JPS61115039A - Production of beta-naphthol - Google Patents

Abstract

PURPOSE:To produce the titled substance, by sulfonating naphthalene while removing the produced water using an inert solvent capable of forming an azeotropic mixture with water, neutralizing the sulfonation product with an alkali, subjecting the product to alkali fusion without removing impurities, and hydrolyzing the resultant beta-naphthol alkali metal salt. CONSTITUTION:beta-Naphthol is produced by (1) reacting naphthalene with concentrated sulfuric acid in an inert solvent such as saturated hydrocarbon, halogenated hydrocarbon, ether, etc. at 140-180 deg.C while removing the produced water, (2) neutralizing the resultant beta-naphthalenesulfonic acid with an alkalki to form a beta-naphthalenesulfonic acid alkali metal salt, (3) subjecting the salt to alkali fusion without removing the impurities by-produced in the sulfonation reaction, and (4) hydrolyzing the obtained beta-naphthol alkali metal salt. EFFECT:The process can be simplified by carring out the alkali fusion without removing the by-products of the sulfonation reaction and a part of the by- product is converted to beta-naphthol to improve the yield of beta-naphthol.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an improved method for producing β-su7toll by sulfonation of naphthalene and an alkaline melting reaction of β-naphthalene sulfonate.

(Prior Art) In general, β-su7toll is a very useful substance as an intermediate raw material for dyes, medicines, and the like. The method for producing β-naphthol has been known for a long time, and various methods have been proposed, but the process that was first commercialized and still has strong cost competitiveness is β-naphthalenesulfonic acid. -・There is an alkali melting reaction of alkali metal salts. In order to obtain this alkali metal salt of β-7talenesulfonic acid, for example, 7talene is sulfonated with a sulfonating agent such as sulfuric acid or fuming sulfuric acid, and converted into an alkali metal salt by the appropriate method. As shown in Figure 2, this requires a very complicated process.

(Problems to be Solved by the Invention) In the complicated process of producing an alkali metal salt of β-naphthalenesulfonic acid by the conventional method described above, the crystallization and passing steps take a long time, and it is necessary to make them continuous and automated. Not only is operation difficult, but the wastewater generated from these processes contains naphthalene sulfonate salts, which poses a problem in wastewater treatment.

(Means for Solving the Problems) As a result of various studies on the above-mentioned problems, the present inventors have found that after neutralizing the sulfonation reaction product, impurities produced as by-products in the sulfonation reaction are removed from the neutralization reaction product. We have developed a new method for producing β-naphthol that can solve all of these problems and improve the yield of β-naphthol by supplying it as a raw material for an alkali melting reaction without any problems.
This has led to the present invention.

That is, the first aspect of the present invention is to neutralize naphthalenesulfonic acid with an alkali to produce an alkali β-su7thalenesulfonic acid, melt this product with an alkali to obtain an alkali salt of β-naphthol, and then In a method for producing β-su7toll by hydrolysis, a sulfonation reaction product is neutralized with an alkali, and then the neutralized reaction product is supplied as a raw material for an alkali melting reaction without removing impurities produced as by-products in the sulfonation reaction. It is characterized by

A second aspect of the present invention is to perform the sulfonation of naphthalene while removing the reaction product water by adding an inert solvent that is azeotropic with water to the reaction system, and neutralize the sulfonation reaction product with an alkali. After that, the neutralized reaction product is supplied as a raw material for an alkali melting reaction without removing impurities produced by-product in the sulfonation reaction.

In the method for producing β-naphthol of the present invention, various methods can be used to produce β-naphthalenesulfonic acid by sulfonation of naphthalene. Concentrated sulfuric acid can generally be used as the oxidizing agent. In this case, the naphthalene sulfonic acid produced by sulfonation of naphthalene is a monosulfonic acid, for example, in the case of monosulfonic acid, a combination of α-naphthalene sulfonic acid and β-naphthalene sulfonic acid. It gives rise to different isomers.

This product isomer ratio is significantly influenced by the sulfonation reaction temperature; a temperature range of 140-180'C is preferable in order to selectively produce β-naphthalenesulfonic acid; At lower temperatures, α-naphthalene sulfonic acid becomes the main product6.Also, at higher reaction temperatures7
The amount of by-products such as taledisulfonic acids and dinaphthylsulfones increases. For example, Table 1 shows the results of composition analysis of a sulfonated product obtained by sulfonating naphthalene with concentrated sulfuric acid at 160'C.

