JPS6045185B2 - Method for sulfonating aromatic compounds - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for sulfonating aromatic compounds, which is characterized in that sulfonation is carried out with sulfur trioxide so as to increase the coexistence rate of sulfonic acid in a reaction zone from the initial stage of the reaction.

More specifically, by setting the alkylbenzene sulfonation to be carried out in the presence of a considerable amount of sulfonic acid from the initial stage of the reaction, for example, the selectivity of the reaction can be improved,
Alternatively, a sulfonation method with characteristics such as suppressing side reactions, or more specifically, an ortho- ortho The present invention relates to a sulfonation method that makes it possible to produce bulk and bulk alkylbenzenesulfonic acids, particularly bulk alkylbenzenesulfonic acids, and particularly bulk alkylphenols with good purity and high yield at low cost. Lower alkylbenzene sulfonic acids have a wide range of uses and are useful as intermediates for agricultural chemicals, medicines, dyes, and others.In particular, alkylphenols obtained by melting them with alkali are used as phenolic resins and antioxidants. It is widely used as a raw material for making agricultural chemicals, medicines, dyes, etc.

For example, phenolic resins made from rose alkylphenols are known to have significantly better color stability than those made from ortho- or meta-alkylphenols; As, each rose
Cresol and paraethylphenol are used. As described above, industrial demands often require bararalkylphenols with good purity. However, when alkylbenzene is sulfonated using a sulfonating agent such as sulfuric acid, oleum, or sulfur trioxide in the conventional method, the ortho and vara orientation of the alkyl group is not so strong, and especially in the case of alkylbenzenes with small alkyl groups, the steric orientation is Since the effect of disability is small, the generation of meta-bodies reaches a considerable rate that cannot be ignored. In this way, when alkylbenzene is sulfonated to produce alkylbenzene sulfonic acid and this is melted in an alkali to produce alkylphenol, it is important to first control the selectivity of the three isomers, ortho, meta, and rose, during sulfonation. However, this naturally has its limits.

For this reason, in the past, it was necessary to separate the isomers at the sulfonic acid stage or the alkylphenol stage in order to produce each single substance. From an industrial perspective, separation by distillation is generally the cheapest and most advantageous separation method as long as there is a sufficient difference in boiling point, but unfortunately, the boiling points of ortho, meta, and bulk isomers are lower than that of cresol, for example. 191.1℃, 202.7C1202.5 respectively
℃, and in the case of ethylphenol, 204.degree.
Since the temperature is 5° C. and 218.4° C., only the ortho form can be isolated by distillation, but the meta form and bulk form cannot be separated by distillation. Therefore, although various efforts have been made and patents have been issued, there is no inexpensive separation method, and we have no choice but to separate the sulfonic acid based on the difference in solubility, or to convert it into an alkylphenol and then convert it into tertiarybutyl.
Various efforts have been made to separate the alkylphenols, such as separating them by distillation and then removing isobutylene to obtain meta- and bulk alkylphenols, but the drawback of conventional methods is that the cost of separation becomes enormous. Based on the above, if we develop a sulfonation method that generates no or very little meta-form,
Since the isomers of the crude alkylphenol obtained by alkali melting of the alkylbenzenesulfonic acid produced can be isolated only by distillation, the process is much simpler, and it is clear that this is very advantageous industrially. .

Conventionally, as a method for producing sulfonic acid with a small amount of meta-isomer, a method of sulfonation of toluene with sulfuric acid (US Pat. No. 23,626) has been proposed.
1) is well known, but because it requires the use of a large excess of toluene and sulfuric acid to remove the water produced in the sulfonation reaction, the equipment is larger than when using sulfur trioxide. , and wastes a lot of thermal energy, so it cannot be called an economical industrial manufacturing method. In addition, a method of sulfonation using gaseous sulfur trioxide in the presence of acetic anhydride or phosphoric anhydride (
JOurrralfur'゜PraktischenC
hemie. sUfu 139 (1935)), but as a result of repeated trials with this method, contrary to what is described, a considerable amount of meta-form was produced, and in addition, the by-product of sulfone was around 20% when the toluene raw material was used. It was found that the yield of the desired toluenesulfonic acid was significantly reduced.

(See Comparative Example 2). Therefore, this method is far from being a practical method for producing individual bulk alkylbenzenesulfonic acids. Furthermore, in the recently published German patent application No. 2413444, it is necessary to use sulfur trioxide diluted with an inert gas and use a large excess of toluene, so the reactor per unit product is large and a large amount is required. The process and equipment for recovering and recycling toluene and energy consumption are complicated and large, which is not economical or industrial.

