JPS6039250B2 - Method for producing phenols by improved alkali melting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing corresponding phenols by melting aromatic sulfonic acids, sulfonation reaction products of aromatic compounds, or alkali metal salts thereof with caustic alkali.

Specifically, when producing phenols by melting high-purity or low-purity aromatic sulfonic acids or their salts in alkali, even if the alkali used is only caustic soda, 4. In the melt reaction, by making the alkali metal salt of phenol and/or the alkali metal salt of one or more phenols present in an amount of 1 mol % or more and 25 mol % based on the raw materials, a uniformly smooth reaction can be achieved. The present invention relates to a method for producing phenols corresponding to in high yield.

It is widely known that phenols are industrially useful substances, including not only phenol but also cresol.

Particularly in recent years, in the alkylphenol industry, phenols with alkyl groups other than methyl groups are useful as non-polluting antioxidants, resins or plasticizers, and as intermediates for pharmaceuticals and agricultural chemicals. Something has been confirmed and it has begun to attract attention. Therefore, there is currently a strong desire for a stable supply of high-purity products of these phenols at low cost. The present invention relates to a method for producing these useful phenols by the so-called sulfonation-alkali melting method of aromatic compounds, and particularly provides an improved melting method. It goes without saying that the sulfonation-alkali melting method, which is a method of converting sulfonic acid into phenol, is extremely important industrially, and has been studied for a long time and has been adopted as an industrial method for producing phenol, cresol, etc.

However, this manufacturing method has the following various problems that must be improved. In other words, in this alkali melting reaction, the melting agent has extremely strong reactivity, and it is generally carried out under harsh conditions at high temperatures of 300°C or higher, so it inherently has many problems. There is. In general, alkali metal sulfites produced as by-products in melting reactions are difficult to dissolve in caustic alkali or their concentrated aqueous solutions, so the reaction system becomes extremely viscous steel, and in some cases, the entire structure forms lumps, making it difficult to rope or As a result, side reactions such as carbonization and resinization occur due to undesirable phenomena such as local heating, which significantly reduces the yield of the phenol compound. Others, W. W. Hartmann “○r chick nl
cShadathesesCollectedVoL 1,1
75 pages (1941), Nagai, Industrial Chemistry Magazine 6th period cover, 44
8, 1966, and was also confirmed by the research of the present inventors, it is known that the type of raw material sulfonic acid (including differences in isomers), its manufacturing method, or impurities. The optimum conditions for the melting reaction vary greatly depending on the type, amount, purity, etc., and the yield also varies. Therefore, it has not been easy to industrially utilize the conventional alkali melting reaction. Therefore, various efforts have been made and many proposals have been made for a long time in order to improve the above-mentioned problems. For example, British Patent No. 358,
The method of cutting off contact with air according to the specification of No. 952, the method of feeding an aqueous solution of the raw aromatic sulfonate and caustic soda into molten caustic soda according to the specification of U.S. Pat. Since foaming makes it difficult to perform a smooth reaction operation, U.S. Patent No. 2,451,996
No. 2,452,404, a method for preventing foaming by adding an antifoaming agent, Tokukan Sho 49-43, 9
A method of reacting by introducing steam according to specification No. 32,
There is a method of maintaining the powder state throughout the reaction, as described in Tokoseki No. 51-19,735 and No. 51-52,142. Although these various improvement methods have been recognized to be effective, they have not yet been put into industrial practice, as they are limited to specific raw materials or have not yet reached the desired yield. Therefore, the present inventors reexamined various conventional proposals from the viewpoint of searching for industrially possible methods.
Further, as a result of extensive research, it has been found that, especially when alkylbenzenesulfonic acid or its metal salt is used as the target raw material, the yield of the phenol compound is extremely low if only a small amount of caustic soda, which is about the theoretical amount, is used.

It has also been found that the coexistence of expensive caustic potassium or the use of a large amount of caustic soda has the best effect in improving the yield. In addition, we have discovered that this fact is one of the biggest reasons for restraining the widespread industrial use of useful alkali melting reactions. For example, the following data in the literature supports this idea. Benzene sulfonic acid (apart from phenol, in the case of P-toluene sulfonic acid or its salts)
gChemisUy, 43 lids, p. 193, 1952, when using 2.5 moles of caustic soda, the yield of P-cresol was 70%, and U.S. Patent No. 2,225,56
In Specification No. 4, the yield of P-cresol was only 78%.

