Refining method of salicylate compound

Abstract

The invention provides a method for refining salicylate compounds. The method comprises the following steps: separating heavy components in a reaction solution containing the salicylate compounds from distilled fractions, and then rectifying the distilled fractions, the boiling point of the heavy component is higher than that of the salicylate compound; the boiling point of the distilled fraction is less than or equal to that of the salicylate compound. According to the method disclosed by the invention, the heavy component kettle residues are separated before rectification and purification, so that light components generated by continuous decomposition of the heavy components in the kettle residues under heating are reduced, and relatively high impurity residues in the extracted salicylate compounds are avoided.

Description

Technical Field

[0001] The invention relates to the technical field of fine chemical products, and in particular to a method for refining salicylate compounds. Background Art

[0002] In the prior art, ester compounds can be synthesized by dehydration of carboxylic acid and alcohol under acid catalysis (direct esterification method), or by corresponding acyl halide (such as acyl chloride) and alcohol (acyl chloride method), or by other esters and corresponding alcohol (ester exchange method); no matter which method is used, in the process of distillation and purification, it is inevitable that by-product alcohol, raw material alcohol and raw material phenol residues of salicylic acid esters will remain in the finished product, resulting in odor in the finished product, affecting the quality of the product.

[0003] In order to solve the problems of product odor and raw material residue, it is necessary to find a new refining method to prepare high-purity finished products. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for refining salicylate compounds.

[0005] The invention provides a method for refining salicylate compounds, comprising the following steps: separating a heavy component from a distilled fraction in a reaction solution containing salicylate compounds, and then rectifying the distilled fraction; the boiling point of the heavy component is higher than that of the salicylate compounds; and the boiling point of the distilled fraction is less than or equal to that of the salicylate compounds.

[0006] In the existing method, the washed material is directly subjected to negative pressure distillation, and after isophorol and light components are extracted respectively, the finished product is extracted from the tower top by controlling the reflux ratio. In order to improve the product content as much as possible and eliminate the residual odor, this method has to further reduce the system vacuum degree, increase the number of plates or use high-efficiency fillers, increase the height of the distillation tower or increase the reflux ratio, which inevitably increases the production cost and prolongs the distillation time, and improves energy consumption. However, the present invention separates the heavy components first, greatly reducing the decomposition caused by the heating of the heavy components during the distillation process, and extracts salicylate compounds from the bottom of the tower during the distillation process, effectively avoiding the light components enriched at the top of the tower, and can directly extract high-content salicylate compounds at the bottom of the tower when the light component content at the top of the tower is high, reducing the difficulty of distillation and shortening the time to obtain salicylate compounds. The purity of the product salicylate compounds is significantly improved, and energy consumption is reduced, and production capacity is increased.

[0007] In some embodiments, the salicylate compound comprises a structure shown in Formula I:

[0008]

[0009] Wherein, R is selected from substituted or unsubstituted C1-C15 alkyl, substituted or unsubstituted C3-C20 cycloalkyl; the substituted substituent is selected from deuterium, halogen, alkyl with 1-10 carbon atoms, cycloalkyl with 3-10 carbon atoms.

[0010] In some embodiments, R is selected from substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C3-C10 cycloalkyl; the substituted substituent is selected from deuterium, halogen, methyl, ethyl, propyl, isopropyl, and butyl.

[0011] In some embodiments, R is selected from methyl, ethyl, propyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, or 3,3,5-trimethylcyclohexyl.

[0012] In some embodiments, R is selected from 3,3,5-trimethylcyclohexyl.

[0013] In some embodiments, the reaction solution containing salicylate compounds comprises 0.2-0.4 wt% of heavy components and 99.6-99.8 wt% of distilled fractions. The impurities in the present invention mainly come from the residues produced by incomplete reaction of raw materials.

[0014] In some embodiments, in the reaction solution containing salicylate compounds, the mass content of the heavy component is 0.2-0.4wt%, for example, 0.2wt%, 0.22wt%, 0.24wt%, 0.26wt%, 0.28wt%, 0.3wt%, 0.32wt%, 0.34wt%, 0.36wt%, 0.38wt%, 0.4wt% or any value therebetween.

[0015] In some embodiments, in the reaction solution containing salicylate compounds, the mass content of the distilled fraction is 99.6-99.8wt%, for example, 99.6wt%, 99.62wt%, 99.64wt%, 99.66wt%, 99.68wt%, 99.7wt%, 99.72wt%, 99.74wt%, 99.76wt%, 99.78wt%, 99.8wt% or any value therebetween.

[0016] In some embodiments, the heavy component includes an ether compound having a boiling point higher than that of the salicylate compound.

[0017] In some embodiments, the distilled fraction includes salicylate compounds and light components; wherein the light components include ether compounds having a boiling point lower than that of the salicylate compounds, phenol, salicylic acid, unreacted raw materials, and impurities in the raw materials.

