A high-efficiency preparation process of tetraoctyl tin

Abstract

This invention discloses an efficient preparation process for tetraoctyltin. Using isopropyl ether as the single solvent, magnesium and chlorooctane are reacted in isopropyl ether to generate octyl magnesium chloride. Tin tetrachloride is then added dropwise, and the reaction is continuously stirred to generate tetraoctyltin and anhydrous magnesium chloride. Hydrochloric acid is then added dropwise to dissolve the solid precipitate, and the mixture is allowed to stand and separate into layers to obtain the organic phase. Finally, isopropyl ether is recovered by atmospheric distillation, followed by vacuum distillation to obtain tetraoctyltin. This invention utilizes the immiscibility of isopropyl ether with water, ensuring a solvent recovery rate consistently above 95%, avoiding the solvent loss caused by dissolving in wastewater in traditional processes. The low boiling point of isopropyl ether allows for efficient recovery via atmospheric distillation, significantly reducing separation energy consumption. The in-situ water absorption of the byproduct anhydrous magnesium chloride eliminates the need for molecular sieve drying, achieving efficient solvent recovery and recycling. Simultaneously, the product yield and purity are significantly improved, demonstrating green environmental protection and industrial application value.

Description

Technical Field

[0001] This invention belongs to the field of organic compound synthesis, and particularly relates to an efficient preparation process for tetraoctyltin. Background Technology

[0002] Tetraoctyltin is an important organotin intermediate, widely used in the synthesis of polyvinyl chloride stabilizers, organotin catalysts, and precursors for functional materials. Currently, the mainstream industrial method for preparing tetraoctyltin is the Grignard reaction, which involves reacting magnesium with chlorooctane to generate octyl magnesium chloride Grignard reagent, which is then alkylated with tin tetrachloride. This reaction has stringent requirements for the solvent system, balancing the stability, reactivity, and ease of subsequent separation of the Grignard reagent. Traditional processes typically use tetrahydrofuran as a single solvent or a mixture of tetrahydrofuran and toluene. When using tetrahydrofuran as a single solvent, its good solubility and coordination stabilizing effect on the Grignard reagent effectively promotes the Grignard reaction. When using a mixture of tetrahydrofuran and toluene, toluene acts as a co-solvent, adjusting the system polarity and improving subsequent layering. Furthermore, the immiscibility of toluene with water helps reduce solvent loss in the aqueous phase. These solvent systems have been used industrially for many years, resulting in relatively mature process routes.

[0003] However, traditional solvent systems have significant technical drawbacks. When using tetrahydrofuran (THF) as a single solvent, due to its partial miscibility with water, a large amount of THF dissolves in the aqueous phase during the quenching and separation process after the reaction, resulting in severe solvent loss. The solvent recovery rate is typically only around 80%, and the wastewater containing THF has a high chemical oxygen demand (COD), leading to high environmental treatment costs. The recovered THF contains moisture and must be dried using molecular sieves before reuse, adding to the processing steps and generating hazardous solid waste. While using a mixed solvent of THF and toluene can improve the separation effect by utilizing the immiscibility of toluene with water, toluene's high boiling point (110°C) significantly increases the energy consumption of subsequent distillation separation. Furthermore, toluene residues are easily found in THF, requiring purification through distillation before reuse, resulting in high equipment investment and operating costs. In addition, the boiling points of toluene and the product tetraoctyltin are close, requiring the removal of a large amount of fore-distillate during distillation to ensure product purity, further reducing the yield per batch. Meanwhile, traditional processes do not fully utilize the water-absorbing properties of the byproduct anhydrous magnesium chloride, and solvent recovery still requires a separate drying process. The aforementioned solvent system leads to problems such as high solvent loss, high separation energy consumption, complex dehydration processes, and low product yield, directly resulting in high production costs for tetraoctyltin and becoming a technological bottleneck restricting the industry's development. Summary of the Invention

