CN116262763A - Purification method of octamethyl cyclotetrasiloxane - Google Patents
Purification method of octamethyl cyclotetrasiloxane Download PDFInfo
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- octamethyl cyclotetrasiloxane
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- HMMGMWAXVFQUOA-UHFFFAOYSA-N octamethylcyclotetrasiloxane Chemical compound C[Si]1(C)O[Si](C)(C)O[Si](C)(C)O[Si](C)(C)O1 HMMGMWAXVFQUOA-UHFFFAOYSA-N 0.000 title claims abstract description 100
- 238000000034 method Methods 0.000 title claims abstract description 55
- 238000000746 purification Methods 0.000 title claims abstract description 9
- 239000003495 polar organic solvent Substances 0.000 claims abstract description 44
- 229910021645 metal ion Inorganic materials 0.000 claims abstract description 40
- 239000007788 liquid Substances 0.000 claims abstract description 25
- 238000001816 cooling Methods 0.000 claims abstract description 20
- 239000008139 complexing agent Substances 0.000 claims abstract description 15
- 239000007787 solid Substances 0.000 claims abstract description 13
- 238000011010 flushing procedure Methods 0.000 claims abstract description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 70
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 58
- 238000007711 solidification Methods 0.000 claims description 24
- 230000008023 solidification Effects 0.000 claims description 24
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 21
- 239000012535 impurity Substances 0.000 claims description 15
- 150000003983 crown ethers Chemical class 0.000 claims description 11
- XEZNGIUYQVAUSS-UHFFFAOYSA-N 18-crown-6 Chemical compound C1COCCOCCOCCOCCOCCO1 XEZNGIUYQVAUSS-UHFFFAOYSA-N 0.000 claims description 7
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 6
- NRTJGTSOTDBPDE-UHFFFAOYSA-N [dimethyl(methylsilyloxy)silyl]oxy-dimethyl-trimethylsilyloxysilane Chemical compound C[SiH2]O[Si](C)(C)O[Si](C)(C)O[Si](C)(C)C NRTJGTSOTDBPDE-UHFFFAOYSA-N 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 claims description 5
- 239000002798 polar solvent Substances 0.000 claims description 3
- 239000000126 substance Substances 0.000 claims description 3
- 150000003985 15-crown-5 derivatives Chemical group 0.000 claims description 2
- 239000000463 material Substances 0.000 claims description 2
- 239000002904 solvent Substances 0.000 abstract description 6
- 230000000052 comparative effect Effects 0.000 description 10
- 238000003756 stirring Methods 0.000 description 10
- 239000002184 metal Substances 0.000 description 8
- 238000000926 separation method Methods 0.000 description 7
- 239000011259 mixed solution Substances 0.000 description 6
- 238000001914 filtration Methods 0.000 description 5
- 239000003960 organic solvent Substances 0.000 description 3
- 238000010583 slow cooling Methods 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- 239000003463 adsorbent Substances 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 239000012046 mixed solvent Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 1
- 239000003957 anion exchange resin Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003729 cation exchange resin Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 230000000536 complexating effect Effects 0.000 description 1
- 125000000113 cyclohexyl group Chemical group [H]C1([H])C([H])([H])C([H])([H])C([H])(*)C([H])([H])C1([H])[H] 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- HTDJPCNNEPUOOQ-UHFFFAOYSA-N hexamethylcyclotrisiloxane Chemical compound C[Si]1(C)O[Si](C)(C)O[Si](C)(C)O1 HTDJPCNNEPUOOQ-UHFFFAOYSA-N 0.000 description 1
- 239000012456 homogeneous solution Substances 0.000 description 1
- 238000001095 inductively coupled plasma mass spectrometry Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005374 membrane filtration Methods 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- 150000003961 organosilicon compounds Chemical class 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000013557 residual solvent Substances 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000004753 textile Substances 0.000 description 1
- 238000003828 vacuum filtration Methods 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
- C07F7/00—Compounds containing elements of Groups 4 or 14 of the Periodic Table
- C07F7/02—Silicon compounds
- C07F7/21—Cyclic compounds having at least one ring containing silicon, but no carbon in the ring
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
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- Chemical & Material Sciences (AREA)
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Abstract
The invention relates to the technical field of octamethyl cyclotetrasiloxane purification, and discloses a purification method of octamethyl cyclotetrasiloxane, which comprises the steps of dissolving octamethyl cyclotetrasiloxane to be purified and a metal ion complexing agent in a polar organic solvent to obtain mixed liquid; cooling, solidifying and separating octamethyl cyclotetrasiloxane, flushing octamethyl cyclotetrasiloxane solid by a polar organic solvent, removing residual polar organic solvent on the surface of octamethyl cyclotetrasiloxane, converting octamethyl cyclotetrasiloxane into liquid, and rectifying to obtain purified octamethyl cyclotetrasiloxane; the addition amount of the metal ion complexing agent is 0.01-1% of the mass of the polar organic solvent; the mass ratio of the octamethyl cyclotetrasiloxane to the polar organic solvent is 1:0.1-10. The invention greatly reduces the solvent quantity to be removed in the rectification process, and the metal ion content in the octamethyl cyclotetrasiloxane can reach ppb level, thereby meeting the application requirements of the electronic-grade octamethyl cyclotetrasiloxane.
