JP3164691B2 - Method for producing β-naphthalene sulfonate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing high-purity .beta.-naphthalene sulfonate having a very low content of dinaphthyl sulfone and inorganic salts.

[0002]

2. Description of the Related Art β-Naphthalenesulfonic acid obtained by sulfating naphthalene with a sulfating agent such as sulfuric acid, sulfuric anhydride or fuming sulfuric acid contains unreacted naphthalene, a sulfating agent, a by-product dinaphthyl sulfone as impurities. About 10 to 15% by weight of naphthalenedisulfonic acid, α-naphthalenesulfonic acid and the like are mixed, and as a method for removing these, a method of crystallization with an aqueous hydrochloric acid solution is known (Industrial Chemistry Magazine, 66 , 56 (196)
3)). However, in this method, the yield is not good, and the material of the equipment is limited because of handling hydrochloric acid, so that it cannot be said that this method is industrially applicable.

[0003]

SUMMARY OF THE INVENTION The present invention provides a method for neutralizing and purifying crude β-naphthalenesulfonic acid obtained by sulfating naphthalene with a sulfating agent by a simple and efficient method that can be used industrially. An object of the present invention is to provide a method for producing a β-naphthalene sulfonate having a small amount of impurities.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, washed crude β-naphthalenesulfonic acid with an aromatic hydrocarbon solvent and then neutralized with a basic substance. The inventors have found that high purity β-naphthalene sulfonate can be obtained by crystallization, thereby completing the present invention.

That is, according to the present invention, when a crude β-naphthalenesulfonic acid obtained by reacting a sulfating agent with naphthalene is neutralized with a basic substance to obtain a β-naphthalenesulfonic acid salt, the following steps (A) to ( D), a process for producing β-naphthalenesulfonate.

(A) a step of converting β-naphthalenesulfonic acid into an aqueous solution (B) a step of washing the aqueous solution obtained in the step (A) with an aromatic hydrocarbon solvent (C) an aqueous solution obtained in the step (B) Neutralized with a basic substance,
Step (D) of heating the aqueous solution or dispersion obtained in step (C) to 0 to 40 ° C. to obtain an aqueous solution or dispersion by heating to 40 to 100 ° C. Filtration step The crude β-naphthalene sulfonic acid used in the present invention may be any one obtained by reacting naphthalene with a sulfating agent such as sulfuric acid, sulfuric anhydride, fuming sulfuric acid or the like under ordinary conditions,
For example, when sulfuric acid is used as the sulfating agent, it is obtained by reacting 1 to 1.5 times the molar amount of sulfuric acid with respect to naphthalene at a temperature of 150 to 170 ° C for 1 to 5 hours.

The crude β-naphthalenesulfonic acid is usually
In addition to the water 5 to 10 wt%, unreacted naphthalene 1 to 5% by weight as impurities, the H ₂ SO ₄ 5 to 13 wt%, by-products dinaphthyl sulfonate 0.5-1.5 wt%, naphthalene disulfonic acid 1 ５5% by weight and α-naphthalenesulfonic acid in an amount of 3-5% by weight, and the purity of β-naphthalenesulfonic acid is about 70-80% by weight.

Hereinafter, the steps (A) to (D) will be described in detail. Step (A) is a step in which water is added to crude β-naphthalenesulfonic acid to form an aqueous solution, and the mixture may be stirred and mixed at 80 to 100 ° C. for 0.5 to 1 hour. The crude β-naphthalenesulfonic acid is preferably heated to 80 ° C. or higher and handled in a molten state. This step is a step for increasing the efficiency of the solvent washing performed in the next step (B), and the concentration of the aqueous solution is preferably 30 to 60% by weight, particularly 40 to 60% by weight, based on the solubility of crude β-naphthalenesulfonic acid in water. weight%
Is preferred.

Step (B) As the aromatic hydrocarbon solvent used in this step, any solvent may be used, but from the viewpoint of safety, boiling point, cost and the like, toluene, xylene and the like are preferable, and toluene is particularly preferable. In this step, an aromatic hydrocarbon solvent is added to 100 parts by weight of the crude β-naphthalenesulfonic acid aqueous solution obtained in step (A).
10 to 40 parts by weight is added, and the mixture is vigorously stirred or shaken for 0.5 to 2 hours, and then left to stand to separate the aromatic hydrocarbon solvent layer. The temperature is 0 to 100 ° C, preferably 40 to 100 ° C.
~ 60 ° C is good. If necessary, the washing with the aromatic hydrocarbon solvent may be repeated, but the amount of the waste aromatic hydrocarbon solvent increases, and the amount of the waste aromatic hydrocarbon solvent can be selected in consideration of the purity of the target β-naphthalene sulfonate. The number of times of washing is usually 1 to 5 times, preferably 2 to 3 times.

