Aliphatic acyl chloride and purification method thereof

Abstract

The invention provides aliphatic acyl chloride and a purification method thereof. The purification method comprises the following steps: S1, introducing a crude product mixed solution which is obtained by reacting aliphatic carboxylic acid with phosgene and has the temperature of 50-100 DEG C into a gas driving tower at the flow rate of Q1, carrying out first purification, and extracting a first purified solution from the tower bottom of the gas driving tower; s2, the first purified liquid is introduced into a light component removal tower at the flow rate of Q2 for secondary purification, light component impurities are extracted from the tower top, and a second purified liquid is extracted from the tower bottom at the flow rate of Q3; s3, introducing the second purified liquid into a rectifying tower at the flow rate of Q4 for third purification, extracting a third purified liquid at the flow rate of Q5 from the tower top, and extracting heavy component impurities from the tower bottom; and S4, carrying out carbon adsorption treatment on the third purified liquid to obtain aliphatic acyl chloride. According to the method, residual phosgene, hydrogen chloride, amide compounds and light and heavy component impurities in the aliphatic acyl chloride crude product are effectively removed, and the purity of the aliphatic acyl chloride product is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of fine chemicals, and in particular to an aliphatic acyl chloride and a purification method thereof. Background Art

[0002] Aliphatic acid chloride is an important organic chemical raw material, widely used in many industries such as coatings, medicines, pesticides, etc. Its downstream products, such as tert-butyl peroxyisononanoate, tert-amyl peroxyisononanoate and other high-efficiency initiators, are non-toxic and highly active, and play an important role in the polymer field.

[0003] In the industrial production of aliphatic acid chlorides, aliphatic carboxylic acids are generally used with chlorinating agents such as phosgene and thionyl chloride under the catalytic action of dimethylformamide (DMF) to generate a mixture of acyl chloride and Vilsmeier reagent. After layering, an acyl chloride synthesis liquid is obtained, which is then post-treated to obtain the acyl chloride product.

[0004] In the above-mentioned synthesis process of acyl chloride, the obtained Vilsmeier reagent specifically refers to the product formed by DMF and phosgene or thionyl chloride (referring to one of them, i.e., the product formed by DMF and phosgene in the present application). The generation of the Vilsmeier reagent and the subsequent generation of acyl chloride can be written as the following reaction equation:

[0005] 1.

[0006] 2.

[0007] The acyl chloride obtained by the above process often contains a small amount of Vilsmeier reagent decomposition products and a relatively high concentration of acidic gas residues, which affect the content and chromaticity of the acyl chloride, and then affect the downstream application of the acyl chloride product. It has been found that when phosgene is used as a chlorinating agent to synthesize aliphatic acyl chlorides, in the post-processing process, the acyl chloride product, if there is a small amount of catalyst decomposition products such as amides, amines and other substances and residual chlorinating agents, will cause the generation of colored substances after interaction, prompting the product chromaticity value to increase, greatly affecting the downstream application of the acyl chloride product. Therefore, it is an urgent problem to develop a reasonable process to remove the catalyst decomposition products or residual chlorinating agents of the acyl chloride finished product.

[0008] Patent CN1174954C discloses a method for purifying phosgene. The method uses aliphatic carboxylic acid, DMF and phosgene as raw materials to synthesize acyl chloride and Vilsmeier reagent, and obtains a crude phosgene solution, i.e., an acyl chloride synthesis liquid, by two-phase separation. DMF hydrochloride is added to the crude phosgene solution to stir and layer, pass nitrogen to drive out the gas, and repeat the operation for many times to obtain an acyl chloride product with a low chromaticity value. The chromaticity of the acyl chloride product can be significantly reduced by treating the acyl chloride synthesis liquid with the process. However, the process is cumbersome to operate, the process is complicated, and the chromaticity value of the acyl chloride is still high, which does not meet the requirements of industrial products.

[0009] Patent CN1225449C discloses a method for producing acyl chloride. The method uses aliphatic carboxylic acid, DMF and phosgene as raw materials, introduces hydrogen chloride gas at the same time, synthesizes acyl chloride and Vilsmeier reagent, and obtains acyl chloride products with low chromaticity value after two-phase separation. The process has the advantages of simple operation, high acyl chloride content and low product chromaticity value. However, the process does not consider the problem of residual acid gas in acyl chloride, and the acyl chloride obtained by the process will still turn yellow after being left for a long time, which cannot meet the requirements of downstream applications.

[0010] Patent CN105585478A discloses a method for preparing acyl chloride. The method uses aliphatic carboxylic acid and phosgene as raw materials to react at high temperature, and then obtains an acyl chloride product with low chromaticity value by distillation. The process avoids the disadvantage that the decomposition residue of the catalyst causes the chromaticity value of the product to change, and the process is simple. However, the process has a high reaction temperature, a long time, and a low yield, and is not worth engineering implementation.

[0011] Based on this, how to provide a method for purifying aliphatic acyl chloride to obtain aliphatic acyl chloride products with lower chroma in high yield so that they can better meet the synthesis requirements of downstream products is one of the important technical problems that need to be solved in this field. Summary of the invention

[0012] The main purpose of the present invention is to provide an aliphatic acid chloride and a purification method thereof, so as to solve the problem that the prior art cannot purify and obtain a low-chroma aliphatic acid chloride product with high yield.

