JP2016222649A - Method of inhibiting the decomposition of dimethyl sulfoxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of inhibiting the decomposition of dimethyl sulfoxide even at high temperature and in a concentrated state.SOLUTION: A method of inhibiting the decomposition of dimethyl sulfoxide includes adding calcium carbonate to a liquid comprising dimethyl sulfoxide.SELECTED DRAWING: None

Description

  The present invention relates to a method for inhibiting the decomposition of dimethyl sulfoxide (DMSO), which is widely used as a solvent for peeling and washing electronic materials, synthesizing medicines and agricultural chemicals, polymerizing and spinning polymers.

  Dimethyl sulfoxide is widely used industrially as a peeling and cleaning solvent for electronic materials. In addition, recovery and reuse of dimethyl sulfoxide once used has been widely carried out industrially, and a step of purification by heating distillation is indispensable.

  However, it is known that dimethyl sulfoxide is relatively unstable thermally and decomposes slightly when boiled or distilled at normal pressure. When the production or recovery of dimethyl sulfoxide is carried out by distillation, it is not preferable that a partially decomposed decomposition product is contaminated in order to reduce the efficiency as a solvent.

  The thermal decomposition of dimethyl sulfoxide is significantly increased by the addition of acid. In general, dimethyl sulfoxide is stable when a base is added, and in the case of distillation purification, a method of adding a base and distilling is known. For example, a method of adding an alkali metal hydroxide such as lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide (see Patent Documents 1 and 2), sodium formate, sodium oxalate, water Method of adding barium oxide, salt, borax, etc. (see Patent Document 3), method of contacting with sodium hydroxide for a short time (see Patent Document 4), granular sodium hydroxide, potassium hydroxide, and swelling Then, a removal method (see Patent Document 5) is known.

  However, the amount of base added is 0.003 to 0.5% (see Patent Documents 1 and 2), sodium formate, sodium oxalate, barium hydroxide, salt, boron in the method of adding an alkali metal hydroxide. In the method of adding sand or the like, 0.1 to 0.5% (see Patent Document 3), and in the method of adding granular sodium hydroxide and potassium hydroxide and removing them after swelling, 0.5% ( In the method of contact with sodium hydroxide for a short time, it is limited to 1% (see Patent Document 4), and it is reported that the decomposition product increases rather if added more than this. When heated at 150 ° C. for 10 hours, when no sodium hydroxide or potassium hydroxide is added, the amount of decomposition product is 0.031 to 0.032%, when 1% potassium hydroxide is added, It was reported that when the amount of decomposed product was 0.054% and 1% of sodium hydroxide was added, the amount of decomposed product was increased to 0.052%, which promoted decomposition (see Patent Document 1). ).

  From the above, when dimethyl sulfoxide is heated and distilled, even if a base is added in an amount of 0.5% or less, the dimethyl sulfoxide is distilled off and the inside of the can is concentrated, so that the concentration of the base becomes 0.5% or more. However, the decomposition of dimethyl sulfoxide was promoted, and the purity of dimethyl sulfoxide obtained by distillation was low.

  Further, when the concentration of the base is increased, not only the decomposition is promoted, but also there is a problem that crystals of the insoluble base precipitate in the can and become a lump and cannot be stirred (Patent Document 6). 7).

  Moreover, in patent document 1, 3, the fixed_quantity | quantitative_assay of the decomposition product of a dimethylsulfoxide is converted into the weight of formaldehyde, and the decomposition inhibitory effect is measured. However, as a result of analysis using a sensitive gas chromatograph using a capillary column, the decomposition products actually produced by decomposition of dimethyl sulfoxide are not formaldehyde but dimethyl sulfide, dimethyl disulfide mainly containing sulfur atoms. , Dimethylsulfone, and bis (methylthio) methane. In fact, the compounds reported to have a decomposition inhibitory effect in Patent Documents 3 and 4 were re-examined under a sensitive gas chromatograph analysis condition using a capillary column. 3) and calcium hydroxide (see Patent Document 4) had almost no decomposition inhibiting effect.

Japanese Patent Publication No.43-3765 Japanese Examined Patent Publication No. 38-20721 Japanese Patent Publication No. 36-23323 Japanese Patent Publication No.43-12128 Japanese Patent Publication No. 60-1302 JP 2006-96763 A Japanese Patent Laid-Open No. 9-12534

  An object of the present invention is to provide a method for solving such problems and adding a safe additive for suppressing the decomposition of dimethyl sulfoxide to suppress the decomposition of dimethyl sulfoxide.

