JP2000109305A - Method for stabilizing aqueous sulfite solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the remaining rate of a sulfite in an aqueous sulfite solution in the lapse of time and to prevent the coloring of the solution and the deposition of the sulfate by incorporating a specified compound into the solution. SOLUTION: A compound of the formula [wherein (n) is 1 or 2, and R1 and R2 are each groups required to form a ring by bonding to each other] is incorporated into an about 0.01-7 mol/l aqueous sulfite solution of a sulfite compound which releases a sulfurous acid ion in its aqueous solution, e.g. sodium sulfite, potassium sulfite, ammonium sulfite, sodium hydrogensulfite, potassium hydrogensulfite, ammonium hydrogensulfite, sodium metabisulfite, potassium metabisulfite or ammonium metabisulfite. The content of the compound of the formula in the aqueous sulfite solution is about 0.01-1 mol%, preferably about 0.1-1 mol% based on the amount of sulfurous acid radicals. The aqueous sulfite solution can be kept in a stable state over a long period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sulfite aqueous solution, and more particularly to a method for maintaining a sulfite aqueous solution in a stable state for a long period of time.

[0002]

2. Description of the Related Art A sulfite aqueous solution is gradually oxidized by oxygen in the air to be converted into a sulfate, and the concentration of the sulfite decreases. At the same time, the sulfate generated by the oxidation has a low solubility, and thus precipitates in the aqueous sulfite solution. In order to obtain a sulfite aqueous solution that does not cause this precipitation, a stabilization method is known. As a stabilizer to stabilize,
Ethylenediaminetetraacetic acid and its salt (Japanese Patent Application Laid-Open No. 57-20
5314), ascorbic acid, erythorbic acid and salts thereof (JP-A-55-109210).

[0003] However, the effect is short and insufficient for practical use. Also, in the use of erythorbic acid and its salts, although the sulfites have a stabilizing effect, they are colored and reduce the commercial value. However, it was not always satisfactory.

[0004]

The aqueous solution of sulfite undergoes air oxidation during storage, increasing the concentration of sulfate and causing precipitation, and at the same time, decreasing the concentration of sulfite. In order to solve this problem, some stabilizers have been proposed. However, some stabilizers are not effective enough, or it is difficult to maintain the effect for a long period of time. However, since the sulfite aqueous solution is colored, there is a problem when the coloring of the solution is regarded as important. Therefore, an object of the present invention is to provide a stabilization method that improves the residual ratio of sulfite over time in an aqueous solution of sulfite, does not precipitate sulfate, and further, does not cause coloring of the aqueous solution of sulfite. is there.

[0005]

Means for Solving the Problems The present inventor studied an excellent stabilizing method for improving the residual ratio of sulfite and preventing coloring of an aqueous solution as compared with the conventional stabilizing method. ], [II], [III], and [IV] have been found to achieve the object by containing at least one of the compounds. General formula [I]

Embedded image General formula (II)

Embedded image General formula (III)

Embedded image General formula (IV)

Embedded image In the formula, n represents 1 or 2. R ₁ , R ₂ and R ₃ , R4
Represents a group necessary for connecting to each other to form a ring. R
₅ to R ₁₂ represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. R ₇ ,
R ₈ and R ₁₀ and R ₁₁ may be linked to each other to form a ring.

[0006]

[I-1]

Embedded image [I-2]

Embedded image [I-3]

Embedded image [I-4]

Embedded image [I-5]

Embedded image [II-1]

Embedded image [II-2]

Embedded image [II-3]

Embedded image [III-1]

Embedded image [III-2]

Embedded image [III-3]

Embedded image [IV-1]

Embedded image

The sulfite used in the aqueous sulfite solution may be any compound that releases sulfite ions in the aqueous solution.
There are sodium sulfite, potassium sulfite, ammonium sulfite, sodium bisulfite, potassium bisulfite, ammonium bisulfite, sodium metabisulfite, potassium metabisulfite, ammonium metabisulfite, etc.
Two or more of these may be used. The sulfite content in the aqueous sulfite solution is preferably 0.01 to 7 mol / l.