Description
Technical Field
The invention relates to the technical field of purification of octamethyl cyclotetrasiloxane, in particular to a purification method of octamethyl cyclotetrasiloxane.
Background
Octamethyl cyclotetrasiloxane (D4) is widely used as an important intermediate in the organosilicon industry in the industries of electronics, automobiles, aerospace, textile, daily chemicals, medical treatment, machinery, agriculture and the like. With the development of 5G and semiconductor industries, D4 is increasingly gaining attention in industries such as integrated circuits and optical fibers due to its ring structure and excellent performance. However, these fields require very high impurity levels contained in D4, and particularly require metal impurity levels to be controlled at ppb levels. The purity of the current industrial-grade octamethyl cyclotetrasiloxane is 98-99%, and the octamethyl cyclotetrasiloxane contains metal ions, solid particles and other organic impurities, and cannot meet the application requirements, so that the development of an efficient and economic method for removing the impurities such as the metal ions is the development direction of high-purity D4.
In order to meet the higher use requirements of the industries such as electric integrated circuits and the like, reports on reducing the content of metal ions and other impurities in D4 are already presented in the prior art. For example, chinese patent publication No. CN103788124B discloses a purification method of electronic-grade octamethyl cyclotetrasiloxane, which comprises introducing complex tetramethoxybenphos, and vacuum rectifying to obtain D4 with metal impurity content lower than 5ppb and purity up to 99.99%. The method is more convenient and has good product quality, but the price of the used complex is too high, which is not suitable for mass production. In addition, as in the Chinese patent application No. CN113583038A, the method for purifying octamethyl cyclotetrasiloxane is characterized in that D4 is treated by anion exchange resin and cation exchange resin and then subjected to membrane filtration treatment, so that metal ions and nonmetallic impurities in the D4 can be effectively removed, and the moisture is reduced, but the method is difficult to reach the electronic grade use level.
The method for removing metal impurities in the organosilicon compound of Chinese patent publication No. CN103788124B mixes octamethyl cyclotetrasiloxane with polar organic solvent and metal adsorbent, and then rectifies and separates octamethyl cyclotetrasiloxane and organic solvent, so that the metal ion content can be reduced to ppb level, the purity of octamethyl cyclotetrasiloxane reaches 99.95%, and the octamethyl cyclotetrasiloxane not only reaches the electronic grade use level, but also is suitable for industrial production. However, in the method, the polar organic solvent and D4 are completely separated in the rectification process, so that the rectification process has high energy consumption, is complex to operate and brings inconvenience to use.
Disclosure of Invention
Aiming at the problem that the complete rectification separation of octamethyl cyclotetrasiloxane and a polar organic solvent is inconvenient, the invention aims to provide the purification method of octamethyl cyclotetrasiloxane, which aims to simplify the rectification process by solidifying and separating octamethyl cyclotetrasiloxane and the polar organic solvent, and simultaneously, the metal ion level in the purified and separated octamethyl cyclotetrasiloxane can reach ppb level, thereby meeting the electronic-level application requirement.