  The present invention is a method for inhibiting the decomposition of dimethyl sulfoxide with calcium carbonate.

  The method for inhibiting the decomposition of dimethyl sulfoxide according to the present invention makes it difficult for dimethyl sulfoxide to decompose even at high temperatures. When dimethyl sulfoxide is distilled and collected, decomposition of dimethyl sulfoxide can be suppressed, and high-purity dimethyl sulfoxide can be obtained by distillation. Moreover, since it can be distilled at a high temperature, a high vacuum facility is not required, so that it can be purified at low cost. Further, since the decomposition of dimethyl sulfoxide is suppressed even in a concentrated state, the distillation yield is increased, which is economical. Calcium carbonate is safe and can be operated safely compared to conventional decomposition control methods and purification methods that use hazardous materials.

  The method for suppressing the decomposition of dimethyl sulfoxide according to the present invention can suppress, for example, long-term storage in summer and deterioration in quality of dimethyl sulfoxide due to heating for melting dimethyl sulfoxide frozen in winter.

  The method for inhibiting the decomposition of dimethyl sulfoxide according to the present invention can be used for dimethyl sulfoxide used in various applications. In addition, dimethyl sulfoxide purified using the method for inhibiting the decomposition of dimethyl sulfoxide according to the present invention is high in purity with few impurities, and is used for stripping of photoresist stripping solutions for electronic materials, synthesis of medical pesticides, lens molds, etc. -It can be used as a cleaning liquid, a solvent for polymerization of polymers such as cellulose, polyimide, polysulfone, polyurethane, polyacrylonitrile, and a spinning process, or as a coating remover.

  The present invention is a method for inhibiting the decomposition of dimethyl sulfoxide, and calcium carbonate is added to a liquid containing dimethyl sulfoxide.

  In the present invention, by analyzing with a sensitive gas chromatograph using a capillary column, the inhibitory effect of a compound that has been reported to have a decomposition-inhibiting effect is reviewed, and a compound having a decomposition-inhibiting effect is newly found. As a result, we were able to find calcium carbonate.

  The amount of calcium carbonate added is preferably 0.0005 g to 35 g, more preferably 0.001 g to 25 g, based on 100 g of dimethyl sulfoxide in the liquid. If the amount added is lower than 0.0005 g, the decomposition inhibiting effect may not be sufficient.

  Calcium carbonate may be added as a powder or solid, or may be added in the form of a solution if there is a low boiling point solvent that dissolves calcium carbonate well. Moreover, you may add as aqueous solution using water. If calcium carbonate can be charged in the form of a liquid such as an aqueous solution, it is preferable from the viewpoint of safety than powder or solid, and is suitable for industrial continuous production.

  In the present invention, the liquid containing dimethyl sulfoxide may be dimethyl sulfoxide alone, or may be a liquid in which dimethyl sulfoxide and another liquid are mixed.

  In the present invention, the liquid containing dimethyl sulfoxide is a reaction liquid containing dimethyl sulfoxide obtained in the step of synthesizing by oxidation of dimethyl sulfide, a waste liquid containing dimethyl sulfoxide used as a stripping liquid for a photoresist of an electronic material, or a lens mold. Waste liquid containing dimethyl sulfoxide used as a peeling / cleaning liquid, waste liquid containing dimethyl sulfoxide used as a synthetic solvent for medical and agricultural chemicals, dimethyl used in the polymerization and spinning process of polymers such as cellulose, polyimide, polysulfone, polyurethane, polyacrylonitrile, etc. Waste liquid containing sulfoxide and waste liquid containing dimethyl sulfoxide used as a paint peeling liquid.

  In the present invention, when a liquid containing dimethyl sulfoxide is heated, it is preferably heated in an inert gas atmosphere, and more preferably heated in a nitrogen or argon atmosphere.

  In the present invention, when distilling a liquid containing dimethyl sulfoxide, if the concentration of dimethyl sulfoxide in the liquid containing dimethyl sulfoxide is too low, distillation of components other than dimethyl sulfoxide is costly. % Or more is more preferable.

  In addition, in a liquid containing dimethyl sulfoxide, if there are impurities that interfere with the distillation operation, such as insoluble substances and components that easily gel when concentrated, it is preferable to remove them in advance if possible.

  In the present invention, when a liquid containing dimethyl sulfoxide is distilled, dimethyl sulfoxide is distilled in the presence of calcium carbonate.