In addition, Organic S skin ratios, Collect
edVol, 1, p. 169, 1941, the same raw material, unlike benzenesulfonic acid, does not melt with caustic soda alone, but with caustic potassium alone or with 28%
It is necessary to use caustic soda mixed with the above caustic potassium, and even in this case, the yield of P-cresol is only 69%. Industrial chemistry magazine, 6 volumes, 448 pages, 1
According to Band 966, a yield of 81.5% is reported, but this is the result of using a large amount of caustic soda of 4 times the mole and special and strict control of the reaction temperature. Regarding the case where P-ethylbenzenesulfosic acid or its salt is used as a raw material, there are no examples of caustic soda alone in old literature, and the result of mixing caustic potassium is Annalen de
rChemie, vol. 322, p. 187, 1902, or Journal of American Ch.
Chemical Society, Volume 71, Page 3891,
The yield of P-ethylphenol is low at 52% and 57.6%, respectively. Then, for the first time, melting of caustic soda alone was studied in the industrial chemistry magazine mentioned above.
P-ethylphenol was finally obtained with a yield of 75.4% using 4 times the amount of caustic soda. On the other hand, according to the same magazine, if the same amount of caustic potassium alone is melted, 91.8%
It is stated that P-ethylphenol can be obtained with a yield of . The Journal of American reported that when sodium P-isopropylbenzenesulfonate is the raw material, P-inpropylphenol can be obtained in a yield of 53.5% using caustic soda containing potassium hydroxide.
Chemical Society, Volume 71, Page 3891,
Written in 1949. Also, according to the above-mentioned industrial chemistry magazine, caustic soda alone (6 moles) has a concentration of 65.4%,
A yield of 83.8% has been reported for caustic potassium alone (4 moles). Furthermore, although the same sulfonic acid is used, the yield etc. vary considerably depending on the literature, which is partly due to differences in melting conditions, but is also thought to be due to differences in sulfonic acid preparation methods. Studies have already been conducted on ways to reduce the amount of alkali used, and several attempts have been proposed. One of them is the steam pyrolysis method of sulfonate, which is disclosed in U.S. Patent No. 1,789,071.
1,988,156, 2,578,823, 2,632,028, West German Patent No. 665,77
No. 4, Special Publication No. 36-4811 or Special Publication No. 47-4
This can be seen in specifications such as No. 0,783. These methods are
This method uses caustic soda in an amount equivalent to the raw material sodium sulfonate, and coexists with at least an equimolar amount of sodium phenol, and converts the sulfonic acid into a phenol compound using high-temperature steam. Although this amount should certainly be smaller than the theoretical amount (2 moles relative to sulfonic acid) used in a normal alkali melting reaction, in reality it is necessary to use a considerably larger amount. More than that, this process requires a large amount of high-temperature steam, which is considered to be the reason why this process is impossible to industrialize. Other methods that the present inventors have focused on include aromatic sulfonic acid alkali different from the raw material sulfonic acid during melting, as described in U.S. Patent No. 2,139,372 or Japanese Patent Publication No. 46-138-486 There is a method of coexisting a salt or an alkali salt of phenol. However, these documents state that in order to enhance the effect, it is necessary to add a large amount of coexisting substances to the raw materials. Therefore, the addition of an alkali salt of a sulfonic acid different from the raw material should rather be regarded as a method of co-producing two types of phenols. In the case of coexistence of phenolate, the effect of using a large amount as described above is thought to indicate that the phenolate acts as a melting agent for the reactant, and even when the phenolate is added in a proportion to the raw material, the effect of using a large amount It is necessary to use the process repeatedly, and if a different type of phenolate is added that does not correspond to the raw material, an additional phenol separation step is required, which complicates the reaction process, which is not advantageous from an economical point of view. As described above, the conventional methods each have their own drawbacks from an industrial standpoint and are not satisfactory.