Table 1 The neutralized reaction product obtained by alkali salting the sulfonation reaction product produced as described above includes β-s7talenesulfonic acid alkali salt, α-naphthalenesulfonic acid alkali salt,
Contains naphthalene disulfonic acid alkali salts, cinnaptyl sulfones, alkali sulfate, naphthalene and water.

In the present invention, as a result of intensive study on the behavior of impurities other than the alkali β-naphthalene sulfonic acid salt contained in the neutralization reaction product in the alkali melting reaction, it was found that each of these substances has an adverse effect on the alkali melting reaction. In addition, it was confirmed that a part of naphthalenedisulfonic acid alkali salts and dinaphthylsulfones were converted to β-naphthol alkali salts, ultimately improving the yield of β-naphthol.

Next, the alkali melting reaction of each substance contained in the above-mentioned neutralization reaction product will be explained: (1) β
- The alkaline melting reaction of naphthalene sulfonic acid alkali salts can be carried out using various alkali metal hydroxides, for example, as shown in the reaction formula below, and generally sodium hydroxide is used to convert sodium-β-naphthorate. Formation: When using sodium hydroxide as the hydroxide, the temperature of the alkali melting reaction is preferably in the range of 280 to 450°C. If the reaction temperature is lower than this, the reaction rate is slow, and if the reaction temperature is higher, polymerization etc. Many side reactions occur together.

(2) The alkaline melting reaction of sodium α-naphthalenesulfonate is the same as the above-mentioned β-naphthalenesulfonic acid)
Under the same conditions as in the case of IJium, it reacts with sodium hydroxide as shown in the following reaction formula to form sodium-α-su7.
(8) The breakdown of sodium naphthalene disulfonate among the impurities contained in the above-mentioned neutralization reaction product is four types of isomers: sodium 1,5-naphthalene disulfonate, 1,6-sodium naphthalene disulfonate, and They are sodium 7taledisulfonate, sodium 2,6-naphthalenedisulfonate, and sodium 2,7-sodium 7taledisulfonate. These sodium 7thalene disulfonates react with sodium hydroxide in the same way as sodium β-naphthalene sulfonate under the alkali melting reaction conditions of sodium β-naphthalene sulfonate as shown in the reaction formula below. In addition to producing the corresponding naphthalene diol sodium salt, a reaction in which the sulfonic acid group is eliminated also occurs to produce naphthalene. In this case, the α-position is more easily eliminated than the β-position, and the naphthol produced is mainly β-naphthol.

(4) Next, the breakdown of the cina7-tylsulfones in the above impurities is eight types of isomers: α,αl-dinaphthylsulfone, α,β-dinaphthylsulfone, and β,βI-dinaphthylsulfone. Under the conditions of the alkali melting reaction of sodium β-naphthalenesulfonate described above, a portion of these dinaphthylsulfones decomposes to produce s-7talene and the corresponding s-7tole, as shown in the following reaction formula. : (5) Naphthalene and sodium sulfate are hydroxylated under alkaline melting reaction conditions) IJum and β-su7
It is inactive towards sodium talenesulfonate and does not interfere with the sodium-β-naphthrate production reaction.

However, since naphthalene evaporates under alkaline melting reaction conditions, it must be collected in normal pressure reactions;
At temperatures below ℃, it solidifies and causes blockages in condensers and piping. In addition, in order to cause clogging of pulp and the like even in a pressurized reaction, it is preferable that the content of naphthalene in the alkali-melted raw material be as small as possible. In order to reduce this naphthalene content, it is desirable to increase the conversion rate of naphthalene.

Another way to reduce the naphthalene content is to remove unreacted naphthalene by steam distillation.
In this case as well, blockage due to coagulation of naphthalene poses a problem.

(6) Moisture does not have an adverse effect on the alkali melting reaction like the above-mentioned sulfate and sodium sulfate, but if there is a large amount of water, the reaction will be pressurized due to water vapor pressure, and an expensive reaction vessel will be required. However, when carrying out the reaction under normal pressure, it is not only difficult to control the alkali melting temperature within a suitable range due to the large amount of heat of evaporation of water, but also problems such as bumping may occur if the amount of water is too large, which is undesirable. Therefore,
When the reaction is carried out under normal pressure, the water content is preferably at least 50% by weight.

Various methods can be used to sulfonate naphthalene in the present invention. As one method, a sulfonation reaction between naphthalene and concentrated sulfuric acid can be used. Since this method is a reversible reaction, the reaction will stop at the equilibrium reaction rate. If this happens, not only will unreacted sulfur flIm increase, but the amount of by-products such as 7taledisulfonic acids and sina7tylsulfone will increase, and the amount of β-naphthalenesulfonic acid will increase. Selection rate decreases. Therefore, although this method reduces unreacted 7-talene, it increases the amount of sulfuric acid used and the amount of waste acid treated, and since there are many by-products, the burden of purification after alkali melting increases, which is undesirable. .

