JP2000016978A - Purification of nitrile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently remove slight amount of aldehydes in a nitrile at a low cost by bringing the nitrile into contact with an anion exchange resin to purify the nitrile. SOLUTION: A nitrile preferably having 2-4 carbon atoms (e.g. acrylonitrile or methacrylonitrile) is purified by bringing the nitrile into contact with an anion exchange resin (e.g. weakly basic or moderately basic anion exchange resin) supporting a compound having an active methylene group and an acidic group in the same molecule. The compound having an active methylene group and an acidic group in the same molecule is preferably an α-substituted acetic acid (preferably malonic acid, monomethyl malonate, monoethyl malonate, cyanoacetic acid, acetoacetic acid, sulfoacetic acid or acetone dicarboxylic acid), the concentration of the aqueous solution of the compound is preferably 0.1-5 mol/L and the flow quantity of the compound is preferably 2-5 equivalent based on the amino group of the ion exchange resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for purifying a nitrile,
More specifically, the present invention relates to a nitrile purification method capable of efficiently and inexpensively removing an aldehyde contained in a trace amount in a nitrile.

[0002]

BACKGROUND OF THE INVENTION Nitriles, especially many aliphatic nitriles, are obtained by ammoxidation of olefins, with aldehydes being present in trace amounts as impurities. These aldehydes cause problems such as contamination of the system and coloring of the product in the nitrile recovery step. Also,
Recent advances in chemical technology have required higher purity nitriles. However, nitriles and aldehydes contained therein as impurities are often low in specific volatility, require a large number of distillation stages to simply separate by distillation, and consume a large amount of energy, which is extremely uneconomical. Therefore, there is a long-felt need to establish a method for effectively removing aldehydes from nitriles, and several methods have been proposed so far.

For example, as a method of removing methacrolein in methacrylonitrile, a method of separating and removing methacrolein as an addition salt by adding sodium hydrogen nitrite (Japanese Patent Laid-Open No. 57-62247), a method of removing methacrolein in acrylonitrile, and the like. As a method for removing acrolein, a method of adding acetylacetone or the like and separating and removing a reaction product with acrolein by distillation or the like (JP-A-57-266586);
As a method for removing acrolein from acetonitrile, there is a method using ozone (DD217212).

[0004] As a method for removing acrolein in acrylonitrile, contact with a porous anion exchange resin having a primary and / or secondary amino group as an exchange group (Japanese Patent Publication No. 58-1108), or a gel type Contact with ion exchange resin (Japanese Patent Application Laid-Open No. 58-14063)
For example, there is a method using an ion exchange resin. The method using these ion exchange resins can specifically remove aldehydes without increasing new impurities in the system.

However, the method of removing an aldehyde by contacting with an anion exchange resin having a primary and / or secondary amino group as an exchange group forms a covalent bond between the amino group and the aldehyde group by an amino-carbonyl reaction. Therefore, the aldehyde group cannot be removed from the amino group by the usual method. For this reason, the ion exchange resin is difficult to regenerate and must be used on the premise of disposable, which increases the processing cost and is extremely uneconomical. Furthermore, the level of aldehyde removal is also inadequate.

[0006]

Further, by contacting the nitrile with a cation exchange resin carrying a polyvalent amine, the aldehyde in the nitrile is adsorbed.
There is a method (JP-A-10-7638) in which an ion exchange resin from which aldehyde cannot be removed is brought into contact with an acidic aqueous solution and washed with water to recycle the resin.

According to the findings of the present inventors, the level of aldehyde removal that can be achieved by this method is determined by the method of contacting with a gel type anion exchange resin (Japanese Patent Application Laid-Open No. 58-14063).
No.) is not enough. Furthermore, the functional group that reacts with and adsorbs to the cation exchange resin and the functional group that reacts with the aldehyde are both the same amino groups, and the utilization rate of the supported polyvalent amine is low, so that the flow-through exchange capacity is satisfactory. Not something.

According to the present invention, it is possible to regenerate an ion-exchange resin when removing an aldehyde which is an impurity in the nitrile with the ion-exchange resin. It is an object to establish a purification method.

