Production device and method of isooctyl salicylate

Abstract

The invention provides a production device and method of isooctyl salicylate. The production device comprises an ester exchange reaction kettle, a reduced pressure distillation kettle, an isooctanol raw material tank, a methyl salicylate raw material tank, an ME crude product tank, an acetic acid-methanol storage tank, an acid-base neutralization tank, a pure water tank, an ester exchange condenser, a distillation kettle rectifying tower, a distillation condenser, a vacuum pump, a water phase tank, a kettle residue tank, an ME storage tank, an isooctanol crude product tank and an OS product tank. The production method comprises the steps of ester exchange reaction, acid-base neutralization and product purification. Through reaction-separation integrated design, efficient, green and low-cost continuous production of the isooctyl salicylate is realized, and the method has the advantages of high yield, high purity and remarkable resource recycling.

Description

Technical Field

[0001] This invention relates to the field of fine chemical technology, and more specifically, to an apparatus and method for producing isooctyl salicylate. Background Technology

[0002] Octyl salicylate (OS) is an important oil-soluble ultraviolet absorber (primarily absorbing the UVB band). Due to its high safety, low skin irritation, and good compatibility with other components in cosmetic formulations, it is widely used in personal care products such as sunscreens and skincare products. With the increasing awareness of sun protection among global consumers, the market demand for high-purity, high-quality octyl salicylate continues to grow.

[0003] Currently, the mainstream industrial production process uses the direct esterification of salicylic acid and isooctanol, typically employing strong liquid acids such as concentrated sulfuric acid as catalysts. However, this route has many inherent drawbacks that are difficult to overcome, including: the product has a dark color and limited purity; strong acids cause severe corrosion to equipment; waste acid treatment leads to environmental burden; and solid salicylic acid presents inconveniences in terms of feeding, metering, and mass transfer.

[0004] To fundamentally circumvent the aforementioned problems, researchers have recently proposed replacing the traditional direct esterification process with transesterification (i.e., the transesterification route)—using methyl salicylate and isooctyl alcohol to prepare isooctyl salicylate. This route has significant advantages: milder reaction conditions, fewer side reactions, and no need for strong acid catalysts, thus avoiding equipment corrosion; at the same time, methyl salicylate, as a liquid downstream derivative of salicylic acid, is not only easy to transport and accurately measure, but also usually has high purity, which helps to improve the quality of the final product.

[0005] Despite the significant advantages of transesterification technology, its industrial application still faces several key challenges: efficient separation of catalyst and product after reaction, recovery and reuse of excess isooctyl alcohol, effective recovery of byproduct methanol (ME), and low overall yield, all of which directly affect the production cost and purity of the product.

[0006] To address the aforementioned bottlenecks, there is an urgent need to develop a production apparatus and method for isooctyl salicylate, aiming to achieve efficient catalyst separation, closed-loop recovery of raw materials and by-products, and synergistic optimization of high product yield and high purity, thereby promoting the green, efficient, low-cost, and high-quality industrial production of isooctyl salicylate. Summary of the Invention

[0007] The purpose of this invention is to provide an apparatus and method for producing isooctyl salicylate, which aims to solve the problems mentioned in the background art.

[0008] The present invention is implemented as follows: a production apparatus for isooctyl salicylate, comprising an ester exchange reactor and a vacuum distillation reactor. The inlet of the transesterification reactor is connected to the isooctanol feed tank and the methyl salicylate feed tank, respectively. The gas phase pipeline of the transesterification reactor is connected to the crude ME tank through the transesterification condenser in sequence. The outlet of the crude ME tank is connected to the inlet of the acetic acid-methanol storage tank. The outlet of the acetic acid-methanol storage tank is connected to the inlet of the acid-base neutralization tank. The liquid phase pipeline of the transesterification reactor is connected to the inlet of the acid-base neutralization tank, the inlet of the acid-base neutralization tank is also connected to the pure water tank, the organic phase pipeline of the acid-base neutralization tank is connected to the inlet of the vacuum distillation reactor, and the aqueous phase pipeline of the acid-base neutralization tank is connected to the aqueous phase tank. The light component pipeline of the vacuum distillation kettle is connected in sequence to the ME storage tank, the crude isooctanol tank, and the OS product tank through the distillation kettle rectification column and the distillation condenser, respectively. A vacuum pump is also installed on the pipeline connecting the distillation condenser to the ME storage tank, the crude isooctanol tank, and the OS product tank. The outlet of the crude isooctanol tank is connected to the inlet of the transesterification reactor, and the residue pipeline of the vacuum distillation vessel is connected to the residue tank.