[0013] In order to achieve the above-mentioned object, the first aspect of the present invention provides a method for purifying aliphatic acid chloride, comprising: step S1, passing a crude product mixed liquid obtained by the reaction of aliphatic carboxylic acid and phosgene at a temperature of 50°C to 100°C into a gas removal tower for first purification, and extracting a first purified liquid at the bottom of the tower; step S2, passing the first purified liquid into a lightness removal tower at a flow rate of Q1 for second purification, extracting light component impurities at the top of the tower, and extracting a second purified liquid at the bottom of the tower at a flow rate of Q2; step S3, passing the second purified liquid into a distillation tower at a flow rate of Q2 for third purification, extracting a third purified liquid at the top of the tower, and extracting heavy component impurities at the bottom of the tower; step S4, treating the third purified liquid with carbon adsorption to obtain aliphatic acid chloride; the ratio of the Q2 flow rate to the Q1 flow rate is (0.98-0.99):1.

[0014] Furthermore, in step S3, the flow rate of the third purified liquid is Q3, and the ratio of the flow rate of Q3 to the flow rate of Q2 is (0.96-0.99):1.

[0015] Furthermore, the crude product mixture includes, by weight, 0.4 to 0.6 parts of hydrogen chloride, 1.2 to 1.8 parts of phosgene, 0.01 to 0.02 parts of amide compounds, 0.01 to 0.03 parts of light aliphatic acid chloride components, 97 to 98 parts of aliphatic acid chlorides, and 0.9 to 1.0 parts of heavy aliphatic acid chloride components; preferably, the temperature of the first purification is 90° C. to 110° C., and the time is 1 h to 4 h.

[0016] Furthermore, the number of theoretical plates of the degassing tower is 3 to 15, more preferably 8 to 10; preferably, the flow rate of the crude product mixed liquid into the degassing tower in step S1 is Q0, and step S1 also includes passing an inert gas into the degassing tower at a flow rate of Qg, and the ratio of the Qg flow rate to the Q0 flow rate is (5 to 20):1.

[0017] Furthermore, the first purified liquid includes, by weight, 0.001 to 0.002 parts of phosgene, 0.009 to 0.01 parts of amide compounds, 0.01 to 0.03 parts of light components of aliphatic acid chlorides, 98 to 99 parts of aliphatic acid chlorides, and 0.95 to 1.0 parts of heavy components of aliphatic acid chlorides; preferably, the number of theoretical plates of the light removal tower is 15 to 25, and the reflux ratio is (1 to 3):1.

[0018] Furthermore, the number of theoretical plates of the distillation tower is 5 to 10, and the reflux ratio is (1 to 2):1.

[0019] Furthermore, the third purified liquid includes, by weight, 0.001 to 0.002 parts of an amide compound, 99.0 to 99.5 parts of an aliphatic acid chloride and 0.5 to 0.6 parts of an aliphatic acid chloride heavy component; preferably, the temperature of the carbon adsorption treatment is 25° C. to 45° C., and the adsorption rate is 0.5 BV / h to 2.0 BV / h.

[0020] The second aspect of the present invention provides an aliphatic acyl chloride, which is obtained by purifying a crude aliphatic acyl chloride product by the above-mentioned aliphatic acyl chloride purification method, and the chromaticity of the aliphatic acyl chloride is 2-3, and the chromaticity after being placed at room temperature and pressure for 60 days is 2-10.

[0021] Furthermore, the crude aliphatic acid chloride product includes, by weight, 0.4 to 0.6 parts of hydrogen chloride, 1.2 to 1.8 parts of phosgene, 0.01 to 0.02 parts of an amide compound, 0.01 to 0.03 parts of aliphatic acid chloride light components, 97 to 98 parts of aliphatic acid chloride, and 0.9 to 1.0 parts of aliphatic acid chloride heavy components.

[0022] Furthermore, the aliphatic acid chloride is selected from one of isooctanoyl chloride, octanoyl chloride, nonanoyl chloride, isononanoyl chloride, neodecanoyl chloride and lauroyl chloride; preferably isononanoyl chloride.

[0023] By applying the technical scheme of the present invention, residual phosgene, hydrogen chloride, amide compounds and light and heavy impurities in the crude aliphatic acyl chloride product are effectively removed, the purity of the aliphatic acyl chloride product is significantly improved, and low-chroma aliphatic acyl chloride is obtained with a high purification yield, and the chroma can still be maintained at a low level after being stored for a long time. DETAILED DESCRIPTION

[0024] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0025] As described in the background technology, the prior art has the problem that it is not possible to purify and obtain a low-chroma aliphatic chloride product with a high yield. In order to solve the above technical problems, the first aspect of the present invention provides a method for purifying aliphatic chloride, comprising: step S1, passing a crude product mixed solution obtained by reacting aliphatic carboxylic acid with phosgene at a temperature of 50°C to 100°C into a gas removal tower for first purification, and extracting a first purified solution at the bottom of the tower; step S2, passing the first purified solution into a light removal tower at a flow rate of Q1 for second purification, extracting light component impurities at the top of the tower, and extracting a second purified solution at the bottom of the tower at a flow rate of Q2; step S3, passing the second purified solution into a distillation tower at a flow rate of Q2 for third purification, extracting a third purified solution at the top of the tower, and extracting heavy component impurities at the bottom of the tower; step S4, the third purified solution is subjected to carbon adsorption treatment to obtain aliphatic chloride; the ratio of the flow rate of Q2 to the flow rate of Q1 is (0.98-0.99):1.

[0026] In the above purification method, a plate tower is preferably used as the gas removal tower. Phosgene is carbonyl chloride (chemical formula is COCl2).

[0027] Regarding the chromaticity index, it should be noted in advance that acyl chloride products, as an organic compound, are usually colorless liquids in a pure state. However, during the actual production or storage process, due to the presence of impurities, colored byproducts such as Vilsmeier reagent will slowly be produced, causing acyl chloride products to exhibit a certain color, affecting the downstream application of acyl chlorides. Usually, acyl chlorides are tested using the General Method for Colorimetric Determination of Chemical Reagents (GB / T 605-2006) as the standard to obtain the product color value.