[0018] In some embodiments, the mass content of the light component is 0.05-0.1% of the mass of the reaction solution containing salicylate compounds, for example, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 1% or any value therebetween.

[0019] In some embodiments, the separation method comprises one or more of distillation tower separation, evaporator separation or membrane separation.

[0020] In some embodiments, the separation method comprises evaporator separation and / or membrane separation.

[0021] In some embodiments, the separation reaction pressure is 50-300 Pa, for example, 60 Pa, 90 Pa, 120 Pa, 150 Pa, 180 Pa, 210 Pa, 240 Pa, 270 Pa, 300 Pa or any value therebetween.

[0022] In some embodiments, the separation temperature is 100-160°C, for example, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C or any value therebetween.

[0023] In some embodiments, the distillation pressure is 50-300 Pa, for example, 60 Pa, 90 Pa, 120 Pa, 150 Pa, 180 Pa, 210 Pa, 240 Pa, 270 Pa, 300 Pa or any value therebetween.

[0024] In some embodiments, the reflux ratio of the distillation is 1:(1-20), for example, 1:2, 1:4, 1:6, 1:8, 1:10, 1:12, 1:14, 1:16, 1:18, 1:20 or any value therebetween.

[0025] The present invention respectively extracts unreacted raw materials (such as alcohol compounds, specifically including isophorol) and other light components by adjusting the reflux ratio.

[0026] In some embodiments, when the light components are extracted, the reflux ratio of the distillation is 1:(15-20).

[0027] In some embodiments, when unreacted raw materials (such as alcohol compound raw materials) are withdrawn, the reflux ratio of the distillation is 1:(1-10).

[0028] In some embodiments, the distillation temperature is 100-160°C, for example, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C or any value therebetween.

[0029] In some embodiments, the distillation is performed in a distillation column.

[0030] In some embodiments, after the light component is extracted, the valve opening of the bottom regulating valve of the distillation tower is controlled to be 5-95%, for example, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or any value therebetween.

[0031] In some embodiments, the reaction solution containing salicylate compounds is prepared by the following steps: mixing salicylate raw materials with alcohol compounds, and performing an ester exchange reaction under the action of a catalyst.

[0032] In some embodiments, the salicylate starting material comprises an alkyl salicylate.

[0033] In some embodiments, the salicylate raw material is selected from one or more of methyl salicylate, ethyl salicylate, benzyl salicylate, phenethyl salicylate, isobutyl salicylate or butyl salicylate.

[0034] In some embodiments, the alcohol compound is selected from substituted or unsubstituted C1-C15 alkyl alcohols, substituted or unsubstituted C3-C20 cycloalkyl alcohols; the substituted substituents are selected from deuterium, halogen, alkyl groups having 1-10 carbon atoms, and cycloalkyl groups having 3-10 carbon atoms.

[0035] In some embodiments, the alcohol compound is selected from substituted or unsubstituted C1-C10 alkyl alcohols, substituted or unsubstituted C3-C10 cycloalkyl alcohols; the substituted substituents are selected from deuterium, halogen, methyl, ethyl, propyl, isopropyl, and butyl.

[0036] In some embodiments, the alcohol compound is selected from C1-C10 straight-chain alkyl alcohol, substituted or unsubstituted C3-C10 cycloalkyl alcohol; the substituted substituent is selected from methyl, ethyl, propyl, isopropyl, and butyl.

[0037] In some embodiments, the alcohol compound is selected from methanol, ethanol, propanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, isophorol and isomers thereof.

[0038] In some embodiments, the ether compound having a higher boiling point than the salicylate compound is obtained by an alcohol compound after an ester exchange reaction between a salicylate compound and an alcohol compound.

[0039] In some embodiments, the ether compound having a boiling point lower than that of the salicylate compound is obtained by reacting a salicylate raw material with an alcohol compound after an ester exchange reaction.

[0040] For example, when methyl salicylate and isophorol undergo an ester exchange reaction to obtain a reaction solution containing original membrane ester, the heavy components include ether compounds obtained by the reaction of original membrane ester and methanol, wherein methanol is formed after the reaction of methyl salicylate and isophorol; the light components include unreacted methyl salicylate, methyl paraben, phenol, salicylic acid, methyl salicylate methyl ether, unreacted isophorol and impurities in isophorol; wherein methyl salicylate methyl ether is obtained by the reaction of methyl salicylate and methanol.

[0041] In some embodiments, the catalyst comprises a basic catalyst.

[0042] In some embodiments, the catalyst is selected from one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, cupric hydroxide, ferrous hydroxide, sodium methoxide or tetraisopropyl titanate.

[0043] In some embodiments, the molar ratio of the salicylate raw material to the alcohol compound is 1:1-10, for example, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10 or any value therebetween.

[0044] In some embodiments, the temperature of the transesterification reaction is 100-160°C, for example, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C or any value therebetween.