[0009] Optionally, it also includes isooctanol feed pump, methyl salicylate feed pump, crude ME pump, acetic acid-methanol pump, transesterification tank liquid pump, pure water pump and crude isooctanol pump; The isooctanol feed tank is connected to the transesterification reactor via an isooctanol feed pump, and the methyl salicylate feed tank is connected to the transesterification reactor via a methyl salicylate feed pump. The crude ME tank is connected to the acetic acid-methanol storage tank via a crude ME pump, and the acetic acid-methanol storage tank is connected to the acid-base neutralization tank via an acetic acid-methanol pump. The ester exchange reactor is connected to the acid-base neutralization tank via an ester exchange reactor liquid pump, and the pure water tank is connected to the acid-base neutralization tank via a pure water pump. The crude isooctanol tank is connected to the transesterification reactor via a crude isooctanol pump.

[0010] Optionally, the transesterification reactor and the vacuum distillation vessel are respectively equipped with a stirrer, a heat exchange structure and an interlocking control system, wherein the interlocking control system is used to realize the interlocking control of the reaction / distillation temperature and the heating steam.

[0011] Optionally, the ester exchange condenser and the distillation condenser are respectively equipped with an interlock control unit for temperature and coolant, which is used to realize automatic adjustment of cooling temperature and coolant flow rate.

[0012] Optionally, a vapor phase temperature monitoring system is installed at the top of the distillation column, and the vapor phase temperature monitoring system is interlocked with the shut-off valves in front of the ME storage tank, the crude isooctanol tank, and the OS product tank. When the vapor temperature at the top of the distillation column is ≥25℃ and <50℃, the shut-off valve controls the flow of condensate from the distillation condenser to the ME storage tank. When the gas phase temperature is ≥50℃ and <120℃, the shut-off valve controls the flow of condensate to the crude isooctanol tank; When the gas phase temperature is ≥120℃ and ≤150℃, the shut-off valve controls the flow of condensate to the OS product tank; The OS product container is also equipped with an online detection system for real-time monitoring of the purity of isooctyl salicylate.

[0013] Another object of the present invention is a method for producing isooctyl salicylate, using the aforementioned production apparatus, comprising the following steps: S1. Transesterification reaction: Methyl salicylate and isooctanol are added to the transesterification reactor at a mass ratio of 1:(1-3), and a catalyst of 0.1% to 2% of the total mass of the raw materials is added. The reaction is stirred at 100 to 200°C for 8 to 48 hours. The byproduct methanol generated by the reaction is collected in the ME crude product tank after distillation and condensation in the transesterification condenser. The organic phase material after the reaction is transferred to the acid-base neutralization tank. S2, acid-base neutralization: Add 5% to 20% acetic acid-methanol solution (by mass of organic phase) to the acid-base neutralization tank to adjust the system to neutral; then add 10% to 90% deionized water (by mass of organic phase) for washing, and allow to stand for separation; the resulting aqueous phase is sent to an aqueous phase tank and potassium acetate is recovered by vacuum distillation; the resulting organic phase is transferred to a vacuum distillation kettle. S3. Product Purification: Start the vacuum pump to maintain the pressure inside the vacuum distillation vessel at -0.098 MPa, and gradually increase the temperature to carry out vacuum distillation; collect the fractions in stages according to the vapor temperature at the top of the distillation column: When the vapor phase temperature is ≥25℃ and <50℃, the condensate is methanol and is collected in the ME storage tank; When the gas phase temperature is ≥50℃ and <120℃, the condensate is unreacted isooctanol, which is collected in the crude isooctanol tank and recycled to the transesterification reactor. When the vapor phase temperature is ≥120℃ and ≤150℃, the condensate is isooctyl salicylate and is collected in the OS product tank.

[0014] Optionally, in step S1, the catalyst is at least one of potassium carbonate, sodium methoxide, sodium carbonate, or p-toluenesulfonic acid.

