JPS58118530A - Preparation of m-alkylhydroxybenzene - Google Patents

Abstract

PURPOSE:To obtain the titled compound without forming a by-product in sulfonating an alkylbenzene, by adding an inorganic salt to the alkylbenzene, hydrolyzing the reaction product, allowing the hydrolytic product to stand at a high temperature, separating the resultant product into the sulfonic acid layer and the sulfuric acid layer, and collecting and removing the excess sulfuric acid with ease. CONSTITUTION:An alkylbenzene or alkylbenzenesulfonic acid mixture is reacted with 5-15mol% inorganic salt of sulfuric acid, optimally Glauber's salt or acid sodium sulfate, at 50-150 deg.C to give an alkylbenzensulfonic acid. The alkylbenzenesulfonic acid other than the m-isomer is selectively hydrolyzed, and the resultant hydrolytic product is allowed to stand at 80 deg.C or above, preferably as high as 80-170 deg.C, and separated into the sulfonic acid layer and the sulfuric acid layer. The excess sulfuric acid is easily collected, and the separated alkylbenzenesulfonic acid layer is collected and caustically fused to give the aimed compound.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rational and economical method for producing m-alkylhydroxybenzenes.

As a method for obtaining substantially pure m-alkylhydroxybenzene from alkylbenzene through alkylbenzene sulfonic acid, for example, the method described in Equity IV (43-7837, Japanese Patent Publication No. 43-9713, Japanese Patent Application Publication E ¥49-110638, etc.) These techniques are known and consist of the following steps:

(A) heating an alkylbenzene sulfonic acid mixture obtained by sulfonating alkylbenzene with sulfuric acid at a low temperature in the presence of sulfuric acid at a temperature in the range of 150°C to 210°C;
or 150 to 210 with alkylbenzene or sulfuric acid
(B) contacting the alkylbenzene sulfonic acid mixture with water, preferably steam, to obtain an alkylbenzene sulfonic acid layer having a high monomer content by maintaining the mixture at a temperature in the range of The acid is selectively hydrolyzed into alkylbenzene and sulfuric acid, and the alkylbenzene is azeotroped with water and removed from the system.

(C) The m-alkylbenzenesulfonic acid that has not undergone hydrolysis is converted into an alkali salt, and then (D) the m-alkylhydroxybenzene is obtained by melting with an alkali.

These known methods have several problems. First of all, in the reaction of alkylbenzene' and sulfate, step A1, that is, sulfonation and isomerization, increases the amount of m as the reaction temperature increases, but on the other hand, oxidation and decomposition rapidly occur especially from around 190°C. As the process progresses, dealkylation and tar formation appear, and the sulfonated product becomes black tar-like and becomes unusable. Hydrolysis in step B is also carried out at high temperatures and takes a long time, so hydrolysis of the m itself and side reactions occur. This is likely to occur in parallel or sequentially, which inevitably leads to a decrease in the purity and quality of the final product, or a decrease in yield.

The second problem is that the steps C and D mentioned above, namely,
The presence of inorganic salts during alkali salification of the hydrolyzed product and caustic melting. Add sodium hydroxide to the reaction product of alkylbenzene and sulfuric acid until it becomes basic, convert the sulfonic acid into an alkaline salt, and at the same time neutralize the excess sulfuric acid. When the total 1+1 is subjected to caustic melting, a large amount of Glauber's salt is included. In this method, the sodium sulfate that precipitates out before melting becomes too viscous and cannot be stirred and stirred, and a large amount of sodium sulfate mixed in by-product sodium sulfite obtained during post-processing loses its utility value. There is a way to separate p, but
Since the adhesion loss of sulfonic acid is large, steps such as washing with water, concentration, and refiltration are required, making it complicated. For this purpose, excess sulfuric acid during the sulfonation reaction is removed by an appropriate method. A commonly used method for separating sulfuric acid is the liming sortion method, in which sulfuric acid is removed as gypsum. However, this method is industrially disadvantageous in terms of process and energy consumption, such as disposal before waste rock and concentration of sulfonate aqueous solution. In recent years, a method has been proposed in which alkylbenzenesulfonic acid is extracted with a mixture of a primary to quaternary amine and a water-insoluble organic solvent. (JP 55-154935) Although this method is also advantageous when recovering dilute organic acids, it requires a large amount of amine and solvent to produce alkylhydroxybenzene, and it is expensive in terms of equipment costs. , cannot be said to be an advantageous method.

