Electronic-grade purification method of N, N-2, 2-bitetrahydropyrrolidine

Abstract

The invention relates to an electronic grade purification method of N, N-2, 2-bitetrahydropyrrolidine, which comprises the following steps: step 1, distilling N, N-2, 2-bitetrahydropyrrolidine, and collecting corresponding boiling point fractions; step 2, preparing a bitetrahydropyrrolidine aqueous solution, adding the N, N-2, 2-bitetrahydropyrrolidine fraction obtained in the step 1 into a medium for dissolving, cooling, and adding an electronic-grade acidic cosolvent while stirring; step 3, adding electronic-grade organic acid into the N, N-2, 2-bitetrahydropyrrolidine aqueous solution obtained in the step 2, and heating while stirring; step 4, cooling the solution obtained in the step 3, standing, and filtering to obtain a filter residue crystal N, N-2, 2-bitetrahydropyrrolidine salt; step 5, drying and baking; and step 6, dissolving the compound obtained in the step 5 in ultrapure water, adding an electronic-grade inorganic base to adjust the pH value to 14, cooling the aqueous solution, adding an electronic-grade organic solvent for extraction, combining the organic extraction phases, and carrying out distillation concentration to obtain the electronic-grade N, N-2, 2-bitetrahydropyrrolidine.

Description

Technical Field

[0001] The invention relates to the technical field of compound preparation, in particular to an electronic grade purification method of N,N-2,2-tetrahydropyrrolidine. Background Art

[0002] Electronic-grade reagents are one of the indispensable raw materials in the integrated circuit industry. With the rapid development of integrated circuits, the demand for electronic-grade reagents is getting higher and higher, and the categories are increasing. With the rapid development of semiconductor process technology, the corresponding requirements for electronic-grade reagents have also reached a corresponding increase, and thus gradually become one of the factors restricting the development of integrated circuits. The production of electronic-grade reagents generally uses the corresponding industrial-grade products as raw materials, and removes the target impurities in the raw materials through post-processing purification. Due to the late start of the semiconductor industry and the immature purification technology, electronic-grade reagents are highly dependent on imports.

[0003] With the rapid development of the semiconductor industry, the demand for electronic-grade reagents is increasing, and the original electronic-grade reagents can no longer meet the demand. N, N-2, 2-tetrahydropyrrolidine is a new type of reagent used in the semiconductor industry. It has been developed to be compounded with other reagents in the STI process of chemical mechanical polishing, adjust the pH value, inhibit silicon nitride polishing, and reduce scratches and pits. In addition, due to the special ortho-diamine structure of N, N-2, 2-tetrahydropyrrolidine, it can play a role in complexing metal ions, and is expected to be further used in chemical mechanical polishing of copper and other metals.

[0004] At present, the research and development of new electronic-grade reagents for electronic-grade purification of N, N-2, 2-tetrahydropyrrolidine in China has great strategic significance. There are many reports in the industry on the removal of metal ions in organic matter, most of which use the principle of static adsorption exchange to remove metal ions: using cation or anion exchange resin to remove calcium, magnesium, sodium, potassium, iron and other ions in the reagent. However, the static adsorption exchange operation is time-consuming, the removal rate is low, and it is difficult to achieve mass production. In addition, due to the structural characteristics of N, N-2, 2-tetrahydropyrrolidine, it can form stable complexes with many metal ions such as sodium ions, potassium ions, magnesium ions, and iron ions, which poses a great challenge to the removal of metal ions.

[0005] Therefore, it is urgent to develop a method for removing metal ions in N, N-2, 2-tetrahydropyrrolidine, and to effectively reduce the content of metal ions such as sodium, potassium, magnesium, calcium, iron, and copper, so as to meet the requirements for application in semiconductor chemical mechanical polishing. Summary of the invention

[0006] In view of the deficiencies in the prior art, the purpose of the present invention is to provide an electronic grade purification method for N, N-2, 2-tetrahydropyrrolidine, which is used to remove metal ions in N, N-2, 2-tetrahydropyrrolidine so that it meets electronic grade standards and can be applied to high-end semiconductor chemical mechanical polishing liquids.