[0009]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that the use of an anion exchange resin carrying a compound having an active methylene group and an acidic group in the same molecule is extremely high. The present invention has been found to be effective and has led to the present invention.

That is, the present invention provides a method for removing an aldehyde contained in a nitrile by bringing the nitrile into contact with an anion exchange resin carrying a compound having an active methylene group and an acidic group in the same molecule. This is a characteristic method for purifying nitriles.

Here, the active methylene group is, for example, Organi
c Reactions Vol.15 (1967), JOHN WILEY & SONS, INC.
As described on page 223 of the publication, X-CH
Has the general formula ₂ -Y, X and Y are, NO _2, CN, CO
R, COAR, CONHR, CONHAr, CO ₂ R,
CO ₂ H, SO ₂ , S, Ar having an electron-withdrawing group at the ortho-position and / or para-position, and a methylene group having a structure that is an electron-withdrawing group such as a quaternary pyridinium salt and a similar heterocycle thereof. Here, R represents an alkyl group and Ar represents an aryl group.

These compounds used in the present invention have an acidic group together with an active methylene group, and the type of the acidic group is a carboxylic acid group, a sulfonic acid group, a sulfinic acid group, a phosphonic acid group, A phosphinic acid group, and the like. Among such acidic groups, the carboxylic acid group and the sulfonic acid group also correspond to X and Y described above, and also serve as an acidic group. Therefore, the compound may not have an acidic group other than X and Y. . Such a compound is preferable because it has a simple structure, and thus has advantages such as low cost and easy availability.

Examples of such compounds in which X and Y also serve as an acidic group include malonic acid, malonic acid monoester, malonic acid monoamide, cyanoacetic acid, acetoacetic acid, acetonedicarboxylic acid, sulfoacetic acid, sulfoacetic ester, sulfoacetic ester, and sulfoacetic acid. Acetamide, acetonesulfonic acid and the like can be mentioned.

Among them, α-substituted acetic acid in which the carbon at the α-position of acetic acid is substituted with the above-mentioned X and Y functional groups, that is, malonic acid, monomethyl malonate, monoethyl malonate, cyanoacetic acid, acetoacetic acid, sulfoacetic acid and the like. Acetic acid and acetone dicarboxylic acid are particularly preferred in view of their effect and availability. These α-substituted acetic acids may be used alone or in combination of two or more.

The type of the anion exchange resin used in the present invention is not particularly limited, but in order to suppress nitrile hydrolysis, a weakly basic or neutrally basic anion exchange resin is preferred. For example, a weakly basic resin such as Levatit MP62 (trade name, manufactured by Bayer), Diaion WA20 (trade name, manufactured by Mitsubishi Chemical Corporation), Dowex MWA-1 (trade name, manufactured by Dow Chemical Company), or Rebatit M
P64 (trade name, manufactured by Bayer AG), Amberlite IR
Medium-basic resins such as A68 (trade name, manufactured by Organo Corporation) are exemplified. These resins are preferably used after pre-treatment of a commercially available resin with a dilute alkali in advance, followed by sufficient washing with water.

The nitrile of the present invention includes both aliphatic nitriles and aromatic nitriles. Specifically, for example, acrylonitrile, methacrylonitrile,
2 carbon atoms such as acetonitrile and propionitrile
~ 4 aliphatic nitriles, aromatic nitriles such as benzonitrile, and the aldehydes contained in these nitriles are acrolein, methacrolein, acetaldehyde,
And propylene aldehyde and benzaldehyde.

The nitrile purification method of the present invention can be applied not only to the removal of nitriles but also to the removal of impurity aldehydes in other products.

The loading of a compound having an active methylene group and an acidic group in the same molecule on an ion-exchange resin is performed by transferring an aqueous solution of a compound having an active methylene group and an acidic group in the same molecule as the ion-exchange resin to a fixed layer, Using a bed or a fluidized bed, it can be carried out by batch or continuous contact, but from the viewpoint of economy and operability, continuously using a fixed bed in which the columns are filled with the ion exchange resin. The preferred method is to do so.

