JP2009096792A - Method for purifying dimethylsulfoxide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for purification by distillation which is easy to industrially scale up without adding an acid being a factor for reducing the yield of DMSO in purifying DMSO containing a nucleophilic component as an impurity. <P>SOLUTION: The method for purifying dimethylsulfoxide containing a nucleophilic component as an impurity by distillation comprises adding acrylonitrile, and the nucleophilic component is any one of a primary amine, a secondary amine, and a thiol and preferably has a boiling point at 101.3 kPa (absolute pressure) of 160-220°C. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for distilling and purifying DMSO from dimethyl sulfoxide (hereinafter referred to as DMSO) containing a nucleophilic component as an impurity.

  DMSO is widely used industrially as a synthetic solvent for pharmaceuticals, a special cleaning solution used for processing electronic materials, and a polymer production solvent. The DMSO waste liquid used in these applications can be reused by purification. However, when components having a boiling point close to that of DMSO are mixed, purification becomes extremely uneconomical. For example, monoethanolamine (hereinafter referred to as MEA) is used in DMSO waste liquids and the like as a representative component mixed with DMSO, and has a boiling point of 171 ° C. and DMSO (boiling point 189). Since the boiling point is close to that of (° C.), it was difficult to recover high-purity DMSO only by distillation purification.

  Much technology has been developed for the separation method of MEA, which is a component having a boiling point close to that of DMSO. For example, Patent Documents 1 and 2 describe crystallization methods. Therefore, it was not suitable for scaling up to a facility for purifying a large amount of DMSO.

  In addition, although the MEA can be removed by the ion exchange treatment, when the MEA concentration is high, the ion exchange cost is increased, which is uneconomical. For this reason, in Patent Document 3, ion exchange treatment is performed after the MEA concentration is reduced by other means.

Patent Documents 3 and 4 describe means for facilitating distillative separation of DMSO and MEA, which forms a neutralized salt by adding an acid to a DMSO mixture containing MEA, and has a boiling point of MEA. It is a technique that facilitates distillation separation by ascending. However, when an acid is excessively added or a strong acid is used in order to increase the separation efficiency of MEA, it is necessary to use a corrosion-resistant material for the equipment, and as described in these patent documents, DMSO In the acidic atmosphere, thermal decomposition is likely to occur, which causes problems such as a decrease in distillation yield.
JP 7-118223 A JP 2006-069960 A JP 2001-89438 A JP-A-9-12534

  An object of the present invention is to provide a purification method by distillation that facilitates industrial scale-up without adding an acid that causes a decrease in the yield of DMSO in purifying DMSO containing DMSO and a nucleophilic component as impurities. The point is to provide.

  As a result of diligent studies to solve the above problems, the present inventors have found that the nucleophilic component in DMSO easily undergoes an addition reaction with acrylonitrile and has a high boiling point, so that purification separation by distillation becomes possible. The headline and the present invention have been completed.

  That is, the present invention is a method for purifying dimethyl sulfoxide, characterized in that acrylonitrile is added in a method for distilling and purifying dimethyl sulfoxide containing a nucleophilic component as an impurity.

  According to the present invention, when DMSO containing a nucleophilic component as an impurity is purified, it is possible to purify by distillation, which can be easily scaled up industrially, without adding an acid that causes a decrease in the yield of DMSO. .

  An object of the present invention relates to a method for distilling and purifying DMSO containing a nucleophilic component as an impurity. In order to reduce the energy cost by increasing the recovery rate of DMSO and the purification efficiency, there are some as described below. There are preferable conditions.

  Even if the crude DMSO to be purified in the present invention contains components other than the nucleophilic component to be separated, the effect of the invention is exhibited by the addition of acrylonitrile. Moreover, although crude DMSO exhibits the effect of the invention even if it does not contain moisture, the addition reaction proceeds faster in the state containing moisture, so that more effective purification can be achieved. The water concentration suitable for the addition reaction is 20 wt% to 75 wt%, more preferably 25 wt% to 70 wt%. When the water concentration of the crude DMSO is low, water can be added before distillation to obtain a preferable water concentration.