[0045] In some embodiments, the pressure of the transesterification reaction is 5-50 KPa, for example, 5 KPa, 10 KPa, 15 KPa, 20 KPa, 25 KPa, 30 KPa, 35 KPa, 40 KPa, 45 KPa, 50 KPa or any value therebetween.

[0046] In a second aspect, the present invention provides a method for purifying 3,3,5-trimethylcyclohexanol salicylate, comprising the following steps: separating a heavy component from a distilled fraction in a reaction solution containing 3,3,5-trimethylcyclohexanol salicylate, and then distilling the distilled fraction; the boiling point of the heavy component is higher than that of salicylate compounds; and the boiling point of the distilled fraction is less than or equal to that of salicylate compounds.

[0047] In some embodiments, the heavy component includes an ether compound obtained by the reaction of 3,3,5-trimethylcyclohexanol salicylate and methanol, wherein methanol is formed by the reaction of methyl salicylate and isophorol.

[0048] In some embodiments, the distilled fraction includes salicylic acid ester compounds and light components.

[0049] In some embodiments, the light component includes unreacted methyl salicylate, methyl paraben, phenol, salicylic acid, methyl salicylate methyl ether, unreacted isophorol and impurities in isophorol; wherein methyl salicylate methyl ether is obtained by reacting methyl salicylate with methanol.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] (1) The present invention separates the heavy component still residue before distillation and purification, thereby reducing the continuous decomposition of the heavy component in the still residue under heating to produce light components, and avoiding the presence of high impurities in the produced finished salicylate compound;

[0052] (2) The finished salicylate compounds are extracted from the bottom of the distillation tower instead of from the top of the tower, which can effectively retain the odorous light component impurities (such as alcohol compound raw materials such as isophorol) at the top of the tower, and the light components are continuously extracted at the top reflux ratio to ensure that there are no light components remaining at the bottom of the distillation tower, thereby obtaining a high-purity finished product. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. The specific embodiments described herein are only used to explain the present invention and are not intended to constitute any limitation to the present invention.

[0054] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0055] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the raw materials, instruments and equipment used in the following examples, etc., can all be purchased on the market or can be obtained by existing methods; the reagent amounts, unless otherwise specified, are the reagent amounts used in conventional experimental operations; the experimental methods, unless otherwise specified, are all conventional methods.

[0056] The room temperature in the present invention refers to 20-25°C.

[0057] In the embodiment of the present invention, the light components include methyl salicylate, methyl salicylate methyl ether, phenol, methyl paraben, salicylic acid, unreacted isophorol and impurities in isophorol, and the heavy components include ether compounds generated by the original membrane ester and methanol.

[0058] HMS, scientific name 3,3,5-trimethylcyclohexanol salicylate, also known as homosalate, molecular formula C 16 H 22 O3. The structural formula is as follows:

[0059]

[0060] Original membrane ester can efficiently absorb ultraviolet rays with a wavelength of 295 to 315nm, so it is widely used in various fields as an efficient ultraviolet absorber. For example, original membrane ester has good fat solubility and is often added to polyvinyl chloride plastics, nitrocellulose, acrylic resins and polyurethane coatings as a light stabilizer; original membrane ester has good biocompatibility and good safety, and is often added to high-end cosmetics as a chemical sunscreen to protect the skin from damage by ultraviolet radiation.

[0061] Valve opening refers to the ratio of the flow area between the valve disc and the valve seat during the valve adjustment process to the flow area when the valve is fully open, usually expressed as a percentage.

[0062] The size of the valve opening determines the flow rate and pressure of the medium in the pipeline. When the valve opening increases, the flow area between the valve disc and the valve seat increases, the channel through which the medium flows becomes wider, the flow rate increases, and the pressure in the pipeline decreases. On the contrary, when the valve opening decreases, the flow area decreases, the channel through which the medium flows becomes narrower, the flow rate decreases, and the pressure in the pipeline increases.

[0063] The present invention takes the production of homosalate as an example, and lists the following embodiments and comparative examples:

[0064] Example 1

[0065] At room temperature, 180g of methyl salicylate and 400g of isophorol were added to a reactor equipped with a distillation tower and a thermometer. After the addition was completed, the reactor was heated to 80°C, and then 35g of a 15% potassium carbonate solution as a catalyst was added dropwise. After the addition was completed, the temperature was raised to 130°C, the system was evacuated to a pressure of 30KPa, and an ester exchange reaction was carried out in the reactor equipped with a distillation tower until the reaction was completed to obtain a reaction solution containing the original membrane ester. The reaction solution was washed twice with 50g of 5wt% potassium carbonate and once with 50g of pure water.