[0015] Optionally, the raw material for preparing the acetic acid-methanol solution in step S2 is methanol, a byproduct collected in the ME crude product tank, and the isooctanol entrained in the byproduct methanol is recovered together with the unreacted isooctanol during the vacuum distillation process in step S3.

[0016] Optionally, the isooctyl salicylate prepared by the method has a yield of ≥85% and a purity of ≥99.5%.

[0017] The present invention provides an apparatus and method for producing isooctyl salicylate, which has the following beneficial effects: This invention achieves synergistic optimization of the reaction and separation processes by integrating transesterification, acid-base neutralization, and vacuum distillation. It cleverly utilizes byproduct methanol to prepare an acetic acid-methanol solution for neutralization, and simultaneously recovers isooctyl alcohol entrained in the solution during distillation, eliminating the need for a separate separation step and significantly reducing energy consumption and costs. Unreacted isooctyl alcohol is efficiently recovered and recycled, and the potassium acetate byproduct of neutralization can be purified and sold for added value. The aqueous phase can also be reused, greatly reducing wastewater discharge. The entire device has a simple structure, high degree of automation, and is easy to operate continuously in the industrial sector. The yield of isooctyl salicylate exceeds 85%, and the purity is higher than 99.5%, fully meeting the application requirements of the daily chemical industry for high-quality UVB absorbers, and possessing significant economic, environmental, and technological advantages.

[0018] In summary, this invention achieves efficient, green, and low-cost continuous production of isooctyl salicylate through reaction-separation integrated design, with advantages of high yield (>85%), high purity (>99.5%), and significant resource recycling.

[0019] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0021] Figure 1 This is a schematic diagram of the production apparatus for isooctyl salicylate provided in an embodiment of the present invention.

[0022] In the diagram: 1-Isooctanol feed tank, 2-Isooctanol feed pump, 3-Ester exchange reactor, 4-Acid-base neutralization tank, 5-Ester exchange condenser, 6-ME crude product tank, 7-Distillation kettle and distillation column, 8-Reduced pressure distillation kettle, 9-Distillation condenser, 10-Vacuum pump, 11-Methyl salicylate feed tank, 12-Methyl salicylate feed pump, 13-Ester exchange reactor liquid pump, 14-Pure water tank, 15-Pure water pump, 16-Acetic acid-methanol storage tank, 17-Acetic acid-methanol pump, 18-ME crude product pump, 19-Isooctanol crude product pump, 20-Aqueous phase tank, 21-Residue tank, 22-ME storage tank, 23-Isooctanol crude product tank, 24-OS product tank. Detailed Implementation

[0023] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0024] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0025] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0026] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0027] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0028] The following describes, with reference to the accompanying drawings, a production apparatus and method for isooctyl salicylate according to an embodiment of the present invention.

[0029] like Figure 1 As shown, this invention provides a production apparatus for isooctyl salicylate, comprising an ester exchange reactor 3 and a vacuum distillation vessel 8. The inlet of the ester exchange reactor 3 is connected to an isooctyl alcohol feed tank 1 and a methyl salicylate feed tank 11, respectively. The gas phase pipeline of the ester exchange reactor 3 is also connected to an ME crude product tank 6 via an ester exchange condenser 5. The outlet of the ME crude product tank 6 is connected to the inlet of an acetic acid-methanol storage tank 16, and the outlet of the acetic acid-methanol storage tank 16 is connected to the inlet of an acid-base neutralization tank 4. The liquid phase pipeline of the ester exchange reactor 3 is also connected to the inlet of the acid-base neutralization tank 4, and the inlet of the acid-base neutralization tank 4 is also connected to a pure water tank 14.

[0030] The organic phase pipeline of the acid-base neutralization tank 4 is connected to the inlet of the vacuum distillation vessel 8, and the aqueous phase pipeline of the acid-base neutralization tank 4 is connected to the aqueous phase tank 20; the light component pipeline of the vacuum distillation vessel 8 is also connected to the distillation condenser 9 through the distillation vessel rectification column 7, and the distillation condenser 9 is connected to the ME storage tank 22, the isooctyl alcohol crude product tank 23 and the OS product tank 24 through the vacuum pump 10.

[0031] The crude isooctanol tank 23 is also connected to the inlet of the transesterification reactor 3; the residue pipeline of the vacuum distillation vessel 8 is connected to the residue tank 21.