The main impurities removed in this step are oil-soluble naphthalene and dinaphthyl sulfone, which can be reduced to 0.001% by weight or less and 0.02% by weight or less, respectively. In the aqueous β-naphthalenesulfonic acid solution from which the aromatic hydrocarbon solvent has been separated, since a small amount of the aromatic hydrocarbon solvent and the raw material naphthalene are still mixed, these are distilled under reduced pressure together with some water, A step of blowing an inert gas such as N ₂ may be performed.

Step (C) As the basic substance used in this step, NaOH, KOH, Na ₂ CO 3
₃ , NH ₄ OH and alkanolamines having 6 or less carbon atoms, such as monoethanolamine, diethanolamine, and triethanolamine, are preferred, and NaOH and KOH are preferred. In this step, β-naphthalenesulfonic acid is neutralized to form a corresponding salt, then heated to a high temperature, and the β-naphthalenesulfonic acid salt and by-product water-soluble substance are heated and dissolved. That is, for β-naphthalenesulfonic acid, a theoretical equivalent of a basic substance is added to adjust the pH to 5 to 7, and then heated to 40 to 100 ° C, preferably 70 to 90 ° C to obtain an aqueous solution or dispersion. It is a process. If the heating temperature is lower than 40 ° C., the impurities are insufficiently dissolved to lower the purity, and the β-naphthalenesulfonate precipitated in the step (D) is less, resulting in a lower yield. Also 10
If the temperature exceeds 0 ° C., a pressurizing facility is required, which is not practical.
The concentration of the neutralized aqueous solution varies depending on the type of the basic substance used, but may be set based on the saturation solubility at a high temperature. For example, when NaOH is used as the basic substance,
Since the solubility of β-naphthalenesulfonic acid sodium salt at 80 ° C. is about 18% by weight, the neutralized substance concentration is 13 to
It is preferably 25% by weight.

Since the impurity Na ₂ SO ₄ is usually higher in water solubility than β-naphthalenesulfonate and its amount is very small, the purity of the desired β-naphthalenesulfonate is small. Depending on the case, the amount of water used may be reduced and the process may be moved to the next step while being partially insoluble.

Step (D) In this step, the high-temperature aqueous solution or dispersion of β-naphthalenesulfonate obtained in Step (C) is cooled, and the precipitated β-naphthalenesulfonate crystals are collected by filtration. It is a process. The lower the cooling temperature of the aqueous solution or dispersion, the lower the β-
Although the yield of naphthalene sulfonate is improved, cooling energy is required, solubility of impurities is reduced, and precipitation is easy.
~ 20 ° C.

[0014] To 100 parts by weight of the cake of β-naphthalenesulfonate precipitated and separated by filtration, 30 to 150 parts by weight of water is further added, followed by washing and filtration to remove water-soluble impurities more efficiently. Can also. In this step, examples of the water-soluble impurities washed out into water include naphthalenedisulfonic acid salts, α-naphthalenesulfonic acid salts, and alkali salts of sulfuric acid.

The β-naphthalenesulfonate thus obtained can be returned to the step (C) if necessary, and the crystallization operation can be repeated to purify the β-naphthalenesulfonate. It must be taken into account that the yield of the compound decreases. The β-naphthalenesulfonate thus obtained usually contains 30 to 60% by weight of water, and may be used as it is in an aqueous solution depending on the application.
When dried under normal pressure or reduced pressure at ~ 120 ° C, moisture is 1% by weight
Hereinafter, a high-purity β-naphthalene sulfonate having an impurity of 1% by weight or less can be obtained.

[0016]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. The percentages in the examples are on a weight basis unless otherwise specified.

Synthesis Example 1000 g (7.802 mol) of purified naphthalene was charged into a four-necked flask, melted, and heated to 110 to 120 ° C. next
1000 g of 98% sulfuric acid was dropped in about 30 minutes, and the temperature was raised to 160 ° C.
It reacted for 2.5 hours. After the reaction is completed, cool to about 110 ° C,
2000 g of water was added to obtain a 50% aqueous solution of crude β-naphthalenesulfonic acid. When this crude β-naphthalenesulfonic acid aqueous solution was analyzed, the composition was as shown in Table 1.

[0018]

[Table 1]

Example 1 270 g of a 50% aqueous solution of the crude β-naphthalenesulfonic acid obtained in the synthesis example was placed in a four-necked flask, 60 g of toluene was added, and the mixture was stirred and mixed at 40 to 50 ° C. for about 30 minutes. And the lower layer was returned to the four-necked flask. Further, 60 g of fresh toluene was added, and the second extraction and separation operations were performed in the same manner. Return the lower layer four-necked flask, 80 until toluene odor at normal pressure or reduced pressure under blowing N ₂ is eliminated
Deodorization was performed at 100 ° C., and water corresponding to the weight loss was returned to the flask. 600 g of water and NaOH in another four-necked flask
33 g was charged, and after dissolution, the temperature was raised to about 50 ° C., a deodorized crude β-naphthalenesulfonic acid aqueous solution was added, and the pH was adjusted with 10% NaOH.
Was adjusted to 6 ± 1. Furthermore, after the temperature of the neutralized aqueous solution was raised to around 80 ° C, the mixture was cooled with stirring to about 10 ° C, and the precipitate was filtrated under reduced pressure or pressure. did. Finally, add 100 filter cakes
After drying at 110 ° C. for 2 to 3 hours, 85 g of purified sodium β-naphthalenesulfonate was obtained. The analysis results of this purified product were as shown in Table 2. In addition, about the quantification method of each component, it performed by the method shown in the synthesis example.