In this case, the concentration of an aqueous solution of a compound having an active methylene group and an acidic group in the same molecule is usually 0.01%.
Mol / L to saturation concentration, preferably 0.1 to 5 mol / L
It is. The SV at the time of distribution is usually 0.1 to 10
hr ^-1, preferably 0.5~5hr ^-1. Note that S
V is a value obtained by dividing the flow rate [mL · hr ⁻¹ ] by the filling amount [mL]. Furthermore, the amount of the compound having an active methylene group and an acidic group in the same molecule is usually 1 to 10 equivalents, preferably 2 to 10 equivalents to the amino group of the ion exchange resin.
~ 5 equivalents.

The contact of the nitrile with an anion exchange resin carrying a compound having an active methylene group and an acidic group in the same molecule can be carried out batchwise or continuously using a fixed bed, a moving bed or a fluidized bed. Although it is possible, from the viewpoint of economy and operability, a method in which the column is continuously used using a fixed bed filled with the ion exchange resin is preferable.

In this case, the SV at the time of distributing the nitrile
Although it depends on the aldehyde concentration in the nitrile, it is usually 0.1 to 20 hr ^-1 , preferably 0.5 to 10 hr ^-1 . Regeneration of ion-exchange resin after aldehyde adsorption, that is, a compound formed by the reaction of an active methylene group of a compound having an active methylene group and an acidic group in the same molecule supported by an ion-exchange reaction with an aldehyde in a nitrile From the resin can be extremely easily carried out by a usual method for regenerating an anion exchange resin. That is, after contacting with a basic aqueous solution, it may be sufficiently washed with water. Next, the compound having an active methylene group and an acidic group in the same molecule is again supported, washed with distilled water and removed with nitrile, and then used for purification of nitrile containing aldehyde as an impurity.

[0022]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples.

Examples 1 to 7 15 mL of a weakly basic anion exchange resin Levatit MP62 (manufactured by Bayer) were packed in three glass columns, and a 2N aqueous sodium hydroxide solution was passed at room temperature for 4 hours at a rate of 45 mL / hr. The solution was washed with 1 L of distilled water. 1 mol / L of a compound having an active methylene group and an acidic group in the same molecule shown in Table 1 was passed from the top of the column at a rate of 15 mL / hr for 4 hours to allow the active methylene group and the acidic group to flow in the same molecule. The compound was carried on an ion exchange resin. After sufficiently washing this with 1 L of distilled water, water was removed with nitrile. Then, acrylonitrile (containing 3 ppm of acrolein), methacrylonitrile (containing 3 ppm of methacrolein), and acetonitrile (containing 3 ppm of acetaldehyde) at 45 mL / hr from the top of the column.
The liquid was passed at the speed shown in FIG. Three days after the passage, the nitrile flowing out from the lower part of the column was sampled, and the concentration of aldehyde contained as an impurity was measured by a gas chromatograph.

COMPARATIVE EXAMPLE 1 A weakly basic anion exchange resin Levatit MP62 (manufactured by Bayer) was replaced with a strongly acidic cation exchange resin Amberlyst 15
Examples 1 to 7 except that 2N caustic soda was changed to 1N sulfuric acid and a compound having an active methylene group and an acidic group in the same molecule was changed to ethylenediamine.
The operation was performed in the same manner as described above.

Comparative Example 2 The same operation as in Examples 1 to 7 was carried out except that a compound having an active methylene group and an acidic group in the same molecule was not carried. Table 1 shows the results of Examples 1 to 7 and Comparative Examples 1 and 2.

[0026]

[Table 1]

Example 8 The same operation as in Example 1 was carried out except that the nitrile containing an aldehyde as an impurity was only acrylonitrile (containing 3 ppm of acrolein) and the number of passing days was 50 days.

Comparative Example 3 The same operation as in Comparative Example 1 was carried out except that the nitrile containing an aldehyde as an impurity was only acrylonitrile (containing 3 ppm of acrolein) and the number of passing days was 50 days. Table 2 shows the results of Example 8 and Comparative Example 3.