[0032] The isooctanol feedstock tank 1 is connected to the transesterification reactor 3 via the isooctanol feedstock pump 2; the methyl salicylate feedstock tank 11 is connected to the transesterification reactor 3 via the methyl salicylate feedstock pump 12. The outlet of the crude ME tank 6 is connected to the acetic acid-methanol storage tank 16 via the crude ME pump 18; the outlet of the acetic acid-methanol storage tank 16 is connected to the inlet of the acid-base neutralization tank 4 via the acetic acid-methanol pump 17. The outlet of the transesterification reactor 3 is also connected to the inlet of the acid-base neutralization tank 4 via the transesterification reactor liquid pump 13. The inlet of the acid-base neutralization tank 4 is also connected to the pure water tank 14 via the pure water pump 15. The crude isooctanol tank 23 is also connected to the transesterification reactor 3 via the crude isooctanol pump 19.

[0033] In the transesterification reactor 3, a certain proportion of isooctanol and methyl salicylate are pumped in through feed pumps (isooctanol feed pump 2 and methyl salicylate feed pump 12), and an appropriate amount of catalyst is added to carry out the transesterification reaction. The gaseous ME after the reaction is condensed through the transesterification condenser 5 and collected in the ME crude product tank 6. The liquid phase material is pumped into the acid-base neutralization tank 4 through the transesterification reactor liquid pump 13. The material in the ME crude product tank 6 is pumped into the acetic acid-methanol storage tank 16 through the ME crude product pump 18. After thorough mixing, it enters the acid-base neutralization tank 4 through the acetic acid-methanol pump 17 for acid-base neutralization to neutrality. Then, pure water is added for water washing and separation. The aqueous phase in the acid-base neutralization tank 4 is stored in the aqueous phase tank 20. The salt can be recovered by vacuum distillation to achieve water recycling. The organic phase in the acid-base neutralization tank 4 enters the vacuum distillation reactor 8 for purification. The light components in the vacuum distillation kettle 8 are separated by the distillation column 7 and then enter different storage tanks through the distillation condenser 9; the kettle residue is stored in the kettle residue tank 21.

[0034] Preferably, the ester exchange reactor 3 and the vacuum distillation vessel 8 are respectively equipped with a stirrer, a heat exchange structure and an interlocking control system to realize the interlocking control of temperature and heating steam.

[0035] Preferably, the ester exchange condenser 5 and the distillation condenser 9 are respectively equipped with interlocked control of temperature and coolant to realize automatic control of cooling temperature and coolant flow rate.

[0036] Preferably, the top of the distillation column 7 is equipped with a vapor phase temperature monitoring system and an interlock control between the temperature and the shut-off valve before the storage tank. When the top vapor phase temperature is ≥25℃ and <50℃, the liquid condensed from the distillation condenser 9 flows to the ME storage tank 22; when the top vapor phase temperature is ≥50℃ and <120℃, the liquid condensed from the distillation condenser 9 flows to the isooctanol crude product tank 23; when the top vapor phase temperature is ≥120℃ and ≤150℃, the liquid condensed from the distillation condenser 9 flows to the OS product tank 24; the OS product tank 24 is also equipped with an online detection system to monitor product quality in real time.

[0037] like Figure 1 As shown, the present invention also provides a method for producing isooctyl salicylate, which is carried out using the aforementioned isooctyl salicylate production apparatus, and mainly includes three core steps: transesterification reaction, acid-base neutralization, and product purification, as detailed below: S1. Transesterification reaction: Methyl salicylate and isooctanol are added to transesterification reactor 3 at a mass ratio of 1:(1-3), along with a catalyst (potassium carbonate, sodium methoxide, sodium carbonate, or p-toluenesulfonic acid, etc.) accounting for 0.1%-2% of the total mass of the raw materials. The reaction is stirred at 100-200℃ for 8-48 hours. The byproduct methanol (ME) generated during the reaction is recovered by distillation and collected in the crude ME tank 6. After the reaction is completed, the organic phase material is transferred to the acid-base neutralization tank 4.