The amount of the compounds of the general formulas [I], [II], [III] and [IV] used in the aqueous sulfite solution is as follows:
In the compound of the general formula [I], 0.01 to 1
mol% is preferable, and 0.1 to 1 mol is more preferable.
%. In the compounds of the general formulas [II], [III] and [IV], the amount is preferably 0.01 to 0.5 mol%, more preferably 0.1 to 0.5 mol%, based on the sulfite.

Other components may be added to the aqueous sulfite solution of the present invention without departing from the purpose of the present invention. For example, potassium hydroxide, sodium hydroxide, or the like may be used to adjust the pH of the aqueous sulfite solution. , Ammonium hydroxide, potassium carbonate, sodium carbonate, ammonium carbonate, etc., whereby the present invention can stabilize the aqueous sulfite solution at any pH from acidic to alkaline.

[0010]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited by these examples. Example 1 One liter of the following aqueous sulfurous acid solution was placed in a beaker, left open, and allowed to stand at room temperature for 50 days. Sulfite aqueous solution (1) Sodium bisulfite 200 g 1 l by adding water Stabilizer Compounds and amounts used are shown in Table 1. The aqueous solution was adjusted to pH 7 with sodium hydroxide. Table 1 shows the state of each sulfite aqueous solution.

[Table 1]

As can be seen from the above results, the compounds of the general formulas [I], [II] and [III] of the present invention can improve the sulfite remaining ratio of a sulfite aqueous solution over time, and There is no coloration and no precipitation.
On the other hand, sodium erythobilin outside the present invention is
Although the residual ratio of sulfite is improving, the aqueous solution is colored,
Disodium ethylenediaminetetraacetate has no sulfite residual rate and generates a large amount of precipitate.

Example 2 The same test as in Example 1 was performed. Sulfite aqueous solution (2) 650 g of sodium hydrogen sulfite was added to add 1 l of stabilizer. The compound and the amount used are shown in Table 2. The aqueous solution was adjusted to pH 6.5 with ammonium hydroxide. Table 2 shows the condition of each sulfite aqueous solution.

[Table 2]

As can be seen from the above results, the compounds of the general formulas [I], [II] and [III] of the present invention can improve the sulfite remaining ratio of a sulfite aqueous solution over time, and There is no coloration and no precipitation.
On the other hand, compounds other than the present invention do not have the above effects.

Example 3 The same test as in Example 1 was performed. Sulfite aqueous solution (3) Potassium bisulfite 20 g 1 l by adding water Stabilizer Compound and amount used are shown in Table 3 Table 3 shows the state of each sulfite aqueous solution.

[Table 3]

As can be seen from the above results, the compounds of the general formulas [I], [III], and [IV] of the present invention can improve the sulfite residual ratio over time of the aqueous sulfite solution, Is not colored. On the other hand, compounds other than the present invention do not have the above effects.

[0016]

As described above, by using the compound of the present invention, the residual ratio of sulfite over time in the aqueous sulfite solution is improved, and the aqueous solution is not colored.
Further, it is possible to stabilize the sulfite aqueous solution without generating a precipitate.

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[Procedure amendment]

[Submission date] April 30, 1999 (1999.4.3)
0)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

Embedded image General formula (II)

Embedded image General formula (III)

Embedded image General formula (IV)

Embedded image In the formula, n represents 1 or 2. R ₁ , R ₂ and R ₃ , R ₄
Represents a group necessary for connecting to each other to form a ring. R
₅ to R ₁₂ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group. R ₇ , R
₈ and R ₁₀ and R ₁₁ may be linked to each other to form a ring.

Claims (1)

[Claims] (1) The following general formulas (I), (II), [III], [I
A method for stabilizing an aqueous sulfite solution, comprising at least one compound represented by the formula [V]. General formula [I] General formula [II] General formula [III] General formula [IV] In the formula, n represents 1 or 2. R ₁ , R ₂ and R ₃ , R ₄
Represents a group necessary for forming a ring with each other. R _{5 to} R
₁₂ represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. R ₇ and R ₈ and R ₁₀ and R ₁₂ may be linked to each other to form a ring.