Therefore, the present inventors conducted intensive research on an alkali melting method that uses only caustic soda without using any expensive caustic potassium as the alkali, and that can increase a sufficient yield even with a small excess of the theoretical amount. the result,
When performing a melting reaction by supplying an aqueous solution of aromatic sulfonic acid or its alkali metal salt as a raw material to caustic soda that has been heated to a temperature that allows the reaction to proceed sufficiently and is melted, a suitable phenolic metal If salts or substances containing them are added before or at the initial stage of the reaction so that the phenolate content is substantially 1 mol% or more and less than 25 mol% based on the raw aromatic sulfonic acid or its salt, it can be added during the reaction. The present invention was completed based on the knowledge that the foaming phenomenon of can be suppressed. That is, the gist of the present invention is a method for producing a corresponding phenol by an alkali melt reaction of an aromatic sulfonic acid or an alkali metal salt thereof, in which the aromatic sulfonic acid or its alkali metal salt is dissolved in a molten alkali maintained at a temperature at which the alkali melt reaction sufficiently proceeds. When carrying out a reaction by adding an aqueous solution of sulfonic acid or its alkali metal salt, before starting the reaction,
Or, at any time during the initial stage of the reaction, that is, until the end of adding 10 mol% of the raw material sulfonic acid or its alkali metal salt, an amount corresponding to 1 mol% or more and less than 25 mol% of the raw material sulfonic acid or its metal salt. An improved method characterized by adding an alkali metal salt of phenol and/or an alkali metal salt of one or more phenols, and then adding the remaining raw material, the sulfonic acid or an alkali metal salt thereof, to carry out the reaction. The present invention relates to a method for producing phenols using an alkali melting method.

The object of the present invention is to carry out an alkali melting reaction of aromatic sulfonic acids, especially alkylibenzenesulfonic acids, in industrially smooth manner in high yields without using expensive caustic potassium and using only a small amount of caustic soda. Our goal is to provide the following.

Although any aromatic sulfonic acid can be used as the raw material for use in the present invention, the sulfonic acids of alkylbenzenes such as toluene, ethylbenzene, or isopropylbenzene are the ones that bring out the characteristics and effects of the method of the present invention to a greater extent. Furthermore, the alkali salt of aromatic sulfonic acid that can be applied in the method of the present invention may be a highly purified one;
It may also be a low-purity product containing unreacted products or sulfone obtained by directly neutralizing a sulfonated product with sodium carbonate or sodium sulfite. As is clear from the purpose of the method of the present invention, the alkali that can be used in the method of the present invention is preferably caustic soda alone, which is currently inexpensive, but it is also possible to use caustic potassium alone or a mixture of both caustic soda and potassium.

Caustic alkali may be produced by any method and can be used in either solid or liquid form. The amount of caustic alkali to be used is the theoretical amount necessary for converting the raw material into a phenolic compound, that is, in the case of sulfonic acid, it is 3 times the mole, and in the case of an alkali metal salt, it is 2 times the mole, which is preferred in the method of the present invention. The amount of alkali is only a 25% excess over the theoretical amount. In the method of the present invention, the alkali metal salt of phenol and/or the alkali metal salt of one or more phenols that are added in advance before the start of the reaction or at the initial stage of the reaction do not have any particular definition. It is not affected by the type of alkali metal salt.

Therefore, when producing a desired phenol, an appropriate phenol
metal salts can be selected. For example, these may be metal salts of phenol corresponding to the raw material aromatic sulfonic acid, or metal salts of phenols not corresponding to the raw material sulfonic acid, such as phenol, 0- Metal salts such as ethylphenol, cresol, propylphenol, butylphenol can be used alone or in mixtures. Furthermore, if a substance such as the distillation residue after removing the target phenol from the alkali-molten reaction mixture by distillation contains phenol, the metal salt of the phenol may also have the same effect as phenolate alone. It can be used as a substance to indicate. The amount of the metal salt of phenol and/or the metal salt of phenols added is 1 mol% or more and less than 25 mol%, preferably 2 mol% to 10 mol%, based on the raw material aromatic sulfonic acid. A small amount of less than 1 mol % is insufficient to suppress foaming occurring in the reaction system, while a content of 25 mol % or more is undesirable because it causes a decrease in yield.

In most cases, the maximum effect can be obtained by adding about 6 mol%. In addition, the general method for adding metal salts of phenol and/or metal salts of phenols is to supply the raw material sulfonic acid or its metal salt and add it to the system before starting the reaction. Although the effect is great, it is not limited to this method.