As a result of repeated detailed research in order to improve the drawbacks of the conventional method, the present inventors discovered that from the beginning of sulfonation, by adding 1 to 5 mol% of Glauber's salt to the sulfuric acid used, the isomerization After discovering that the side reactions mentioned above during hydrolysis could be suppressed, he applied for a patent.

Subsequently, the inventors of the present invention continued to conduct related research, and found that from the beginning of the sulfonation of alkylbenzenes, the
Products with mol% to 15 mol% of Glauber's salt added have the same side reaction suppressing effect as those with 1 to 5 mol%, and those with 5 mol% added have a hydrolyzed product of 80%. They found that when left to stand at a high temperature of .degree. C. or higher, the product separates into a sulfonic acid layer and a sulfuric acid layer, and the supercharge sulfuric acid can be easily separated and removed, and after studying the surrounding circumstances, they completed the present invention.

In the present invention, an alkylbenzene or an alkylbenzenesulfonic acid mixture is heated in the presence of sulfuric acid and an inorganic salt of 5 to 15 mol % of the sulfuric acid at a temperature in the range of 150 to 210°C to obtain an alkylbenzenesulfonic acid with a high m content. After selectively hydrolyzing the monomer extra alkylbenzene sulfonic acid obtained, the hydrolysis reaction solution is allowed to stand still and separated into layers,
This is a method for producing m-alkylhydroxybenzene, characterized by separating the separated alkylbenzenesulfonic acid layer and causticly melting the separated alkylbenzenesulfonic acid layer.

Alkylbenzenes suitable for use in the present invention include:
Examples include toluene, ethylbenzene, isopropylbenzene, xylene, and the like, which are alkylbenzenes from which alkylbenzene sulfonic acids with a high content of m monoisomer can be obtained by isomerization or hydrolysis. In addition, the inorganic salt used in the present invention includes sodium sulfate (
Glauber's Salt), acidic sodium sulfate are most preferred.

The reaction between alkylbenzene and sulfuric acid in the present invention can be carried out under conditions well known in this type of technology in the presence of an inorganic salt. That is, when anhydrous sodium sulfate is added to alkylbenzene and the mixture is reacted with sulfuric acid at a temperature of 50 to 150°C, an alkylbenzene sulfonic acid having a high content of p-units can be obtained. The alkylbenzenesulfonic acid is added in the presence of sulfuric acid, preferably at a molar ratio of sulfonic acid to sulfuric acid of about 2:1, to a concentration of 150 to 210
Temperatures in the range of 180 to 210 °C, preferably 180 to 210 °C
By heating, the alkylbenzenesulfonic acid is isomerized, and the p-unit and the m-unit are equimolar at about 7 degrees or m
The total content increases. Alternatively, by adding an inorganic salt to alkylbenzene and reacting it with an excess amount of sulfuric acid at a temperature in the range of 150 to 210°C, a sulfonic acid mixture containing equal moles of p-units and m-units or a high m-unit content is produced. .

Next, the obtained sulfonation or isomerization reaction mixture was
Temperature in the range of ~180°C, preferably 150-170°C
Addition of water or steam distillation at temperatures in the range of
Under selective hydrolysis, the p-alkylbenzenesulfonic acid becomes alkylbenzene and sulfuric acid, and the alkylbenzene is distilled out of the thread azeotropically with water and reused as additional feedstock or used as starting material. Ru.