[0066] After washing, the reaction liquid includes 0.05-0.1wt% light components (including methyl salicylate, methyl salicylate methyl ether, phenol, methyl paraben, salicylic acid, and impurities in isophorol), and 0.2-0.4wt% heavy components (ether compounds generated by the original film ester and methanol). The heavy components are separated by a falling film evaporator, the heating temperature is 150°C, the pressure is 300Pa, and the distilled fraction enters a distillation tower for negative pressure distillation, and the reflux ratio is adjusted by a solenoid valve to extract isophorol and light components, the heating temperature is 145°C, the pressure is 250Pa, the reflux ratio of isophorol is 1:5, and the reflux ratio of light components is 1:15. After the light component is produced, the opening of the regulating valve at the bottom of the tower is controlled to be 40%, and the finished product is produced from the bottom of the tower. The other part is refluxed to the reactor for continued distillation to maintain the balance of the distillation system. The distillation is completed after 8 hours of distillation to obtain a finished product with a content of 99.21%, no phenol was detected, no methyl paraben was detected, 113 ppm of isophorol, a sweet taste, and a yield of 92%.

[0067] Example 2

[0068] At room temperature, 180g of methyl salicylate and 400g of isophorol were added to a reactor equipped with a distillation tower and a thermometer. After the addition was completed, the reactor was heated to 80°C, and then 35g of a 15% potassium carbonate solution as a catalyst was added dropwise. After the addition was completed, the temperature was raised to 130°C, the system was evacuated to a pressure of 30KPa, and an ester exchange reaction was carried out in the reactor equipped with a distillation tower until the reaction was completed to obtain a reaction solution containing the original membrane ester. The reaction solution was washed twice with 50g of 5% potassium carbonate and once with 50g of pure water.

[0069] After washing, the heavy components are separated by falling film evaporation device, heated to 150℃, pressure 300Pa, and the distilled fraction enters the distillation tower for negative pressure distillation. The reflux ratio of isophorol and light components is extracted by the solenoid valve. The heating temperature is 145℃, the pressure is 250Pa, the reflux ratio of isophorol is 1:5, and the reflux ratio of light components is 1:5. After the extraction of light components, the valve opening of the bottom regulating valve of the tower is controlled to be 50%, and the finished product is extracted from the bottom of the tower. The other part is refluxed to the reactor for continued distillation to maintain the balance of the distillation system. The distillation is completed after 6 hours of distillation, and the content of the finished product is 99.13%, phenol is not detected, methyl paraben is not detected, isophorol is 133ppm, and there is a sweet taste. The yield is 94.5%.

[0070] Example 3

[0071] At room temperature, 180g of methyl salicylate and 400g of isophorol were added to a reactor equipped with a distillation tower and a thermometer. After the addition was completed, the reactor was heated to 80°C, and then 35g of a 15% potassium carbonate solution as a catalyst was added dropwise. After the addition was completed, the temperature was raised to 130°C, the system was evacuated to a pressure of 30KPa, and an ester exchange reaction was carried out in the reactor equipped with a distillation tower until the reaction was completed to obtain a reaction solution containing the original membrane ester. The reaction solution was washed twice with 50g of 5% potassium carbonate and once with 50g of pure water.

[0072] After washing, the heavy components are separated by falling film evaporation device, heated to 150℃, pressure 300Pa, and the distilled fraction enters the distillation tower for negative pressure distillation. The reflux ratio of isophorol and light components is extracted by the solenoid valve. The heating temperature is 155℃, the pressure is 250Pa, the reflux ratio of isophorol is 1:5, and the reflux ratio of light components is 1:20. After the extraction of light components, the valve opening of the bottom regulating valve of the tower is controlled to be 40%, and the finished product is extracted from the bottom of the tower. The other part is refluxed to the reactor for continued distillation to maintain the balance of the distillation system. The distillation is completed after 8 hours of distillation, and the finished product content is 99.63%, phenol is not detected, methyl paraben is not detected, isophorol is 52ppm, and there is a sweet taste. The yield is 91.8%.

[0073] Example 4

[0074] At room temperature, 180 g of methyl salicylate and 366 g of isooctyl alcohol are added to a reactor equipped with a distillation tower and a thermometer. After the addition is completed, the reactor is heated to 80° C., and then 35 g of a 15% potassium carbonate solution as a catalyst is added dropwise; after the addition is completed, the temperature is raised to 130° C., the system is evacuated to a pressure of 30 KPa, and an ester exchange reaction is carried out in the reactor equipped with a distillation tower until the reaction is completed; a reaction solution containing isooctyl salicylate is obtained, and the reaction solution is washed twice with 50 g of 5wt% potassium carbonate and once with 50 g of pure water;

[0075] After washing, the reaction liquid includes 0.05-0.1wt% light components (raw materials methyl salicylate, methyl salicylate methyl ether, phenol, methyl paraben, salicylic acid, and impurities in isooctyl alcohol), and 0.2-0.4wt% heavy components. The heavy components are separated by a falling film evaporator, heated to 150°C and 300Pa, and the distilled fraction is sent to a distillation tower for negative pressure distillation. The isooctyl alcohol and light components are extracted by a solenoid valve with a reflux ratio of 1:5 and a reflux ratio of 1:15 for the extracted isooctyl alcohol and light components. After the light component is produced, the opening of the regulating valve at the bottom of the tower is controlled to be 40%, and the finished product is produced from the bottom of the tower. The other part is refluxed to the reactor for continued distillation to maintain the balance of the distillation system. The distillation is completed after 8 hours of distillation to obtain a finished product with a content of 99.19%, no phenol was detected, no methyl paraben was detected, 116 ppm of isooctyl alcohol, a sweet taste, and a yield of 92.7%.