In short, in the initial stage of the reaction, at any time before adding 10 mol% of the raw material sulfonic acid or its alkali salt, phenolate can be added in the above amount or mixed with the raw material sulfonic acid or its metal salt solution to coexist in the system. Just let it happen. Addition of phenolate when the amount of the raw material sulfonic acid or its metal salt exceeds 10 mol % has no effect of suppressing foaming during the reaction, and results in extremely unfavorable yields. In the present invention, the aromatic sulfonic acid or its alkali salt as a raw material is supplied as an aqueous solution, and the faster the supply rate, the better.

However, charging the entire amount at once at the same time as the supply starts causes a rapid temperature drop and deterioration of the fluidity state, resulting in a rather bad result. Therefore, it is preferable that the feed rate is as fast as possible while maintaining a predetermined reaction temperature and without causing excessive deterioration of the fluidization state. Usually, the raw material supply time is multiplied by 1/technical temperature of the total reaction time. Note that this raw material supply time varies somewhat depending on the type of raw material sulfonic acid or its alkali salt, heating method, etc. due to differences in reaction heat, etc. However, these differences do not depart from the essence of the present invention. It is customary to continue the reaction (post-reaction) in order to complete the reaction even after the supply of raw materials is finished. It is convenient from an operational point of view to set the reaction temperature for the post-reaction to be the same as the reaction temperature during raw material supply, but it does not necessarily have to be the same temperature, and the reaction time may vary depending on other factors such as the reaction temperature and the type of sulfonic acid. Determined by reaction conditions. The melting reaction temperature in the method of the present invention is 3.0 mol even when using caustic soda alone as the caustic alkali and in a small amount of 2.5 times the mole of sulfonic acid.
The reaction proceeds even at a temperature of 00° C., which is in the low temperature range for melting reactions.

However, considering the reaction rate and fluidity of the reactants, it is usually 310
A temperature of 00 to 40,000 is used, but the preferred range is 320 to 37,000. Further, in the method of the present invention, when the raw material sulfonic acid or its metal salt is supplied as an aqueous solution during the reaction, this water acts as an absorbent for a large amount of reaction heat, and as a result, the reaction temperature can be easily controlled. Also, since water vapor is always present in the system,
This has the advantage of preventing the reactants from being oxidized by air. However, this does not negate the usefulness of taking measures to prevent oxidation and partial overheating, such as carrying out the reaction under an inert gas atmosphere, which are explored in conventional methods. According to the method of the present invention, sodium alkylbenzenesulfonate,
In particular, it completely suppresses the foaming phenomenon that tends to occur when using sodium alkylbenzenesulfonate having a side chain of 2 or more carbon atoms as a raw material, improves the fluidity state in the system, and prevents the formation of tar, which is a side reaction product in the reaction product. As a result of the extremely low production of phenols, it is possible to produce phenols with high yield and good operability.

Additionally, the yield of the target phenols was greatly improved because foaming was completely suppressed without requiring a particularly long raw material supply time.

The method of the present invention will be specifically explained below using Examples and Comparative Examples, but the method of the present invention is not limited thereto.
Example 1 Ethylbenzene was sulfonated by passing gaseous sulfur trioxide diluted with nitrogen gas, and the resulting reaction mixture was neutralized with caustic soda to prepare an approximately 55% aqueous solution of sodium ethylbenzenesulfonate, which was used as a raw material. , reacted with the following steps.

This raw material aqueous solution 4309 contains 218.2 parts of sodium ethylbenzenesulfonate (of which 203.3% is sodium p-ethylbenzenesulfonate), 8.2 parts of jetyl phenyl sulfone, and 5.5 parts of sodium sulfate. . In addition, P- in the dried product obtained by evaporating water from this raw material liquid to dryness.
The content of sodium ethylbenzenesulfonate is 84.7%
This is the purity of sodium P-ethylbenzenesulfonate. 104 ml of caustic soda equivalent to 2.5 times the mole of sodium ethylbenzenesulfonate as the above raw material.
The reactor was made of stainless steel, had a capacity of 1, was equipped with an attenuator, a cooler, and an anchor-shaped cylindrical blade that was sufficiently close to the entire wall of the reactor, and was placed in a reactor capable of heating in an electric furnace to raise the temperature.