[0004] To overcome the above-mentioned defects of the prior art, the present invention provides an efficient preparation process for tetraoctyltin, which solves the problems of high solvent loss, high separation energy consumption, complex water removal and low product yield in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: An efficient preparation process for tetraoctyltin includes the following steps: S1: Add 750-800 mL of isopropyl ether and 35-45 g of magnesium shavings to the reaction vessel, heat the mixture to 50-70°C, stop heating after the system refluxes, add 209-235 g of chlorooctane dropwise to the system, and keep the reaction at the temperature for 1-2 hours after the addition is complete to obtain a mixture of magnesium octyl chloride and isopropyl ether. S2: Dissolve 108~109g of tin tetrachloride in 50mL of isopropyl ether and add it dropwise to the mixture of octyl magnesium chloride and isopropyl ether obtained in S1 at a dropping rate of 1~3 drops / second. During the dropwise addition, stir continuously at a speed of 400~800 rpm for 20~40 minutes. After the dropwise addition is completed, continue stirring for 20~40 minutes. During the reaction, control the temperature of the mixture at 20~30℃ to obtain a mixture of tetraoctyltin, anhydrous magnesium chloride and isopropyl ether. S3: Transfer the mixture of tetraoctyltin, anhydrous magnesium chloride, and isopropyl ether obtained in S2 to a distillation vessel, add 50-150 mL of isopropyl ether, heat and distill, and collect the anhydrous isopropyl ether. The added isopropyl ether acts as a dehydrating agent and works synergistically with the byproduct anhydrous magnesium chloride: on the one hand, it forms a low-boiling-point water-isopropyl ether azeotrope to promote water evaporation; on the other hand, the anhydrous magnesium chloride absorbs trace amounts of water in the system in situ during the distillation process, ensuring that the recovered isopropyl ether reaches the anhydrous level. S4: Add hydrochloric acid with a mass percentage concentration of 1-3% to the remaining system after distillation of S3, stir until magnesium chloride is completely dissolved, let stand and separate into layers to obtain the organic phase of tetraoctyltin and isopropyl ether and the aqueous solution of magnesium chloride. S5: Heat the organic phase of tetraoctyltin and isopropyl ether obtained in S4 to 50~70℃, remove isopropyl ether by distillation, and distill the remaining liquid under reduced pressure at a vacuum of -0.09~-0.07MPa and a temperature of 100~120℃ for 40~60 minutes to collect the tetraoctyltin product.

[0006] Preferably, the molar ratio of chlorooctane to magnesium in S1 is 1~1.2:1.

[0007] Preferably, the heat preservation reaction time in S1 is 1.5 hours.

[0008] Preferably, the molar ratio of tin tetrachloride in S2 to magnesium octyl chloride in S1 is 1.0~1.2:4.

[0009] Preferably, the stirring speed in S2 is 500~700 rpm.

[0010] Preferably, the temperature of the reaction system in S2 is 23~27℃.

[0011] Preferably, the anhydrous isopropyl ether collected in S3 is reused as a solvent in step S1.

[0012] Preferably, the mass percentage concentration of the hydrochloric acid in S4 is 1~2%.

[0013] Preferably, the isopropyl ether removed by distillation in S5 is reused in step S3 as added isopropyl ether.

[0014] Preferably, the vacuum degree of the vacuum distillation in S5 is -0.08MPa, the temperature is 105~115℃, and the distillation time is 50 minutes.

[0015] The technical effects and advantages of the efficient preparation process of tetraoctyltin in this invention are as follows: 1. This invention uses isopropyl ether as a single solvent, producing unexpected technical effects, rather than being a simple solvent replacement. First, the steric hindrance of the ether oxygen atom in isopropyl ether is greater than that in tetrahydrofuran, resulting in a moderate coordination effect with Grignard reagents. This ensures the stability of octyl magnesium chloride while avoiding excessive stability that could lead to a decrease in reactivity. This "moderate stability" effect is excellent in the specific synthesis system of tetraoctyltin in this invention, achieving a yield of 93.8%, significantly higher than the 84.2% of the traditional tetrahydrofuran system. Second, isopropyl ether is almost immiscible with water and will not dissolve in the aqueous phase during quenching and layering, avoiding the loss problem caused by solvent dissolving in wastewater in the traditional tetrahydrofuran process. At the same time, isopropyl ether has a low boiling point, allowing for efficient recovery by atmospheric distillation, eliminating the need for energy-intensive vacuum distillation like that used for toluene, thus significantly reducing separation energy consumption.

[0016] 2. This invention creatively utilizes the in-situ water-absorbing properties of anhydrous magnesium chloride, a reaction byproduct, to form a unique "reaction-distillation-in-situ drying" synergistic mechanism with the isopropyl ether system. Traditionally, the water absorption of anhydrous magnesium chloride is often considered a side reaction to be avoided (easily absorbing moisture from the air, leading to product hydrolysis). However, this invention takes the opposite approach, actively adding a small amount of isopropyl ether in step S3. Utilizing its property of forming a low-boiling-point azeotrope with water, it efficiently removes trace amounts of moisture from the system during distillation. Simultaneously, the freshly generated anhydrous magnesium chloride acts as an in-situ drying agent, preferentially chemically binding residual moisture. This synergistic effect allows the recovered isopropyl ether to reach an anhydrous level and be directly reused without additional drying, eliminating the molecular sieve drying step required in traditional processes, reducing operational steps and the generation of hazardous solid waste.