Next, the obtained hydrolysis reaction solution is preferably 80 to 170
The culm is allowed to stand for 30 minutes to 1 hour at a temperature in the range of °C to separate the layers. Separate the separated sulfonic acid layer and sulfuric acid layer. In this case, the difficulty of layer separation and separation efficiency depend on the amount of the inorganic salt added at the beginning of the sulfonation, the monolithic content of the reaction solution after hydrolysis, the temperature, etc. The first objective of the present invention is to stabilize sulfonic acid during the high-temperature reaction between alkylbenzene and sulfuric acid, and the addition of inorganic salts for this purpose requires the addition of IR! L1 to 15 mol%. If the amount is less than 1 mol %, side reactions such as oxidation and decomposition cannot be suppressed. 15
When the amount exceeds mol %, the hydrolysis reaction is also suppressed and the content of p is increased.

The amount of mirabilite added, which has the effect of suppressing such side reactions, is also
The static separation of the hydrolyzed solution, which is the second object of the present invention, must be further restricted.

In other words, for those containing 4 mol% or less of mirabilite, 80
At temperatures above ℃, the sulfuric acid layer cannot be separated because the layers do not separate. When lowered to a temperature of 80° C. or lower and allowed to stand still, it separates into layers, but the boundaries are unclear and there is an industrial disadvantage in terms of cooling time and the like. Therefore, the amount of Glauber's salt added in the present invention is 5 to 15 mol %, which is substantially effective. The amount of sulfonic acid dissolved in the separated sulfuric acid layer is 1% by weight or less, and the inorganic salts dissolved in the same layer precipitate at room temperature, so they can be easily separated by P and reused next time. be done. The P solution obtained by separating the inorganic salts into P parts can be used for other purposes as highly concentrated sulfuric acid. Furthermore, the effect of adding Glauber's sulfate can be obtained not only by adding Glauber's sulfate from the beginning of sulfonation, but also after sulfonation and before isomerization. Even if it is added just before hydrolysis, the effect remains the same. Furthermore, the effect of layer separation between the sulfonic acid layer and the sulfuric acid layer due to the addition of an inorganic salt exhibits an excellent effect on the liquid that has completed the hydrolysis reaction, but does not separate the layers in the liquid that has completed the sulfonation or isomerization. It is also impossible to separate sulfuric acid.

This suggests that the layer separation effect due to the addition of an inorganic salt is recognized in relation to the isomer composition in the reaction solution. In other words, in a mixed solution of 0- or p-alkylbenzenesulfonic acid or a mixed sulfonic acid with a high ratio of those sulfonic acids and sulfuric acid, even if an inorganic salt is added, layer separation does not occur, and when the monolithic content reaches a certain ratio, the inorganic salt is added. This results in a sharp layer splitting effect.

After hydrolysis, the alkylbenzene sulfonic acid that has been left to stand, separated into layers at a temperature of 80 to 170°C is converted into an alkali salt with, for example, sodium hydroxide, and then caustic-dissolved with sodium hydroxide under conditions well known in the art. hand,
The desired m-alkylhydroxybenzene is obtained. In the method of the present invention, the amount of free sulfuric acid in the sulfonic acid layer separated from the hydrolysis reaction solution is less than half of that in the case of no separation, so when making it into an alkali salt, the amount of alkali used is reduced. , it is economically advantageous.

In addition, the neutralized sulfonate can be directly melted with caustic material without removing the formed inorganic salt, and even when the sulfonate and the formed inorganic salt are separated, the amount of inorganic salt is small. It does not require concentration and can be separated very easily, which is advantageous compared to other previously known methods.

By the production method of the present invention, the oxidative decomposition of alkylbenzenesulfonic acid is significantly suppressed even at high temperatures of 200°C or higher,
As a result, it has become possible to carry out sulfonation, isomerization, and hydrolysis reactions at high temperatures and over long periods of time, and it has become possible to obtain hydroxybenzene with a monolithic m content of over 98% in a high yield and with high economic efficiency.

The method of the present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples.

Examples 1 to 4 Comparative Examples 1 to 2 In the presence of anhydrous sodium sulfate, ethylbenzene is sulfonated with sulfuric acid, isomerized, and hydrolyzed, excess sulfuric acid is separated, neutralized, and melted with alkali to synthesize m-ethylphenol. The composition of the reactants was confirmed for each step, and the relationship with the amount of added sodium sulfate was investigated.