The invention provides the following technical scheme:
a method for purifying octamethyl cyclotetrasiloxane, comprising the steps of:
(1) Dissolving octamethyl cyclotetrasiloxane and a metal ion complexing agent to be purified in a polar organic solvent to obtain mixed feed liquid;
(2) Cooling the mixed material liquid, and solidifying and separating octamethyl cyclotetrasiloxane from the polar solvent, wherein the solidifying temperature is less than or equal to 10 ℃;
(3) Flushing octamethyl cyclotetrasiloxane solid by using a polar organic solvent with the temperature less than or equal to 10 ℃, and then removing residual polar organic solvent on the surface of octamethyl cyclotetrasiloxane;
(4) Heating to convert octamethyl cyclotetrasiloxane into liquid, and rectifying to obtain purified octamethyl cyclotetrasiloxane;
the addition amount of the metal ion complexing agent is 0.01-1% of the mass of the polar organic solvent;
the mass ratio of the octamethyl cyclotetrasiloxane to the polar organic solvent is 1:0.1-10.
Unlike the prior art that the polar organic solvent and the octamethyl cyclotetrasiloxane are completely separated by rectification, the method separates the industrial octamethyl cyclotetrasiloxane (with the purity of 98-99%) from the polar organic solvent by cooling solidification, separates the residual extremely small amount of the polar organic solvent by rectification, and greatly reduces the workload of rectification separation. Specifically, the inventor selects a metal ion complexing agent which is soluble in a polar organic solvent to replace a metal adsorbent, and mixes octamethyl cyclotetrasiloxane, the metal ion complexing agent and the polar organic solvent to form a homogeneous solution, wherein the purity of the used polar organic solvent is superior pure or higher, such as electronic grade, the metal ions are removed through the dissolution of the polar organic solvent and the action of the metal ion complexing agent, the addition amount of the metal ion complexing agent is controlled to be 0.01% -1% of the mass of the polar organic solvent, more preferably 0.25% -0.5%, the mass ratio of the octamethyl cyclotetrasiloxane to the polar organic solvent is 1:0.1% -10, more preferably 1:1% -2, and the solidification temperature is less than or equal to 10 ℃, more preferably less than or equal to 0 ℃, so that the octamethyl cyclotetrasiloxane can be solidified and separated from the polar organic solvent, and can be stirred at a proper low speed in the cooling and solidification separation process, the stirring speed is 20-50 rpm, and the cooling process is placed in a temperature controllable environment, and the cooling rate is 1-5/. The octamethyl cyclotetrasiloxane solid is converted into liquid rectification after being washed, and the separation work in the rectification operation process is greatly reduced due to only a small amount of polar organic solvent residues, and meanwhile, the octamethyl cyclotetrasiloxane after the rectification treatment can reach ppb level.
Preferably, the metal ion complexing agent is a crown ether or crown ether derivative which is soluble in the polar organic solvent used in the process of the invention. Crown ether or crown ether derivative has good metal ion complexing ability and good dissolving ability in polar organic solvent, and crown ether or crown ether derivative such as 15-crown ether-5, 18-crown ether-6, crown ether containing cyclohexyl, etc.
Preferably, the metal ion complexing agent is 15-crown-5 or 18-crown-6. More preferred is 18-crown-6.
As a preferred aspect of the process of the present invention, the mass ratio of octamethyl cyclotetrasiloxane to polar organic solvent is 1:1-2. The octamethyl cyclotetrasiloxane keeps higher concentration, is easy to be solidified and separated from the polar organic solvent, and the polar organic solvent keeps proper dosage, thereby realizing the full separation of metal ions.
As a preferred embodiment of the process of the present invention, the polar organic solvent is one of methanol, ethanol, isopropanol and acetone. The reagent has good solubility, and the boiling point is lower than 100 ℃, so that the residual solvent is convenient to separate by rectification at a lower temperature.
As a preferred feature of the method of the present invention,
the polar organic solvent at least contains ethanol and isopropanol;
the isopropyl alcohol accounts for 60-70% based on the volume of the two components and the volume of 100%. In further studies, it was found that the use of a mixed system of ethanol and isopropanol further reduced the metal ion content in octamethyl cyclotetrasiloxane, which may be due to the more similar polarity of ethanol and isopropanol and the different solvency for different metal ions.