[0017] 3. This invention significantly improves the initiation efficiency of the Grignard reaction by raising the reaction system to 50~70℃, shortening the initiation time to the minute level and greatly improving the utilization rate of magnesium scrap; by controlling the stirring speed during the addition of tin tetrachloride at 400~800 rpm, it ensures uniform dispersion of reactants, avoids the multi-substitution side reactions caused by local overconcentration, and improves the selectivity of the main reaction.

[0018] 4. This invention significantly simplifies the product distillation process through the synergistic effect of a single solvent system and low boiling point characteristics. Isopropyl ether has a boiling point much lower than that of the product tetraoctyltin, and there is no high-boiling-point toluene residue, making distillation separation extremely easy. The amount of fore-fraction removed is significantly reduced, and both single-batch capacity and raw material utilization are improved.

[0019] 5. This invention controls the hydrochloric acid concentration within the range of 1-3%, avoiding the risk of acidic hydrolysis of tetraoctyltin caused by high concentration of hydrochloric acid, and ensuring the stability of the product during the quenching process; it controls the vacuum distillation temperature within the range of 100-120℃, avoiding thermal decomposition and isomerization side reactions of the product caused by excessive temperature, and ensuring product purity and yield.

[0020] 6. This invention achieves full recycling of solvents. The anhydrous isopropyl ether collected in step S3 can be directly reused in step S1 as a reaction solvent, and the isopropyl ether containing a small amount of water recovered in step S5 can be reused in step S3 as an additive solvent. The solvent loss in the entire process is extremely low, which meets the requirements of green chemistry and clean production. Attached Figure Description

[0021] Figure 1 This is a flow chart of an efficient preparation process for tetraoctyltin proposed in this invention; Figure 2 This is a schematic diagram of solvent circulation and in-situ water absorption of anhydrous magnesium chloride in a highly efficient preparation process of tetraoctyltin proposed in this invention. Figure 3 This is a comparison chart of the solvent separation effect of the present invention and the traditional process for the efficient preparation of tetraoctyltin proposed in this invention. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0023] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include," "contain," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "includes..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0024] refer to Figure 1-3This invention provides an efficient preparation process for tetraoctyltin, aiming to solve the technical problems of high solvent loss, high separation energy consumption, complex dehydration process, and low product yield in the traditional process using a mixed solvent of tetrahydrofuran and toluene. The method uses isopropyl ether as a single solvent. First, magnesium and chlorooctane are reacted in isopropyl ether at 50-70°C to generate octyl magnesium chloride, and the reaction is maintained at this temperature for 1-2 hours to ensure sufficient formation of the Grignard reagent. Then, 10⁸-10⁹ g of tin tetrachloride is dissolved in 50 mL of isopropyl ether and added dropwise to the octyl magnesium chloride at a dropping rate of 1-3 drops / second. During the addition, the mixture is stirred continuously at 400-800 rpm for 20-40 minutes. After the addition is complete, stirring continues for another 20-40 minutes, controlling the reaction system temperature at 20-30°C, to generate tetraoctyltin and anhydrous magnesium chloride. Subsequently, 50-150 mL of isopropyl ether is added to the reaction system, followed by heating and distillation to collect the anhydrous magnesium chloride. Isopropyl ether is recycled in the reaction step. The key role of this addition operation is to utilize the in-situ water absorption characteristics of the byproduct anhydrous magnesium chloride, combined with the water-carrying effect of isopropyl ether, to achieve self-drying of the solvent during distillation, eliminating the molecular sieve drying step in the traditional process. Then, hydrochloric acid with a mass percentage concentration of 1-3% is added dropwise to the remaining system to completely dissolve the magnesium chloride. After standing and separating the layers, an organic phase of tetraoctyltin and isopropyl ether is obtained. Finally, the organic phase is heated to 50-70℃ to desolvent and recover the isopropyl ether. The remaining liquid is then distilled under reduced pressure at a vacuum of -0.07 to -0.09 MPa and a temperature of 100-120℃ for 40-60 minutes to obtain a high-purity tetraoctyltin product. This invention utilizes the immiscibility of isopropyl ether with water to maintain a solvent recovery rate of over 95%, avoiding the solvent loss caused by solvent dissolution in wastewater in traditional tetrahydrofuran processes. Taking advantage of the low boiling point of isopropyl ether, efficient recovery is achieved through atmospheric distillation, significantly reducing separation energy consumption. Utilizing the in-situ water absorption properties of the byproduct anhydrous magnesium chloride, it preferentially binds to water after the addition of the recovered wet solvent, eliminating the molecular sieve drying step required in traditional processes. By precisely controlling process parameters such as reaction temperature, stirring speed, hydrochloric acid concentration, and distillation temperature, problems such as multi-substitution side reactions and product hydrolysis and thermal decomposition are effectively avoided, significantly improving product yield and purity, and achieving efficient and green preparation of tetraoctyltin.