[0007] The above-mentioned object of the present invention is achieved through the following technical solutions:

[0008] A method for electronic grade purification of N,N-2,2-tetrahydropyrrolidine comprises the following steps:

[0009] Step 1, distilling N,N-2,2-tetrahydropyrrolidine, and collecting the corresponding boiling point fractions;

[0010] Step 2, preparing a tetrahydropyrrolidine aqueous solution, adding the N,N-2,2-tetrahydropyrrolidine fraction obtained in step 1 into a medium to dissolve, cooling, and adding an electronic grade acidic co-solvent while stirring;

[0011] Step 3, adding an electronic grade organic acid to the aqueous solution of N,N-2,2-tetrahydropyrrolidine obtained in step 2, and heating the mixture while stirring;

[0012] Step 4, cooling the solution obtained in step 3, standing it, and filtering it to obtain a residue crystal N, N-2, 2-tetrahydropyrrolidine salt;

[0013] Step 5, drying the filter residue crystals N, N-2, 2-tetrahydropyrrolidine salt in a vacuum drying oven;

[0014] Step 6: Dissolve the residue crystal N, N-2, 2-tetrahydropyrrolidine salt in ultrapure water, add electronic grade inorganic base to adjust the pH to 14, cool the aqueous solution, add electronic grade organic solvent for extraction, combine the organic extracts, and distill and concentrate to obtain electronic grade N, N-2, 2-tetrahydropyrrolidine.

[0015] As a further technical solution of the present invention: the N, N-2, 2-tetrahydropyrrolidine includes its chiral isomers, (R, R)-N, N-2, 2-tetrahydropyrrolidine, (S, S)-N, N-2, 2-tetrahydropyrrolidine, and its racemate.

[0016] As a further technical solution of the present invention: in the step 1, the distillation is one or more of atmospheric distillation, vacuum distillation, and rectification.

[0017] As a further technical solution of the present invention: in the step 1, the distillation is a reduced pressure distillation.

[0018] As a further technical solution of the present invention: in step 2, the medium is selected from one or more of water, methanol, acetonitrile, propionitrile, ethanol, isopropanol, n-hexane, acetone, dimethyl sulfoxide, ethyl acetate, N-methylpyrrolidone, ethylene glycol methyl ether, ethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monobutyl ether and cyclohexane.

[0019] As a further technical solution of the present invention: in step 2, the medium is water.

[0020] As a further technical solution of the present invention: in the step 2, the temperature is lowered in the range of 10°C-100°C.

[0021] As a further technical solution of the present invention: in step 2, the acidic co-solvent is an organic small molecule acid, and the acidic co-solvent is one or more of acetic acid, propionic acid, isopropionic acid, butyric acid, isobutyric acid, and tert-butyric acid.

[0022] As a further technical solution of the present invention: in step 2, the acidic co-solvent is acetic acid.

[0023] As a further technical solution of the present invention: in step 3, the electronic grade organic acid is a combination of one or more of L-tartaric acid, D-tartaric acid, citric acid, and p-toluenesulfonic acid.

[0024] As a further technical solution of the present invention: in the step 3, the temperature range of the heating is 40°C-100°C.

[0025] As a further technical solution of the present invention: in the step 4, the cooling temperature range is 0°C-20°C.

[0026] As a further technical solution of the present invention: in step 4, the standing time is 10h-48h.

[0027] As a further technical solution of the present invention: in the step 5, the drying is carried out under reduced pressure in a vacuum drying oven, the temperature of the vacuum drying oven is controlled at 20° C.-100° C., and the reduced pressure drying is carried out for more than 8 hours.

[0028] As a further technical solution of the present invention: in the step 5, the drying is carried out by controlling the temperature of the vacuum drying oven at 30°C-50°C and drying under reduced pressure for 12h-24h.

[0029] As a further technical solution of the present invention: in step 6, the electronic grade inorganic base is potassium hydroxide, sodium hydroxide or a combination thereof.