[0038] S2. Acid-Base Neutralization: Add 5%–20% (by weight of the organic phase) of an acetic acid-methanol solution to the acid-base neutralization tank 4 to adjust the system to neutrality, thereby neutralizing any residual alkaline catalyst. Then, add 10%–90% (by weight of the organic phase) of deionized water for washing, and allow to stand for separation. The resulting aqueous phase, rich in potassium acetate, is sent to the aqueous phase tank 20 for vacuum distillation to recover high-purity potassium acetate, which can be sold as a byproduct. The organic phase is then transferred to the vacuum distillation vessel 8 for further purification.

[0039] S3. Product Purification: Start the vacuum system (i.e., vacuum pump 10), maintain the system pressure at approximately -0.098 MPa, and gradually increase the temperature to perform reduced-pressure distillation. Collect the fractions in stages according to the vapor temperature at the top of the distillation column 7: When the vapor phase temperature is ≥25℃ and <50℃, the condensate is methanol (ME) and is collected in ME storage tank 22; When the gas phase temperature rises to ≥50℃ and <120℃, the condensate is mainly unreacted isooctanol, which is recovered to the crude isooctanol tank 23 for recycling. When the vapor phase temperature reaches ≥120℃ and ≤150℃, the high-purity fraction obtained by condensation is isooctyl salicylate (OS), which is collected in OS product tank 24.

[0040] In step S2, the raw material for preparing the acetic acid-methanol solution is methanol, a byproduct collected in the ME crude product tank 6. The isooctanol carried in the byproduct methanol is recovered together with the unreacted isooctanol during the vacuum distillation process in step S3.

[0041] Using this process, the yield of OS products can reach over 85%, and the purity is higher than 99.5%, achieving the production goals of high efficiency, greenness, and high value.

[0042] Example 1 like Figure 1 As shown in the figure, this invention provides a method for producing isooctyl salicylate, using the aforementioned isooctyl salicylate production apparatus, and mainly includes three core steps: transesterification reaction, acid-base neutralization, and product purification, as detailed below: S1. Transesterification reaction: Methyl salicylate and isooctanol are added to transesterification reactor 3 at a mass ratio of 1:1, along with potassium carbonate catalyst accounting for 2% of the total raw material mass. The reaction is stirred at 100°C for 48 hours. The byproduct methanol (ME) generated during the reaction is recovered by distillation and collected in ME crude product tank 6. After the reaction is completed, the organic phase material is transferred to acid-base neutralization tank 4.

[0043] S2. Acid-Base Neutralization: Add 5% (by weight of the organic phase) of an acetic acid-methanol solution to the acid-base neutralization tank 4 to adjust the system to neutrality, thereby neutralizing the residual alkaline catalyst. Then, add 10% (by weight of the organic phase) of deionized water for washing, and allow to stand for separation. The resulting aqueous phase, rich in potassium acetate, is sent to the aqueous phase tank 20 for vacuum distillation to recover high-purity potassium acetate, which can be sold as a byproduct. The organic phase is then transferred to the vacuum distillation vessel 8 for further purification.

[0044] S3. Product Purification: Start the vacuum system (i.e., vacuum pump 10), maintain the system pressure at approximately -0.098 MPa, and gradually increase the temperature to perform reduced-pressure distillation. Collect the fractions in stages according to the vapor temperature at the top of the distillation column 7: When the vapor phase temperature is 35℃, the condensate is methanol (ME) and is collected in ME storage tank 22; When the gas phase temperature rises to 70°C, the condensate is mainly unreacted isooctanol, which is recovered to the crude isooctanol tank 23 for recycling. When the vapor phase temperature reaches 140℃, the high-purity fraction obtained by condensation is isooctyl salicylate (OS), which is collected in OS product tank 24.

[0045] Using this process, the OS product yield is 92% and the purity is 99.8%, achieving the production goals of high efficiency, greenness, and high value.

[0046] Example 2 like Figure 1As shown in the figure, this invention provides a method for producing isooctyl salicylate, using the aforementioned isooctyl salicylate production apparatus, and mainly includes three core steps: transesterification reaction, acid-base neutralization, and product purification, as detailed below: S1. Transesterification reaction: Methyl salicylate and isooctanol are added to transesterification reactor 3 at a mass ratio of 1:2, along with potassium carbonate catalyst accounting for 1% of the total mass of the raw materials. The reaction is stirred at 150°C for 24 hours. The byproduct methanol (ME) generated during the reaction is recovered by distillation and collected in ME crude product tank 6. After the reaction is completed, the organic phase material is transferred to acid-base neutralization tank 4.

