wash water phase was directly discharged into the wastewater treatment system, while the second and third wash water phases were discharged into a storage tank for the next batch of product washing. The washed organic phase was then transferred into a drying vessel. A vacuum pump was used to evacuate the drying vessel to a negative pressure (-0.1 MPa), and the product was dried at 100°C for 2 hours. After drying, the product was filtered while still hot through a precision filter with a pore size of 0.2 μm, yielding 960.12 kg of a pale yellow oily liquid product. The product contained 25.10% tin, 0.12% chlorine, 0.05% sodium, and had a Pt-Co content of 53, a purity of 99.22%, and a yield of 98.5%.

[0028] Example 3 The method for synthesizing dibutyltin dibenzoate involves adding 766 kg of ammonia solution with a mass concentration of 10% to a reaction vessel. After stirring, 500 kg of benzoic acid is added, and the mixture is heated with steam. The stirring speed is 400 r / min, and the temperature inside the vessel is raised to 50°C. This temperature is maintained for 30 minutes. Subsequently, 622 kg of dibutyltin dichloride is added dropwise from a feeding vessel to the reaction vessel at a rate of 20 kg / min. After the addition is complete, the temperature of the reaction vessel is raised to 75-80°C and maintained for 3 hours. After the reaction is completed, stirring is stopped, and the mixture is allowed to stand for 30 minutes for phase separation. The lower organic phase is separated and transferred to a washing vessel for washing, while the upper aqueous phase is discharged into the wastewater system. 3000 kg of pure water was transferred into the washing vessel to wash the organic phase (the washing water volume was approximately 3 times the mass of the organic phase). Washing was performed for 60 minutes, followed by 30 minutes of settling and phase separation. This washing process was repeated three times. The first wash water phase was directly discharged into the wastewater treatment system, while the second and third wash water phases were discharged into a storage tank for the next batch of product washing. The washed organic phase was then transferred into a drying vessel. A vacuum pump was used to evacuate the drying vessel to a negative pressure (-0.1 MPa), and the product was dried at 100°C for 2 hours. After drying, the product was filtered while still hot through a precision filter with a pore size of 0.2 μm. 958 kg of a pale yellow oily liquid product was obtained, with a tin content of 24.98%, a chlorine content of 0.18%, a sodium content of 0.07%, a Pt-Co ratio of 68, a purity of 99.35%, and a yield of 98.3%.

[0029] Currently, there are three main processes for synthesizing dibutyl benzoate: one is the direct reaction of sodium benzoate with dibutyltin dichloride; the second is the direct reaction of benzoic acid with dibutyltin oxide; and the third is the process described in this paper. Compared with the first and second processes, this method uses lower-cost raw materials, has a shorter process, and is more suitable for large-scale production.

[0030] The screening experiments and data for key technical parameters or raw materials are as follows: Cost calculations showed that sodium benzoate and dibutyltin oxide were significantly more expensive than benzoic acid and dibutyltin dichloride. Therefore, benzoic acid, alkali solution, and dibutyltin dichloride were directly selected as raw materials. After determining the process route, the control conditions for the reaction were studied. Orthogonal experiments revealed that factors such as the amount of alkali solution, alkali solution concentration, reaction temperature, reaction time, and feeding rate all affected the product quality indicators. Therefore, the above control conditions were studied in detail. Compared with Example 1, the comparative examples were identical to Example 1 except for the process parameters in Tables 1-6. The key process parameter screening experiments and data are as follows: Saponification reaction stage: 1. Screening of alkali (taking sodium hydroxide as an example) dosage: Table 1. Screening results of alkali (taking sodium hydroxide as an example) dosage.

[0031] Note: The qualified tin content of dibutyltin dibenzoate is 24.98% ± 0.5%, and the dosage is calculated as a molar ratio.

[0032] The data in the table shows that when the ratio of benzoic acid to sodium hydroxide is 1:1, the product has high tin and chlorine content, indicating that the reaction is incomplete. Therefore, the amount of sodium hydroxide should be increased further. When the amount is increased to 10% excess, the tin content is qualified and the chlorine content is low. Therefore, the ratio of benzoic acid to sodium hydroxide is 1:1.1. According to the stoichiometric formula, the mass ratio is 1:0.36.

[0033] 2. Screening of sodium hydroxide solution concentration: Table 2 Screening results for sodium hydroxide solution concentration

[0034] Screening revealed that the concentration of sodium hydroxide solution had a relatively small impact on the synthesis of dibutyltin dibenzoate, with 10% being the optimal concentration. Therefore, based on the stoichiometric formula, the mass ratio of benzoic acid to sodium hydroxide solution was calculated to be 1:3.6. The amounts of potassium hydroxide and ammonia can be calculated using their respective chemical formulas.

[0035] 3. Screening of saponification reaction temperature: Table 3. Screening results for saponification reaction temperature

[0036] Screening revealed that the reaction at room temperature would result in incomplete reaction, leading to substandard quality of dibutyl benzoate. Therefore, it was necessary to increase the reaction temperature. When the temperature was increased to 50°C, the quality was acceptable. Further increasing the temperature would not affect the product quality. Thus, the optimal saponification temperature was 50-60°C.