As mentioned above, several sulfonation methods have been reported that produce no or only a small amount of meta-isomers for sulfonation of toluene, but as a result of additional trials or studies, all of them are unsatisfactory for industrial implementation. It is.

Furthermore, ethylbenzene and other alkyl groups have 2 carbon atoms.
I can't find any reports of this type for anything other than that. Furthermore, in the sulfonation reaction, by-products such as disulfonic acid and sulfone cannot be ignored as they reduce the yield of the desired sulfonic acid.

This by-product rate varies depending on the sulfonating agent used, and for example, literature values in the case of sulfonation of toluene are as shown in the following table. That is, when sulfur trioxide is used, it is recognized that particularly large amounts of sulfone and disulfonic acid are produced as by-products.

Sulfone is not substantially produced in the sulfonation of alkylbenzenes with large alkyl groups, such as dodecylbenzene, but when the alkyl groups are small or in the case of benzene, as long as sulfur trioxide is used, there is a tendency for a considerable amount of sulfone to be produced. , especially in the case of benzene.

Therefore, when sulfonating benzene and lower alkylbenzenes such as toluene and ethylbenzene using sulfur trioxide as a sulfonating agent, it is necessary to sufficiently suppress these by-products. Conventionally, in order to suppress by-products such as disulfonic acid and sulfone and to improve the yield of alkylbenzenesulfonic acid, sulfur trioxide was added with various ethers such as dioxane, various amines such as pyridine, and dimethylformamide. The reactivity of sulfur trioxide can be reduced by creating a compound, or the reactivity of sulfur trioxide can be reduced by coexisting with an inert solvent such as liquid sulfur dioxide, dichloroethane, trichloroethane, carbon tetrachloride, sulfolane, or nitrobenzene. Methods for suppressing reactivity have been proposed.

According to these methods, by-products such as disulfonic acid and sulfone are significantly suppressed, and alkyl bene. The yield of sulfonic acid improves accordingly, but on the other hand, it requires a great deal of labor and expense to separate and recover the solvent and added substances, the equipment becomes complicated, and measures against the risk of explosion and toxicity need to be taken. necessary, so it was impractical from an industrial standpoint. As a result of extensive research, the present inventors have discovered that when sulfonating alkylbenzene having an alkyl group having 1 to 8 carbon atoms with sulfur trioxide, a considerable amount of sulfonic acid is allowed to coexist in the raw alkylbenzene in advance. By performing sulfonation, almost no meta-alkylbenzene sulfonic acid is produced in the sulfonation reaction product, and in addition, undesirable by-products such as disulfonic acid, sulfone, and sulfuric acid are significantly produced. The present invention was completed based on this finding.

The reason for this effect is not clear, but at least the sulfonic acid forms a complex with sulfur trioxide, which relaxes the reaction, or the selectivity of the reaction improves due to steric factors. It is thought that this may be the case. In the process of the invention, sulfur trioxide can be supplied in liquid or gaseous form.

Therefore, compared to a method using a diluting gas, there is an advantage that there is no entrainment loss due to the diluting gas. Under the conditions of the invention:
Although the reactivity of sulfur trioxide is moderated, it still easily reacts with alkylbenzenes.

The reaction mixture during the reaction therefore consists primarily of alkylbenzene sulfonic acid, unreacted alkylbenzene and excess sulfur trioxide, especially if added in excess. In the process of the present invention, sulfonation is carried out in the presence of a considerable amount or a similar amount of sulfonic acid in the reaction mixture at the initial stage of the reaction, and meta-alkylbenzene sulfonic acid, disulfonic acid and sulfonic acid are Although the production is greatly suppressed, the higher the concentration of sulfonic acid in the reaction mixture during the sulfonation reaction, the lower the production rate of meta-alkylbenzenesulfonic acids, disulfonic acids, and sulfones. Therefore, the coexistence ratio of sulfonic acid is preferably at least 0.5 times the mole of raw material alkylbenzene, preferably at least equimolar times! More preferably, the amount is 1.5 times or more by mole or more. Note that if alkylbenzene and excess sulfur trioxide are simultaneously supplied, the sulfonic acid concentration at the initial stage of the reaction will be further increased, resulting in the production of meta-alkylbenzene sulfonic acid and sulfone, disulf! Although it has the effect of suppressing the formation of fonic acid, etc., undesirable by-products such as disulfonic acid may increase only when the reaction temperature is particularly high. The content is preferably 10 mol% or less. Therefore 1
If the excess amount is 0 mol % or more, the reaction temperature should be lowered accordingly, and if it is 50% or more, it is desirable to lower the reaction temperature to 30°C or less. In addition, in a batch reaction in which sulfur trioxide is added to alkylbenzene, there is no point in adding excessive amount. In the method of the present invention, the sulfonic acids coexisting at the initial stage of the reaction may be the same as or different from the sulfonic acids produced, but it is more convenient for them to be the same in view of the necessity of the subsequent separation step.