Another method of sulfonation is a method of removing the water produced in order to shift the equilibrium of naphthalene sulfonation in the direction of decreasing unreacted naphthalene. There are eight methods for removing water from the reaction system as described below. In other words, ■ Adding a solvent that is azeotropic with water,
A method for azeotropically removing water, ■ Performing sulfonation under reduced pressure,
There are two methods: (1) a method in which an inert gas is introduced into the reaction system and water is removed along with it; Among these methods, methods (1) and (2) are not preferred because they have the problem of blockage due to coagulation of naphthalene. Method (2) can be advantageously used to carry out the present invention.

In method (2) for sulfonating naphthalene, the solvent that is azeotropic with water is preferably a solvent that is inert to sulfuric acid, which is incompatible with water, and has a boiling point aIilig of 80 to 170°C. The solvent used is, for example, n
- Paraffins, i-paraffins, saturated hydrocarbons such as cycloaliphatic saturated hydrocarbons, halogenated hydrocarbons, ethers, and mixtures thereof may be mentioned. Specific examples of these solvents are as follows: (1) n-paraffins such as n-octane and n-nonane; (2) 1-paraffins with 7 carbon atoms such as 2-methyloctane and 2,6-dimethyloctane. ~11 branched paraffins, (8) alicyclic saturated hydrocarbons cycloheptane, methylcyclohexane, etc. (4)
Halogenated hydrocarbon trichloroethane, tetrachloroethane, etc. (5)
Ethers butyl ether, ethyl butyl ether.

Among these solvents, paraffins such as n-paraffin and 1-paraffin are preferred from the viewpoint of water removal ability and ease of removal of the solvent after sulfonation. As the solvent, one having a boiling point in the range of 80 to 17 G'C can be used. If a solvent with a boiling point of less than 80°C is used, the temperature difference from the sulfonation temperature of 140 to 180°C will be too large, and when a solvent is added to the reaction system, the bumping phenomenon of the solvent will become significant, which is not preferable. Furthermore, a solvent with a boiling point of 170'C or higher not only has a low ability to remove water, but also makes it difficult to remove the solvent after sulfonation is completed.

The solvent can be circulated by refluxing it using a reflux device equipped with a water separation device, or by distilling the solvent from one side while introducing the solvent from the other side, but the former method is preferred.

The amount of solvent used can be determined depending on the sulfonation temperature and dehydration rate, but the circulating amount of solvent (amount other than the amount of retained solvent) is usually 1 to 80% by weight based on the total amount of naphthalene and sulfuric acid charged. , preferably 1 to 5% by weight. The amount retained in the reaction system is usually 1 to 80% by weight, preferably 1 to 5% by weight.

By employing the above-mentioned solvent dehydration sulfonation method in the present invention, the naphthalene conversion rate is increased and unreacted 7.
In addition to being able to reduce the talene content, it is also possible to reduce the amount of concentrated sulfuric acid used and the amount of waste acid treated, thereby reducing the production cost of β-su7)-ol.

The amount of concentrated sulfuric acid used is 1.0 to 1.15 per naphthalene.
A range of multiple moles is preferred.

Table 2 shows the results of compositional analysis of one example of the sulfonated reaction product when n-nonane is used as the azeotropic dehydration solvent mentioned above: Table 2 From Table 2 above, the amounts of unreacted naphthalene and unreacted sulfuric acid are It can be seen that the amount is significantly reduced compared to the conventional sulfonation shown in Table 1 in which no solvent dehydration operation is performed.

An example of the present invention in which sodium β-naphthalene sulfonate is produced by sulfonating 7-talene by adding an inert solvent that is azeotropic with water into the reaction system and removing the reaction product water as described above. A flow sheet of the manufacturing process is shown in Figure 1.

(Effects of the Invention) As described above, in the present invention, after neutralizing the sulfonation reaction product produced by sulfonating naphthalene with an alkali, impurities generated by-product in the sulfonation reaction are not removed, but the neutralization By supplying the reactant as a raw material for the alkali melting reaction, complicated steps such as crystallization and passing can be omitted, and continuous and automated operation can be easily achieved. In addition, since wastewater containing waste sulfates, naphthalene sulfonates, etc. is not generated, wastewater treatment costs can be greatly reduced, and β-
The naphthol yield can be increased and the production cost of β-naphthol can be significantly reduced.