  The nucleophilic component to be separated is a component having a boiling point of 150 ° C. to 230 ° C. at 101.3 kPa (absolute pressure, hereinafter, all pressures are expressed in absolute pressure), and can effectively exert the effect of the present invention. In view of this, it is a component having a boiling point of 160 ° C to 220 ° C. Components having other boiling points can be separated by ordinary distillation. However, the addition of acrylonitrile often makes it possible to purify under cheaper distillation conditions (low number of stages, low reflux ratio). Is possible. As a representative example of the component to be separated, MEA can be mentioned, but other components having impurities that function as nucleophiles and having a boiling point close to that of DMSO can be easily distilled by addition reaction with acrylonitrile. As such a nucleophilic component, any of primary amine, secondary amine, and thiol is preferable, and among these, any of primary amine, secondary amine, and thiol having the above boiling point is preferable.

  If the nucleophilic component is a primary amine, it will be converted to a secondary amine when one molecule of acrylonitrile is added, but if there is an excess of acrylonitrile, an additional reaction will occur, and when converted to a tertiary amine, the boiling point will change significantly. Therefore, the effect of the invention tends to appear remarkably.

  Specific examples include MEA, benzylamine, n-octylamine, dipentylamine, 1-heptanethiol, aniline, and the like. Among these impurities, a strong nucleophilic component easily undergoes an addition reaction, so that the effect of the invention appears remarkably. From this viewpoint, in addition to MEA, benzylamine, n-octylamine, dipentylamine, and 1-heptanethiol are preferable. When the present invention is applied to a component having low nucleophilicity, a certain effect can be expected by setting the reaction conditions at a higher temperature for a longer time. Moreover, even if it is a trace amount and an unidentified nucleophilic component, when the component which reduces the quality of DMSO exists, the quality improvement of DMSO can be anticipated by addition of acrylonitrile.

  Acrylonitrile that can be used as an additive reagent in the present invention is not limited to those that can be obtained as general industrial raw materials, and acrylonitrile recovered from the polymer production process can also be used. Since DMSO is used as a polymerization solvent for acrylonitrile, some DMSO waste liquids from this step contain unreacted acrylonitrile. When DMSO to be purified contains two or more systems including those containing a nucleophilic component and those containing unreacted acrylonitrile, purification can be performed more economically by using this acrylonitrile.

  With regard to the content of the nucleophilic component, the effect of the present invention can be expected even with a minute amount of ppm (the weight of the nucleophilic component relative to the weight of the crude DMSO, hereinafter, ppm is defined similarly) with respect to the crude DMSO. However, when the nucleophilic component is contained in an amount of 20 wt% or more, the amount of acrylonitrile added is increased. Therefore, it is preferable to add acrylonitrile after reducing the concentration of the nucleophilic component by distillation or the like in advance. The present invention can be applied particularly effectively when the nucleophilic component is in the range of 100 ppm to 5 wt%.

  The amount of acrylonitrile added can be freely set depending on the quality and economy of purified DMSO. When a small amount of nucleophilic component is completely separated, DMSO can be easily purified by adding acrylonitrile in excess. In addition, when the amount of acrylonitrile that can be used economically is limited, a certain effect can be expected even if the addition amount is small. In general, the addition amount is preferably 0.1 to 5 equivalents, more preferably 0.3 to 3 equivalents, relative to the nucleophilic component. This is because when the amount is 5 equivalents or more, the residual amount of acrylonitrile increases, and when the amount is 0.1 equivalents or less, the residual amount of the nucleophilic component increases.