[0025] Example 1 Purpose of implementation: This embodiment aims to provide a preferred embodiment for preparing tetraoctyltin using isopropyl ether as a single solvent, in order to verify the comprehensive performance of the technical solution of the present invention under optimal process parameters.

[0026] Implementation steps: 750 mL of isopropyl ether and 42 g of magnesium shavings were added to the reaction vessel. The mixture was heated to 60 °C. After the system refluxed, the heating was stopped. 222 g of chlorooctane was added dropwise to the system at a uniform rate. After the addition was complete, the reaction was kept at the temperature for 1.5 hours to obtain a mixture of magnesium octyl chloride and isopropyl ether.

[0027] 108g of tin tetrachloride was dissolved in 50mL of isopropyl ether and added dropwise to the above mixture of octyl magnesium chloride and isopropyl ether at a dropping rate of 2 drops / second. During the addition, the mixture was stirred continuously at 600 rpm for 30 minutes. After the addition was completed, the mixture was stirred for another 30 minutes. The temperature of the mixture was controlled at 25℃ during the reaction to obtain a mixture of tetraoctyltin, anhydrous magnesium chloride and isopropyl ether.

[0028] Transfer the above mixture to a distillation vessel, add 100 mL of isopropyl ether, heat and distill to collect anhydrous isopropyl ether.

[0029] Add 2% hydrochloric acid dropwise to the remaining system after distillation, stir until magnesium chloride is completely dissolved, let stand for 30 minutes to separate the layers, and obtain the organic phase of tetraoctyltin and isopropyl ether and the aqueous solution of magnesium chloride.

[0030] The organic phase was heated to 60°C, and isopropyl ether was removed by distillation. The remaining liquid was then distilled under reduced pressure for 50 minutes at a vacuum of -0.08 MPa and a temperature of 110°C to obtain the tetraoctyltin product.

[0031] Test results: The tetraoctyltin prepared in this embodiment had a yield of 93.8%, a purity of 98.9% as determined by gas chromatography, and an isopropyl ether solvent recovery rate of 97.6%. The results indicate that excellent overall performance can be obtained in a single isopropyl ether solvent system by combining continuous stirring, quenching with 2% dilute hydrochloric acid, and precise two-stage distillation.

[0032] Example 2 Purpose of implementation: This embodiment aims to verify the feasibility of the lower limit of the feed amount and the lower limit of the reaction temperature in step S1, so as to fully support the scope of protection of the claims.

[0033] Implementation steps: Add 750 mL of isopropyl ether and 35 g of magnesium shavings to the reaction vessel, heat the mixture to 50 °C, and stop heating after the system refluxes. Add 209 g of chlorooctane dropwise to the system at a uniform rate. After the addition is complete, keep the mixture at the temperature for 1 hour to obtain a mixture of magnesium octyl chloride and isopropyl ether.

[0034] 108g of tin tetrachloride was dissolved in 50mL of isopropyl ether and added dropwise to the above mixture of octyl magnesium chloride and isopropyl ether at a dropping rate of 1 drop / second. During the addition, the mixture was stirred continuously at 400 rpm for 40 minutes. After the addition was completed, the mixture was stirred for another 40 minutes. The temperature of the mixture was controlled at 20℃ during the reaction to obtain a mixture of tetraoctyltin, anhydrous magnesium chloride and isopropyl ether.

[0035] Transfer the above mixture to a distillation vessel, add 50 mL of isopropyl ether, heat and distill to collect anhydrous isopropyl ether.

[0036] Add 1% hydrochloric acid dropwise to the remaining system after distillation, stir until magnesium chloride is completely dissolved, let stand and separate into layers to obtain an organic phase of tetraoctyltin and isopropyl ether and an aqueous solution of magnesium chloride.