[0076] Example 5

[0077] At room temperature, 180g of methyl salicylate and 400g of isophorol were added to a reactor equipped with a distillation tower and a thermometer. After the addition was completed, the reactor was heated to 80°C, and then 35g of a 15% potassium carbonate solution as a catalyst was added dropwise. After the addition was completed, the temperature was raised to 130°C, the system was evacuated to a pressure of 30KPa, and an ester exchange reaction was carried out in the reactor equipped with a distillation tower until the reaction was completed to obtain a reaction solution containing the original membrane ester. The reaction solution was washed twice with 50g of 5wt% potassium carbonate and once with 50g of pure water.

[0078] After washing, the reaction liquid includes 0.05-0.1wt% light components (raw materials methyl salicylate, methyl salicylate methyl ether, phenol, methyl paraben, salicylic acid, and impurities in isophorol), and 0.2-0.4wt% heavy components. The heavy components are separated by a falling film evaporator, heated to 100°C and 300Pa, and the distilled fraction is sent to a distillation tower for negative pressure distillation, and the reflux ratio of isophorol and light components is adjusted by a solenoid valve, heated to 145°C and 250Pa, and the reflux ratio of isophorol is 1:5, and the reflux ratio of light components is 1:15. After the light component is produced, the opening of the regulating valve at the bottom of the tower is controlled to be 40%, and the finished product is produced from the bottom of the tower. The other part is refluxed to the reactor for continued distillation to maintain the balance of the distillation system. The distillation is completed after 7 hours of distillation to obtain a finished product with a content of 99.02%, no phenol was detected, no methyl paraben was detected, 96 ppm of isophorol, a sweet taste, and a yield of 90.3%.

[0079] Example 6

[0080] At room temperature, 180g of methyl salicylate and 400g of isophorol were added to a reactor equipped with a distillation tower and a thermometer. After the addition was completed, the reactor was heated to 80°C, and then 35g of a 15% potassium carbonate solution as a catalyst was added dropwise. After the addition was completed, the temperature was raised to 130°C, the system was evacuated to a pressure of 30KPa, and an ester exchange reaction was carried out in the reactor equipped with a distillation tower until the reaction was completed to obtain a reaction solution containing the original membrane ester. The reaction solution was washed twice with 50g of 5wt% potassium carbonate and once with 50g of pure water.

[0081] After washing, the reaction liquid includes 0.05-0.1wt% light components (raw materials methyl salicylate, methyl salicylate methyl ether, phenol, methyl paraben, salicylic acid, and impurities in isophorol), and 0.2-0.4wt% heavy components. The heavy components are separated by a falling film evaporator, heated to 80°C and 300Pa, and the distilled fraction is sent to a distillation tower for negative pressure distillation, and the reflux ratio of isophorol and light components is adjusted by a solenoid valve, heated to 145°C and 250Pa, and the reflux ratio of isophorol is 1:5, and the reflux ratio of light components is 1:15. After the light component is produced, the opening of the regulating valve at the bottom of the tower is controlled to be 40%, and the finished product is produced from the bottom of the tower. The other part is refluxed to the reactor for further distillation to maintain the balance of the distillation system. The distillation is completed after 6.5 hours of distillation to obtain a finished product with a content of 99.07%, no phenol detected, no methyl paraben detected, 91 ppm of isophorol, a sweet taste, and a yield of 85.2%.

[0082] Example 7

[0083] At room temperature, 180g of methyl salicylate and 400g of isophorol were added to a reactor equipped with a distillation tower and a thermometer. After the addition was completed, the reactor was heated to 80°C, and then 35g of a 15% potassium carbonate solution as a catalyst was added dropwise. After the addition was completed, the temperature was raised to 130°C, the system was evacuated to a pressure of 30KPa, and an ester exchange reaction was carried out in the reactor equipped with a distillation tower until the reaction was completed to obtain a reaction solution containing the original membrane ester. The reaction solution was washed twice with 50g of 5wt% potassium carbonate and once with 50g of pure water.