From an economic point of view, it is therefore advantageous to recycle 1 part of the previous reaction product. (Hereinafter, the reaction product to be recycled will be referred to as a recycle liquid.) The method of the present invention is a new method for increasing the purity and yield of the target sulfonic acid, and is a method for ensuring the coexistence state of the sulfonic acid. In short, sulfonic acid is appropriately added in advance.

More specifically, specific methods for sulfonation in a state in which a considerable amount of sulfonic acid is present in the raw materials or reaction mixture from the initial stage of the reaction include (1) a complete mixing type, preferably in a stirring tank; Alkylbenzene and sulfur trioxide (hereinafter referred to as two raw materials) are simultaneously fed using a metering pump at a molar ratio of approximately 1 while a considerable amount to some amount of sulfonic acid or recycle liquid is present in the reaction tank at the initial stage of the reaction.

At this time, the smaller the amount of sulfonic acid or recycle liquid present at the beginning of the reaction, the simultaneous supply of the two raw materials is started at a feed rate that is not faster than the sulfonation rate, and the production of sulfonic acid increases.
As the supply rate accumulates, the supply rate can be increased and when a suitable rate is reached, withdrawal can be started to achieve a steady state (continuous method), or the withdrawal method can be omitted and the sulfonic acid content remains high throughout. Sulfonation can also be carried out at a lower coexistence rate (Example 3). If the amount of sulfonic acid or recycle liquid initially present is 0.1 mole or more relative to the reactor capacity, the amount of the two raw materials (depending on the feed rate of the two raw materials, but if the rate is normal) It is also possible to supply the mixture at a constant supply rate from the beginning and start withdrawing it after an appropriate period of time to achieve a steady state (continuous type). Generally, when converting a batch type to a continuous type, for example, a continuous tank type reaction tank (single tank)
A reaction method based on the simultaneous supply of two raw materials is used, but in this case, it is said that back mixing is usually disadvantageous. From the point of view of the present invention, this disadvantage is actually an advantage, and the greater the degree of back-mixing, the more advantageous it becomes because sulfonation can be carried out at a high yield with a high coexistence rate of the reaction product sulfonic acid. As mentioned above, in the case of a batch type reaction, if a small amount of sulfonic acid is allowed to coexist at the beginning of the reaction, or the two raw materials are slowly fed, or the two raw materials are temporarily stopped by advancing the 100-shaku head and then restarted appropriately, the reaction can be carried out from beginning to end. This allows for sulfonation with a high coexistence rate of sulfonic acid, but among the existing reaction methods, the simultaneous supply of two raw materials is difficult, whether it is a batch method or a continuous method, even if sulfonic acid is not initially added. This is a reaction method that allows sulfonation with a high coexistence rate of sulfonic acid from the early stage of the reaction. Particularly in the continuous system, the above-mentioned coexistence rate of sulfonic acid is much higher after the steady state. The design for sulfonation with a high coexistence rate of sulfonic acid is as follows:
First, the reaction method is a simultaneous supply of two raw materials, and a design that promotes back-mixing is used, in other words, the sulfonation reaction is carried out in a complete mixing type reaction tank, and furthermore, the sulfonation reaction is carried out in a reaction tank in which more or less sulfonic acid is present at first, and then the sulfonation reaction is carried out. It is most effective if the reaction takes place. As a specific method for promoting back-mixing, known methods for complete mixing such as making the L/D smaller and using a stirrer with strong stirring with vertical mixing power are adopted.

In short, examples are given of the shape of the reaction vessel, stirring equipment, and devised method of supplying raw materials that should be adopted in order to carry out sulfonation in a state where the coexistence rate of sulfonic acid in the reaction zone is as high as possible from the early stage of the reaction.