[0037] The organic phase was heated to 50°C, and isopropyl ether was removed by distillation. The remaining liquid was then distilled under reduced pressure for 60 minutes at a vacuum of -0.07 MPa and a temperature of 100°C to obtain the tetraoctyltin product.

[0038] Test results: The tetraoctyltin prepared in this embodiment had a yield of 91.2%, a purity of 97.5% as determined by gas chromatography, and an isopropyl ether solvent recovery rate of 96.8%. The results demonstrate that, within the boundary parameter range of claim 1, the present invention can still achieve good yield and purity, verifying the rationality of the scope of protection of the claims.

[0039] Example 3 (Boundary Value Verification – Higher Feed Amount and Higher Reaction Temperature) Purpose of implementation: This embodiment aims to verify the feasibility of the upper limit of the feed amount and the upper limit of the reaction temperature in step S1 of claim 1, so as to fully support the scope of protection of the claim.

[0040] Implementation steps: Add 800 mL of isopropyl ether and 45 g of magnesium shavings to the reaction vessel, heat the mixture to 70 °C, and stop heating after the system refluxes. Add 235 g of chlorooctane dropwise to the system at a uniform rate. After the addition is complete, keep the mixture at the temperature for 2 hours to obtain a mixture of magnesium octyl chloride and isopropyl ether.

[0041] 109 g of tin tetrachloride was dissolved in 50 mL of isopropyl ether and added dropwise to the above mixture of octyl magnesium chloride and isopropyl ether at a dropping rate of 3 drops / second. During the addition, the mixture was stirred continuously at 800 rpm for 20 minutes. After the addition was completed, the mixture was stirred for another 20 minutes. The temperature of the mixture was controlled at 30 °C during the reaction to obtain a mixture of tetraoctyl tin, anhydrous magnesium chloride and isopropyl ether.

[0042] Transfer the above mixture to a distillation vessel, add 150 mL of isopropyl ether, heat and distill to collect anhydrous isopropyl ether.

[0043] Add 3% hydrochloric acid dropwise to the remaining system after distillation, stir until magnesium chloride is completely dissolved, let stand and separate into layers to obtain an organic phase of tetraoctyltin and isopropyl ether and an aqueous solution of magnesium chloride.

[0044] The organic phase was heated to 70°C, and isopropyl ether was removed by distillation. The remaining liquid was then distilled under reduced pressure for 40 minutes at a vacuum of -0.09 MPa and a temperature of 120°C to obtain the tetraoctyltin product.

[0045] Test results: The tetraoctyltin prepared in this embodiment had a yield of 92.5%, a purity of 98.1% as determined by gas chromatography, and an isopropyl ether solvent recovery rate of 97.1%. The results demonstrate that, within the boundary parameter range of claim 1, the present invention can still achieve good yield and purity, further validating the rationality of the scope of protection of the claims.

[0046] Example 4 Purpose of this implementation: This example aims to investigate the effect of hydrochloric acid concentration on the stability of tetraoctyltin, in order to verify the importance of quenching conditions for product protection.

[0047] Implementation steps: Add 750 mL of isopropyl ether and 42 g of magnesium shavings to the reaction vessel, heat the mixture to 50 °C, and stop heating after the system refluxes. Add 222 g of chlorooctane dropwise to the system at a uniform rate. After the addition is complete, keep the mixture at the temperature for 1.5 hours to obtain a mixture of magnesium octyl chloride and isopropyl ether.

[0048] 108g of tin tetrachloride was dissolved in 50mL of isopropyl ether and added dropwise to the above mixture of octyl magnesium chloride and isopropyl ether at a dropping rate of 2 drops / second. During the addition, the mixture was stirred continuously at 600 rpm for 30 minutes. After the addition was completed, the mixture was stirred for another 30 minutes. The temperature of the mixture was controlled at 20℃ during the reaction to obtain a mixture of tetraoctyltin, anhydrous magnesium chloride and isopropyl ether.

[0049] Transfer the above mixture to a distillation vessel, add 100 ml of propyl ether, heat and distill to collect anhydrous isopropyl ether.

[0050] Add 5% hydrochloric acid dropwise to the remaining system after distillation, stir until magnesium chloride is completely dissolved, let stand for 30 minutes to separate the layers, and obtain the organic phase of tetraoctyltin and isopropyl ether and the aqueous solution of magnesium chloride.

[0051] The organic phase was heated to 60°C, and isopropyl ether was removed by distillation. The remaining liquid was then distilled under reduced pressure for 50 minutes at a vacuum of -0.08 MPa and a temperature of 110°C to obtain the tetraoctyltin product.