[0084] After washing, the reaction liquid includes 0.05-0.1wt% light components (raw materials methyl salicylate, methyl salicylate methyl ether, phenol, methyl paraben, salicylic acid, and impurities in isophorol), and 0.2-0.4wt% heavy components. The heavy components are separated by a falling film evaporator, heated to 180°C and 300Pa, and the distilled fraction is sent to a distillation tower for negative pressure distillation, and the reflux ratio of isophorol and light components is adjusted by a solenoid valve, heated to 145°C and 250Pa, and the reflux ratio of isophorol is 1:5, and the reflux ratio of light components is 1:15. After the light component is produced, the opening of the regulating valve at the bottom of the tower is controlled to be 40%, and the finished product is produced from the bottom of the tower. The other part is refluxed to the reactor for continued distillation to maintain the balance of the distillation system. The distillation is completed after 8.5 hours of distillation, and the finished product content is 99.01%, phenol is not detected, methyl paraben is not detected, isophorol is 783ppm, there is a distinct isophorol smell, and the yield is 91.2%.

[0085] Example 8

[0086] At room temperature, 180g of methyl salicylate and 400g of isophorol were added to a reactor equipped with a distillation tower and a thermometer. After the addition was completed, the reactor was heated to 80°C, and then 35g of a 15% potassium carbonate solution as a catalyst was added dropwise. After the addition was completed, the temperature was raised to 130°C, the system was evacuated to a pressure of 30KPa, and an ester exchange reaction was carried out in the reactor equipped with a distillation tower until the reaction was completed to obtain a reaction solution containing the original membrane ester. The reaction solution was washed twice with 50g of 5wt% potassium carbonate and once with 50g of pure water.

[0087] After washing, the reaction liquid includes 0.05-0.1wt% light components (raw materials methyl salicylate, methyl salicylate methyl ether, phenol, methyl paraben, salicylic acid, and impurities in isophorol), and 0.2-0.4wt% heavy components. The heavy components are separated by a falling film evaporator, heated to 150°C and 50Pa, and the distilled fraction is sent to a distillation tower for negative pressure distillation, and the reflux ratio of isophorol and light components is adjusted by a solenoid valve, heated to 145°C and 250Pa, and the reflux ratio of isophorol is 1:5, and the reflux ratio of light components is 1:15. After the light component is produced, the opening of the regulating valve at the bottom of the tower is controlled to be 40%, and the finished product is produced from the bottom of the tower. The other part is refluxed to the reactor for further distillation to maintain the balance of the distillation system. The distillation is completed after 8.5 hours of distillation to obtain a finished product with a content of 99.21%, no phenol was detected, no methyl paraben was detected, 416 ppm of isophorol was detected, there was a slight smell of isophorol, and the yield was 90.4%.

[0088] Example 9

[0089] At room temperature, 180g of methyl salicylate and 400g of isophorol were added to a reactor equipped with a distillation tower and a thermometer. After the addition was completed, the reactor was heated to 80°C, and then 35g of a 15% potassium carbonate solution as a catalyst was added dropwise. After the addition was completed, the temperature was raised to 130°C, the system was evacuated to a pressure of 30KPa, and an ester exchange reaction was carried out in the reactor equipped with a distillation tower until the reaction was completed to obtain a reaction solution containing the original membrane ester. The reaction solution was washed twice with 50g of 5wt% potassium carbonate and once with 50g of pure water.

[0090] After washing, the reaction liquid includes 0.05-0.1wt% light components (raw materials methyl salicylate, methyl salicylate methyl ether, phenol, methyl paraben, salicylic acid, and impurities in isophorol), and 0.2-0.4wt% heavy components. The heavy components are separated by a rectification device, heated to 180°C and 300Pa, and the distilled fraction is sent to a rectification tower for negative pressure distillation, and the reflux ratio of isophorol and light components is adjusted by a solenoid valve, heated to 145°C and 250Pa, and the reflux ratio of isophorol is 1:5, and the reflux ratio of light components is 1:15. After the light component is produced, the opening of the regulating valve at the bottom of the tower is controlled to be 40%, and the finished product is produced from the bottom of the tower. The other part is refluxed to the reactor for continued distillation to maintain the balance of the distillation system. The distillation is completed after 8.5 hours of distillation to obtain a finished product with a content of 99.11%, no phenol was detected, no methyl paraben was detected, 1175 ppm of isophorol, a distinct isophorol smell, and a yield of 91.3%.

[0091] Example 10

[0092] At room temperature, 180g of methyl salicylate and 400g of isophorol were added to a reactor equipped with a distillation tower and a thermometer. After the addition was completed, the reactor was heated to 80°C, and then 35g of a 15% potassium carbonate solution as a catalyst was added dropwise. After the addition was completed, the temperature was raised to 130°C, the system was evacuated to a pressure of 30KPa, and an ester exchange reaction was carried out in the reactor equipped with a distillation tower until the reaction was completed to obtain a reaction solution containing the original membrane ester. The reaction solution was washed twice with 50g of 5% potassium carbonate and once with 50g of pure water.