[0028] The larger the chromaticity value, the darker the color of the acyl chloride product, and the greater the impact on the downstream applications of the acyl chloride.

[0029] However, in the synthesis process of the aliphatic acyl chloride targeted by the present invention, DMF is used as a catalyst and phosgene is used as a chlorinating agent. During the subsequent separation, a small amount of Vilsmeier reagent decomposition or dissolution products such as amides, amines and the like and phosgene will remain in the crude acyl chloride. If they are not completely removed, they will interact with each other to generate colored substances, resulting in an increase in the chromaticity value of the product.

[0030] The above-mentioned purification method provided by the present invention can effectively reduce the residual phosgene, hydrogen chloride, amide compounds and light and heavy impurity contents in the crude aliphatic chloride product, and then obtain aliphatic chloride with low chromaticity with high purification yield. Specifically, the plate tower is used to drive out the gas, which can effectively achieve the effect of fully driving out the dissolved phosgene and hydrogen chloride and other gases in the synthetic liquid of the crude acyl chloride product, and then significantly avoid the acidity and chromaticity of the final product. Before the distillation, the light removal process is added, and the substances such as amides, amines, phosgene and other light components of the acyl chloride containing Vilsmeier reagent decomposition products can be further fully removed on the basis of removing phosgene and HCl, and the purity and chromaticity of the obtained acyl chloride product can be more significantly avoided. After the distillation, the activated carbon adsorption treatment is used to deeply remove the trace colored substances and acyl chloride light components present in the acyl chloride product after the distillation, ensuring that the final acyl chloride product still shows low chromaticity after being placed for a long time.

[0031] In particular, the above steps in the purification method provided by the present invention cooperate with each other as an overall technical solution, that is, a complete technical route of changing to degassing (phosgene, hydrogen chloride) → light removal → distillation and heavy removal → carbon adsorption is formed. For the purification of aliphatic acyl chlorides, compared with the conventional method including dephosgene + distillation process commonly used in the art, the impurities that may be left behind are less, and the purity of the final product aliphatic acyl chloride is also higher. In other words, the above steps in the purification method provided by the present invention, in addition to the advantages of impurity removal themselves, are more importantly able to cooperate with each other, that is, as an overall solution, to achieve high-purity purification of low-chromaticity aliphatic acyl chlorides.

[0032] In particular, the present invention strictly limits the flow ratio of the input and output during the light removal process to the above value, thereby enabling the light removal tower to more fully separate the light component impurities, improve the purity of the aliphatic acyl chloride, and reduce the formation of subsequent colored impurities, thereby obtaining aliphatic acyl chlorides with lower chroma and higher purity.

[0033] Specifically, in the above purification method provided by the present invention, the light impurities involved are mainly dimethylformamide, dimethylamine, and low-aliphatic acid chlorides (i.e., aliphatic acid chlorides with a lower carbon number than the target product aliphatic acid chloride). The heavy impurities involved are mainly isononanoic anhydride and isononanoic anhydride isomers.

[0034] In several typical implementations, the flow rate of the third purified liquid extracted in step S3 is Q3, and the ratio of the flow rate of Q3 to the flow rate of Q2 is (0.96-0.99): 1. Optimizing the flow rate ratio in the distillation and de-weighting process allows the distillation tower to retain the aliphatic acyl chloride product to a greater extent while removing the heavy component impurities, thereby improving the purification yield of the product at a lower chroma.

[0035] In practical applications, the crude product mixture of the purified aliphatic acyl chloride of the present invention comes from the upper layer obtained by layering after the corresponding aliphatic carboxylic acid and phosgene react under the catalysis of DMF. Further, in order to better adapt to the above-mentioned purification process provided by the present invention, and finally obtain an aliphatic acyl chloride product with lower chromaticity, the crude product mixture purified by the present invention includes 0.4-0.6 parts of hydrogen chloride, 1.2-1.8 parts of phosgene, 0.01-0.02 parts of amide compounds, 0.01-0.03 parts of aliphatic acyl chloride light components, 97-98 parts of aliphatic acyl chlorides and 0.9-1.0 parts of aliphatic acyl chloride heavy components. After a large number of experiments, the inventors preferably select the temperature of the first purification to be 90°C to 110°C and the time to be 1h to 4h. In order to more effectively remove phosgene and hydrogen chloride in the crude product mixture, reduce the complexity of subsequent steps, and thus obtain aliphatic acyl chloride products with higher yields and lower costs.

[0036] The present invention adopts a plate tower as a gas-eliminating tower, which can improve the gas-eliminating efficiency. By achieving a low nitrogen flow rate, the acidity and phosgene content in the acyl chloride can be reduced to an acceptable level. It can achieve the purpose of low phosgene content, save nitrogen, and improve the gas-eliminating efficiency. It is further preferred that the theoretical number of plates of the gas-eliminating tower is 3 to 15, and more preferably 8 to 10. It is preferred that the flow rate of the crude product mixed liquid entering the gas-eliminating tower in step S1 is Q0, and step S1 also includes passing an inert gas into the gas-eliminating tower at a flow rate of Qg, and the ratio of the Qg flow rate to the Q0 flow rate is (5 to 20): 1. That is, by introducing a specific flow rate of inert gas into the tower-type gas-eliminating tower, it is ensured that the gas and liquid phases are fully in contact, so as to further improve the efficiency of removing phosgene and hydrogen chloride in step S1.