(2) A method in which a mixed solution of sulfonic acid or recycle liquid and alkylbenzene is continuously reacted with, for example, gaseous sulfur trioxide while being brought into contact with each other in a cocurrent or countercurrent manner, for example, in a wet wall column or a bubble column.

(At this time, another method is to continuously react a mixture of sulfonic acid or recycle liquid and sulfur trioxide (liquid) at as low a temperature as possible while contacting it with alkylbenzene in cocurrent or countercurrent flow just before feeding it to the reactor. (It is also possible to do this.) Simply put, it is a method in which two raw materials are continuously reacted in co-current or counter-current fashion while recycling a portion of the reaction product. (3) A batch method in which sulfonic acid or a recycle liquid is added and mixed in advance to alkylbenzene, and if necessary, sulfur trioxide is supplied to this mixture while stirring as needed (
A method such as Example 7) is exemplified.

Another method for increasing the coexistence rate of sulfonic acid from the early stage of the reaction is to reduce the molar ratio of the two raw materials, alkylbenzene and sulfur trioxide, to be supplied simultaneously as described above to 1 or less. That is, the more sulfur trioxide is used in excess, the greater the proportion of the produced sulfonic acid coexisting with the alkylbenzene at the initial stage of the reaction, and good results can be obtained. Below that, the decrease in yield based on sulfur trioxide cannot be ignored. Therefore, the molar ratio of the two raw materials is generally from 1.5 to 0.5, but for the purpose of the present invention, a range of from 1.0 to 0.6 is particularly preferred. However, when S is in the range of 0.8 to 0.6, it is preferable to lower the reaction temperature from room temperature to 0°C or less. At this time, as a post-treatment, it is economically effective to add an equimolar amount of alkylbenzene to the sulfur trioxide remaining in the product after the reaction and stir to complete the reaction. The feature of the method of the present invention, unlike conventional methods, is that sulfonation is carried out by allowing sulfonic acid to coexist in the reaction zone from the initial stage of the reaction. As shown in Example (3) above, the supply of sulfur trioxide is started after adding a considerable amount of alkylbenzene sulfonic acid to the raw material alkylbenzene, but in this case, the sulfonic acid may be added before the start of the reaction. It may be done immediately after the start of the reaction, or it may be done when the conversion rate of alkylbenzene is 3% after the start of the reaction, but the earlier the addition time after the start of the reaction, the higher the coexistence rate of sulfonic acid at the beginning of the reaction, so the purity and yield of the sulfonic acid obtained will be lower. It is clear that there is an improvement, and the "initial stage of reaction"
In this way, it refers to the time range from before the start of the reaction to the point in time after the start of the reaction when no substantial adverse results appear.

In addition, in the case of the batch type in Example (1), a complete mixing type reaction tank (even a continuous tank type reaction tank is a single tank type, and is equipped with a powerful stirrer that simultaneously causes an upward flow or a downward flow, for example). L/
2) preferably in the presence of a small amount of sulfonic acid or recycle liquid in advance.
As mentioned above, even if there is no sulfonic acid in advance, in example (1), two raw materials are supplied simultaneously, so the coexistence rate of sulfonic acid at the initial stage of the reaction is higher than in other methods. Similarly, in the case of a continuous type reaction tank, in the case of a continuous tank type reaction tank with increased back mixing (single tank type) or a complete mixing type reaction tank, it is preferable that a small amount of sulfonic acid or recycled liquid be present in advance. In the case of a small continuous tank type (multi-vessel type) with back mixing, or in the case of a normal co-current type or counter-current type continuous reaction tower close to piston flow, As in example (2), at least 2
Either one of the raw materials is mixed with a sulfonic acid or recycled liquid in an amount of, for example, 0.5 times or more mole of alkylbenzene, or the sulfonic acid or recycled liquid itself is used as a feed material in addition to the two raw materials. In this continuous system, when two raw materials are supplied to the reaction zone, a considerable amount of sulfonic acid (
This means that the reaction zone is designed so that the recycle liquid (recycled liquid) is continuously supplied and coexists in the reaction zone, and the initial stage of the reaction includes the initial stage of the residence time. Also, to explain the "substantial amount" of the sulfonic acid coexisting in the above-mentioned equivalent amount, in Examples (2) and (3), the larger the amount, the better the result, and it depends on the required purity or yield of the product. However, if high purity and high yield are desired, the coexistence ratio should be determined as shown in example (2).
) and Example (3), the amount of alkylbenzene is at least 0.5 mole times or more, preferably equimolar times or more, particularly preferably 1
．． It means a quantitative ratio of 5 moles or more.