[0052] Test results: The tetraoctyltin prepared in this embodiment had a yield of 65.7%, a purity of 84.5% as determined by gas chromatography, and an isopropyl ether solvent recovery rate of 96.8%.

[0053] In Example 4, a high concentration of 5% hydrochloric acid was used for quenching. Excess acid triggered an acidic hydrolysis reaction of tetraoctyltin, and the resulting trioctyltin cation was further converted into oxide and entered the aqueous phase, causing severe product loss and a significant decrease in both yield and purity. This result indicates that the hydrochloric acid concentration should be controlled within the range of 1-3%, preferably 1-2%, to avoid acidolysis of the product during quenching.

[0054] Example 5 Purpose of this implementation: This example aims to investigate the effect of vacuum distillation temperature on the purity and yield of tetraoctyltin, in order to verify the key role of distillation conditions in product stability.

[0055] Implementation steps: 750 mL of isopropyl ether and 42 g of magnesium shavings were added to the reaction vessel. The mixture was heated to 60 °C. After the system refluxed, the heating was stopped. 222 g of chlorooctane was added dropwise to the system at a uniform rate. After the addition was complete, the reaction was kept at the temperature for 1.5 hours to obtain a mixture of magnesium octyl chloride and isopropyl ether.

[0056] 108g of tin tetrachloride was dissolved in 50mL of isopropyl ether and added dropwise to the above mixture of octyl magnesium chloride and isopropyl ether at a dropping rate of 2 drops / second. No stirring was performed during the addition. After the addition was completed, the mixture was stirred continuously at 600 rpm for 30 minutes. The temperature of the mixture was controlled at 25℃ during the reaction to obtain a mixture of tetraoctyltin, anhydrous magnesium chloride and isopropyl ether.

[0057] Transfer the above mixture to a distillation vessel, add 100 ml of isopropyl ether, heat and distill to collect anhydrous isopropyl ether.

[0058] Add 2% hydrochloric acid dropwise to the remaining system after distillation, stir until magnesium chloride is completely dissolved, let stand for 30 minutes to separate the layers, and obtain the organic phase of tetraoctyltin and isopropyl ether and the aqueous solution of magnesium chloride.

[0059] The organic phase was heated to 60°C, and isopropyl ether was removed by distillation. The remaining liquid was then distilled under reduced pressure for 50 minutes at a vacuum of -0.08 MPa and a temperature of 130°C to obtain the tetraoctyltin product.

[0060] Test results: The tetraoctyltin prepared in this embodiment had a yield of 89.4%, a purity of 91.7% as determined by gas chromatography, and an isopropyl ether solvent recovery rate of 95.2%.

[0061] In Example 5, the vacuum distillation temperature was increased to 130°C, leading to thermal decomposition and isomerization side reactions in some tetraoctyltin, reducing the product purity to 91.7%. Simultaneously, due to localized overheating at high temperatures, some product remained in the distillation vessel, further decreasing the yield. These results indicate that the vacuum distillation temperature should be controlled within the range of 100–120°C, preferably 105–115°C, to ensure the stability of the product during distillation.

[0062] Comparative Example 1 Purpose of this comparative example: This example aims to prepare tetraoctyltin using a traditional process of mixing tetrahydrofuran and toluene as a solvent, in order to compare the technical effects of the present invention and highlight the advantages of the isopropyl ether single solvent system.

[0063] Implementation steps: Under nitrogen protection, 42g of magnesium shavings, 750mL of anhydrous tetrahydrofuran and 222g of chlorooctane were added to the reaction vessel. The dropping rate was controlled to maintain a stable reflux. After the addition was complete, the mixture was heated in a water bath at 60℃ and refluxed for 3 hours to obtain a Grignard reagent solution of magnesium octyl chloride.

[0064] The Grignard reagent solution was cooled to room temperature. 108 g of tin tetrachloride was dissolved in 50 mL of toluene to prepare a mixed solution while stirring at 600 rpm. The solution was added dropwise at a rate of 1 drop / second, and the temperature was controlled by an ice-water bath to keep the reaction temperature below 35°C. After the addition was complete, the reaction was stirred at 40°C for 2 hours to produce tetraoctyltin and a large amount of white anhydrous magnesium chloride precipitate.

[0065] After the reaction was completed, the system was cooled to 10°C, and 600 mL of 2% hydrochloric acid was slowly added dropwise with stirring until the magnesium salt was completely dissolved. The mixture was then allowed to stand and separate into layers to obtain an organic phase and an aqueous phase.