[0047] S2. Acid-Base Neutralization: Add 10% (by weight of the organic phase) of an acetic acid-methanol solution to the acid-base neutralization tank 4 to adjust the system to neutrality, thereby neutralizing the residual alkaline catalyst. Then, add 40% (by weight of the organic phase) of deionized water for washing, and allow to stand for separation. The resulting aqueous phase, rich in potassium acetate, is sent to the aqueous phase tank 20 for vacuum distillation to recover high-purity potassium acetate, which can be sold as a byproduct. The organic phase is then transferred to the vacuum distillation vessel 8 for further purification.

[0048] S3. Product Purification: Start the vacuum system (i.e., vacuum pump 10), maintain the system pressure at approximately -0.098 MPa, and gradually increase the temperature to perform reduced-pressure distillation. Collect the fractions in stages according to the vapor temperature at the top of the distillation column 7: When the vapor phase temperature is 35℃, the condensate is methanol (ME) and is collected in ME storage tank 22; When the gas phase temperature rises to 70°C, the condensate is mainly unreacted isooctanol, which is recovered to the crude isooctanol tank 23 for recycling. When the vapor phase temperature reaches 140℃, the high-purity fraction obtained by condensation is isooctyl salicylate (OS), which is collected in OS product tank 24.

[0049] Using this process, the OS product yield is 89% and the purity is 99.75%, achieving the production goals of high efficiency, greenness, and high value.

[0050] Example 3 like Figure 1 As shown in the figure, this invention provides a method for producing isooctyl salicylate, using the aforementioned isooctyl salicylate production apparatus, and mainly includes three core steps: transesterification reaction, acid-base neutralization, and product purification, as detailed below: S1. Transesterification reaction: Methyl salicylate and isooctanol are added to transesterification reactor 3 at a mass ratio of 1:3, along with potassium carbonate catalyst at 0.1% of the total raw material mass. The reaction is stirred at 200℃ for 8 hours. The byproduct methanol (ME) generated during the reaction is recovered by distillation and collected in ME crude product tank 6. After the reaction is completed, the organic phase material is transferred to acid-base neutralization tank 4.

[0051] S2. Acid-Base Neutralization: Add 20% (by weight of the organic phase) of an acetic acid-methanol solution to the acid-base neutralization tank 4 to adjust the system to neutrality, thereby neutralizing the residual alkaline catalyst. Then, add 90% (by weight of the organic phase) of deionized water for washing, and allow to stand for separation. The resulting aqueous phase, rich in potassium acetate, is sent to the aqueous phase tank 20 for vacuum distillation to recover high-purity potassium acetate, which can be sold as a byproduct. The organic phase is then transferred to the vacuum distillation vessel 8 for further purification.

[0052] S3. Product Purification: Start the vacuum system (i.e., vacuum pump 10), maintain the system pressure at approximately -0.098 MPa, and gradually increase the temperature to perform reduced-pressure distillation. Collect the fractions in stages according to the vapor temperature at the top of the distillation column 7: When the vapor phase temperature is 35℃, the condensate is methanol (ME) and is collected in ME storage tank 22; When the gas phase temperature rises to 70°C, the condensate is mainly unreacted isooctanol, which is recovered to the crude isooctanol tank 23 for recycling. When the vapor phase temperature reaches 140℃, the high-purity fraction obtained by condensation is isooctyl salicylate (OS), which is collected in OS product tank 24.

[0053] Using this process, the yield of OS products is 87% and the purity is 99.7%, achieving the production goals of high efficiency, greenness, and high value.

[0054] Table 1 below shows the OS yield and purity data for Examples 1-3.

[0055] Project Name OS yield % OS purity % Example 1 92 99.8 Example 2 89 99.75 Example 3 87 99.7 The above embodiments of the present invention provide a production apparatus and method for isooctyl salicylate, which has the advantages of simple structure, low equipment investment, convenient operation, high degree of automation, and ease of continuous and industrialization. By optimizing the integrated reaction and separation process, the overall process efficiency and economy are significantly improved.