[0037] By optimizing the conditions in the first purification process, in several typical embodiments, the first purified solution includes 0.001-0.002 parts of phosgene, 0.009-0.01 parts of amide compounds, 0.01-0.03 parts of aliphatic acid chloride light components, 98-99 parts of aliphatic acid chloride, and 0.95-1.0 parts of aliphatic acid chloride heavy components, by weight. Such composition control of the first purified solution can more effectively promote the smooth progress of subsequent light and heavy removal steps, further reduce the chromaticity of the obtained aliphatic acid chloride, and improve its storage resistance.

[0038] For the light removal process, the inventors have optimized the theoretical number of plates of the light removal tower to be 15 to 25 and the reflux ratio to be (1 to 3): 1 through a large number of experiments. Under these light removal conditions, more effective separation of light component impurities is achieved, further improving the purity of the obtained aliphatic acyl chloride.

[0039] In several typical embodiments, the obtained light component impurities include 0.06-0.07 parts of phosgene, 0.06-0.07 parts of amide compounds, 1-2 parts of aliphatic acyl chloride light components, and 97-99 parts of aliphatic acyl chlorides by weight. The composition of the light component impurities obtained in the light removal process is analyzed to obtain the above-mentioned component range, thereby achieving real-time evaluation of the efficiency and effect of the purification process, which helps to obtain acyl chloride products with lower chromaticity. In several more typical embodiments, the purification method provided by the present invention also includes the secondary utilization of light component impurities, that is, the obtained light component impurities are recycled to the synthesis process of the crude aliphatic acyl chloride product for repeated utilization to further reduce costs and increase the added value of related products. And, the flow rate of the extracted light component impurities is recorded as Qa flow rate, and the ratio of Qa flow rate to Q1 flow rate is preferably (0.01-0.02): 1, so as to further significantly reduce the chromaticity and improve the purity.

[0040] During the distillation process, the inventors have optimized the theoretical number of plates of the distillation tower to be 5 to 10 and the reflux ratio to be (1 to 2):1 through a large number of experiments, thereby more effectively removing heavy impurities, further improving the purity of the aliphatic acyl chloride product and reducing its chromaticity.

[0041] The third purified liquid extracted from the bottom of the distillation tower under the above preferred conditions preferably includes 0.001-0.002 parts of amide compounds, 99.0-99.5 parts of aliphatic acid chlorides, and 0.5-0.6 parts of aliphatic acid chloride heavy components by weight. In other words, the purified liquid obtained by the distillation of the present invention has a lower content of amide compounds and heavy component impurities, and the purity of the obtained aliphatic acid chloride product is higher. At the same time, the third purified liquid with this composition can also better adapt to the subsequent carbon adsorption treatment step to obtain a more storage-resistant aliphatic acid chloride product.

[0042] Furthermore, for carbon adsorption treatment, in order to obtain low-color aliphatic acid chloride whose color will not increase significantly after long-term storage at a higher treatment efficiency, the preferred carbon adsorption treatment temperature is 25°C to 45°C, and the adsorption rate is 0.5BV / h to 2.0BV / h.

[0043] The second aspect of the present invention provides an aliphatic acyl chloride, which is obtained by purifying a crude aliphatic acyl chloride product through the above-mentioned aliphatic acyl chloride purification method, and the chromaticity of the aliphatic acyl chloride is 2 to 3, and the chromaticity after being placed at room temperature and pressure for 60 days is 2 to 10. That is to say, the aliphatic acyl chloride product obtained by the purification method of the present invention not only has a low chromaticity, but also its chromaticity can still be maintained at a low level after being placed for a long time, thereby improving the quality of the product during storage and transportation, reducing the product index failure caused by chromaticity changes, and better meeting the strict requirements of various application fields on the purity and stability of the acyl chloride product.

[0044] Furthermore, the crude aliphatic acid chloride product includes, by weight, 0.4-0.6 parts of hydrogen chloride, 1.2-1.8 parts of phosgene, 0.01-0.02 parts of amide compounds, 0.01-0.03 parts of aliphatic acid chloride light components, 97-98 parts of aliphatic acid chloride, and 0.9-1.0 parts of aliphatic acid chloride heavy components. The aliphatic acid chloride obtained by the above purification method has higher purity and lower chromaticity, and can be used as a key raw material for synthesizing various high value-added chemicals, especially suitable for fine chemicals and pharmaceutical industries.

[0045] In several preferred embodiments, the aliphatic acid chloride is selected from one of isooctanoyl chloride, octanoyl chloride, nonanoyl chloride, isononanoyl chloride, neodecanoyl chloride and lauroyl chloride, more preferably isononanoyl chloride. Compared with aliphatic acid chlorides of other carbon numbers and configurations, the above-mentioned aliphatic acid chlorides, especially isononanoyl chloride, can better adapt to the above-mentioned purification method provided by the present invention, thereby showing a higher purification yield and a lower product chromaticity.

[0046] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0047] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0048] Example 1

[0049] A method for purifying isononanoyl chloride:

[0050] Step S1, preheating the crude isononanoyl chloride mixed solution obtained by using isononanoic acid as raw material and phosgene as chlorinating agent to 90° C., 3 / h (Q0 flow rate) is continuously transported from the top of the tower to the plate tower, i.e. the gas removal tower, which has 8 theoretical plates. 3 / h (Qg flow rate) of nitrogen was introduced for gas removal. In the tower, the first purification temperature was controlled at 100°C for 2h. After that, the first purified liquid obtained after gas removal was heated at 0.94m 3 / h flow rate is continuously produced, and no hydrogen chloride gas can be detected at the bottom of the tower. At this time, the ratio of Qg flow rate to Q0 flow rate is 14.7:1.