In addition, in the case of example (1), the two raw materials are supplied simultaneously without necessarily coexisting a considerable amount of sulfonic acid in advance,
In addition, since the reaction is carried out in a complete mixing type reactor, for example, depending on the supply rate of the two raw materials, by the time the conversion rate is 3%, the coexistence rate of sulfonic acid has reached a considerable level, and after that, the raw material supply method can gradually maintain a high level. Further, if at least a small amount of sulfonic acid is present in advance, even more preferable results can be obtained.
Moreover, even if the reaction is started without sulfonic acid, the feeding rate of the two raw materials is initially slowed down only in the early stage of the reaction, and then as sulfonic acid is produced and accumulated, the feeding rate is increased to maintain a constant rate, and the batch process is performed. It is also possible to guarantee sulfonation in the presence of a high sulfonic acid, regardless of whether it is a continuous method or not. In contrast to known toluene sulfonation methods, in which the temperature of the sulfonation reaction is generally limited to a relatively narrow temperature range, in the method of the present invention, the temperature range is wide, i.e., from -50°C to
A temperature range of 180°C may be employed.

However, since the formation of meta-alkylbenzenesulfonic acid tends to be suppressed at lower temperatures, a temperature within the range of -10°C to 50'C is preferably employed. The starting material in the present invention is an alkylbenzene having a side chain of an alkyl group having 1 to 8 carbon atoms, such as toluene, ethylbenzene, propylbenzene, butylbenzene, pentylbenzene, hexylbenzene, heptylbenzene, octylbenzene, and the like.

Further, the above alkylbenzenes may be used alone or in mixtures. In the method of the present invention, by simply carrying out sulfonation with sulfur trioxide in the presence of sulfonic acid, on the one hand, the production rate of meta-alkylbenzenesulfonic acids can be reduced, and on the other hand, it is possible to reduce the production rate of meta-alkylbenzenesulfonic acids, and on the other hand, it is possible to reduce the production rate of meta-alkylbenzenesulfonic acids. By-products can be suppressed, but if necessary, a known sulfone inhibitor may be used in combination.

For example, ethers such as dioxane, amines such as pyridine, organic carboxylic acids such as acetic acid, etc. can also be used at the same time. Acetic acid is also a preferred sulfone inhibitor because it is inexpensive, requires no or easy removal or separation in subsequent steps, and is nontoxic. The present invention is industrially advantageous because good results can be obtained without using a solvent.

However, a solvent may also be present. After the reaction is completed, the reaction solution can be used as is in the next reaction, unless an excess of sulfur trioxide is used.

Alternatively, it is generally possible to precipitate and separate the target substance by injecting water. One advantage of the present invention is that the meta-alkylbenzene sulfonic acid is produced in such a small amount that it cannot be detected without a specially developed analytical method. The advantage is that, by simply melting the alkylphenol with an alkali and separating it by distillation, highly pure orthoalkylphenol and paraalkylphenol can be produced industrially in very high yields and in good purity, that is, at low cost. . Furthermore, another advantage of the present invention is that by-products such as sulfone, disulfonic acid, and sulfuric acid can be suppressed, so the desired ortho- and para-alkylbenzene sulfonic acids can be obtained in high yield and with good purity. The advantage is that alkylphenol can be obtained with good purity and high yield.

Furthermore, the sulfonation method of the present invention does not involve the use of toxic compounds or the risk of explosion, can be easily and safely operated, and is an extremely simple process in terms of equipment and process. It is an economical sulfonation method or a method for producing alkylbenzene sulfonic acids. Although the method of the present invention can be carried out either batchwise or continuously as described above, it will be explained more specifically in Examples and Comparative Examples below.

It should be noted that these are merely illustrative, and needless to say, the present invention is not limited thereto. Example 1 A 1 mol each of alkylbenzenesulfonic acid and alkylbenzene was charged in advance into a 4-bottle flask with an internal volume of 1 L equipped with a stirrer, a cooler, a raw material supply port, and a thermometer, and then the alkylbenzene and the alkylbenzene were charged while maintaining the reaction temperature at 50°C. Liquid sulfur trioxide was continuously supplied using a metering pump for reaction.