[0056] Specifically, this invention ingeniously utilizes methanol (ME), a byproduct of transesterification—which contains a small amount of entrained isooctanol—to directly prepare a 5%–20% acetic acid-methanol solution for neutralizing residual alkaline catalyst in the reaction system. This simplifies the preparation of the neutralizing agent and avoids the introduction of additional solvents. Simultaneously, in the subsequent vacuum distillation process, the entrained isooctanol can be recovered together with the unreacted isooctanol, eliminating the need for a separate ME-isooctanol separation unit. This effectively improves the purity of ME and achieves complete recovery of isooctanol, significantly reducing separation costs.

[0057] In addition, unreacted isooctanol can be efficiently recovered by vacuum distillation and recycled, significantly reducing raw material consumption; the potassium acetate aqueous solution produced by neutralization can be recovered by vacuum distillation to obtain high-purity potassium acetate as a by-product for sale, increasing revenue; the aqueous phase obtained by distillation can also be reused in the water washing process, reducing wastewater discharge, which is in line with the concept of green, low-carbon and sustainable development.

[0058] The overall process employs a three-step method: transesterification, acid-base neutralization, and vacuum distillation. This method is simple, minimizes material loss, maximizes equipment utilization, and ensures continuous and stable operation. Methyl salicylate has a high conversion rate, with the total yield of the target product, isooctyl salicylate, exceeding 85% and a purity of over 99.5%. The product quality fully meets the stringent requirements of the daily chemical industry for high-purity UVB absorbers.

[0059] While specific embodiments of the invention have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. A production apparatus of isooctyl salicylate comprising a transesterification reactor (3) and a vacuum distillation reactor (8), characterized by, The inlet of the ester exchange reaction kettle (3) is communicated with the isooctanol raw material tank (1) and the methyl salicylate raw material tank (11) respectively; The gas phase pipeline of the ester exchange reaction kettle (3) is communicated with the ME crude product tank (6) through the ester exchange condenser (5) in sequence, the outlet of the ME crude product tank (6) is communicated with the inlet of the acetic acid-methanol storage tank (16), and the outlet of the acetic acid-methanol storage tank (16) is communicated with the inlet of the acid-base neutralization tank (4); The liquid phase pipeline of the ester exchange reaction kettle (3) is communicated with the inlet of the acid-base neutralization tank (4), the inlet of the acid-base neutralization tank (4) is also communicated with the pure water tank (14), the organic phase pipeline of the acid-base neutralization tank (4) is communicated with the inlet of the reduced pressure distillation kettle (8), and the water phase pipeline of the acid-base neutralization tank (4) is communicated with the water phase tank (20); The light component pipeline of the reduced pressure distillation kettle (8) is communicated with the ME storage tank (22), the isooctanol crude product tank (23) and the OS product tank (24) through the distillation kettle rectifying tower (7) and the distillation condenser (9) in sequence, and the distillation condenser (9) is also provided with a vacuum pump (10) on the communication pipeline of the ME storage tank (22), the isooctanol crude product tank (23) and the OS product tank (24). The outlet of the isooctanol crude product tank (23) is communicated with the inlet of the ester exchange reaction kettle (3), and the kettle residue pipeline of the reduced pressure distillation kettle (8) is communicated with the kettle residue tank (21).

2. The apparatus for producing iso-octyl salicylate according to claim 1, characterized by Further comprising an isooctanol raw material pump (2), a methyl salicylate raw material pump (12), an ME crude product pump (18), an acetic acid-methanol pump (17), an ester exchange kettle liquid pump (13), a pure water pump (15) and an isooctanol crude product pump (19); The isooctanol raw material tank (1) is communicated with the ester exchange reaction kettle (3) through the isooctanol raw material pump (2), and the methyl salicylate raw material tank (11) is communicated with the ester exchange reaction kettle (3) through the methyl salicylate raw material pump (12); The ME crude product tank (6) is communicated with the acetic acid-methanol storage tank (16) through the ME crude product pump (18), and the acetic acid-methanol storage tank (16) is communicated with the acid-base neutralization tank (4) through the acetic acid-methanol pump (17); The ester exchange reaction kettle (3) is communicated with the acid-base neutralization tank (4) through the ester exchange kettle liquid pump (13), and the pure water tank (14) is communicated with the acid-base neutralization tank (4) through the pure water pump (15); The isooctanol crude product tank (23) is communicated with the ester exchange reaction kettle (3) through the isooctanol crude product pump (19).