When it reaches 34,000, phenol soda salt 5
．． 7 and 1.8 mol of soda salt of ethylphenol (total of both 5.8 mol % based on the raw material sodium ethylbenzenesulfonate) are added in about 2 minutes to make uniform molten caustic soda.

To this, the entire amount of the above sodium sulfonate aqueous solution was added continuously over 35 minutes. Then, the reaction was completed by rinsing the powder for 11 minutes. During this period, the temperature of the reactant is maintained at 330 to 40 qo.The melt is dissolved in water and acidified by adding sulfuric acid to liberate phenol, which is extracted with ether. The ether extract was distilled to remove the ether and the crude phenol 126
．． I got 7 nights. This crude phenol is ethylphenol 1
13.49, of which 105.3 were P-ethylphenol. Therefore, the yield* of P-ethylphenol is 88.2%. Note that the conversion rate of sodium ethylbenzenesulfonate was 98.6%. Incidentally, at any stage of the reaction, no phenomena such as foaming that inhibited the reaction occurred, and the reaction proceeded extremely smoothly. Example 2 Using sodium p-ethylbenzenesulfonate with a purity of 99.0%, which was separated and purified from the sulfonation product of ethylbenzene, as a raw material, the phenol to be added in advance was prepared in the same manner as in Example-1. The reaction was carried out under the same conditions as in Example 11, except that only 2.0 mol% of ○-ethylphenol soda salt was used as the type of soda salt based on the raw material, and the raw material aqueous solution was fed for 5 days. .

The results showed that the yield of P-ethylphenol was 85.3%, and the P-ethylphenol yield was 85.3%.
Conversion rate of sodium ethylbenzenesulfonate is 95.6%
Met. The reaction conditions were extremely smooth from beginning to end. Example 3 In Example-1, the vacuum distillation residue of the crude phenol finally obtained in Example-1 (5% by weight of ethylphenol, about 12% by weight of propylphenol) was used as the soda salt of phenols to be preliminarily added. % by weight, butylphenol about 1 a wt.%.

) The reaction was carried out in the same manner as in Example 1 except that the same amount of sodium salt as in Example 1 was used. The yield of P-ethylphenol was 82.0%, and the conversion rate of sodium ethylbenzenesulfonate was 97.6. %, and no foaming occurred during the reaction.
Example 4 All procedures were carried out in Example-1 except that 7.0 mol of phenol soda salt was used based on the raw material sodium ethylbenzenesulfonate as the alkali metal salt of phenol to be added preliminarily. The reaction occurred in the same manner as in Example 1.

At the beginning of the reaction, a slight tendency to foaming was observed, but it did not interfere with the smooth progress of the reaction, and the yield of p-ethylphenol was 82.5% and the conversion rate was 96.3%. Example 5 In Example-1, mixed cresol (0-cresol:P-cresol:m-cresol=1:1:1) was used as the alkali metal salt of phenol to be added preliminarily.
The amount of mixed cresol was also 5.8 mol% based on the raw material sodium ethylbenzenesulfonate.
All reacted in the same manner as in Example 11.

The reaction contents remained homogeneous throughout and had a viscosity comparable to that of an aqueous solution. The yield of P-ethylphenol at this time was 85
．． 1%, and the conversion rate was 98.2%. Example 6 The sulfonation product of toluene with sulfuric acid was prepared in Example-1.
An alkaline molten raw material solution 430 was prepared in the same manner as the sulfonated product of ethylbenzene.

This contained 212.2% sodium toluenesulfonic acid (of which 177.5% sodium P-toluenesulfonic acid), and the purity of P-toluenesulfonic acid was 74.0%. A reaction was carried out in the same manner as in Example-1 using 163.0 molar amount of caustic soda (2.5 times the amount by mole relative to the raw material sodium toluenesulfonate). The reaction proceeded smoothly and a crude phenol content of 122 kg was obtained. The P-cresol yield was 89.
2%, conversion rate of sodium toluenesulfonate is 98.5%
Met. Comparative Example 1 In Example-1, no preliminary addition of phenolic soda salt was performed, and the raw material supply time was changed to 1. When the reaction was carried out in the same manner as in Example 1 except that the reaction time was changed, severe foaming occurred about 3 minutes after the start of raw material supply, and it became very difficult to control the temperature.

