JPH029012B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an industrially advantageous method for producing m-alkylhydroxybenzenes. As a method for obtaining highly pure m-alkylhydroxybenzene from alkylbenzene via alkylbenzene sulfonic acid, for example,
33192, Japanese Patent Publication No. 49-33193, Japanese Patent Application Laid-open No. 49-110638, etc. Their content consists of the following steps: (A) The alkylbenzene sulfonic acid mixture obtained by sulfonating alkylbenzene with sulfuric acid at low temperature is heated in the presence of sulfuric acid at a temperature in the range of 150 to 210°C, or the alkylbenzene is sulfonated with sulfuric acid to a temperature in the range of 150 to 210°C. (B) By maintaining the alkylbenzenesulfonic acid mixture at a temperature of
Preferably, alkylbenzene sulfonic acids other than the m-form are selectively hydrolyzed by contact with water vapor to produce 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) is melted in a caustic manner to obtain m-alkylhydroxybenzene. While researching a method for obtaining the corresponding m-alkylhydrobenzene from alkylbenzene using the conventional method, the present inventors conducted step (B), that is, each isomer of the alkylbenzene sulfonic acid in the composition immediately after the hydrolysis reaction. body content ratio and further process (C) and
It was found that the content ratio of each isomer of the corresponding alkylhydroxybenzene obtained through (D) is different. In general, m-isomers decrease and p-isomers increase. This phenomenon occurs when the scale of the experiment is increased.
It has been confirmed that this is particularly noticeable when manufacturing on an industrial scale. As a result of studying these phenomena, it was found that if the reaction mass after the hydrolysis reaction is allowed to stay at high temperature, the m-isomer is reduced by local hydrolysis and the alkylbenzene dissolved in the reaction mass is re-sulfated by sulfuric acid. It was found that this is due to the formation of p-isomer upon oxidation. Therefore, the present inventors researched a method for preventing the formation of such p-forms, and found that the temperature of the mass was lowered as soon as possible after the hydrolysis was completed, and more advantageously, the sulfuric acid concentration in the mass was rapidly lowered at the same time. The inventors have discovered that the object can be achieved by doing so, and have arrived at the present invention. That is, the present invention heats an alkylbenzene or an alkylbenzenesulfonic acid mixture in the presence of sulfuric acid to obtain an alkylbenzenesulfonic acid with a high m-isomer content, and then selectively hydrolyzes alkylbenzenesulfonic acids other than the m-isomer. , a method for producing m-alkylhydroxybenzene in which an alkylbenzene sulfonic acid that has not undergone hydrolysis is causticly melted, which is characterized in that water is poured immediately after hydrolysis to bring the temperature of the reactant to 150°C or less. - A method for producing alkylhydroxybenzene. Examples of alkylbenzenes suitable for use in the present invention include toluene, ethylbenzene, isopropylbenzene, xylene, etc., and alkylbenzene sulfonic acids with a high content of m-isomer can be obtained by isomerization or hydrolysis. It is an alkylbenzene that can be produced. The reaction of alkylbenzene and sulfuric acid in the present invention is carried out by
49-33192, Japanese Patent Publication 1973-33193, Japanese Patent Publication 1977-
110638, specifically, it can be easily carried out under the conditions clarified in the above steps (A) and (B) and the Examples described below. The temperature of the hydrolyzed reaction-completed mass containing alkylbenzenesulfonic acid with high m-isomer purity as the main component obtained in this way is usually 160 to 180°C, but the temperature of the mass is raised to 150°C by adding water as soon as possible after the reaction. Cool to below °C. In order to rapidly lower the temperature of the mass by pouring water, it is effective to use water with a low temperature, and it is desirable to cool the mass with ice, ice water, or from the outside of the reaction vessel. By doing so, the amount of water does not increase more than necessary, and it is also possible to prevent a decrease in productivity. The injection rate should be as short as possible, and the injection should be performed so that the temperature drops to 150°C or less within one hour, preferably within 30 minutes. In this way, the effect of preventing the hydrolysis of m-isomer and the formation of p-isomer by injecting into the mass after hydrolysis and rapidly lowering the temperature is that the sulfuric acid concentration in the mass is moderately reduced by water injection. The reciprocal effects of this are also contributing. Therefore, in the present invention, water injection after hydrolysis rapidly lowers the temperature of the mass and simultaneously lowers the sulfuric acid concentration in the mass. In the present invention, the steps (C) and (D), that is, the alkaline chlorination and alkali melting reactions of the hydrolyzed alkylbenzenesulfonic acid with high m-isomer purity, are carried out by the conventionally well-known method described in the above-mentioned Japanese Patent Publication No. carried out by. According to the production method of the present invention, alkylhydroxybenzene having an m-isomer content of more than 97% can be obtained in good yield, and especially when carried out on an industrial scale,
- It is possible to stabilize the purity and yield of the compound, which is economically advantageous, and has great effects. Next, the method of the present invention will be explained with reference to Examples, but the present invention is not limited to these Examples. Example 1 3,600 kg of 98% sulfuric acid was charged into a 6,000 reaction vessel, and 2,544
Kg of ethylbenzene is added dropwise over a period of 1 hour.