[0037] 4. Screening of saponification reaction time: Table 4. Screening results of saponification reaction time

[0038] The data in the table shows that the optimal saponification time is 30 minutes.

[0039] 5. Screening of dibutyltin dichloride dosage (based on benzoic acid): After the saponification reaction is complete, dibutyltin dichloride needs to be added. To determine the optimal dosage, a screening process was conducted, and the results are as follows: Table 5. Screening results for dibutyltin dichloride dosage

[0040] Note: Dosage is expressed in molar ratio.

[0041] Screening showed that when dibutyltin dichloride was added according to the theoretical amount (i.e., 1:1), the synthesized dibutyltin dibenzoate was of qualified quality. According to the stoichiometric formula, the mass ratio of benzoic acid to dibutyltin dichloride was 1:1.25.

[0042] 6. Screening of synthesis reaction temperature: Table 6 Results of the screening of synthesis reaction temperatures

[0043] 7. Screening of synthesis reaction time Table 7 Results of the screening of synthesis reaction time

[0044] By screening the synthesis reaction temperature and time, the optimal synthesis reaction temperature was determined to be 75~80℃ and the reaction time to be 3h.

[0045] The equipment used in the method of this invention, such as reaction vessels, distillation vessels, and precision filters, are all existing technology equipment.

[0046] Unless otherwise stated, all percentages mentioned in this invention are mass percentages.

[0047] The tin content, chlorine content, and purity of dibutyltin benzoate significantly affect the usability of downstream products (Sn: 24.98% ± 0.5%, Cl ≤ 0.3%, purity ≥ 99%). Furthermore, the tin content, chlorine content, and purity vary considerably under different process conditions during its synthesis. Extensive synthesis experiments have demonstrated that the amount of alkali added, saponification temperature and time, the amount of dibutyltin dichloride added, and the synthesis reaction temperature and time are all factors contributing to this effect. Therefore, this method uses a single-factor controlled variable method to determine the optimal control conditions. Under these conditions, the tin and chlorine content of the synthesized dibutyltin benzoate fully meets the requirements for downstream product use. Changing the control conditions significantly reduces the quality of the synthesized dibutyltin benzoate, failing to meet the standards for downstream product use. This invention identifies and screens the factors affecting the quality of dibutyltin benzoate under an optimized process route, which will provide beneficial assistance for the industrial production of dibutyltin benzoate.

[0048] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for synthesizing dibutyltin dibenzoate, characterized in that, Includes the following steps: (1) Add the alkaline solution to the reactor, turn on the stirring and add benzoic acid to carry out a preliminary isothermal reaction; (2) When the initial isothermal reaction reaches the required level, add dibutyltin dichloride dropwise, and continue the isothermal reaction after the dropwise addition is completed; (3) After the reaction is complete, stop stirring, let stand and separate the phases, remove the aqueous phase rich in chloride ions, and collect the colorless to pale yellow oily liquid; (4) The collected oily liquid was washed with water, dried and filtered to obtain dibutyltin dibenzoate product.

2. The method for synthesizing dibutyltin dibenzoate according to claim 1, characterized in that, The alkaline solution in step (1) is a sodium hydroxide solution, a potassium hydroxide solution, or ammonia water, and the mass concentration of the alkaline solution is 10%.

3. The method for synthesizing dibutyltin dibenzoate according to claim 1, characterized in that, In step (1), benzoic acid and alkaline solution are added at a mass ratio of 1:(1.53~5.05).

4. The method for synthesizing dibutyltin dibenzoate according to claim 1, characterized in that, The initial isothermal reaction temperature in step (1) is 50~60℃, the initial isothermal reaction time is 15~30 minutes, and the stirring speed is 400r / min.

5. The method for synthesizing dibutyltin dibenzoate according to claim 1, characterized in that, In step (2), the dibutyltin dichloride is fed in a mass ratio of benzoic acid: dibutyltin dichloride = 1:1.

25.

6. The method for synthesizing dibutyltin dibenzoate according to claim 1, characterized in that, The constant temperature reaction in step (2) is 75~80℃, the constant temperature reaction time is 3 hours, and the dropping rate of dibutyltin dichloride is 20kg / min.

7. The method for synthesizing dibutyltin dibenzoate according to claim 1, characterized in that, The settling time for phase separation in step (3) is 30 minutes.

8. The method for synthesizing dibutyltin dibenzoate according to claim 1, characterized in that, Step (4) Wash for 60 minutes each time, let stand for 30 minutes, wash 3 times, and filter while hot after drying.

9. The method for synthesizing dibutyltin dibenzoate according to claim 1, characterized in that, The drying in step (4) is vacuum drying, with a vacuum degree of -0.1 MPa, a drying temperature of 100°C, and a drying time of 2 hours.

10. The method for synthesizing dibutyltin dibenzoate according to claim 1, characterized in that, The filtration in step (4) uses a filter with a pore size of 0.2 μm.

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