[0066] The organic phase was distilled at atmospheric pressure, and the distillate was collected until the distillation temperature reached 80°C to obtain tetrahydrofuran. The remaining liquid was then distilled under reduced pressure at a vacuum of -0.09 MPa. The liquid was first heated to 40-50°C to distill off toluene, and then the temperature was raised to 180-200°C to collect the tetraoctyltin product obtained from the distillation.

[0067] Test results: The yield of tetraoctyltin prepared in this comparative example was 84.2%, and the purity was 96.1% as determined by gas chromatography. The recovery rate of tetrahydrofuran solvent was 79%, and the recovery rate of toluene solvent was 88%.

[0068] Comparative Example 1 uses a traditional process with a mixed solvent of tetrahydrofuran and toluene. Because tetrahydrofuran is partially miscible with water, the aqueous phase after separation contains 8-10% tetrahydrofuran, which cannot be directly recovered. The tetrahydrofuran recovery rate is only 79%, resulting in solvent waste and increased wastewater treatment costs. Furthermore, the two-stage distillation separation of the mixed solvent, combined with toluene's high boiling point, significantly increases distillation energy consumption. The recovered tetrahydrofuran contains a small amount of water and must be dried using molecular sieves before reuse, further increasing process and solid waste treatment costs.

[0069] Comprehensive comparison of the examples and comparative examples: Comparing the test results of Examples 1 to 5 with Comparative Example 1, Example 1 achieved the optimal balance in terms of reaction efficiency, product purity, solvent recovery, and process simplicity. Example 1 used isopropyl ether as a single solvent to react magnesium with chlorooctane in isopropyl ether to generate magnesium octyl chloride, which was then alkylated with tin tetrachloride. During the reaction, continuous stirring at 600 rpm ensured uniform dispersion of the materials. The reaction temperature was controlled at 25°C. In the quenching stage, 2% dilute hydrochloric acid was used for gentle hydrolysis of the magnesium salt. Finally, the product was collected by vacuum distillation at 110°C, achieving excellent overall performance with a yield of 93.8%, purity of 98.9%, and solvent recovery rate of 97.6%.

[0070] In Example 2, the reaction temperature was lowered to 50°C for initiation and 20°C for reaction. Due to the decrease in temperature, the activation degree of magnesium surface decreased, making it difficult to initiate the Grignard reaction. Some magnesium did not participate in the reaction, resulting in insufficient production of octyl magnesium chloride. Consequently, the subsequent tin tetrachloride reaction was incomplete, with the yield dropping to 91.2% and the purity dropping to 97.5%. However, the solvent recovery rate remained at 96.8%, indicating that the isopropyl ether system still has excellent recovery performance when deviating from the optimal reaction temperature.

[0071] Example 3 used a higher feed amount (800 mL isopropyl ether, 45 g magnesium shavings, 235 g chlorooctane) and a higher reaction temperature (70 °C initiation, 30 °C reaction), with a yield of 92.5%, purity of 98.1%, and solvent recovery rate of 97.1%, indicating that good overall performance can still be obtained within the boundary parameter range of claim 1 of this invention.

[0072] Example 4 used 5% high-concentration hydrochloric acid for quenching. Excess acid triggered an acidic hydrolysis reaction of tetraoctyltin. The generated trioctyltin cation was further converted into oxide and entered the aqueous phase, resulting in severe product loss. The yield was only 65.7% and the purity was 84.5%, which proves that the concentration of hydrochloric acid must be controlled within the range of 1~3% to avoid acidolysis of the product.

[0073] In Example 5, the vacuum distillation temperature was increased to 130°C, which caused some tetraoctyltin to undergo thermal decomposition and isomerization side reactions, reducing the product purity to 91.7%. At the same time, the system was locally overheated at high temperature, and some product remained in the distillation vessel, reducing the yield to 89.4% and the solvent recovery rate to 95.2%. This indicates that the distillation temperature should be controlled within the range of 100~120°C to ensure product stability and yield.

[0074] Comparative Example 1 uses a traditional process with a mixed solvent of tetrahydrofuran and toluene. Because tetrahydrofuran is partially miscible with water, the aqueous phase after separation contains 8-10% tetrahydrofuran that cannot be directly recovered, resulting in a tetrahydrofuran recovery rate of only 79%. This leads to solvent waste and increased wastewater treatment costs. Toluene has a high boiling point, significantly increasing energy consumption in the two-stage distillation process. The recovered tetrahydrofuran contains moisture and requires drying with molecular sieves before reuse, increasing process and solid waste treatment costs. The final yield of this process is 84.2%, and the purity is 96.1%, significantly lower than that of Example 1. It is noteworthy that the solvent recovery rate in all embodiments of this invention is consistently above 95%, while the tetrahydrofuran recovery rate in Comparative Example 1 is only 79%, fully demonstrating the inherent advantages of the isopropyl ether single solvent system in solvent recovery.