[0029]

[Table 2]

Example 9 and Comparative Example 4 A glass column was filled with 15 mL of weakly basic anion exchange resin Levatit MP62 (manufactured by Bayer AG),
A 2N aqueous solution of caustic soda was passed at a rate of 45 mL / hr for 4 hours, and sufficiently washed with 1 L of distilled water. 1 mol / L malonic acid was passed from the top of the column at a rate of 15 mL / hr for 4 hours to carry the malonic acid on the ion exchange resin. This resin was placed in a beaker, washed sufficiently with 1 L of distilled water, and then water was removed with acrylonitrile. To this, 50 mL of acrylonitrile containing 1.5% of acrolein was added, stirred at room temperature for 5 hours, and left overnight to complete the reaction between malonic acid supported on the resin and acrolein. This resin was filled again in a glass column, and acrylonitrile (containing 3 ppm of acrolein) was added from the top of the column to 15 g.
The solution was passed for 3 days at a rate of mL / hr, and acrylonitrile flowing out from the lower part of the column was sampled. It was confirmed that the concentration of acrolein contained as an impurity was 3 ppm (Comparative Example 4). This ion exchange resin was sufficiently washed with 1 L of distilled water, and a 2N aqueous solution of caustic soda was applied for 15 m.
The mixture was regenerated by passing the solution at a rate of L / hr for 4 hours, and further washed with 1 L of distilled water. Comparative Example 4 supported malonic acid and passed through acrylonitrile (containing 3 ppm of acrolein)
Three days after the passage, acrylonitrile flowing out from the lower part of the column was sampled, and the concentration of acrolein contained as an impurity was measured in the same manner as in Examples 1 to 7. Table 3 shows the results.

[0031]

[Table 3]

Examples 10 to 13 Each of Diaion WA20, Dowex MWA-1, Levatit MP64 and Amberlite IRA68 was 15 m each.
L was packed in a glass column, and a 2N aqueous solution of sodium hydroxide was passed through the column at a rate of 45 mL / hr for 4 hours at room temperature, and sufficiently washed with 1 L of distilled water. 1 mol / L malonic acid was passed from the top of the column at a rate of 15 mL / hr for 4 hours to be supported on the ion exchange resin. After sufficiently washing this with 1 L of distilled water, water was removed with acrylonitrile. Next, acrylonitrile (acrolein 3p
pm) was passed at a rate of 45 mL / hr. Three days after the passage, acrylonitrile flowing out from the lower part of the column was sampled, and the concentration of acrolein contained as an impurity was measured in the same manner as in Examples 1 to 7. Table 4 shows the results
Shown in

[0033]

[Table 4]

[0034]

According to the present invention, a compound having an active methylene group and an acidic group in the same molecule supported on an ion exchange resin is reacted with an aldehyde which is an impurity in a nitrile, and then easily reacted by a usual ion exchange resin regeneration method. Since the ion exchange resin can be separated from the ion exchange resin, it is possible to regenerate the ion exchange resin having lost the aldehyde removing ability. In addition, since the active methylene group reacts quickly with the aldehyde, the level of removal of the aldehyde is high, and the functional group reactively adsorbed on the anion exchange resin is an acidic group in the supported compound, and the functional group reacting with the aldehyde is Since it is an active methylene group in the supported compound, the flow-through exchange capacity is sufficiently large, so that the nitrile can be purified efficiently.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshiichi Uehara 1-6-6 Takasago, Takaishi-shi, Osaka Mitsui Chemicals, Inc. F-term (reference) 4H006 AA02 AC25 AC54 AD17 AD30 BA50 BA51 BA72 BB17 BB21 BC18 BE90 DA66 DA80 QN24

Claims (4)

[Claims] 1. A method for purifying a nitrile, comprising: bringing a nitrile into contact with an anion exchange resin carrying a compound having an active methylene group and an acidic group in the same molecule. 2. The method for purifying a nitrile according to claim 1, wherein the compound having an active methylene group and an acidic group in the same molecule is α-substituted acetic acid. 3. The α-substituted acetic acid is malonic acid, monomethyl malonate, monoethyl malonate, cyanoacetic acid, acetoacetic acid,
3. The method for purifying a nitrile according to claim 2, wherein the nitrile is sulfoacetic acid or acetone dicarboxylic acid. 4. The method for purifying a nitrile according to claim 1, wherein the nitrile is a nitrile having 2 to 4 carbon atoms.