As a preferred embodiment of the process according to the invention, the solidification temperature is from-20 to 10 ℃. The lower solidification temperature requires greater energy consumption, and the economic level is reduced, more preferably-20 to 0 ℃.
As a preferred feature of the method of the present invention,
the solidification process of the step (2) is as follows:
firstly cooling to 0-10 ℃ for solidification, then cooling to-10 to-20 ℃ for solidification according to the rate of 3-5 min/DEG C, and finally completely solidifying and separating octamethyl cyclotetrasiloxane. The method is characterized in that partial solidification is realized at a slightly higher temperature, preferably 0-2 ℃, then under the condition that partial solidification crystals exist, the solidification process is carried out in a dynamic slow cooling process, then the solidification process is fully carried out at a lower temperature, the solidification process is precisely controlled, the grain size of crystals is finely compacted, the solidification separation effect is improved, the entrainment of impurities such as metal ions in the solidification process is avoided, and the metal ions are further removed. When combining a bi-solvent system of ethanol and isopropanol, the partial metal ion concentration reaches even 0.1ppb level.
As a preferred embodiment of the process according to the invention, the rectification process is as follows:
1) Transferring the liquid octamethyl cyclotetrasiloxane to a light component removal tower for negative pressure rectification, and removing low-boiling-point substance impurities from the tower top;
2) Transferring the light octamethyl cyclotetrasiloxane to a heavy-removal tower for negative pressure rectification, and collecting the fraction at 98-112 ℃ at the top of the tower to obtain the purified octamethyl cyclotetrasiloxane.
Because only a very small amount of polar organic solvent is remained in the octamethyl cyclotetrasiloxane after solidification and separation, the rectification process is greatly shortened, no fraction flows out at the top of the light component removal tower at 80-92 ℃, and the polar solvent, the hexamethylcyclotrisiloxane and other low-boiling components are removed. And D4, sending the mixture to a heavy-removal tower for heavy removal, and collecting a fraction at 98-112 ℃ at the top of the heavy-removal tower to obtain the purified octamethyl cyclotetrasiloxane.
As a preferred feature of the method of the present invention,
the vacuum degree of the step 1) is 0.097-0.098 MPa;
the vacuum degree of the step 2) is 0.099-0.0995 MPa.
The beneficial effects of the invention are as follows:
compared with the prior art for rectifying and separating the organic solvent and the octamethyl cyclotetrasiloxane, the invention separates the octamethyl cyclotetrasiloxane by optimizing the mixed system composition of the polar organic solvent and the octamethyl cyclotetrasiloxane and cooling and solidifying the octamethyl cyclotetrasiloxane at a proper temperature, thereby greatly reducing the amount of the polar organic solvent to be removed in the rectifying process, then rectifying and separating the octamethyl cyclotetrasiloxane, wherein the metal ion content in the octamethyl cyclotetrasiloxane can reach ppb level, and meeting the application requirement on the electronic octamethyl cyclotetrasiloxane.
Detailed Description
The following is a further description of embodiments of the invention.
Unless otherwise indicated, all starting materials used in the present invention are commercially available or are commonly used in the art, and unless otherwise indicated, the methods in the examples below are all conventional in the art.
The concentrations of the respective metal ions of the octamethyl cyclotetrasiloxane raw materials in the following examples and comparative examples are shown in table 1 below.
TABLE 1 concentration of Metal ions in octamethyl cyclotetrasiloxane feedstock
| Ion(s) | Fe | Ca | Al | Mn | Ni | Sn | Cu | Mg | Sb |
| Concentration/ppm | 1.602 | 0.875 | 0.65 | 0.226 | 0.280 | 0.474 | 0.735 | 0.338 | 0.601 |
The total concentration of each metal ion in the feed was 6.054ppm.