Example 2 A purified product of sodium β-naphthalenesulfonate was obtained in the same manner as in Example 1 except that the number of extractions with toluene was changed to three times. The analysis results of the purified product were as shown in Table 2.

Example 3 A purified product of sodium β-naphthalenesulfonate was obtained in the same manner as in Example 1 except that xylene was used instead of toluene as an extraction solvent. Table 2 shows the analysis results of purified products.
As shown in FIG.

Example 4 A purified product of sodium β-naphthalenesulfonate was obtained in the same manner as in Example 1 except that the amount of water added to the filter cake in step (D) was increased to about 140 g. The analysis results of the purified product were as shown in Table 2.

Example 5 The procedure of Example 1 was repeated except that the concentration of the neutralized substance in the step (C) was 23% and the amount of water added to the filter cake in the step (D) was increased to about 210 g. And a purified product of sodium β-naphthalenesulfonate. The analysis results of the purified product were as shown in Table 2.

Comparative Example 1 A purified product of sodium β-naphthalenesulfonate was obtained in the same manner as in Example 1 except that hexane was used instead of toluene as an extraction solvent. Table 2 shows the analysis results of purified products.
As shown in FIG.

Comparative Example 2 A purified product of sodium β-naphthalenesulfonate was obtained in the same manner as in Example 1 except that the extraction step with toluene was omitted. The analysis results of the purified product were as shown in Table 2.

Comparative Example 3 The neutralization and crystallization steps of Example 1 were omitted, and only the extraction operation with toluene was performed to obtain a purified product of β-naphthalenesulfonic acid. The analysis results of the purified product were as shown in Table 2.

Comparative Example 4 The same procedure as in Example 1 was repeated except that the toluene extraction operation was carried out. The concentration was adjusted to a 12% hydrochloric acid solution of 10% crude β-naphthalenesulfonic acid without neutralization. After cooling, the precipitated crystals were filtered. Table 2 shows the analysis results of the purified product.
As shown in FIG.

Reference Example A 50% aqueous solution of β-naphthalenesulfonic acid obtained in the synthesis example was neutralized by a usual method with NaOH, and dried to obtain sodium β-naphthalenesulfonic acid. The analysis results of the obtained sodium β-naphthalenesulfonate are as shown in Table 2.

[0029]

[Table 2]

Note) * 1: An example of calculation of the total yield of sodium β-naphthalenesulfonate of Example 1 (hereinafter abbreviated as β-NSA (Na salt)) is shown below.

[0031]

(Equation 1)

* 2: A 1% aqueous solution of the obtained β-naphthalenesulfonic acid or its sodium salt was prepared, and transparency was observed with the naked eye. ○: completely transparent ×: turbid

[0033]

Industrial Applicability The production method of the present invention is a simple and efficient method that can be used industrially. An acid salt can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C07C 309/00 C07C 303/00 CA (STN)

Claims (5)

(57) [Claims] 1. A process for producing a β-naphthalenesulfonic acid salt by neutralizing crude β-naphthalenesulfonic acid obtained by reacting a sulfating agent with naphthalene with a basic substance to obtain β-naphthalenesulfonic acid salt:
(A) to (D), a process for producing β-naphthalene sulfonate. (A) a step of converting β-naphthalenesulfonic acid into an aqueous solution; (B) a step of washing the aqueous solution obtained in step (A) with an aromatic hydrocarbon solvent; and (C) a step of washing the aqueous solution obtained in step (B) with a basic solution. Neutralize with a substance,
Step (D) of heating the aqueous solution or dispersion obtained in step (C) to 0 to 40 ° C. to obtain an aqueous solution or dispersion by heating to 40 to 100 ° C. Filtration process 2. The method according to claim 1, wherein the sulfating agent is sulfuric acid, sulfuric anhydride or fuming sulfuric acid. 3. The process for producing β-naphthalene sulfonate according to claim 1, wherein the aromatic hydrocarbon solvent used in step (B) is toluene or xylene. 4. The method according to claim 1, wherein the basic substance used in the step (C) is NaOH,
The method for producing β-naphthalene sulfonate according to claim 1, 2 or 3, which is KOH, Na ₂ CO ₃ , NH ₄ OH or an alkanolamine having 6 or less carbon atoms. 5. The step (C) comprises neutralizing the aqueous solution obtained in the step (B) with an aqueous NaOH solution and heating the solution to 40 to 100 ° C. to obtain an aqueous solution or dispersion having a neutralized substance concentration of 13 to 25% by weight. 4. The method for producing a β-naphthalene sulfonate according to claim 1, 2 or 3, wherein