Gradually raise the temperature to 200°C over a period of 2 hours while removing distilled water. Heat and stir at the same temperature for 4 hours,
Become isomerized. Next, the internal temperature was lowered to 170°C, and at the same temperature, while stirring, steam equivalent to 7,800 ml of water was continuously blown in for 12 hours to perform hydrolysis. 1260Kg
of ethylbenzene was recovered. The isomer ratio m/p of sulfonic acid in the reaction mass immediately after completion of hydrolysis was 96.5/3.5. The sulfuric acid concentration in the water-sulfuric acid system excluding ethylbenzenesulfonic acid in the same reaction mass was 63%. After the completion of the reaction, the hydrolyzed reaction product is analyzed and samples necessary for small experiments are collected. Immediately, external cooling is started, and at the same time, 500 g of water is injected every 30 minutes to lower the temperature and simultaneously reduce the sulfuric acid concentration. At the end of water injection, the temperature had dropped to 130℃. The isomer ratio of sulfonic acid in the obtained reaction mass was m/p=95.5/4.5.
The sulfuric acid concentration in the trout was 56%. 47% in reaction solution
Neutralize to pH 8 by adding caustic soda, heat at 80℃, separate the mirabilite, and mix the mother liquor with 1709 kg of caustic soda and 250 kg.
of caustic potash is added dropwise into the molten mixture heated at a temperature of 330°C in a 6000°C melting pot. 330℃ after dropping
The temperature was raised to 340°C, and the mixture was kept stirring at 340°C for 1 hour. The resulting melted reaction product was dissolved in 6000 ml of water,
Neutralize to PH7.2 with 35% hydrochloric acid. The generated phenols are separated into layers, separated, and distilled to achieve a purity of 93.8%.
Crude m-ethyl phere was obtained. 97.7 by fractional distillation
% purity m-ethylphenol was obtained. The yield was 63% based on consumed ethylbenzene. Comparative Example 1 Immediately after the hydrolysis in Example 1, 1/2
A sample was taken on a 1000 scale, and the temperature was lowered to 130°C in 4 hours using only external cooling without injection. The isomer ratio of sulfonic acid in the obtained reaction mass was m/p=91.5/8.5. Thereafter, crude m-ethylphenol with a purity of 90.5% was obtained in the same manner as in Example 1. By fractional distillation, m-ethylphenol with a purity of 94.1% was obtained. Examples 2 to 4 Table 1 was added to each sample taken on a 1/1000 scale from the reaction mass immediately after the hydrolysis in Example 1 was completed.
Sulfuric acid concentration shown in (concentration in water-sulfuric acid system in mass)
Water was added so that the temperature was as shown in Table 1, and the temperature was adjusted externally to maintain the temperature shown in Table 1 for 4 hours. Among the sulfonic acid compositions in the mass, the values of m- and p-ethylbenzenesulfonic acid were measured, and the relative ratios of m-form and p-form were determined as m/p ratios and are shown in Table 1. Furthermore, the purity of m-ethylphenol obtained by post-treatment according to Example 1 is shown in Table 1. Comparative Example 2-4 Immediately after the completion of the hydrolysis in Example 1, samples were taken on a 1/1000 scale from the reaction mass and were maintained at the temperature shown in Table 1 for 4 hours without adding water while controlling the temperature from the outside. The m/p ratio in the mass was determined according to Examples 2 to 4 and is shown in Table 1. Furthermore, the purity of m-ethylphenol obtained by post-treatment according to Example 1 is shown in Table 1.