[0093] After washing, the reaction liquid includes 0.05-0.1wt% light components (including methyl salicylate, methyl salicylate methyl ether, phenol, methyl paraben, salicylic acid, and impurities in isophorol), and 0.2-0.4wt% heavy components (ether compounds generated by the original film ester and methanol). The heavy components are separated by a falling film evaporator, heated to 150°C and 300Pa, and the distilled fraction enters a distillation tower for negative pressure distillation. The isophorol and light components are extracted by a solenoid valve with a reflux ratio of 1:5, and the reflux ratio of the extracted isophorol is 1:15. After the light component is produced, the opening of the regulating valve at the bottom of the tower is controlled to be 40%, and the finished product is produced from the bottom of the tower. The other part is refluxed to the reactor for continued distillation to maintain the balance of the distillation system. The distillation is completed after 7.5 hours of distillation, and the finished product content is 99.31%, phenol is not detected, methyl paraben is not detected, isophorol is 103ppm, has a sweet taste, and the yield is 90.8%.

[0094] Embodiment 11

[0095] At room temperature, 180 g of methyl salicylate and 400 g of isophorol are added to a reactor equipped with a distillation tower and a thermometer. After the addition is completed, the reactor is heated to 80° C., and then 35 g of a 15% potassium carbonate solution as a catalyst is added dropwise; after the addition is completed, the temperature is raised to 130° C., the system is evacuated to a pressure of 30 KPa, and an ester exchange reaction is carried out in the reactor equipped with a distillation tower until the reaction is completed to obtain a reaction solution containing the original membrane ester; the reaction solution is washed twice with 50 g of 5% potassium carbonate and once with 50 g of pure water;

[0096] After washing, the reaction liquid includes 0.05-0.1wt% light components (including methyl salicylate, methyl salicylate methyl ether, phenol, methyl paraben, salicylic acid, and impurities in isophorol), and 0.2-0.4wt% heavy components (ether compounds generated by the original film ester and methanol). The heavy components are separated by a falling film evaporator, heated to 150°C and 300Pa, and the distilled fraction enters a distillation tower for negative pressure distillation. The isophorol and light components are extracted by a solenoid valve with a reflux ratio of 1:5, and the reflux ratio of the extracted isophorol is 1:15. After the light component is produced, the opening of the regulating valve at the bottom of the tower is controlled to be 40%, and the finished product is produced from the bottom of the tower. The other part is refluxed to the reactor for further distillation to maintain the balance of the distillation system. The distillation is completed after 8.5 hours of distillation to obtain a finished product with a content of 99.16%, no phenol was detected, no methyl paraben was detected, 126 ppm of isophorol, a sweet taste, and a yield of 91.2%.

[0097] Comparative Example 1

[0098] At room temperature, 180 g of methyl salicylate and 400 g of isophorol are added to a reactor equipped with a distillation tower and a thermometer. After the feeding is completed, the reactor is heated to 80° C., and then 35 g of a 15% potassium carbonate solution as a catalyst is added dropwise; after the addition is completed, the temperature is raised to 130° C., the system is evacuated to a kettle pressure of 30 KPa, and an ester exchange reaction is carried out in the reactor equipped with a distillation tower until the reaction is completed; the material is washed twice with 50 g of 5% potassium carbonate and once with 50 g of pure water; after the washing is completed, the material enters the distillation tower for negative pressure distillation, and the isophorol and light components are extracted by adjusting the reflux ratio through a solenoid valve. The heating temperature is 145° C., the pressure is 250 Pa, the reflux ratio of extracted isophorol is 1:5, and the reflux ratio of extracted light components is 1:15. After the light component was taken out, the finished product was continued to be taken out from the top of the tower, with a reflux ratio of 1:30 and distillation completed after 18 hours. The content of the finished product was 98.79%, phenol was 5ppm, methyl paraben was not detected, isophorol was 1037ppm, there was a distinct isophorol odor, and the yield was 92.1%.

[0099] Comparative Example 2

[0100] At room temperature, 180 g of methyl salicylate and 400 g of isophorol are added to a reactor equipped with a distillation tower and a thermometer. After the feeding is completed, the reactor is heated to 80° C., and then 35 g of a 15% potassium carbonate solution as a catalyst is added dropwise; after the addition is completed, the temperature is raised to 130° C., the system is evacuated to a kettle pressure of 30 KPa, and an ester exchange reaction is carried out in the reactor equipped with a distillation tower until the reaction is completed; the material is washed twice with 50 g of 5% potassium carbonate and once with 50 g of pure water; after the washing is completed, the material enters the distillation tower for negative pressure distillation, and the isophorol and light components are extracted by adjusting the reflux ratio through a solenoid valve. The heating temperature is 150° C., the pressure is 200 Pa, the reflux ratio of extracted isophorol is 1:8, and the reflux ratio of extracted light components is 1:15. After the light component was taken out, the finished product was continued to be taken out from the top of the tower, with a reflux ratio of 1:35 and distillation completed after 21 hours. The finished product content was 98.81%, phenol was 3ppm, methyl paraben was not detected, isophorol was 862ppm, there was a distinct isophorol odor, and the yield was 92.8%.

[0101] The reaction conditions of the above examples and comparative examples are shown in Table 1, and the test results are shown in Table 2.