[0030] As a further technical solution of the present invention: in step 6, the electronic grade organic solvent is one or more of dichloromethane, chloroform, carbon tetrachloride, ethyl ether, methyl tert-butyl ether, methyl tetrahydrofuran, propyl ether, isopropyl ether, butyl ether, isobutyl ether, and tert-butyl ether small molecule ether.

[0031] As a further technical solution of the present invention: in the step 2, the weight ratio of the N,N-tetrahydropyrrole (cas: 137037-20-8) to the medium is 1:2-1:5.

[0032] As a further technical solution of the present invention: in the step 2, the volume content of the electronic grade acidic co-solvent is 0.05%-5%.

[0033] As a further technical solution of the present invention: in the step 2, the weight content of the electronic grade acidic co-solvent is 0.05%-5%.

[0034] As a further technical solution of the present invention: in the step 2, the ratio of the N,N-2,2-tetrahydropyrrolidine to the medium is 1:1-1:5.

[0035] As a further technical solution of the present invention: in the step 6, the ratio of the N, N-2, 2-tetrahydropyrrolidine to the ultrapure water is 1:1-1:5.

[0036] As a further technical solution of the present invention: in step 6, the weight content of the electronic grade inorganic base is 20%-80%.

[0037] As a further technical solution of the present invention: in step 6, the volume content ratio of the electronic grade organic solvent and the aqueous phase is 0.3:1-5:1.

[0038] As a further technical solution of the present invention: in step 6, the aqueous solution is cooled in the range of room temperature to -60°C.

[0039] In summary, the present invention includes at least one of the following beneficial technical effects:

[0040] The invention discloses an electronic grade purification method for N, N-2, 2-tetrahydropyrrolidine, which fills the gap in the electronic grade purification of such compounds. The operation is simple, the process is easy to implement, the metal ion content in the purified N, N-2, 2-tetrahydropyrrolidine is reduced to less than 1 ppm, reaching the electronic grade standard, the metal ion removal rate is high, the yield is more than 80%, and it is suitable for industrialized scale-up production. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1This is the GCMs spectrum of the product (S,S)-N,N-2,2-tetrahydropyrrolidine in Example 5 of the present invention.

[0042] Figure 2 This is the HNMR spectrum of the product (S,S)-N,N-2,2-tetrahydropyrrolidine in Example 5 of the present invention.

[0043] Figure 3 This is the ee value detection spectrum of the control racemate of the product (S,S)-N,N-2,2-tetrahydropyrrolidine in Example 5 of the present invention after benzoylation.

[0044] Figure 4 This is the ee value detection spectrum of the test sample after benzoylation of the product (S, S)-N, N-2,2-tetrahydropyrrolidine in Example 5 of the present invention.

[0045] Figure 5 This is a graph showing the ee value detection data of the product (S, S)-N, N-2,2-tetrahydropyrrolidine in Example 5 of the present invention after benzoylation. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application; obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments in the present application without making creative work are within the scope of protection of the present application.

[0047] The N,N-2,2-tetrahydropyrrolidine used in the present invention is a self-developed product of our company, and other reagents and raw materials are commercially available.

[0048] The wt% mentioned in the present invention refers to the mass percentage.

[0049] The metal ion concentrations in three different batches of N,N-2,2-tetrahydropyrrolidine raw materials used in Examples 1 to 3 of the present invention are shown in Table 1. The metal ion concentration in N,N-2,2-tetrahydropyrrolidine was tested by ICP-OES spectrometer.

[0050] Table 1 Metal ion concentrations in three batches of N, N-2,2-tetrahydropyrrolidine (unit: ppb)

[0051]

[0052]

[0053] Embodiment 1:

[0054] The electronic grade purification method of N, N-2, 2-tetrahydropyrrolidine of the present invention uses (R, R)-N, N-2, 2-tetrahydropyrrolidine of batch 1, comprising the following steps:

[0055] 700 g of crude (R, R)-N, N-2,2-tetrahydropyrrolidine was subjected to vacuum distillation (oil pump decompression, pressure 15 torr), and the 150-degree fraction was collected. 640 g of the distilled (R, R)-N, N-2,2-tetrahydropyrrolidine was dissolved in 2200 ml of ultrapure water, and 250 ml of acetic acid was added in batches at room temperature, stirring while adding. 685 g of L-tartaric acid was then added. The mixture was then heated to 80 degrees and heated for 1 hour. The mixed solution was slowly cooled to 30 degrees and kept warm for 18 hours, and then further cooled to 0 degrees and kept warm for 18 hours. The generated filter residue was filtered, the filter residue was washed with ultrapure water, and the filter residue was sent to a vacuum oven and dried at 60 degrees for 18 hours. The filter residue was dissolved in a potassium hydroxide aqueous solution with a pH value of 14 at a weight ratio of 1:3, and extracted three times with electronic grade dichloromethane at room temperature. The organic solvents were combined and distilled under reduced pressure to obtain 147 g of (R, R)-tetrahydropyrrolidine with a yield of 210%.

[0056] Embodiment 2:

[0057] The electronic grade purification method of N, N-2, 2-tetrahydropyrrolidine of the present invention uses (R, R)-N, N-2, 2-tetrahydropyrrolidine of batch 1, comprising the following steps:

[0058] One kilogram of crude (R, R)-N, N-2,2-tetrahydropyrrolidine was subjected to vacuum distillation (oil pump decompression, pressure 15torr), and the 150-degree fraction was collected. 640 grams of distilled (R, R)-N, N-2,2-tetrahydropyrrolidine was dissolved in 2200 ml of ultrapure water, and 250 ml of acetic acid was added in batches at room temperature, stirring while adding. 685 grams of L-tartaric acid were then added. The mixture was then heated to 80 degrees and heated for 1 hour. The mixed solution was slowly cooled to 30 degrees and kept warm for 18 hours, and then further cooled to 0 degrees and kept warm for 18 hours. The generated filter residue was filtered, the filter residue was washed with ultrapure water, and the filter residue was sent to a vacuum oven and dried at 60 degrees for 18 hours. The filter residue was dissolved in a potassium hydroxide aqueous solution with a pH value of 14 at a weight ratio of 1:3, and extracted three times with electronic grade methyl tert-butyl ether at room temperature. The organic solvents were combined and distilled under reduced pressure to obtain 175 g of (R, R)-tetrahydropyrrolidine with a yield of 25%.

[0059] Embodiment 3:

[0060] The electronic grade purification method of N, N-2, 2-tetrahydropyrrolidine of the present invention uses (R, R)-N, N-2, 2-tetrahydropyrrolidine of batch 1, comprising the following steps:

[0061] 700 g of crude (R, R)-N, N-2,2-tetrahydropyrrolidine was subjected to vacuum distillation (oil pump decompression, pressure 15 torr), and the 150-degree fraction was collected. 640 g of the distilled (R, R)-N, N-2,2-tetrahydropyrrolidine was dissolved in 2200 ml of ultrapure water, the temperature was lowered to -60 degrees, and 250 ml of acetic acid was added in batches, stirring while adding. 685 g of L-tartaric acid was then added. The mixture was then heated to 80 degrees and heated for 1 hour. The mixed solution was slowly cooled to 30 degrees and kept warm for 18 hours, and then further cooled to 0 degrees and kept warm for 18 hours. The generated filter residue was filtered, the filter residue was washed with ultrapure water, and the filter residue was sent to a vacuum oven and dried at 60 degrees for 18 hours. The filter residue was dissolved in a potassium hydroxide aqueous solution with a pH value of 14 at a weight ratio of 1:3, and extracted three times with electronic grade methyl tert-butyl ether at room temperature. The organic solvents were combined and distilled under reduced pressure to obtain 245 g of (R, R)-tetrahydropyrrolidine with a yield of 35%.