The alkylbenzene was fed at a rate of 1 mol/Hr, and sulfur trioxide was fed and reacted at a rate such that the molar ratio of each experiment was as shown in the table below. The reaction time was 2 hours in all cases. The results are shown in Table 1, Experiments 1-5. (Calculations were made excluding the charged sulfonic acid.) Comparative Example 1 Using the same equipment as in Example 1, 3 moles of alkylbenzene were charged into four Lof flasks, the reaction temperature was maintained at 50°C, and liquid sulfur trioxide was determined. Yellow was continuously supplied using a metering pump to cause a reaction.

The supply time of sulfur trioxide was 2 hours, and the supply rate was set to the molar ratios shown in Table 1, Experiments 6 to 8, respectively. The results are shown in Table 1, Experiments 6-8. As is clear from now on,
In Example 1, in which sulfonation was started in the coexistence of sulfonic acid in an equimolar amount with the alkylbenzene at the initial stage of the reaction, and two raw materials, alkylbenzene and sulfur trioxide, were simultaneously supplied, the meta-isomer was body and sulfone,
The production rate of disulfonic acid was significantly reduced in both cases of toluene and ethylbenzene, and the effect of the coexistence of sulfonic acid is clear.

Example 2 Using the same equipment as in Example 1, a mixture of 1 mol of ethylbenzene and 1.8 mol of ethylbenzenesulfonic acid was first charged into 4 flasks, and ethylbenzene and liquid sulfur trioxide were added while maintaining the reaction temperature at 50°C. 1.0 mol/hour and Ql. The mixture was fed and reacted for 2 hours at a feed rate of 5 mol.

The results are shown in Table 1, Experiment 9. (The calculation was made by subtracting the ethylbenzenesulfonic acid charged.) It can be seen that as the sulfonic acid concentration at the beginning of the reaction is further increased, the production of m-units decreases accordingly, and the by-products such as sulfones also decrease accordingly. Example 3 Using the same apparatus as in Example 1, a recycled solution of the reaction product of Example 2 (approximately 1 J11) containing 0.3 mole of ethylbenzenesulfonic acid was added to four flasks. Ethylbenzene and liquid sulfur trioxide were each supplied at a rate of 0.5 mol/Hr for the first 30 minutes under strong stirring, and then the next three powders were each fed at a rate of 1.0 mol/Hr. Then, for the next hour, Ar was fed at a rate of 2.25 mol Ar for each reaction.

The results are shown in Table 1, Experiment 10. This shows that sulfonation was carried out at a very high coexistence rate of sulfonic acid from the beginning of the reaction, and o- and p-ethylbenzenesulfonic acid contained almost no meta-isomer and had a small production rate of sulfone, disulfonic acid, and sulfuric acid. was gotten. From the crude ethylphenol obtained by melting it in an alkali (without any separation operation), a light boiling point o. High yield of 80.5% (69% in the method of Comparative Example 1)
．． 5%) with good purity (1.15% in total) (3.79% in the method of Comparative Example 1), that is, purity 96.35
% (93.71% by the method of Comparative Example 1). For reference, the yield of p-ethylphenol in the best conventional method obtained by the same alkaline melting method, in which sulfonation was performed with concentrated sulfuric acid instead of the method in the comparative example, was 4%. The isomers are separated using the difference in solubility during the formation of the m-unit and the sulfonic acid stage.
It is low, at about 69%. The purity of p-ethylphenol is 0.62% due to isomer separation at the sulfonic acid stage, and the purity of p-ethylphenol is 96.88%, which is as good as the method of the present invention. However, this separation process requires a considerable portion of the manufacturing plant's site and equipment investment, and the cost is correspondingly high. Example 4 Ethylbenzene and sulfur trioxide (
liquid) was fed for 3 hours at a feed rate of 1 mol/Hr each under strong stirring, and the feed ports were kept as far apart from each other as possible.

The results of the reaction are shown in Table 1, Experiment 11. In the simultaneous supply of two raw materials, good results can be obtained because the coexistence rate of sulfonic acid from the early stage of the reaction is considerably higher than that of Comparative Example 1.

Example 5 In Example 4, ethylbenzene and liquid sulfur trioxide were simultaneously supplied at 0.9 mol/Hr and 1.5 mol/Hr, respectively, for 2 hours while maintaining the reaction temperature at 10° C. under strong stirring. The reaction was carried out in exactly the same manner except that only ethylbenzene was continuously supplied in two doses for 1 hour.