  The present invention can be applied to both batch distillation and continuous distillation, but it is preferable to perform distillation under reduced pressure. Since decomposition of DMSO is promoted under high temperature conditions, it is preferable to keep the temperature of the contents of the can (can temperature) at 150 ° C. or lower by distillation under reduced pressure, and more preferably to perform distillation at 130 ° C. or lower. The pressure is preferably 1-30 kPa, more preferably 1.5-15 kPa.

  Acrylonitrile is preferably added before distillation, but acrylonitrile can also be fed directly to the distillation column in the case of continuous distillation. If addition reaction does not proceed sufficiently even if acrylonitrile is added before distillation, heating the mixture to 50 ° C. or higher, preferably 70 to 130 ° C. before distillation accelerates the addition reaction between the nucleophilic component and acrylonitrile. Therefore, it is more preferable. The pressure at that time is preferably 90 to 120 kPa in consideration of volatilization of acrylonitrile. The reaction time is preferably 10 to 120 minutes, but when the present invention is applied to a highly nucleophilic component, the reaction is preferably performed for 10 to 60 minutes. When acrylonitrile is directly supplied to the distillation tower by continuous distillation, it is preferably carried out in a distillation tower having 3 to 20 theoretical plates, and more preferably 5 to 15 distillation towers. The crude DMSO and acrylonitrile are preferably supplied to a stage below the stage corresponding to one third from the top, and these may be supplied to the same stage or to different stages. Under these conditions, the contact time between the nucleophilic component and acrylonitrile can be increased in the distillation column, and the addition reaction can be further advanced.

  The nucleophilic component is increased in boiling point by addition of acrylonitrile and concentrated in the can residue, and the concentration of the nucleophilic component in the distillate containing DMSO as a main component can be reduced. When the nucleophilic component remaining in the distillate affects the quality of DMSO, purified DMSO may be further purified by subjecting the distillate to an ion exchange treatment. In particular, when the nucleophilic component is an amine, ammonium ions are generated by the coexistence of water and become a cation, so that the amine can be completely removed by passing the solution through a cation exchange resin.

  Even if acrylonitrile is mixed in DMSO after purification by distillation, since these have large boiling point differences, acrylonitrile can be easily separated by redistillation. When ion exchange treatment is used in combination, there is no effect on the quality of purified DMSO even if re-distillation is performed before the ion exchange treatment or re-distillation is performed after the ion exchange treatment.

  The DMSO purified by the present invention is suitably used as a reaction solvent for intermediates for medical and agricultural chemicals, a solvent for producing polymers, and a synthesis reagent in addition to electronic material processing.

  EXAMPLES Hereinafter, although an Example and a comparative example are illustrated and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.

[Example 1]
A distillation experiment apparatus equipped with a 500 ml round bottom flask, a Dimroth type cooling agglomerator, and a packed tower corresponding to 7 stages was prepared. Preparation of 300 g of distilled crude liquid of 94 wt% DMSO (Kanto Chemical Special Grade Reagent), water 5 wt%, and MEA (Kanto Chemical Special Grade Reagent) 1 wt% was performed. To the distilled crude liquid, 7.8 g of acrylonitrile (Kanto Chemical Special Grade Reagent) was added (acrylonitrile / MEA = 3 mol / 1 mol). The crude distillation liquid after addition of acrylonitrile was charged into a distillation experiment apparatus, and kept at normal temperature and heated at 100 ° C. for 1 hour. After completion of the heating, the distilled crude liquid was cooled to 60 ° C., then the pressure was reduced to 4 kPa, the reflux ratio was set to 0.1, and batch distillation was performed until the temperature of the can (can temperature) reached 96 ° C. 270 g of distillate was recovered by batch distillation. Since the distillate contained about 5 wt% of water, only the water was distilled off by the same distillation experiment apparatus to perform dehydration (water concentration of 1 wt% or less). When the purified DMSO after dehydration was analyzed by FID-GC, only DMSO was detected in the main peak, and the acrylonitrile and MEA peaks were not detected. When purified DMSO was analyzed by ion chromatography (electric conductivity detector), it was confirmed that the monoethanolamine concentration was reduced to 200 ppm. Moreover, when FID-GC analysis was performed on the distillation residue, a new peak was generated on the higher boiling point side than DMSO, and as a result of identification analysis by GC-MS, N, which is an addition product of MEA and acrylonitrile. It was confirmed that-(2-cyanoethyl) ethanolamine and N, N-bis (2-cyanoethyl) ethanolamine were produced.