[0102] Table 1

[0103]

[0104]

[0105] Table 2

[0106]

[0107]

[0108] According to the comparison between Comparative Examples 1 and 2, it can be seen that, without separation of heavy components, even if the distillation conditions are strengthened, there is no obvious effect on the increase of the original membrane bulk ester content, and the isophorol content is not significantly reduced.

[0109] In Example 9, the distillation method is adopted to separate the heavy components. The heavy components stay in the tower for a long time, and the isophorol produced by decomposition will enter the light components, resulting in more isophorol remaining in the second step.

[0110] In Comparative Example 1, falling film evaporation was not performed, and the heavy components were distilled together with the salicylate compounds, which would result in isophorol produced by the decomposition of the heavy components entering the finished product.

[0111] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for purifying a salicylate compound, comprising the following steps: separating a heavy component from a distilled fraction in a reaction solution containing a salicylate compound, and then rectifying the distilled fraction; The boiling point of the heavy component is higher than that of salicylate compounds; and the boiling point of the distilled fraction is less than or equal to that of salicylate compounds.

2. The refining method according to claim 1, characterized in that The salicylate compound includes a structure shown in Formula I: Wherein, R is selected from substituted or unsubstituted C1-C15 alkyl, substituted or unsubstituted C3-C20 cycloalkyl; The substituted substituent is selected from deuterium, halogen, alkyl having 1 to 10 carbon atoms, cycloalkyl having 3 to 10 carbon atoms; Preferably, R is selected from substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C3-C10 cycloalkyl; The substituted substituent is selected from deuterium, halogen, methyl, ethyl, propyl, isopropyl, butyl; Preferably, R is selected from methyl, ethyl, propyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl or 3,3,5-trimethylcyclohexyl; More preferably, R is selected from 3,3,5-trimethylcyclohexyl.

3. The purification method according to claim 1 or 2, characterized in that: The reaction solution containing salicylate compounds comprises 0.2-0.4 wt % of heavy components and 99.6-99.8 wt % of distilled fractions; Preferably, the heavy component comprises an ether compound having a boiling point higher than that of the salicylate compound; and / or The distilled fraction includes salicylate compounds and light components; wherein the light components include ether compounds having a boiling point lower than that of the salicylate compounds, phenol, salicylic acid, unreacted raw materials and impurities in the raw materials; Preferably, the mass content of the light component is 0.05-0.1% of the mass of the reaction solution containing the salicylate compound.

4. The refining method according to any one of claims 1 to 3, characterized in that: The separation method comprises one or more of separation by distillation tower, separation by evaporator or separation by membrane, preferably separation by evaporator and / or separation by membrane.

5. The refining method according to any one of claims 1 to 4, characterized in that: The separation reaction pressure is 50-300 Pa, and / or The separation temperature is 100-160°C.

6. The refining method according to any one of claims 1 to 5, characterized in that: The distillation pressure is 50-300 Pa, and / or The reflux ratio of the distillation is 1:(1-20); and / or The distillation temperature is 100-160°C; and / or The distillation is carried out in a distillation tower; Preferably, the opening degree of the regulating valve at the bottom of the distillation tower is 5-95%.

7. The refining method according to any one of claims 1 to 6, characterized in that: The reaction solution containing salicylate compounds is prepared by the following steps: The salicylic acid ester raw material is mixed with an alcohol compound, and an ester exchange reaction is carried out under the action of a catalyst; Preferably, the salicylate raw material comprises alkyl salicylate; preferably one or more selected from methyl salicylate, ethyl salicylate, benzyl salicylate, phenethyl salicylate, isobutyl salicylate or butyl salicylate; and / or The alcohol compound is selected from substituted or unsubstituted C1-C15 alkyl alcohols, substituted or unsubstituted C3-C20 cycloalkyl alcohols; Preferably, the alcohol compound is selected from substituted or unsubstituted C1-C10 alkyl alcohols, substituted or unsubstituted C3-C10 cycloalkyl alcohols; Preferably, the alcohol compound is selected from methanol, ethanol, propanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, isophorol and isomers thereof.

8. The refining method according to claim 7, characterized in that: The catalyst comprises an alkaline catalyst, preferably one or more selected from sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, cupric hydroxide, ferrous hydroxide, sodium methoxide or tetraisopropyl titanate; and / or The molar ratio of the salicylate raw material to the alcohol compound is 1:1-10.

9. The purification method according to claim 7 or 8, characterized in that: The temperature of the transesterification reaction is 100-160°C; and / or The pressure of the transesterification reaction is 5-50 KPa.

10. A method for purifying 3,3,5-trimethylcyclohexanol salicylate, comprising the following steps: separating a heavy component from a distilled fraction in a reaction solution containing 3,3,5-trimethylcyclohexanol salicylate, and then rectifying the distilled fraction; The boiling point of the heavy component is higher than that of salicylate compounds; and the boiling point of the distilled fraction is less than or equal to that of salicylate compounds.

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