  Calcium carbonate deposited on the residue after distillation may be disposed of by washing with water as described above, or may be recovered and reused.

  In the present invention, when a liquid containing dimethyl sulfoxide is distilled, it can be applied to either batch distillation or continuous distillation.

  In the present invention, when distilling a liquid containing dimethyl sulfoxide, calcium carbonate may be added before distillation to distill dimethyl sulfoxide, or after distilling off impurities having a boiling point lower than that of dimethyl sulfoxide. In addition, dimethyl sulfoxide may be distilled.

  When continuous distillation is performed, an aqueous solution of calcium carbonate is preferably continuously supplied before the distillation column.

  In the present invention, the theoretical number of distillation columns is preferably 1 to 50 distillation columns, and more preferably 3 to 40 distillation columns.

  In the present invention, when distilling a liquid containing dimethyl sulfoxide, the pressure during distillation is preferably from normal pressure to reduced pressure. In particular, when the difference in boiling point from the impurity to be removed is small, the impurity can be easily removed by increasing the difference in boiling point between the impurity and dimethyl sulfoxide without reducing the degree of vacuum so much.

  In the present invention, when distilling a liquid containing dimethyl sulfoxide, when distilling at normal pressure, it is preferable to distill in an inert gas atmosphere, and more preferably in a nitrogen or argon atmosphere.

  In the present invention, when distilling a liquid containing dimethyl sulfoxide, the temperature during distillation is preferably not more than the boiling point (189 ° C.) of dimethyl sulfoxide, more preferably 180 ° C. or less, and further preferably 170 ° C. or less.

  Conventionally, since dimethyl sulfoxide is decomposed to lower the purity, it is often distilled under a reduced pressure at 110 ° C. or lower. In the present invention, when a liquid containing dimethyl sulfoxide is distilled, dimethyl sulfoxide is not decomposed even at a high temperature, so that a high degree of vacuum is not required. In the present invention, the temperature during distillation is preferably 50 ° C. or higher, more preferably 70 ° C. or higher, and even more preferably 90 ° C. or higher. Yes, industrially preferable.

  In the present invention, when distilling a liquid containing dimethyl sulfoxide, the temperature during distillation is preferably 50 ° C. or more and 189 ° C. or less, more preferably 70 ° C. or more and 180 ° C. or less, and still more preferably 90 ° C. The temperature is 170 ° C. or lower.

  In the present invention, the decomposition rate of dimethyl sulfoxide at 180 ° C. is analyzed by gas chromatography using a capillary column. The decomposition rate of dimethyl sulfoxide at 180 ° C. is preferably 0.06 area% / day or less, more preferably 0.05 area% / day or less, and even more preferably 0.04 area% / day or less. Reduced. Thus, by distilling a liquid containing dimethyl sulfoxide in the presence of calcium carbonate, decomposition of dimethyl sulfoxide is suppressed, and high purity dimethyl sulfoxide can be obtained with few impurities even by simple distillation operation.

  The dimethyl sulfoxide obtained by the present invention is high purity with few impurities, and is a photoresist stripping solution for electronic materials, synthesis of medicines and agricultural chemicals, stripping / cleaning solutions for lens molds, cellulose, polyimide, polysulfone, polyurethane, polyacrylonitrile. It can be used as a solvent for polymer polymerization and spinning process, and as a coating remover.

  Hereinafter, the present invention will be described specifically by way of examples.

  In this example, the GC purity (area%) of dimethyl sulfoxide was measured by a gas chromatographic method (hereinafter abbreviated as “GC”) under the following conditions, and the difference from the blank GC purity was divided by the heating time. The decomposition rate (area% / day) was determined. When the heating time was less than 1 day (24 hours), it was converted to the value of 1 day.

・ Equipment used Shimadzu Corporation GC-2010 (FID)
・ Column DB-WAX 0.25 mm × 60 m, film thickness 0.25 μm
Carrier gas He 165.7kPa
Column heating conditions 35 ° C → 7 ° C / min → 140 ° C x 10 min → 15 ° C / min →
250 ° C x 10 minutes, inlet temperature 200 ° C
・ Detector temperature 250 ℃
・ FID Air 400ml / min
H2 40ml / min
Makeup 30ml / min
・ Split ratio 14
Analytical sample preparation The sample was filtered with a 0.5 μm PTFE syringe filter.
-Injection volume 1.0 μl.