[Table] From the results of Examples 1 to 4 and Comparative Examples 1 to 4,
After the hydrolysis is completed, if the temperature is kept at the same temperature as during the hydrolysis reaction or slightly lower, the hydrolysis of the m-isomer will proceed further, while the p-isomer will increase considerably, but if water is poured It can be seen that side reactions can be suppressed by simply lowering the temperature suddenly (Comparative Example 4).
However, as in Comparative Example 1, there is no effect at all in lowering the temperature to 130°C for a long time. On the other hand, if you add water after hydrolysis, even at 150℃,
It is clear that it is sufficiently effective. Example 5 1509 kg of toluene was charged into a 3000 reaction vessel, and while stirring, 3270 kg of 98% sulfuric acid was added dropwise over 1 hour.
Heat up to 190℃ over time. 4 at 185-190℃
Isomerization is carried out by stirring for hours. Next, the temperature is lowered to 160°C, the temperature is maintained at 160 to 165°C, and steam equivalent to 3000 ml of water is continuously blown in at a constant rate over a period of 10 hours. The hydrolyzed p-toluenesulfonic acid returns to toluene and sulfuric acid, and toluene is distilled out of the system by azeotroping with water. The amount of toluene recovered was 741Kg. When calculating the ratio of m-toluenesulfonic acid and p-toluenesulfonic acid in the mass after hydrolysis,
It was 96.3/3.2. On the other hand, the mass after the hydrolysis reaction was immediately started to be cooled from the outside, and 250 g of water was injected over 30 minutes to lower the sulfuric acid concentration at the same time as the temperature was lowered. The temperature at the end of water injection is
The temperature dropped to 120℃. The m/p ratio in the mass was 96.4/3.6, almost unchanged from the time at the end of hydrolysis. The cooled mass was then neutralized with 47% caustic soda and subjected to alkali melting and post-treatment according to Example 1 to obtain 584 kg of m-cresol with a purity of 97.5%. Comparative Example 5 After sulfonation, isomerization, and hydrolysis were performed simultaneously with Example 5, the internal temperature was reduced to 130°C by cooling only with external cooling.
Keep temperature below ℃. Cooling time required 3 hours. The obtained reaction product was treated in the same manner as in Example 5 to obtain a purity of 94%.
574 kg of m-cresol was obtained. Example 6 1700 kg of 98% sulfuric acid was charged into a 3000 reaction vessel, 1100 kg of meta-xylene was added dropwise with stirring, and the temperature was raised to 180°C over a period of 2.5 hours. Then 3 at 175-180℃
Keep warm for a while to perform isomerization. Temperature drops to 150℃, water
Hydrolysis was carried out by continuously blowing water vapor equivalent to 700 ml of water at the same temperature for 3 hours. Meta-xylene, which was distilled out along with water vapor through hydrolysis, was separated from water and recovered in an amount of 270 kg. After hydrolysis, cooling was started and 200 g of water was injected over 30 minutes. After injection the temperature dropped to 120°C. The mixture was neutralized with 47% caustic soda and subjected to alkaline melting and post-treatment according to Example 1 to obtain 697 kg of 3.5-xylenol with a purity of 96%. Comparative Example 6 In Example 6, when the sample was cooled only by external cooling after hydrolysis, it took 3 hours to cool to 120°C.
After that, it was treated in the same manner as in Example 6 to obtain a purity of 94%.
687 kg of 3.5-xylenol was obtained.

Claims (1)

[Claims] 1 Heating an alkylbenzene or an alkylbenzene sulfonic acid mixture in the presence of sulfuric acid,
After obtaining an alkylbenzenesulfonic acid with a high content of the m-isomer and selectively hydrolyzing the alkylbenzenesulfonic acid other than the m-isomer, the alkylbenzenesulfonic acid that has not undergone hydrolysis is causticly melted to produce m-alkylhydroxybenzene. In the production method, water is poured immediately after hydrolysis to bring the temperature of the reactant to 150°C or less.
-A method for producing alkylhydroxybenzene.