[0051] Step S2: After the first purified liquid is extracted, 3 / h (Q1 flow rate) is continuously transported to the light removal tower for light removal, i.e. the second purification operation. The reflux ratio of the light removal tower is 2:1, and the number of theoretical plates is 20. 3 / h (Qa flow rate) to continuously extract a small amount of light component impurities, and at the bottom of the tower, 0.926m 3 / h (Q2 flow rate) to produce the second purified liquid after light removal. At this time, the ratio of Q2 flow rate to Q1 flow rate is 0.985:1, and the ratio of Qa flow rate to Q1 flow rate is 0.015:1.

[0052] Step S3: After the second purified liquid is extracted, 0.926 m 3 / h (Q2 flow rate) is transported to the distillation tower for distillation, i.e. the third purification operation. The reflux ratio of the distillation tower is 1.5:1, and the number of theoretical plates is 8. 3 / h (Q3 flow rate) to continuously extract high-content acyl chloride, i.e., the third purified liquid. At this time, the ratio of Q3 flow rate to Q2 flow rate is 0.983:1.

[0053] Step S4: The third purified liquid is then adsorbed on activated carbon to obtain a low-color isononanoyl chloride product. The carbon adsorption temperature is 30° C. and the adsorption rate is 1.5 BV / h.

[0054] The composition test results of the crude product mixed solution, the first purified solution, the light component impurities, the third purified solution and the final isononanoyl chloride product are shown in the table below.

[0055]

[0056] Example 2

[0057] A method for purifying isononanoyl chloride:

[0058] Step S1, preheating the crude isononanoyl chloride mixed solution obtained by using isononanoic acid as raw material and phosgene as chlorinating agent to 50° C., 3 / h (Q0 flow rate) is continuously transported from the top of the tower to the plate tower, i.e. the gas removal tower, which has 8 theoretical plates. 3 / h (Qg flow rate) of nitrogen was introduced for gas removal. In the tower, the first purification temperature was controlled at 110°C for 1 hour. After that, the first purified liquid obtained after gas removal was heated at 0.94m 3 / h flow rate is continuously produced, and no hydrogen chloride gas can be detected at the bottom of the tower. At this time, the ratio of Qg flow rate to Q0 flow rate is 14.7:1.

[0059] Step S2: After the first purified liquid is extracted, 3 / h (Q1 flow rate) is continuously transported to the light removal tower for light removal, i.e. the second purification operation. The reflux ratio of the light removal tower is 1:1, and the number of theoretical plates is 15. 3 / h (Qa flow rate) to continuously extract a small amount of light component impurities, and at the bottom of the tower, 0.926m 3 / h (Q2 flow rate) to produce the second purified liquid after light removal. At this time, the ratio of Q2 flow rate to Q1 flow rate is 0.985:1, and the ratio of Qa flow rate to Q1 flow rate is 0.015:1.

[0060] Step S3: After the second purified liquid is extracted, 0.926 m 3 / h (Q2 flow rate) is transported to the distillation tower for distillation, i.e. the third purification operation. The reflux ratio of the distillation tower is 1:1, and the number of theoretical plates is 5. 3 / h (Q3 flow rate) to continuously extract high-content acyl chloride, i.e., the third purified liquid. At this time, the ratio of Q3 flow rate to Q2 flow rate is 0.983:1.

[0061] Step S4: The extracted third purified liquid is then adsorbed on activated carbon to obtain a low-color isononanoyl chloride product. The carbon adsorption temperature is 25° C. The adsorption rate is 0.5 BV / h.

[0062] The composition test results of the crude product mixed solution, the first purified solution, the light component impurities, the third purified solution and the final isononanoyl chloride product are shown in the table below.

[0063]

[0064]

[0065] Example 3

[0066] A method for purifying isononanoyl chloride:

[0067] Step S1, preheating the crude isononanoyl chloride mixed solution obtained by using isononanoic acid as raw material and phosgene as chlorinating agent to 100° C., 3 / h (Q0 flow rate) is continuously transported from the top of the tower to the plate tower, i.e. the gas removal tower, which has 8 theoretical plates. 3 / h (Qg flow rate) of nitrogen was introduced for gas removal. In the tower, the first purification temperature was controlled at 90°C for 4 hours. After that, the first purified liquid obtained after gas removal was heated at 0.94m 3 / h flow rate is continuously produced, and no hydrogen chloride gas can be detected at the bottom of the tower. At this time, the ratio of Qg flow rate to Q0 flow rate is 14.7:1.

[0068] Step S2: After the first purified liquid is extracted,3 / h (Q1 flow rate) is continuously transported to the light removal tower for light removal, i.e. the second purification operation. The reflux ratio of the light removal tower is 3:1, and the number of theoretical plates is 25. 3 / h (Qa flow rate) to continuously extract a small amount of light component impurities, and at the bottom of the tower, 0.926m 3 / h (Q2 flow rate) to produce the second purified liquid after light removal. At this time, the ratio of Q2 flow rate to Q1 flow rate is 0.985:1, and the ratio of Qa flow rate to Q1 flow rate is 0.015:1.

[0069] Step S3: After the second purified liquid is extracted, 0.926 m 3 / h (Q2 flow rate) is transported to the distillation tower for distillation, i.e. the third purification operation. The reflux ratio of the distillation tower is 2:1, and the number of theoretical plates is 10. 3 / h (Q3 flow rate) to continuously extract high-content acyl chloride, i.e., the third purified liquid. At this time, the ratio of Q3 flow rate to Q2 flow rate is 0.983:1.