[0062] Embodiment 4:

[0063] The electronic grade purification method of N, N-2, 2-tetrahydropyrrolidine of the present invention uses (R, R)-N, N-2, 2-tetrahydropyrrolidine of batch 1, comprising the following steps:

[0064] 700 g of crude (R, R)-N, N-2,2-tetrahydropyrrolidine was subjected to vacuum distillation (oil pump decompression, pressure 15 torr), and a 150-degree fraction was collected. 640 g of the distilled (R, R)-N, N-2,2-tetrahydropyrrolidine was dissolved in 2200 ml of ultrapure water, the temperature was lowered to -60 degrees, and 250 ml of acetic acid was added in batches, stirring while adding. 685 g of L-tartaric acid was then added. The mixture was then heated to 80 degrees and heated for 1 hour. The mixed solution was slowly cooled to 30 degrees and kept warm for 18 hours, and then further cooled to 0 degrees and kept warm for 18 hours. The resulting filter residue was filtered, the filter residue was washed with ultrapure water, and the filter residue was sent to a vacuum oven and dried at 60 degrees for 18 hours. The filter residue was dissolved in a potassium hydroxide aqueous solution with a pH value of 14 at a weight ratio of 1:3. The temperature was lowered to -40 degrees. Methyl tert-butyl ether was used for extraction three times. The organic solvents were combined and distilled under reduced pressure to obtain 560 grams of (R, R)-tetrahydropyrrolidine with a yield of 80%.

[0065] Embodiment 5:

[0066] The electronic grade purification method of N, N-2, 2-tetrahydropyrrolidine of the present invention uses (S, S)-N, N-2, 2-tetrahydropyrrolidine of batch 2, comprising the following steps:

[0067] 700 g of crude (S, S)-N, N-2,2-tetrahydropyrrolidine was subjected to vacuum distillation (oil pump decompression, pressure 15 torr), and the 150-degree fraction was collected. 640 g of crude (S, S)-N, N-2,2-tetrahydropyrrolidine was dissolved in 2200 ml of ultrapure water, the temperature was lowered to -60 degrees, and 250 ml of acetic acid was added in batches, stirring while adding. 685 g of D-tartaric acid was then added. The mixture was then heated to 80 degrees and heated for 1 hour. The mixed solution was slowly cooled to 30 degrees and kept warm for 18 hours, and then further cooled to 0 degrees and kept warm for 18 hours. The generated filter residue was filtered, the filter residue was washed with ultrapure water, and the filter residue was sent to a vacuum oven and dried at 60 degrees for 18 hours. The filter residue was dissolved in a potassium hydroxide aqueous solution with a pH value of 14 at a weight ratio of 1:3, the temperature was lowered to -40 degrees, and extracted three times with methyl tert-butyl ether. The organic solvents were combined and distilled under reduced pressure to obtain 600 grams of (S, S)-tetrahydropyrrolidine, the temperature was lowered to -40 degrees, and the yield was 85%.

[0068] Embodiment 6:

[0069] The electronic grade purification method of N, N-2, 2-tetrahydropyrrolidine of the present invention uses (S, S)-N, N-2, 2-tetrahydropyrrolidine of batch three, comprising the following steps:

[0070] 700 g of crude (S, S)-N, N-2,2-tetrahydropyrrolidine was subjected to vacuum distillation (oil pump decompression, pressure 15 torr), and the 150-degree fraction was collected. 640 g of crude (S, S)-N, N-2,2-tetrahydropyrrolidine was dissolved in 2200 ml of ultrapure water, the temperature was lowered to -60 degrees, and 250 ml of propionic acid was added in batches, stirring while adding. 685 g of D-tartaric acid was then added. The mixture was then heated to 80 degrees and heated for 1 hour. The mixed solution was slowly cooled to 20 degrees and kept warm for 16 hours, and then further cooled to 0 degrees and kept warm for 5 hours. The generated filter residue was filtered, the filter residue was washed with ultrapure water, and the filter residue was sent to a vacuum oven and dried at 60 degrees for 18 hours. The filter residue was dissolved in a potassium hydroxide aqueous solution with a pH value of 14 at a weight ratio of 1:3. The temperature was lowered to -40 degrees. Methyl tert-butyl ether was used for extraction three times. The organic solvents were combined and distilled under reduced pressure to obtain 560 grams of (S, S) N, N-2,2-tetrahydropyrrolidine with a yield of 80%.