Example 1
A 300 ml three-necked flask equipped with a Dimroth condenser, a stirrer, and a thermometer was charged with 200 g of dimethyl sulfoxide (GC purity 99.997 area%) and 0.002 g of calcium carbonate as an additive (0.001 g with respect to 100 g of dimethyl sulfoxide). After replacing the inside of the flask with nitrogen, a rubber balloon filled with nitrogen was attached to the top of the Dimroth condenser and sealed. Starting from the time when the internal temperature reached 178 ° C. in an oil bath at 192 ° C., heating was performed at 180 ± 2 ° C. for 24 hours. After cooling to 25 ° C. or lower, the liquid on the wall of the flask was mixed with the internal liquid. The GC purity of this dimethyl sulfoxide was 99.979 area%. Table 1 shows the decomposition rates determined from the GC purity.

(Example 2)
Example 1 was repeated except that the concentration of calcium carbonate was changed as described in Table 1. The results of the decomposition rate of Example 2 are shown in Table 1.

(Comparative Examples 1-5)
The procedure was the same as in Example 1 except that the type of additive and the concentration of the additive were changed as described in Table 1. The GC purity was 99.928 area% in Comparative Example 1 and 99.712 area% in Comparative Example 3. Table 1 shows the results of the decomposition rates of the comparative examples.

Example 3
A 100 ml three-necked flask equipped with a Dimroth condenser, a stirrer, and a thermometer was charged with 37.5 g of dimethyl sulfoxide (GC purity 99.997 area%) and 12.5 g of calcium carbonate (25 g based on 100 g of dimethyl sulfoxide) as an additive. After replacing the inside of the flask with nitrogen, a rubber balloon filled with nitrogen was attached to the top of the Dimroth condenser and sealed. Starting from the time when the internal temperature reached 178 ° C. in an oil bath at 192 ° C., heating was performed at 180 ± 2 ° C. for 24 hours. After cooling to 25 ° C. or lower, the liquid on the wall of the flask was mixed with the internal liquid. Table 2 shows the decomposition rate of dimethyl sulfoxide.

(Comparative Examples 6-8)
The procedure was the same as Example 3 except that the type of additive was changed as shown in Table 2. The results of each comparative example are shown in Table 2.

(Comparative Example 9)
Example 3 was repeated except that the additive type was changed to lithium formate. Gelation occurred at the beginning of heating, and stirring became impossible.

(Comparative Examples 10 and 11)
The same procedure as in Example 3 was performed except that the type of additive was changed as shown in Table 2 and the heating time was changed to 4 hours. The results of each comparative example are shown in Table 2.

Example 4
720 g of dimethyl sulfoxide (GC purity 99.997 area%), 80 g of ion-exchanged water, calcium carbonate 0 in a 1 L four-necked flask equipped with a Dimroth condenser necessary for simple distillation operation, a receiver for distillate, a stirrer, and a thermometer .72 g (0.1 g with respect to 100 g of dimethyl sulfoxide) was charged, and the inside of the flask was replaced with nitrogen. Then, a rubber balloon filled with nitrogen was attached to the upper part of the Dimroth condenser and sealed. Heating was performed in an oil bath at 200 ° C., and the start of distillation was set as the start. After distilling 100 ml as a pre-distillation, the temperature of the oil bath was raised to 230 ° C., and the distillate was distilled until the concentration of the additive in the flask became 6.5% by mass. The heating time from the start was 3 hours. Table 3 shows the decomposition rate and GC purity (area%) of dimethyl sulfoxide in this distillate.

(Comparative Examples 12 and 13)
The procedure was the same as Example 4 except that the type of additive, the concentration of the additive at the time of charging, and the concentration of the additive in the flask at the end of distillation were changed. The results of each comparative example are shown in Table 3.

Claims (4)

A method for suppressing decomposition of dimethyl sulfoxide, wherein calcium carbonate is added to a liquid containing dimethyl sulfoxide. The method for inhibiting decomposition of dimethyl sulfoxide according to claim 1, wherein calcium carbonate is added to the liquid containing dimethyl sulfoxide when the liquid containing dimethyl sulfoxide is distilled. The method for suppressing decomposition of dimethyl sulfoxide according to claim 1 or 2, wherein the liquid containing dimethyl sulfoxide is heated in an inert gas atmosphere. The method for suppressing decomposition of dimethyl sulfoxide according to any one of claims 1 to 3, wherein the amount of calcium carbonate added is 0.0005 g to 35 g with respect to 100 g of dimethyl sulfoxide.