[0070] Step S4: The extracted third purified liquid is then adsorbed on activated carbon to obtain a low-color isononanoyl chloride product. The carbon adsorption temperature is 45° C. and the adsorption rate is 2.0 BV / h.

[0071] The composition test results of the crude product mixed solution, the first purified solution, the light component impurities, the third purified solution and the final isononanoyl chloride product are shown in the table below.

[0072]

[0073]

[0074] Example 4

[0075] A method for purifying isononanoyl chloride:

[0076] The difference between this embodiment and embodiment 1 is that in step S1, the theoretical number of plates of the gas removal tower is changed to 15; the temperature of the first purification is changed to 80°C, and the time is changed to 5h; the nitrogen flow rate Qg is changed to 23m 3 / h.

[0077] The purification conditions in this embodiment have little effect on the final product, but the increase in nitrogen volume will cause serious waste. At the same time, the gas removal time is extended, the production capacity is reduced, and the industrial value is sharply reduced, so it has no practical application value.

[0078] Example 5

[0079] A method for purifying isononanoyl chloride:

[0080] Step S1, preheating the crude isononanoyl chloride mixed solution obtained by using isononanoic acid as raw material and phosgene as chlorinating agent to 90° C., 3 / h (Q0 flow rate) is continuously transported from the top of the tower to the plate tower, i.e. the gas removal tower, which has 3 theoretical plates. 3 / h (Qg flow rate) of nitrogen was introduced for gas removal. In the tower, the first purification temperature was controlled at 120°C for 0.5h. After that, the first purified liquid obtained after gas removal was heated to 0.94m 3 / h flow rate is continuously produced, and no hydrogen chloride gas can be detected at the bottom of the tower. At this time, the ratio of Qg flow rate to Q0 flow rate is 2.1:1.

[0081] Step S2: After the first purified liquid is extracted, 3 / h (Q1 flow rate) is continuously transported to the light removal tower for light removal, i.e. the second purification operation. The reflux ratio of the light removal tower is 2:1, and the number of theoretical plates is 20. 3 / h (Qa flow rate) to continuously extract a small amount of light component impurities, and at the bottom of the tower, 0.926m 3 / h (Q2 flow rate) to produce the second purified liquid after light removal. At this time, the ratio of Q2 flow rate to Q1 flow rate is 0.985:1, and the ratio of Qa flow rate to Q1 flow rate is 0.015:1.

[0082] Step S3: After the second purified liquid is extracted, 0.926 m 3 / h (Q2 flow rate) is transported to the distillation tower for distillation, i.e. the third purification operation. The reflux ratio of the distillation tower is 1.5:1, and the number of theoretical plates is 8. 3 / h (Q3 flow rate) to continuously extract high-content acyl chloride, i.e., the third purified liquid. At this time, the ratio of Q3 flow rate to Q2 flow rate is 0.983:1.

[0083] Step S4: The third purified liquid is then adsorbed on activated carbon to obtain a low-color isononanoyl chloride product. The carbon adsorption temperature is 30° C. and the adsorption rate is 1.5 BV / h.

[0084] The composition test results of the crude product mixed solution, the first purified solution, the light component impurities, the third purified solution and the final isononanoyl chloride product are shown in the table below.

[0085]

[0086]

[0087] That is, the difference between this embodiment and embodiment 1 is that: in step S1, the theoretical number of plates of the gas removal tower is changed to 3; the temperature of the first purification is changed to 120°C, and the time is changed to 0.5h; the nitrogen flow rate Qg is changed to 2m 3 / h, the ratio of Qg flow rate to Q0 flow rate is changed to 2.1:1.

[0088] Example 6

[0089] A method for purifying isononanoyl chloride:

[0090] The only difference between this embodiment and embodiment 1 is that in step S2, the reflux ratio of the lightness removal tower is changed to 4:1, and the number of theoretical plates is changed to 12.

[0091] The purification conditions in this example have little effect on the final product, but the operating costs increase dramatically, the practical application value is extremely low, and it is not suitable for industrial production.

[0092] Example 7

[0093] A method for purifying isononanoyl chloride:

[0094] The only difference between this embodiment and embodiment 1 is that in step S2, the reflux ratio of the lightness removal tower is changed to 0.5:1, and the number of theoretical plates is changed to 28.

[0095] In this embodiment as well, the purification conditions have little effect on the final product, but the equipment-related costs increase dramatically, and the actual application value is extremely low.

[0096] Example 8

[0097] A method for purifying isononanoyl chloride:

[0098] Step S1, preheating the crude isononanoyl chloride mixed solution obtained by using isononanoic acid as raw material and phosgene as chlorinating agent to 90° C., 3 / h (Q0 flow rate) is continuously transported from the top of the tower to the plate tower, i.e. the gas removal tower, which has 8 theoretical plates. 3 / h (Qg flow rate) of nitrogen was introduced for gas removal. In the tower, the first purification temperature was controlled at 100°C for 2h. After that, the first purified liquid obtained after gas removal was heated at 0.94m 3 / h flow rate is continuously produced, and no hydrogen chloride gas can be detected at the bottom of the tower. At this time, the ratio of Qg flow rate to Q0 flow rate is 14.7:1.

[0099] Step S2: After the first purified liquid is extracted, 3 / h (Q1 flow rate) is continuously transported to the light removal tower for light removal, i.e. the second purification operation. The reflux ratio of the light removal tower is 2:1, and the number of theoretical plates is 20. 3 / h (Qa flow rate) to continuously extract a small amount of light component impurities, and at the bottom of the tower, 0.926m 3 / h (Q2 flow rate) to produce the second purified liquid after light removal. At this time, the ratio of Q2 flow rate to Q1 flow rate is 0.985:1, and the ratio of Qa flow rate to Q1 flow rate is 0.015:1.