Example 1 (ethanol/crown ether, 0 ℃,100 parts/200 parts)
A method for purifying octamethyl cyclotetrasiloxane comprises the following steps:
(1) 100 parts by weight of industrial octamethyl cyclotetrasiloxane and 0.5 part of 18-crown ether-6 are dissolved in 200 parts of electronic grade ethanol and stirred uniformly to obtain mixed liquid, and the mixed liquid is stood for 24 hours;
(2) Cooling the mixed solution to 0 ℃ from room temperature within 40min, maintaining the mixed solution, stirring at a low speed at a speed of 20rpm until octamethyl cyclotetrasiloxane is completely coagulated and separated from ethanol, taking out coagulated solids, stirring the coagulated solids, and collecting the solids after the solvent is removed by vacuum filtration; (3) Washing with 0 deg.C electronic grade ethanol for 2 times, and vacuum filtering to remove solvent;
(4) Heating octamethyl cyclotetrasiloxane to 40 ℃ to be converted into liquid, then sending the liquid into a light component removing tower with the vacuum degree of 0.098MPa, rectifying until no fraction flows out from the tower top within 90 ℃, then flowing the light component removing octamethyl cyclotetrasiloxane into a heavy component removing tower from the tower bottom, rectifying under the vacuum degree of 0.0995MPa, and collecting the fraction with the vacuum degree of 110 ℃ at the tower top to obtain the octamethyl cyclotetrasiloxane with the high purity and low metal impurities with the content of more than 99.99 percent.
Example 2 (ethanol/crown ether, 0 ℃,100 parts/100 parts)
A method for purifying octamethyl cyclotetrasiloxane comprises the following steps:
(1) 100 parts by weight of industrial octamethyl cyclotetrasiloxane and 0.5 part of 18-crown ether-6 are dissolved in 100 parts of electronic grade ethanol and stirred uniformly to obtain mixed liquid, and the mixed liquid is stood for 24 hours;
(2) Cooling the mixed solution to 0 ℃ from room temperature within 40min, maintaining the mixed solution, stirring at a low speed at a speed of 50rpm until octamethyl cyclotetrasiloxane is completely coagulated and separated from ethanol, taking out coagulated solids, stirring, vacuum-filtering, and collecting the solids;
(3) Washing with 0 deg.C electronic grade ethanol for 2 times, and vacuum filtering to remove solvent;
(4) Heating octamethyl cyclotetrasiloxane to 40 ℃ to be converted into liquid, then sending the liquid into a light component removing tower with the vacuum degree of 0.097MPa, rectifying the liquid until no fraction flows out in the range of 92 ℃ at the top of the tower, then flowing the light component removing octamethyl cyclotetrasiloxane into a heavy component removing tower from the bottom of the tower, rectifying the liquid under the vacuum degree of 0.0995MPa, and collecting the fraction at 112 ℃ at the top of the tower to obtain the octamethyl cyclotetrasiloxane with the high purity and low metal impurities content of more than 99.99%.
Example 3 (electronic grade isopropanol)
The difference from example 1 is that electronic grade isopropanol was used instead of ethanol.
Example 4 (electronic grade methanol)
The difference from example 1 is that electronic grade methanol was used instead of ethanol.
Example 5 (ethanol+isopropanol)
The difference from example 1 is that 120 parts of electronic grade isopropanol and 80 parts of electronic grade ethanol are used instead of 200 parts of ethanol.
Example 6 (ethanol+isopropanol)
The difference from example 1 is that 140 parts of electronic grade isopropanol and 60 parts of electronic grade ethanol are used instead of 200 parts of ethanol.
Example 7 (ethanol+isopropanol)
The difference from example 1 is that 120 parts of electronic grade isopropanol and 80 parts of electronic grade ethanol are used instead of 200 parts of ethanol, and the cooling solidification temperature is-20 ℃.
Comparative example 1 (methanol and isopropanol)
The difference from example 1 is that 120 parts of electronic isopropanol and 80 parts of electronic grade methanol are used instead of 200 parts of ethanol.
Comparative example 2 (isopropyl alcohol 90%)
The difference from example 1 is that 180 parts of electronic grade isopropanol and 20 parts of electronic grade ethanol are used instead of 200 parts of ethanol.