[0071] Embodiment 7:

[0072] The electronic grade purification method of N, N-2, 2-tetrahydropyrrolidine of the present invention uses racemic-N, N-2, 2-tetrahydropyrrolidine of batch four, comprising the following steps:

[0073] One kilogram of crude racemic-N, N-2,2-tetrahydropyrrolidine was subjected to vacuum distillation (oil pump decompression, pressure 15torr), and the 150-degree fraction was collected. 640 grams of crude racemic-N, N-2,2-tetrahydropyrrolidine was dissolved in 2200 milliliters of ultrapure water, the temperature was lowered to -60 degrees, and 250 milliliters of propionic acid were added in batches, stirring while adding. Then 685 grams of D-tartaric acid were added. The mixture was then heated to 80 degrees and heated for 1 hour. The mixed solution was slowly cooled to 20 degrees and kept warm for 16 hours, and then further cooled to 0 degrees and kept warm for 5 hours. The resulting filter residue was filtered, the filter residue was washed with ultrapure water, and the filter residue was sent to a vacuum oven and dried at 60 degrees for 18 hours. The filter residue was dissolved in a potassium hydroxide aqueous solution with a pH value of 14 at a weight ratio of 1:3. The temperature was lowered to -40 degrees. Methyl tert-butyl ether was used for extraction three times. The organic solvents were combined and distilled under reduced pressure to obtain 130 grams of (S, S)-N, N-2,2-tetrahydropyrrolidine with a yield of 13%.

[0074] A certain amount of the above N, N-2, 2-tetrahydropyrrolidine was taken and the purity was tested using GCMs. The yield and purity of each example are shown in Table 2:

[0075] Table 2, yield and product purity of different purification methods

[0076]

[0077]

[0078] As shown in Table 2, in Example 1, an organic solvent such as dichloromethane was used for extraction. The experiment found that the initial purity of the product dropped from 95% to 79%. The product was visually observed to change from a clear transparent solution to a slightly yellow turbid solution containing a large amount of solids. It can be inferred that this is because dichloromethane can react slowly with N, N-tetrahydropyrrole, resulting in a large amount of solid impurities in the extraction liquid and a decrease in purity. In subsequent experiments, the organic solvent was changed to an organic solvent such as methyl tert-butyl ether to avoid such problems.

[0079] In step 2, in Example 1 and Example 2, before adding electronic grade organic acids such as electronic grade acetic acid, the solutions were all at room temperature. Experiments have found that the product yield is low, with yields of only 21% and 25%. Observation of the experimental phenomena revealed that the solution quickly turned black and the solution temperature rose rapidly. It can be inferred that due to the increase in solution temperature, N, N-2,2-tetrahydropyrrolidine reacted in the system to generate impurities, resulting in a decrease in product yield. In Example 3, the temperature of step 2 was reduced to -60 degrees, and acetic acid was added in batches to control the solution temperature, and the yield was increased from the original 25% to 35%.

[0080] The yields of Example 1, Example 2, and Example 3 are all relatively low. The experiment found that in step 6, the aqueous phase after organic solvent extraction still contained a large amount of product in the aqueous phase. Since N, N-2,2-tetrahydropyrrolidine has good water solubility, repeated extraction of the aqueous phase cannot completely remove it from the aqueous phase. And a large number of extraction operations have the risk of electronic grade contamination. It has been found experimentally that lowering the temperature of the aqueous phase can reduce the solubility of the product in the aqueous phase. Reference Figure 1-5 In Example 4, Example 5, and Example 6, by lowering the temperature in step 6 to -40 degrees, the product can be completely extracted from the aqueous solution, and the yield is increased to more than 80%.

[0081] The above-mentioned thin layer chromatography analysis of the aqueous phase is carried out by deriving the product into the corresponding acryloyl derivative for comparison. The specific operation is as follows:

[0082] Preparation of reference standard: Take 10 mg of the first batch of N, N-2, 2-tetrahydropyrrolidine and place it in a sample tube. Add 1 mL of methyl tert-butyl ether, add 1 drop of acryloyl chloride, shake for 5 seconds, add 1 mL of saturated sodium carbonate aqueous solution, shake for 5 seconds, separate the liquids, and take the organic phase as the standard.