[0100] Step S3: After the second purified liquid is extracted, 0.926 m 3 / h (Q2 flow rate) is transported to the distillation tower for distillation, i.e. the third purification operation. The reflux ratio of the distillation tower is 1.5:1, and the number of theoretical plates is 8. 3 / h (Q3 flow rate) to continuously extract high-content acyl chloride, i.e., the third purified liquid. At this time, the ratio of Q3 flow rate to Q2 flow rate is 0.983:1.

[0101] Step S4: The extracted third purified liquid is then adsorbed on activated carbon to obtain a low-color isononanoyl chloride product. The carbon adsorption temperature is 50° C. and the adsorption rate is 2.5 BV / h.

[0102] The composition test results of the crude product mixed solution, the first purified solution, the light component impurities, the third purified solution and the final isononanoyl chloride product are shown in the table below.

[0103]

[0104] That is, the only difference between this embodiment and embodiment 1 is that in step S4, the carbon adsorption temperature is changed to 50°C, and the adsorption rate is changed to 2.5 BV / h.

[0105] Comparative Example 1

[0106] A method for purifying isononanoyl chloride:

[0107] Step S1, preheating the crude isononanoyl chloride mixed solution obtained by using isononanoic acid as raw material and phosgene as chlorinating agent to 90° C., 3 / h (Q0 flow rate) is pumped into the gas-eliminating kettle. At the same time, a 14m 3 / h (Qg flow rate) of nitrogen was introduced for gas removal. In the reactor, the first purification temperature was controlled at 100°C for 2h. After that, the first purified liquid obtained after gas removal was heated at 0.94m 3 / h is extracted from the reactor, at which time hydrogen chloride gas and phosgene can still be detected in the reactor.

[0108] Steps S2 to S4 are all consistent with those in Example 1.

[0109] The composition test results of the crude product mixed solution, the first purified solution, the light component impurities, the third purified solution and the final isononanoyl chloride product are shown in the table below.

[0110]

[0111]

[0112] In this comparative example, when the gas-removing reactor is used instead of the plate tower for phosgene removal, the gas-removing effect is significantly worse. There is still a small amount of phosgene in the final acyl chloride product, which reacts with a trace amount of Vilsmeier reagent decomposition product (no specific value, because the content is below the detection limit), thereby causing the obtained acyl chloride product to change color and increase chromaticity.

[0113] Comparative Example 2

[0114] A method for purifying isononanoyl chloride:

[0115] The difference between this comparative example and Example 1 is that the light removal in step S2 is not performed, but the first purified liquid is directly transported to the distillation tower after being produced to perform distillation in step S3 and carbon adsorption treatment in step S4.

[0116] The composition test results of the crude product mixture, the first purified solution, the third purified solution and the final isononanoyl chloride product are shown in the table below.

[0117]

[0118] There is no light removal process in this comparative example, and the decomposition products of Vilsmeier reagent, the light components of the chlorinating agent and the acyl chloride are still present in the top of the distillation tower. Although activated carbon can adsorb a part of them (the specific value of phosgene is not detected because the content is below the detection limit), the residual substances will still make the final acyl chloride product not meet the application requirements due to the increased chroma.

[0119] Comparative Example 3

[0120] A method for purifying isononanoyl chloride:

[0121] The only difference between this comparative example and Example 1 is that the carbon adsorption treatment in step S4 is not performed, and the third purified liquid taken from the top of the tower in step S3 is directly used as the isononanoyl chloride product.

[0122] The composition test results of the crude product mixed solution, the first purified solution, the light component impurities and the final isononanoyl chloride product are shown in the table below.

[0123]

[0124]

[0125] In this comparative example, there is no activated carbon adsorption treatment step, and the final acyl chloride product will have a very small amount of Vilsmeier reagent decomposition products and phosgene (the specific value of phosgene was not detected because the content was below the detection limit) that were not completely removed. The residual substances will slowly generate colored substances after interaction, resulting in an increase in the chromaticity of the obtained acyl chloride product.

[0126] Comparative Example 4

[0127] A method for purifying isononanoyl chloride:

[0128] The difference between this comparative example and Example 1 is that in step S1, the preheating temperature of the mixed solution of crude isononanoyl chloride product is changed to 40°C.

[0129] The composition test results of the crude product mixed solution, the first purified solution, the light component impurities, the third purified solution and the final isononanoyl chloride product are shown in the table below.

[0130]

[0131] Comparative Example 5

[0132] A method for purifying isononanoyl chloride:

[0133] The difference between this embodiment and embodiment 1 is that in step S2, the flow rate of Q1 is changed to 0.99m 3 / h, Q2 flow rate changed to 0.99m 3 / h, (i.e., Q2 flow: Q1 flow is changed to 1:1); at the same time, in step S3, Q2 flow is changed to 0.99m 3 / h, (i.e. Q3 flow: Q2 flow changes to 0.92:1).

[0134] Comparative Example 6

[0135] A method for purifying isononanoyl chloride:

[0136] The difference between this embodiment and embodiment 1 is that in step S2, the flow rate of Q1 is changed to 0.958m 3 / h, Q2 flow rate changed to 0.91m 3 / h, (i.e., Q2 flow: Q1 flow is changed to 0.95:1); at the same time, in step S3, Q2 flow is changed to 0.91m 3 / h, (i.e. Q3 flow: Q2 flow is changed to 0.98:1).