II! Pour 600y of 98% sulfuric acid into a Yotsuro flask,
While stirring, add anhydrous sodium sulfate in an amount equivalent to the mole % based on sulfuric acid shown in Table 1. Next, ethylbenzene 4249 was added over 30 minutes, and the temperature was gradually increased. It takes 2 hours to raise the temperature to 200°C while removing distilled water. The mixture is heated and stirred at the same temperature for 4 hours for isomerization.

The composition of the sulfonated product was determined and shown in Table I. The composition ratios in the table are expressed in weight %. BSA is benzenesulfonic acid,
TSA is an abbreviation for toluenesulfonic acid, and ESA is an abbreviation for ethylbenzenesulfonic acid.

Table I Sulfonic acid composition at the end of isomerization Next, the internal temperature of the isomerization reaction product is lowered to 170°C.

While maintaining the same temperature and stirring, 1100 me of water was continuously added dropwise at a uniform rate over a period of 10 hours to carry out hydrolysis. The obtained reaction mass is allowed to stand at a temperature of 150° C. for 30 minutes, and the separated sulfonic acid layer and sulfuric acid layer are separated. Table H shows the sulfonic acid composition of the sulfonic acid layer and the sulfuric acid cut rate. The composition ratios in the table are expressed in weight %. BSA, T
The abbreviations of SA and ESA are the same as in Table I. However, in the case of no addition of mirabilite and in the case of addition of 2 mol % of mirabilite, no layer separation occurred even when the temperature of the hydrolysis reaction solution was lowered to 80° C. and allowed to stand, so the sulfuric acid cut rate was set as I/'io.

Table ■ Sulfonic acid composition and separated sulfuric acid cut rate at the end of hydrolysis (
%) Subsequently, 50% caustic potassium solution was added to the separated sulphonic acid layer to neutralize it to pH 8, and the resulting slurry was
Drop into a mixture of 282y of caustic soda and 42y of caustic potassium molten at .

After the dropwise addition, the temperature of the contents was raised from 330°C to 340°C, and stirred and held at 340°C for 60 minutes. The resulting molten reaction product was dissolved in 1,000 ml of water and neutralized to pH 7.2 with 35% hydrochloric acid.

The produced phenols were extracted with ether, distilled, and further fractionated to determine the phenol composition and ethylphenol yield, which are shown in Table 3. Yields were determined relative to ethylbenzene consumed. The composition ratio is expressed in weight percent; PH is phenol, cR is cresol, and EpH-t is ethylphenol.

Table ■ Phenol composition after caustic melting and yield of ethylbenzene to consumed ethylphenol (%) As can be seen from these experimental results, when sulfonate is added to ethylbenzene, the amount of benzene sulfone is increased compared to when no addition is made. It contains less acid, toluenesulfonic acid, and unknown components, and has high purity and yield of ethylphenol. That is, in high-temperature sulfonation of ethylbenzene, 2 to 1
It is clear that when 5 mol% of Glauber's salt is present, Glauber's salt contributes to the stability of ethylbenzenesulfonic acid and suppresses side reactions.

However, when the amount of added mirabilite was 2 mol %, although the effect of suppressing side reactions was promoted, the layer did not separate even if it was allowed to stand at the end of hydrolysis, and sulfuric acid could not be separated. When the amount of Glauber's salt used is about 4 mol % based on the sulfuric acid used, phase separation and separation after hydrolysis become easier, and side reactions are also suppressed. However, if it exceeds 15 mol %, the hydrolysis reaction will also be suppressed and the composition ratio of p will increase, and the interface between the sulfonic acid layer and the sulfuric acid layer will become unclear and separation will become difficult.

Example 5 1200p of 98% i acid was charged into a 21-four flask,
While stirring, 102 y of anhydrous sodium sulfate (addition rate: 6 mol %) was added, and 424 y of ethylbenzene was added over 30 minutes. The temperature was gradually increased to 200° C. over a period of 2 hours while removing distilled water.