(Example 1) 5.3 g of sodium β-naphthalene sulfonate (hydroxide) was charged into a vertically shaking SUS autoclave (inner volume: 50 mm), and placed in a sand bath while shaking at a speed of SOO times/min. Raise the temperature to 320℃, 820'
The reaction was carried out at C for 2 hours. Thereafter, the reaction product was allowed to cool and was taken out, dissolved in hot water, neutralized with sulfuric acid, extracted with chloroform, and the extract was analyzed using Gaskada Madogra 7 and high performance liquid chromatography.

As a result of analysis, the conversion rate of sodium β-naphthalenesulfonate was 99%, and the yield of β-su7toll was 92%.

(Examples 2 to 6) Toga β-naphthol was obtained in the same manner as in Example 1, except that 9 g of sodium β-naphthalene sulfonate and 1 g of each sodium 7-talene sulfonate shown in Table 8 were used as raw materials. These reaction results are shown in Table 8: Table 8 (Note) * I-MS conversion rate: β-naphthene sodium sulfonate conversion rate * β-naphthol yield From Table 3 above, 1,6-naphthalenedisulfonic acid It can be seen that the β-naphthol yield increases in the case of sodium, sodium 2,6-naphthalenedisulfonate, and sodium 2,7-naphthalenedisulfonate.

(Example 7) 9 g of sodium β-naphthalene sulfonate and mixed Cina 7
1 g of tilsulfone (α, αl-sina 7 tilsulfone 17
β-naphthol was obtained in the same manner as in Example 1 except that 61% by weight of α,β-dinaphthylsulfone and 22% by weight of β,βI-dinaphthylsulfone were used as raw materials.

As a result of analysis in the same manner as in Example 1, the conversion rate of sodium β-naphthalenesulfonate was 99% and the yield of β-naphthol was 95%.

(Examples 8 to 9) As shown in Table 4, Example 1 except that 1 g of water was added in Example 8) and 1 g of water in Example 9.
It was processed in the same way. These reaction results are shown in Table 4: Table 4 (Example 10) 128 g of sulfur was placed in a 4-glass vJlt flask with stirring blades, heated to 155°C, and 106 g of 98% sulfur was added.
was added over about 10 minutes. After that, it was kept at 160'C for 1 hour, and then 43 g of n-/nan was added over 0.5 hours, and kept at 160'C for 0.5 hours.Then, 100-degree water was added to dilute the sulfonation reaction solution. 89 g of 50% NaOH solution was added to neutralize.

The neutralized solution was dried with a spray dryer to obtain 5 g of crude sodium naphthalene sulfonate za.

120 g of NaOH was placed in a nickel-made 114-bottle flask with stirring blades and heated to 820° C. for 7 J[], and 235 g of crude sodium naphthalene sulfonate was added over about 1 hour, and the reaction was continued for another 1 hour. The reaction solution was poured into water, diluted, and then neutralized with 98% H, So. Chloroform was added to the neutralized solution to extract β-naphthol, which was analyzed by gas chromatography. The yield of β-naphthol obtained was 80 mol% based on the consumed naphthalene.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet of an example of 94 production steps for producing sodium β-7talenesulfonate according to the present invention, and FIG. 2 is a flow sheet of 70 production steps for producing sodium β-naphthalenesulfonate by a conventional method. -It is a sheet.

Claims (1)

[Claims] 1. Neutralize β-naphthalene sulfonic acid produced by sulfonating naphthalene with an alkali to obtain an alkali β-naphthalene sulfonate, and melt this product with an alkali to obtain β-naphthalene sulfonic acid.
- In a method of producing β-naphthol by hydrolyzing the naphthol alkali salt, the sulfonation reaction product is neutralized with an alkali, and then the neutralization reaction product is alkalised without removing impurities that are by-produced in the sulfonation reaction. A method for producing β-naphthol, characterized in that it is supplied as a raw material for a melting reaction. 2. Neutralize β-naphthalenesulfonic acid produced by sulfonating naphthalene with an alkali to obtain an alkali β-naphthalenesulfonic acid, and melt this product with an alkali to obtain β-naphthalenesulfonic acid.
- In a method of producing β-naphthol by hydrolyzing the naphthalene alkali salt, the sulfonation of naphthalene is carried out while removing the water produced by the reaction by adding an inert solvent that is azeotropic with water to the reaction system. β-, which is characterized in that the sulfonation reaction product is neutralized with an alkali, and then the neutralized reaction product is supplied as a raw material for an alkali melting reaction without removing impurities that are by-produced in the sulfonation reaction.
Method for producing naphthol.