[0137] The chromaticity of the acyl chloride products obtained in each embodiment and comparative example was tested according to GB / T 605-2006, and then the chromaticity of each product was tested again after being placed at room temperature and pressure for 60 days. The results are shown in Table 1. The purification yield of the acyl chloride products in each embodiment and comparative example is also shown in Table 1.

[0138] Table 1

[0139] Purification yield / % Product color Product color after 60 days at room temperature and pressure Example 1 98.22 2 3 Example 2 98.17 2 4 Example 3 98.26 2 2 Example 4 98.20 2 5 Example 5 98.18 3 10 Example 6 98.22 3 5 Example 7 98.15 2 3 Example 8 98.21 3 10 Comparative Example 1 98.23 3 45 Comparative Example 2 98.38 3 70 Comparative Example 3 98.25 2 20 Comparative Example 4 98.22 3 15 Comparative Example 5 98.10 3 18 Comparative Example 6 97.80 3 24

[0140] From the above description, it can be seen that the above embodiments of the present invention can achieve the purification of aliphatic acyl chloride products with high yield. The obtained acyl chloride products not only have low chroma, but also are stable in nature and can still maintain a low chroma after long-term storage.

[0141] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those described herein, for example.

[0142] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for purifying aliphatic acid chlorides, characterized in that: The purification method of the aliphatic acyl chloride comprises: Step S1, passing a crude product mixed solution obtained by the reaction of aliphatic carboxylic acid and phosgene at a temperature of 50° C. to 100° C. into a degassing tower for first purification, and collecting a first purified solution at the bottom of the tower; Step S2, passing the first purified liquid into a light component removal tower at a flow rate of Q1 for second purification, extracting light component impurities at the top of the tower, and extracting the second purified liquid at the bottom of the tower at a flow rate of Q2; Step S3, passing the second purified liquid into a distillation tower at the flow rate Q2 for third purification, taking out the third purified liquid at the top of the tower, and taking out the heavy component impurities at the bottom of the tower; Step S4, the third purified liquid is treated by carbon adsorption to obtain the aliphatic acyl chloride; The ratio of the Q2 flow rate to the Q1 flow rate is (0.98-0.99):

1.

2. The method for purifying aliphatic acid chloride according to claim 1, characterized in that: The flow rate of the third purified liquid collected in step S3 is Q3, and the ratio of the Q3 flow rate to the Q2 flow rate is (0.96-0.99):

1.

3. The method for purifying aliphatic acid chloride according to claim 1 or 2, characterized in that: The crude product mixture comprises, by weight, 0.4 to 0.6 parts of hydrogen chloride, 1.2 to 1.8 parts of phosgene, 0.01 to 0.02 parts of an amide compound, 0.01 to 0.03 parts of aliphatic acid chloride light components, 97 to 98 parts of aliphatic acid chloride, and 0.9 to 1.0 parts of aliphatic acid chloride heavy components; Preferably, the temperature of the first purification is 90° C. to 110° C., and the time is 1 h to 4 h.

4. The method for purifying aliphatic acid chloride according to any one of claims 1 to 3, characterized in that: The number of theoretical plates of the gas removal tower is 3 to 15, more preferably 8 to 10; Preferably, in step S1, the flow rate of the crude product mixed liquid entering the degassing tower is Q0, and step S1 also includes passing an inert gas into the degassing tower at a flow rate of Qg, and the ratio of the Qg flow rate to the Q0 flow rate is (5-20):

1.

5. The method for purifying aliphatic acid chloride according to any one of claims 1 to 4, characterized in that: In parts by weight, the first purified liquid includes 0.001 to 0.002 parts of phosgene, 0.009 to 0.01 parts of amide compounds, 0.01 to 0.03 parts of aliphatic acid chloride light components, 98 to 99 parts of aliphatic acid chloride, and 0.95 to 1.0 parts of aliphatic acid chloride heavy components; Preferably, the number of theoretical plates of the lightness removal tower is 15 to 25, and the reflux ratio is (1 to 3):

1.

6. The method for purifying aliphatic acid chloride according to any one of claims 1 to 5, characterized in that: The number of theoretical plates of the distillation tower is 5 to 10, and the reflux ratio is (1 to 2):

1.

7. The method for purifying aliphatic acid chloride according to any one of claims 1 to 6, characterized in that: The third purified solution comprises, by weight, 0.001 to 0.002 parts of an amide compound, 99.0 to 99.5 parts of an aliphatic acid chloride, and 0.5 to 0.6 parts of an aliphatic acid chloride heavy component; Preferably, the temperature of the carbon adsorption treatment is 25° C. to 45° C., and the adsorption rate is 0.5 BV / h to 2.0 BV / h.

8. An aliphatic acid chloride, characterized in that The aliphatic acyl chloride is obtained by purifying a crude aliphatic acyl chloride product by the method for purifying aliphatic acyl chloride according to any one of claims 1 to 7, and the chromaticity of the aliphatic acyl chloride is 2 to 3, and the chromaticity after being placed at room temperature and pressure for 60 days is 2 to 10.

9. The aliphatic acid chloride according to claim 8, characterized in that In parts by weight, the crude aliphatic acid chloride product includes 0.4-0.6 parts of hydrogen chloride, 1.2-1.8 parts of phosgene, 0.01-0.02 parts of amide compounds, 0.01-0.03 parts of aliphatic acid chloride light components, 97-98 parts of aliphatic acid chloride and 0.9-1.0 parts of aliphatic acid chloride heavy components.

10. The aliphatic acid chloride according to claim 8 or 9, characterized in that The aliphatic acid chloride is selected from one of isooctanoyl chloride, octanoyl chloride, nonanoyl chloride, isononanoyl chloride, neodecanoyl chloride and lauroyl chloride; preferably isononanoyl chloride.

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