[0075] In summary, this invention systematically solves the technical challenges of high solvent loss, high separation energy consumption, complex dehydration process, and low product yield in traditional processes by selecting isopropyl ether as a single solvent system and synergistically optimizing key process parameters. The immiscibility of isopropyl ether with water ensures a stable solvent recovery rate of over 95%, its low boiling point significantly reduces distillation energy consumption, and the in-situ water absorption of the byproduct anhydrous magnesium chloride eliminates the need for molecular sieve drying. Precise process parameter control ensures high yield and high purity, representing a significant advancement in tetraoctyltin preparation technology.

[0076] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of protection of the claims.

[0077] In conclusion, the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A highly efficient preparation process for tetraoctyltin, characterized in that, Includes the following steps: S1: Add 750-800 mL of isopropyl ether and 35-45 g of magnesium shavings to the reaction vessel, heat the mixture to 50-70°C, stop heating after the system refluxes, add 209-235 g of chlorooctane dropwise to the system, and keep the reaction at the temperature for 1-2 hours after the addition is complete to obtain a mixture of magnesium octyl chloride and isopropyl ether. S2: Dissolve 108~109g of tin tetrachloride in 50mL of isopropyl ether and add it dropwise to the mixture of octyl magnesium chloride and isopropyl ether obtained in S1 at a dropping rate of 1~3 drops / second. During the dropwise addition, stir continuously at a speed of 400~800 rpm for 20~40 minutes. After the dropwise addition is completed, continue stirring for 20~40 minutes. During the reaction, control the temperature of the mixture at 20~30℃ to obtain a mixture of tetraoctyltin, anhydrous magnesium chloride and isopropyl ether. S3: Transfer the mixture of tetraoctyltin, anhydrous magnesium chloride and isopropyl ether obtained in S2 to a distillation vessel, add 50-150 mL of isopropyl ether, heat and distill, and collect the anhydrous isopropyl ether. S4: Add hydrochloric acid with a mass percentage concentration of 1-3% to the remaining system after distillation of S3, stir until magnesium chloride is completely dissolved, let stand and separate into layers to obtain the organic phase of tetraoctyltin and isopropyl ether and the aqueous solution of magnesium chloride. S5: Heat the organic phase of tetraoctyltin and isopropyl ether obtained in S4 to 50~70℃, remove isopropyl ether by distillation, and distill the remaining liquid under reduced pressure at a vacuum of -0.09~-0.07MPa and a temperature of 100~120℃ for 40~60 minutes to collect the tetraoctyltin product.

2. The efficient preparation process of tetraoctyltin as described in claim 1, characterized in that, The molar ratio of chlorooctane to magnesium in S1 is 1~1.2:

1.

3. The efficient preparation process of tetraoctyltin as described in claim 1, characterized in that, The heat preservation reaction time described in S1 is 1.5 hours.

4. The efficient preparation process of tetraoctyltin as described in claim 1, characterized in that, The molar ratio of tin tetrachloride in S2 to magnesium octyl chloride in S1 is 1.0~1.2:

4.

5. The efficient preparation process of tetraoctyltin as described in claim 1, characterized in that, The stirring speed described in S2 is 500~700 rpm.

6. The efficient preparation process of tetraoctyltin as described in claim 1, characterized in that, The temperature of the reaction system described in S2 is 23~27℃.

7. The efficient preparation process of tetraoctyltin as described in claim 1, characterized in that, The anhydrous isopropyl ether collected in step S3 is reused as a solvent in step S1.

8. The efficient preparation process of tetraoctyltin as described in claim 1, characterized in that, The mass percentage concentration of hydrochloric acid mentioned in S4 is 1~2%.

9. The efficient preparation process of tetraoctyltin as described in claim 1, characterized in that, The isopropyl ether removed by distillation in step S5 is reused in step S3 as added isopropyl ether.

10. The efficient preparation process of tetraoctyltin as described in claim 1, characterized in that, The vacuum distillation described in S5 is performed at a vacuum level of -0.08 MPa, a temperature of 105~115℃, and a distillation time of 50 minutes.

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