Example 8 (Mixed solvent/dynamic slow cooling solidification)
A method for purifying octamethyl cyclotetrasiloxane comprises the following steps:
(1) 100 parts by weight of industrial octamethyl cyclotetrasiloxane to be purified, 0.5 part of 18-crown ether-6 are dissolved in 120 parts of electronic grade isopropyl alcohol and 80 parts of ethanol, and mixed solution is obtained by stirring;
(2) Cooling the mixed solution from room temperature to 0 ℃ for 5min, stirring at a speed of 20rpm at a low speed, cooling to-20 ℃ for 60min under stirring, keeping until octamethyltetrasiloxane is completely solidified and separated from ethanol, taking out the solid, stirring, vacuum-filtering, and collecting the solid;
(3) Washing the collected solid with 0 ℃ electronic grade ethanol for 2 times, and then vacuum filtering to remove the solvent;
(4) Heating octamethyl cyclotetrasiloxane to 40 ℃ to be converted into liquid, firstly delivering the liquid to a light component removal tower, rectifying the liquid to the tower top at the vacuum degree of 0.098MPa until no fraction flows out at the temperature of 90 ℃, then flowing the light component-removed octamethyl cyclotetrasiloxane into a heavy component removal tower from the tower bottom, rectifying the liquid at the vacuum degree of 0.0995MPa, and collecting the fraction at the temperature of 110 ℃ at the tower top to obtain the octamethyl cyclotetrasiloxane with the high-purity low-metal impurities content of more than 99.99%.
Comparative example 3 (quick cooling)
The difference from example 8 is that the temperature was lowered from 0℃to-20℃in 30min under stirring.
Example 9 (isopropanol/dynamic slow cooling solidification)
The difference from example 8 is that 200 parts of electronic grade isopropanol are used instead of 120 parts of electronic grade isopropanol and 80 parts of methanol.
The octamethyltetrasiloxane finally collected in the above examples and comparative examples was subjected to ICP-MS metal ion detection, and the results are shown in table 2.
TABLE 1 concentration of metal ions in octamethyl cyclotetrasiloxane
| Ions/ppb | Fe/ppb | Ca/ppb | Al/ppb | Mn/ppb | Ni/ppb | Sn/ppb | Cu/ppb | Mg/ppb | Sb/ppb |
| Raw material D4 | 1602 | 875 | 650 | 226 | 280 | 474 | 735 | 338 | 601 |
| Example 1 | 42.1 | 28.0 | 18.4 | 3.1 | 3.0 | 3.3 | 1.2 | 2.0 | 1.1 |
| Example 2 | 33.4 | 16.2 | 9.9 | 2.4 | 2.1 | 2.7 | 0.8 | 1.3 | 0.9 |
| Example 3 | 25.3 | 10.1 | 7.8 | 1.6 | 1.5 | 1.9 | 0.6 | 0.8 | 0.5 |
| Example 4 | 19.0 | 8.3 | 6.5 | 1.1 | 1.7 | 1.2 | 0.5 | 0.6 | 0.4 |
| Example 5 | 12.4 | 8.7 | 7.2 | 1.2 | 1.3 | 1.4 | 0.3 | 0.3 | 0.4 |
| Example 6 | 10.8 | 8.1 | 6.5 | 1.1 | 1.4 | 1.2 | 0.4 | 0.3 | 0.2 |
| Example 7 | 9.6 | 7.5 | 6.3 | 0.8 | 1.2 | 1.0 | 0.3 | 0.2 | 0.3 |
| Comparative example 1 | 22.3 | 9.1 | 7.2 | 1.3 | 1.5 | 1.4 | 0.5 | 0.7 | 0.4 |
| Comparative example 2 | 27.1 | 12.3 | 9.4 | 2.2 | 2.3 | 2.5 | 0.8 | 1.4 | 0.7 |
| Example 8 | 2.8 | 1.1 | 0.5 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 |
| Comparative example 3 | 9.4 | 7.6 | 6.5 | 0.8 | 1.3 | 1.2 | 0.2 | 0.3 | 0.2 |
| Example 9 | 23.4 | 9.0 | 5.2 | 1.5 | 1.3 | 2.1 | 0.5 | 0.7 | 0.4 |
As can be seen from Table 2, the metal ion impurities in the octamethyl cyclotetrasiloxane feedstock can be effectively removed by the scheme.