3. The apparatus for producing iso-octyl salicylate according to claim 2, characterized by The ester exchange reaction kettle (3) and the reduced pressure distillation kettle (8) are respectively provided with a stirrer, a heat exchange structure and an interlocking control system, and the interlocking control system is used for realizing interlocking control of reaction / distillation temperature and heating steam.

4. The apparatus for producing iso-octyl salicylate according to claim 3, characterized by The ester exchange condenser (5) and the distillation condenser (9) are respectively provided with a temperature and cooling liquid interlocking control unit, and the interlocking control unit is used for realizing automatic adjustment of cooling temperature and cooling liquid flow.

5. The apparatus for producing iso-octyl salicylate according to claim 4, characterized by The top of the distillation kettle rectifying tower (7) is provided with a gas phase temperature monitoring system, and the gas phase temperature monitoring system and the shut-off valves before the ME storage tank (22), the isooctanol crude product tank (23) and the OS product tank (24) respectively constitute interlocking control. When the temperature of the gas phase at the top of the distillation column (7) is ≥25℃ and <50℃, the cut-off valve controls the condensed liquid of the distillation condenser (9) to flow to the ME storage tank (22); When the temperature of the gas phase is ≥50℃ and <120℃, the cut-off valve controls the condensed liquid to flow to the isooctanol crude product tank (23); When the temperature of the gas phase is ≥120℃ and ≤150℃, the cut-off valve controls the condensed liquid to flow to the OS product tank (24); The OS product tank (24) is also provided with an online detection system for real-time monitoring of the purity of the isooctyl salicylate.

6. A process for the production of isooctyl salicylate using the production apparatus according to any one of claims 1 to 5, characterized in that, The method comprises the following steps: S1, transesterification reaction: the methyl salicylate and isooctanol are put into a transesterification reactor (3) at a mass ratio of 1:(1-3), and 0.1%-2% of the total mass of the raw materials of a catalyst is added, and the reaction is stirred at 100-200℃ for 8-48 hours; the byproduct methanol generated in the reaction is collected into the ME crude product tank (6) after being condensed by distillation and the ester exchange condenser (5), and the organic phase material after the reaction is transferred to the acid-base neutralization tank (4); S2, acid-base neutralization: 5%-20% of the mass of the organic phase of acetic acid-methanol solution is added to the acid-base neutralization tank (4), and the system is adjusted to be neutral; then 10%-90% of the mass of the organic phase of deionized water is added for water washing, and the system is left to stand and separate; the obtained water phase is sent to the water phase tank (20), and potassium acetate is recovered by reduced pressure distillation; the obtained organic phase is transferred to the reduced pressure distillation kettle (8); S3, product purification: the vacuum pump (10) is started, the pressure in the reduced pressure distillation kettle (8) is maintained at-0.098 MPa, and the temperature is gradually increased for reduced pressure distillation; according to the temperature of the gas phase at the top of the distillation column (7), the distillate is collected in sections: When the temperature of the gas phase is ≥25℃ and <50℃, the condensed liquid is methanol, which is collected into the ME storage tank (22); When the temperature of the gas phase is ≥50℃ and <120℃, the condensed liquid is unreacted isooctanol, which is collected into the isooctanol crude product tank (23) and recycled to the transesterification reactor (3); When the temperature of the gas phase is ≥120℃ and ≤150℃, the condensed liquid is isooctyl salicylate, which is collected into the OS product tank (24).

7. The method for producing iso-octyl salicylate according to claim 6, characterized by, In step S1, the catalyst is at least one of potassium carbonate, sodium methoxide, sodium carbonate or p-toluene sulfonic acid.

8. The method for producing iso-octyl salicylate according to claim 7, characterized by, In step S2, the raw material for preparing the acetic acid-methanol solution is the byproduct methanol collected in the ME crude product tank (6), and the isooctanol entrained in the byproduct methanol is recovered together with the unreacted isooctanol in the reduced pressure distillation process in step S3.

9. The method for producing iso-octyl salicylate according to claim 8, characterized by, The isooctyl salicylate prepared by the method has a yield of ≥85% and a purity of ≥99.5%.

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