As shown in Experiment 12 in Table 1, the results are particularly excellent in the effects of low temperature and excess sulfur trioxide. The resulting crude ethylphenol was separated by distillation only, with a high yield (79.6%) and good purity (meta form: 0.95%, purity: 96%). .55%) Varethylphenol was obtained. Example 6 In the same apparatus as in Example 1, a recycled solution of the reaction product of Example 2 (approximately 116 amounts thereof) containing 0.5 mol of sulfonic acid was initially added, and then ethylbenzene was added under strong stirring. and liquid sulfur trioxide were simultaneously supplied for 2 hours at supply rates of 1.2 mol/Hr and 1.5 mol/Ylr, respectively,
After that, only ethylbenzene was continuously supplied in -3 powders.

The results are shown in Table 1, Experiment 13. This shows that sulfonation was carried out at a very high coexistence rate of sulfonic acid from the beginning of the reaction, and the sulfonate, containing almost no meta-sulfonic acid,
Disulfonic acid, ortho and para-ethylbenzene sulfonic acids with little formation of sulfuric acid were obtained. A high yield (80.0%) was obtained by simply distilling the crude ethylphenol obtained by melting it in alkali without any separation operation.
) with good purity (meta form: 1.05%, purity: 96.45
%) Varethylphenol was obtained. Example 7 In the same reactor as in Example 1, a recycled liquid (reaction product of Example 5) containing 2 moles of ethylbenzene and about 3 moles of sulfonic acid was charged, and while the reaction temperature was maintained at 50°C, the liquid was Sulfur trioxide was fed at a feed rate of 1.0 mol/Hr for 2 hours with gentle stirring.

The results are shown in Experiment 14 in Table 1. Since it is not a simultaneous feeding reaction system, the effect is not as good as using 3 mol of recycled liquid, but even so, results far superior to those of Comparative Example 1 can be obtained. Example 8 Using the same reactor as in Example 1, 1.5 mol of ethylbenzenesulfonic acid and Te
1 mol of rt-butylbenzene was charged, and tert-butylbenzene and liquid sulfur trioxide were supplied at flow rates of 1 mol/Hr and 1.5 mol/Hr, respectively, for 2 hours under strong stirring to cause a reaction.

As shown in Table 1, Experiment 15, good results were obtained. Example 9 Using a 300 ml four-bottle flask equipped with a stirrer, a cooler, a thermometer, a raw material inlet tube, and a product outlet tube, the stoichiometric ratio of alkylbenzene and sulfur trioxide was changed continuously (single tank). The reaction was carried out.

The reaction results when the steady state is reached are shown in Table 2 (Experiment 16~
20). (Common reaction conditions: average residence time 54 minutes,
Reaction temperature: 50°C. ) At this time, to start the reaction, 100 ml of the reaction product of Example 2 was first charged into the reaction flask, and when the amount of the reaction solution reached 250 wL1, withdrawal was started to establish a steady state. (Even if sulfonic acid is not necessarily added at the start, the sulfonic acid abundance will be the same after a steady state.) In the simultaneous supply of two raw materials, continuous pumping also showed good results, and m-unitary sulfonic acid , the production rate of disulfonic acid and sulfone is significantly reduced compared to Comparative Example 1. Example 10 In Experiment 19 of Example 9, the reaction was carried out under the same conditions as Experiment 19, except that the reaction temperature was changed from 50'C to 25C and -10C.

The results are shown in Table 2, Experiments 21 and 22. From the above results, it is clear that the production rate of meta isomer and sulfone decreases as the temperature decreases. Example 11 In Experiment 19 of Example 9, the reaction was carried out under the same conditions as Experiment 19 except that the addition of the sulfone inhibitor was omitted.

The results are shown in Table 2 (Experiment 23). Compared to Experiment 8 of Comparative Example 1, the production rates of meta isomer and sulfone are markedly reduced, but the production rates of sulfone and disulfonic acid are slightly increased compared to Experiment 19 in the presence of acetic acid. Example 12 The reaction was carried out under the same conditions as in Experiment 19 of Example 9, except that sulfur trioxide was added in gaseous form.

The results are shown in Table 2 (Experiment 24). Comparative Example 2 Ethylbenzene containing 2% acetic anhydride was charged into a four-bottle flask equipped with a stirrer, a cooler, a sulfur trioxide (gas) inlet tube, and a thermometer, and sulfur trioxide gas was introduced at 50°C for 1 hour. Made it react.