  The FID-GC, ion chromatography, and GC-MS were performed under the conditions described in Table 1.

[Comparative Example 1]
The same purification treatment as in Example 1 was performed, except that there was no addition of acrylonitrile and no heat treatment before distillation. When purified DMSO after dehydration was analyzed by FID-GC, a peak of monoethanolamine was confirmed in addition to a peak of DMSO. When purified DMSO was analyzed by ion chromatography, the monoethanolamine concentration was 1.1 wt%, and it was confirmed that the monoethanolamine concentration was not reduced.

[Example 2]
A distillation experiment apparatus equipped with a 300 ml round bottom flask, a Dimroth type cooling aggregator, and a packed tower corresponding to 7 stages was prepared. Preparation of 150 g of distilled crude liquid with DMSO (Kanto Chemical Special Grade Reagent) 99 wt% and n-octylamine (Kanto Chemical Special Grade Reagent) 1 wt% was performed. To the distilled crude liquid, 1.9 g of acrylonitrile (Kanto Chemical Special Grade Reagent) was added (acrylonitrile / n-octylamine = 3.1 mol / 1 mol). The crude distillation liquid after addition of acrylonitrile was charged into a distillation experiment apparatus, and kept at normal temperature and heated at 100 ° C. for 1 hour. After completion of the heating, the distilled crude liquid was cooled to 50 ° C., then the pressure was reduced to 4 kPa, the reflux ratio was set to 0.1, and batch distillation was performed until the can temperature reached 97 ° C. 132 g of a distillate containing DMSO as a main component was recovered by batch distillation. When the distillate was analyzed by FID-GC, the n-octylamine concentration was 0.48 wt%.

[Comparative Example 2]
The same purification treatment as in Example 2 was performed, except that acrylonitrile was not added. When the distillate was analyzed by FID-GC, it was confirmed that the n-octylamine concentration was 1.1 wt%, which was higher than Example 2.

Example 3
The same experimental apparatus as in Example 2 was prepared. Preparation of 150 g of distilled crude liquid with 99 wt% DMSO (Kanto Chemical Special Grade Reagent) and 1 wt% 1-heptanethiol (Kanto Chemical Special Grade Reagent) was performed. To the distilled crude liquid, 1.8 g of acrylonitrile (Kanto Chemical Special Grade Reagent) was added (acrylonitrile / 1-heptanethiol = 3.0 mol / 1 mol), and the same purification treatment as in Example 2 was performed. When the distillate was analyzed by FID-GC, the concentration of 1-heptanethiol was 0.30 wt%.

[Comparative Example 3]
The same purification treatment as in Example 3 was performed, except that acrylonitrile was not added. When the distillate was analyzed by FID-GC, it was confirmed that the 1-heptanethiol concentration was 1.1 wt%, which was higher than Example 3.