[0083] Preparation of aqueous phase sample: Take 1 mL of aqueous phase, add 1 mL of methyl tert-butyl ether, add 1 drop of acryloyl chloride, shake for 5 seconds, add 1 mL of saturated sodium carbonate aqueous solution, shake for 5 seconds, separate the liquids, and take the organic phase as the aqueous sample.

[0084] The aqueous phase sample and the reference standard were subjected to thin layer chromatography with the developing solvent being petroleum ether:ethyl acetate = 1:2, so as to determine whether N, N-2,2-tetrahydropyrrolidine still remained in the aqueous phase.

[0085] In Example 7, the crystal solubility of the (S, S)-bipyrrolidine generated in D-tartaric acid and the racemate is poor, and is preferentially precipitated. Since the (S, S)-bipyrrolidine content in the system is only half, the concentration is relatively dilute, and in addition, since half of the (R, R)-bipyrrolidine exists in the system, the crystal form of the (S, S)-bipyrrolidine generated in D-tartaric acid and the racemate is preferentially precipitated. In Examples 1, 2, 3, 4, 5, and 6, the precipitated crystal form is a rock sugar type, and in Example 7, the precipitated crystal form is a sheet, the crystal yield is low, the final product yield is low, and the purity is only 97%.

[0086] In Table 2, the yield and purity of N, N-2, 2-tetrahydropyrrolidine in Example 4, Example 5, and Example 6 all meet the standards. A certain amount of N, N-2, 2-tetrahydropyrrolidine in Example 4, Example 5, and Example 6 was prepared into a solution, and the metal ion concentration therein was tested by ICP-OES spectrometer. The metal ion concentrations before and after treatment and the removal rate data are shown in Table 3.

[0087] Table 3 Concentration and removal rate of metal ions before and after treatment

[0088]

[0089] As can be seen from Table 2, after using the purification method of N, N-2, 2-tetrahydropyrrolidine of the present invention, the removal rate of sodium ions in N, N-2, 2-tetrahydropyrrolidine is as high as more than 99%, the removal rate of iron ions is as high as more than 91%, and the removal rates of other metal ions are all above 71%, and the content of all metal ions is less than 1 ppm. The high-purity N, N-2, 2-tetrahydropyrrolidine obtained by the purification method of the present invention is formulated into a chemical mechanical polishing liquid for the semiconductor industry to meet the requirements of the semiconductor industry.

[0090] It should be noted that the embodiments of the present invention have better practicability and do not impose any form of limitation on the present invention. Any technician familiar with the field may use the technical content disclosed above to change or modify it into an equivalent effective embodiment. However, any modification or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for electronic grade purification of N,N-2,2-tetrahydropyrrolidine, characterized in that: The following steps are involved: Step 1, distilling N,N-2,2-tetrahydropyrrolidine, and collecting the corresponding boiling point fractions; Step 2, preparing a tetrahydropyrrolidine aqueous solution, adding the N,N-2,2-tetrahydropyrrolidine fraction obtained in step 1 into a medium to dissolve, cooling, and adding an electronic grade acidic co-solvent while stirring; Step 3, adding an electronic grade organic acid to the aqueous solution of N,N-2,2-tetrahydropyrrolidine obtained in step 2, and heating the mixture while stirring; Step 4, cooling the solution obtained in step 3, standing it, and filtering it to obtain a residue crystal N, N-2, 2-tetrahydropyrrolidine salt; Step 5, drying the filter residue crystals N, N-2, 2-tetrahydropyrrolidine salt in a vacuum drying oven; Step 6: Dissolve the residue crystal N, N-2, 2-tetrahydropyrrolidine salt in ultrapure water, add electronic grade inorganic base to adjust the pH to 14, cool the aqueous solution, add electronic grade organic solvent for extraction, combine the organic extracts, and distill and concentrate to obtain electronic grade N, N-2, 2-tetrahydropyrrolidine.

2. The method for electronic grade purification of N,N-2,2-tetrahydropyrrolidine according to claim 1, characterized in that: The N,N-2,2-tetrahydropyrrolidine includes its chiral isomers, (R,R)-N,N-2,2-tetrahydropyrrolidine, (S,S)-N,N-2,2-tetrahydropyrrolidine, and racemates thereof.