Specific:
as shown in examples 1 to 4, the total content of metal ions in the purified octamethyltetrasiloxane is not more than 100ppb, reaching ppb level and meeting the application requirements of electronic level at the optimized use amount of octamethyltetrasiloxane, complexing agent, organic solvent and cooling temperature. As shown by comparing examples 5 to 7 with comparative examples 1 and 2, the concentration of metal ions can be further reduced by using ethanol and isopropanol in combination and controlling the appropriate amount ratio. When the optimized mixed solvent of ethanol and isopropanol is adopted and the proper and controllable dynamic cooling solidification process is combined, as shown in the embodiment 8, the removal effect of metal ions can be improved, and the concentration of most metal ions can reach the level of 0.1 ppb. Whereas example 7 was comparable to comparative example 3, example 9 was slightly improved over example 3.
Claims (10)
1. A method for purifying octamethyl cyclotetrasiloxane, comprising the steps of:
(1) Dissolving octamethyl cyclotetrasiloxane and a metal ion complexing agent to be purified in a polar organic solvent to obtain mixed feed liquid;
(2) Cooling the mixed material liquid, and solidifying and separating octamethyl cyclotetrasiloxane from the polar solvent, wherein the solidifying temperature is less than or equal to 10 ℃;
(3) Flushing octamethyl cyclotetrasiloxane solid by using a polar organic solvent with the temperature less than or equal to 10 ℃, and then removing residual polar organic solvent on the surface of octamethyl cyclotetrasiloxane;
(4) Heating to convert octamethyl cyclotetrasiloxane into liquid, and rectifying to obtain purified octamethyl cyclotetrasiloxane;
the addition amount of the metal ion complexing agent is 0.01-1% of the mass of the polar organic solvent;
the mass ratio of the octamethyl cyclotetrasiloxane to the polar organic solvent is 1:0.1-10.
2. The method for purifying octamethyl cyclotetrasiloxane according to claim 1, wherein,
the metal ion complexing agent is crown ether or crown ether derivative which is soluble in the polar organic solvent used.
3. The method for purifying octamethyl cyclotetrasiloxane according to claim 1 or 2, wherein the metal ion complexing agent is 15-crown-5 or 18-crown-6.
4. The method for purifying octamethyl cyclotetrasiloxane according to claim 1, wherein,
the mass ratio of the octamethyl cyclotetrasiloxane to the polar organic solvent is 1:1-2.
5. The method for purifying octamethyl cyclotetrasiloxane according to claim 1, wherein,
the polar organic solvent is one of methanol, ethanol, isopropanol and acetone.
6. The method for purifying octamethyl cyclotetrasiloxane according to claim 1, wherein,
the polar organic solvent at least contains ethanol and isopropanol;
the isopropyl alcohol accounts for 60-70% based on the volume of the two components and the volume of 100%.
7. The method for purifying octamethyltetrasiloxane according to claim 5 or 6, wherein,
the solidification temperature is-20-10 ℃.
8. The method for purifying octamethyl cyclotetrasiloxane according to claim 7,
the solidification process of the step (2) is as follows:
firstly cooling to 0-10 ℃ for solidification, then cooling to-10 to-20 ℃ for solidification according to the rate of 3-5 min/DEG C, and finally completely solidifying and separating octamethyl cyclotetrasiloxane.
9. The method for purifying octamethyl cyclotetrasiloxane according to claim 1, wherein the rectification process is as follows:
1) Transferring the liquid octamethyl cyclotetrasiloxane to a light component removal tower for negative pressure rectification, and removing low-boiling-point substance impurities from the tower top;
2) Transferring the light octamethyl cyclotetrasiloxane to a heavy-removal tower for negative pressure rectification, and collecting the fraction at 98-112 ℃ at the top of the tower to obtain the purified octamethyl cyclotetrasiloxane.
10. The purification method according to claim 9, wherein,
the vacuum degree of the step 1) is 0.097-0.098 MPa;
the vacuum degree of the step 2) is 0.099-0.0995 MPa.
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