At that time, the supply of raw materials was temporarily interrupted and the reaction was carried out for 2 hours. As a result, the conversion rate of ethylbenzenesulfonic acid was 92.5%, and the yield of P-ethylphenol was 77.8%. Considerable amounts of phenol and tar were produced. Example 7 In Example-1, the phenol added preliminarily and ○-
Mixed phenolate of ethylphenol to 1 part per raw material
The reaction was carried out in the same manner as in Example 11 except that 2.2 mol% was added.

The reaction proceeded smoothly, and the yield of P-ethylphenol was 81
．． It was 8%. The conversion rate of sodium ethylbenzenesulfonate was 95.8%. Example 8 Everything was the same as in Example 1, except that the mixed phenolate of phenol and soda salt of ○-ethylphenol, which was added preliminarily in Example 1, was added in an amount of 18.5 mol% based on the raw material ethylbenzenesulfonic acid. When I reacted in the same way,
The reaction proceeded smoothly, and the yield of P-ethylphenol was 79.7%, and the conversion rate of sodium ethylbenzenesulfonate was 96.1%.

Comparative Example 2 In Example-1, phenol added preliminarily and ○-
The reaction was carried out in the same manner as in Example 11, except that 24.3 mol % of mixed phenolate of ethylphenol soda salt was added to the raw material sodium ethylbenzenesulfonate.

As a result, the yield of P-ethylphenol was 76.9%, and a considerable amount of decomposition products such as phenol and cresol were observed in the product, but the reaction state showed a slight tendency to foam. It was just that. The conversion rate of sodium ethylbenzenesulfonate was 96.8%. Comparative Example 3 In Example-1, the reaction was carried out in the same manner as in Example-1 except that 100 mol% of the mixed phenolate of phenol and ○-ethylphenol was added to the raw materials in an equimolar amount. did.

Claims (1)

[Scope of Claims] 1. In a method for producing corresponding phenols by an alkali melt reaction of an aromatic sulfonic acid or an alkali metal salt thereof, in a molten alkali maintained at a temperature at which the alkali melt reaction sufficiently proceeds, When carrying out a reaction by adding the aqueous solution of the sulfonic acid or its alkali metal salt, at any time before the start of the reaction or at the beginning of the reaction, that is, until the end of adding 10 mol% of the sulfonic acid or its alkali metal salt as a raw material. , an alkali metal salt of phenol and/or an amount corresponding to 1 mol% or more and less than 25 mol% of the sulfonic acid or alkali metal salt thereof as a raw material.
Production of phenols by an improved alkali melting method characterized by adding at least one alkali metal salt of phenol and then adding the remaining raw material, the sulfonic acid or its alkali metal salt, to carry out the reaction. Method. 2. The method for producing phenols according to claim 1, wherein the aromatic sulfonic acid is ethylbenzenesulfonic acid. 3. The method for producing phenols according to claim 1, wherein the alkali metal salt of aromatic sulfonic acid is sodium ethylbenzenesulfonate. 4. The method for producing phenols according to claim 1, wherein the aromatic sulfonic acid is toluenesulfonic acid. 5. The method for producing phenols according to claim 1, wherein the alkali metal salt of aromatic sulfonic acid is sodium toluenesulfonate. 6. The method for producing phenols according to claim 1, wherein the aromatic sulfonic acid is isopropylbenzenesulfonic acid. 7. The method for producing phenols according to claim 1, wherein the alkali metal salt of aromatic sulfonic acid is sodium isopropylbenzenesulfonate. 8. The method for producing phenols according to claim 1, wherein the alkali melting reaction temperature is 310 to 400°C. 9. The method for producing phenols according to claim 1, wherein the molten alkali is caustic soda. 10. The method for producing phenols according to claim 1, wherein the molten alkali is a mixture of caustic soda and caustic potassium. 11. The method for producing phenols according to claim 1, wherein the alkali metal salt of phenols is a sodium salt of O-ethylphenol. 12. The method for producing phenols according to claim 1, wherein the alkali metal salt of phenols is a sodium salt of cresol. 13. The method for producing phenols according to claim 1, wherein the alkali metal salt of phenols is a sodium salt of propylphenol. 14. The method for producing phenols according to claim 1, wherein the alkali metal salt of phenols is a sodium salt of butylphenol.