3. The electronic grade purification method of N,N-2,2-tetrahydropyrrolidine according to claim 1, characterized in that: In the step 1, the distillation is a reduced pressure distillation.

4. The method for electronic grade purification of N,N-2,2-tetrahydropyrrolidine according to claim 1, characterized in that: In the step 2, the medium is water.

5. The method for electronic grade purification of N,N-2,2-tetrahydropyrrolidine according to claim 1, characterized in that: In step 2, the temperature is lowered in the range of 10°C to 100°C.

6. The method for electronic grade purification of N,N-2,2-tetrahydropyrrolidine according to claim 1, characterized in that: In step 2, the acidic co-solvent is acetic acid.

7. The method for electronic grade purification of N,N-2,2-tetrahydropyrrolidine according to claim 1, characterized in that: In step 3, the electronic grade organic acid is a combination of one or more of L-tartaric acid, D-tartaric acid, citric acid, and p-toluenesulfonic acid.

8. The method for electronic grade purification of N,N-2,2-tetrahydropyrrolidine according to claim 1, characterized in that: In step 3, the temperature range of the heating is 40°C-100°C.

9. The method for electronic grade purification of N,N-2,2-tetrahydropyrrolidine according to claim 1, characterized in that: In step 4, the temperature range of the cooling is 0°C-20°C.

10. The method for electronic grade purification of N,N-2,2-tetrahydropyrrolidine according to claim 1, characterized in that: In step 4, the standing time is 10h-48h.

11. The method for electronic grade purification of N,N-2,2-tetrahydropyrrolidine according to claim 1, characterized in that: In the step 5, the drying is carried out in a vacuum drying oven, the temperature is controlled at 30° C.-50° C., and the reduced pressure is dried for 12 h-24 h.

12. The method for electronic grade purification of N,N-2,2-tetrahydropyrrolidine according to claim 1, characterized in that: In step 6, the electronic grade inorganic base is potassium hydroxide, sodium hydroxide or a combination thereof.

13. The method for electronic grade purification of N,N-2,2-tetrahydropyrrolidine according to claim 1, characterized in that: In step 6, the electronic grade organic solvent is one or more of dichloromethane, chloroform, carbon tetrachloride, ethyl ether, methyl tert-butyl ether, methyl tetrahydrofuran, propyl ether, isopropyl ether, butyl ether, isobutyl ether, and tert-butyl ether small molecule ether.

14. The method for electronic grade purification of N,N-2,2-tetrahydropyrrolidine according to claim 1, characterized in that: In the step 2, the weight ratio of the N,N-pyrrole to the medium is 1:2-1:

5.

15. The method for electronic grade purification of N,N-2,2-tetrahydropyrrolidine according to claim 1, characterized in that: In step 2, the volume content of the electronic grade acidic co-solvent is 0.05%-5%.

16. The method for electronic grade purification of N,N-2,2-tetrahydropyrrolidine according to claim 1, characterized in that: In the step 2, the ratio of the N,N-2,2-tetrahydropyrrolidine to the medium is 1:1-1:

5.

17. The method for electronic grade purification of N,N-2,2-tetrahydropyrrolidine according to claim 1, characterized in that: In the step 6, the ratio of the N,N-2,2-tetrahydropyrrolidine to the ultrapure water is 1:1-1:

5.

18. The method for electronic grade purification of N,N-2,2-tetrahydropyrrolidine according to claim 1, characterized in that: In step 6, the weight content of the electronic grade inorganic base is 20%-80%.

19. The method for electronic grade purification of N,N-2,2-tetrahydropyrrolidine according to claim 1, characterized in that: In step 6, the volume content ratio of the electronic grade organic solvent to the aqueous phase is 0.3:1-5:

1.

20. The method for electronic grade purification of N,N-2,2-tetrahydropyrrolidine according to claim 1, characterized in that: In step 6, the aqueous solution is cooled in a range from room temperature to -60°C.

Images