Example 4
A distillation experiment apparatus equipped with a 300 ml round bottom flask, a Dimroth type cooling aggregator, and a packed tower corresponding to 7 stages was prepared. A mixed solution of 176.5 g of DMSO (Kanto Chemical Special Grade Reagent), 0.7 g of MEA (Kanto Chemical Special Grade Reagent) and 10.0 g of ion-exchanged water was prepared. 200 g of a crude distillation liquid was prepared by adding 12.9 g of DMSO waste liquid containing acrylonitrile discharged from the polymer production process to the mixed liquid. The composition of the DMSO waste liquid was DMSO 95.1 wt% and acrylonitrile 4.9 wt%, and the composition of the distilled crude liquid was DMSO 94.3 wt%, water 5.0%, MEA 0.36 wt%, and acrylonitrile 0.31 wt% (acrylonitrile). /MEA=1.0 mol / 1 mol). The distilled crude liquid was charged into a distillation experimental apparatus and heated at 100 ° C. for 1 hour with normal pressure. After completion of the heating, the distilled crude liquid was cooled to 50 ° C., then the pressure was reduced to 4 kPa, the reflux ratio was set to 0.1, and batch distillation was performed until the can temperature reached 97 ° C. 161 g of distillate containing DMSO as a main component was recovered by batch distillation. The water concentration of the distillate was 6.0 wt%. When the distillate was analyzed by ion chromatography, the MEA concentration was 0.11 wt%, and it was confirmed that the MEA concentration was reduced as compared with the distilled crude liquid.

Example 5
A column equipped with a glass filter was packed with 10 cc of a strongly acidic cation exchange resin (Lewatit K2629). Of the distillate collected in Example 4, 120 g was dropped onto the column over 2 hours for ion exchange. When the liquid subjected to the ion exchange treatment was analyzed by ion chromatography, it was confirmed that the MEA concentration was reduced from 0.11 wt% to 10 ppm or less.

Example 6
A 300 ml round bottom flask was charged with 100 g of DMSO (Kanto Chemical Special Reagent) and 0.40 g of MEA (Kanto Chemical Special Reagent), 4.5 g of water was added, and the temperature of the mixture was adjusted to 20 ° C. (water concentration 4 .3 wt%). Acrylonitrile (0.35 g) was added (acrylonitrile / MEA = 1.0 mol / 1.0 mol), and the mixture was kept at 20 ° C. for 60 minutes. After 60 minutes, the mixture was promptly analyzed by FID-GC and ion chromatography, and it was confirmed that 1.8% of the charged MEA was consumed by the addition reaction.

Example 7
The same operation as in Example 6 was performed except that the amount of water added to the mixed solution was 100 g (water concentration 50 wt%). When the mixed liquid kept at 20 ° C. for 60 minutes was analyzed, it was confirmed that 86% of the charged MEA was consumed by the addition reaction, and it was found that the reaction rate was faster than Example 6.

Example 8
The same operation as in Example 6 was performed except that the temperature condition was 70 ° C. and the heat retention time was 40 minutes (water concentration 4.3 wt%). When the mixed solution kept at 70 ° C. for 40 minutes was analyzed, it was confirmed that 34% of the charged MEA was consumed by the addition reaction.

Example 9
The same operation as in Example 8 was performed except that the amount of water added to the mixed solution was 100 g (water concentration 50 wt%). Analysis of the mixed liquid kept at 70 ° C. for 40 minutes confirmed that 86% of the charged MEA was consumed by the addition reaction, and it was found that the reaction rate was faster than Example 8.

Claims (6)

A method for purifying dimethyl sulfoxide, which comprises adding acrylonitrile in a method for distillation purification of dimethyl sulfoxide containing a nucleophilic component as an impurity. 2. The dimethyl sulfoxide according to claim 1, wherein the nucleophilic component is any one of a primary amine, a secondary amine, and a thiol, and has a boiling point of 160 ° C. to 220 ° C. at 101.3 kPa (absolute pressure). Purification method. The method for purifying dimethyl sulfoxide according to claim 2, wherein the nucleophilic component is monoethanolamine. The method for purifying dimethyl sulfoxide according to any one of claims 1 to 3, wherein the remaining nucleophilic component is removed by ion exchange treatment after distillation purification. The method for purifying dimethyl sulfoxide according to any one of claims 1 to 4, wherein the acrylonitrile is acrylonitrile recovered from the production process of the polymer. The method for purifying dimethyl sulfoxide according to any one of claims 1 to 5, wherein the water concentration of the distillation raw material after addition of acrylonitrile is 20 wt% to 75 wt%.