The mixture was kept at the same temperature for 4 hours for isomerization.・Reactant at 170℃
At the same temperature, 2000 y of water was injected at a constant rate over 10 hours while stirring to complete the hydrolysis. When the obtained reaction mass was allowed to stand at around 150° C. for 30 minutes, it was separated into a sulfonic acid layer and a sulfuric acid layer, and the sulfuric acid layer was separated and removed. The sulfonic acid layer of the fractionated 1074p (which was 854y) was neutralized with a 50% caustic potassium solution at pH 7.84,
Caustic No. 5632 and Caustic Potassium 83y were added dropwise into a mixed melt heated and melted at a temperature of 330° C. in a No. 21 melting pot. After dropping, the temperature of the contents was set to 340t? The temperature was raised to , and stirred and maintained at the same temperature for 60 minutes. The melted reactant was then heated to 2000
Dissolved in me water, neutralized to pH 7.2 with 35% hydrochloric acid,
The produced phenols were extracted with ether and distilled to obtain 348 g of crude m-ethylphenol. Yield of ethylbenzene based on consumption was 71%. The purity of fractionally purified m-ethylphenol was 9862%.

Example 6 98% sulfuric acid 1090% is charged into a 1 liter flask, and anhydrous sodium sulfate 103y (11 addition rate 6.7%) is added while stirring. 503y of toluene was poured over 30 minutes. The temperature was gradually increased to 195° C. over 2 hours, and the mixture was then heated and stirred at the same temperature for 4 hours to perform isomerization. Then, after lowering the temperature to 165℃, 100% water was added while maintaining the same temperature.
0y was continuously added dropwise at a constant rate over a period of 10 hours. The recovered toluene distilled out together with water vapor by hydrolysis is 21
It was 62. When the reaction mass after hydrolysis is left at 150°C for 30 minutes, it separates into two layers, a 695y sulfuric acid layer and a 104y sulfuric acid layer.
The 0y sulfonic acid layer could be separated. The sulfonic acid layer is 50
After neutralization with a % caustic potash solution, m-cresol 242y with a purity of 98% was obtained by caustic melting, post-treatment, and fractional distillation according to the method of Example 5.

Example 7 1,700 y of 98% sulfuric acid was charged into a flask 31, 120 y of anhydrous sodium sulfate (addition rate 5%) was added while stirring, and further m
-Dropped 1100y of xylene, took 2.5 hours to
The temperature was raised to 0°C and kept at 175-180°C for 3 hours to perform isomerization. The temperature was lowered to 150°C, 700y of water was continuously added dropwise over 3 hours at the same temperature, and the reaction product was allowed to stand for 1 hour to form a sulfonic acid layer of 2334y and 60% of 760y.
The concentrated sulfuric acid layer was separated. Recovered mexylene is 2702
Met. After neutralizing the sulfonic acid layer according to the method of Example 5, caustic melting and post-treatment were performed to obtain 3,5-xylenol 7.
Obtained 07y. The purity was 97%.

Patent applicant: Taoka Chemical Industry Co., Ltd.

Claims (1)

[Claims] 1. Heating an alkylbenzene or a mixture of alkylbenzenesulfonic acids at a temperature in the range of 150 to 210°C in the presence of sulfuric acid and an inorganic salt of 5 to 15 mol% of the sulfuric acid, After obtaining a large amount of alkylbenzene sulfonic acid and selectively hydrolyzing m monomer alkylbenzene sulfonic acid, the hydrolysis reaction solution is allowed to stand still and separated into layers.
'IJ method' 1k of m-alkylhydroxybenzene, which is characterized by separating the entire separated alkylbenzenesulfonic acid layer and causticly melting it. 2. The step of allowing the hydrolysis reaction solution to stand still, separating the layers, and separating the separated alkylbenzenesulfonic acid layer is from 80 to 170
The manufacturing method according to claim 1, characterized in that the manufacturing method is carried out at a temperature in the range of °C.