(K.Llueretal, J.Prakt.Chem
．． , Tama, 139-142 (1935). ) The resulting isomer distribution (m:o:p) of the sulfonic acid is 3
．． 5:7.5:89. Production rate of hesulfonic acid 83.9%
It was hot. The sulfone production rate was 10.5% for this ethylbenzene raw material, 0.2% for disulfonic acid, and 5.1% for sulfuric acid. Compared to the method of this document, when sulfur trioxide is also supplied in gaseous form, the method of the present invention (Table 2, Experiment 24) reduces the amount of meta isomer by almost half, and produces by-products such as sulfone. It can be seen that the rate has also decreased significantly. Example 13 In a wet wall column type continuous reaction apparatus, two or three of the products are recycled from the outlet of the reaction column, mixed with ethylbenzene, and fed from the upper part of the reaction column along the column wall. 1 mol/Hr each of ethylbenzene and gaseous sulfur trioxide (accompanied by N2, N2/SO3 = 1/5)
The reaction was carried out continuously with a residence time of 2 particles in a co-current manner.

The results are shown in Experiment 25 in Table 3. Although the capacity of the reaction column needs to be about 3 times larger, it produces ethylbenzenesulfonic acid with high purity and high yield. )was gotten. Example 14 The reaction was carried out under the same conditions as in Example 2 except that metasulfonic acid was used instead of varaethylbenzenesulfonic acid.

Claims (1)

[Claims] 1 General formula▲There are mathematical formulas, chemical formulas, tables, etc.▼(However,
When sulfonating an aromatic compound (R is an alkyl group having 1 to 8 carbon atoms) using sulfur trioxide, the sulfonation is carried out by increasing the coexistence rate of sulfonic acid in the reaction zone from the initial stage of the reaction. A method for sulfonating aromatic compounds, characterized by: 2. The method for sulfonating an aromatic compound according to claim 1, wherein the sulfonic acid coexisting from the initial stage of the reaction is an aromatic sulfonic acid. 3. A method for sulfonating an aromatic compound according to claim 1, wherein the sulfonic acid coexisting from the initial stage of the reaction is the target alkylbenzenesulfonic acid, a liquid containing the same, or a sulfonation reaction product. 4. A method for sulfonating an aromatic compound according to claim 1, in which the sulfonation is carried out in the presence of sulfonic acid in an equimolar amount or more of the aromatic compound from the initial stage of the reaction. 5. The method for sulfonating an aromatic compound according to claim 1, in which the sulfonation is carried out in the presence of sulfonic acid in an amount equal to or more than 1.5 molar amount of the aromatic compound from the initial stage of the reaction. 6 In claim 1, the sulfonic acid concentration in the reaction zone is increased from the initial stage of the reaction, including by adopting a reaction method in which an aromatic compound and sulfur trioxide are simultaneously supplied to the reaction zone in a continuous or batch manner. A method for sulfonating aromatic compounds. 7. The method for sulfonating aromatic compounds according to claim 6, wherein the reaction zone is of a completely mixed type. 8 In claim 6 or 7, sulfonic acid is produced by pre-existing sulfonic acid in the reaction zone or by simultaneously supplying an aromatic compound and sulfur trioxide while supplying sulfonic acid or a sulfonated reaction product. A method for sulfonating aromatic compounds. 9. A method for sulfonating an aromatic compound according to each of claims 1 to 8, wherein the molar ratio of the raw material aromatic compound to sulfur trioxide is 1.5 to 0.5. 10. The method for sulfonating an aromatic compound according to claim 9, wherein the molar ratio of the raw material aromatic compound to sulfur trioxide is 1.0 to 0.6. 11. A method for sulfonating an aromatic compound according to each of claims 1 to 10, wherein the aromatic compound as a raw material is an alkylbenzene having a side chain of an alkyl group having 1 to 4 carbon atoms. 12. The method for sulfonating an aromatic compound according to each of claims 1 to 10, wherein the raw aromatic compound is an alkylbenzene having a side chain of an alkyl group having 1 to 2 carbon atoms. 13. A method for sulfonating an aromatic compound, which is carried out at a reaction temperature of -50 to 180°C in each of claims 1 to 12. 14. A method for sulfonating an aromatic compound, which is carried out at a reaction temperature of -10 to 50°C in each of claims 1 to 12.