JPH0215526B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to phenol and/or 2-tert-
From butylphenol and isobutylene, 2,6-
It relates to a method for producing di-tert-butylphenol, in particular, the target product 2,6-di-tert is produced without separating or removing the catalyst from the crude reaction product in advance.
- A method for separating butylphenol with high purity. 2,6-di-produced by the method of the present invention
Tert-butylphenol has important industrial uses and is used as an intermediate for antioxidants and insecticides. (Prior art) As a method for producing 2,6-di-tert-butylphenol by selectively alkylating the ortho position of phenol with isobutylene, a method using aluminum salts of phenols as a catalyst (Japanese Patent Publication No. 33 −7535, etc.) are known. Here, the aluminum salt of phenols is 2,6-di-tert-
It has excellent performance as a catalyst for the production of butylphenol, and is the only method that is used industrially. However, because the catalyst is uniformly dissolved in the reaction solution, it is difficult to separate the product from the catalyst. be. Additionally, if the catalyst is present in the crude product in an active state, the heating during distillation will cause elimination or transfer of the alkyl group, and this tendency is particularly noticeable when the alkyl group is a tertiary alkyl group. be. According to the known prior art, the separation and purification of 2,6-di-tert-butylphenol from the crude product is entirely carried out by distillation, and therefore it is difficult to remove the catalyst from the crude product before distillation. It is essential. As a method for removing the catalyst from such crude products, a method has been proposed in which the catalyst is decomposed with an aqueous substance and then separated (for example, Japanese Patent Publication No. 40-15013, Japanese Patent Application Laid-Open No. 1983-133324, etc.)
However, all of these methods have drawbacks such as complicated separation operations and the fact that an oil phase may adhere to the separated catalyst residue or that phenol-containing wastewater may be generated. The present inventors have developed a method for producing 2,6-di-2,6-di-propylene derivatives using a crystallization separation method that overcomes the drawbacks of the above-mentioned known prior art techniques.
A method for producing tert-butylphenol was previously proposed (Japanese Unexamined Patent Publication No. 1986-36), but it was recognized that there were still issues to be improved, including the purity of the product. Problems to be Solved by the Invention The purpose of the invention is to overcome the drawbacks of the prior art methods mentioned above. That is, the object of the present invention does not require removing the catalyst from the crude product;
High purity, good yield, and economical 2,6-di-
An object of the present invention is to provide a method for producing tert-butylphenol. (Means for Solving the Problems) As a result of various studies to overcome the drawbacks of the prior art described above, the present inventors discovered that the catalyst present in the crude product produced by the reaction was unexpectedly 2,
Suppressing the formation of a eutectic between 6-di-tert-butylphenol and other components; therefore, the presence of a catalyst reduces the 2,6-di-tert-butylphenol in the eutectic composition compared to when the catalyst is removed. It has been found that the proportion of tert-butylphenol can be significantly lowered. In addition, when crystallizing 2,6-di-tert-butylphenol from the crude product, if crystallization is carried out under high pressure such as 500 to 3000 atm, crystallization under normal pressure at the same temperature will occur. However, in the crude product used in the method of the present invention, the eutectic composition changes slightly depending on the pressure during crystallization, and it is difficult to obtain crystals under high pressure. It was also found that the proportion of 2,6-di-tert-butylphenol in the eutectic composition during crystallization was lower than that under low pressure. This means that even if a crude product with the same composition is used, crystallization under high pressure will yield higher purity crystals of 2,6-di-tert-butylphenol in one step than crystallization under low pressure. This means that you can get a lot of it. The energy required for pressurization is much less than the cooling energy required for cooling crystallization, and in particular, the use of a refrigerator is usually required to industrially obtain the temperature required for cooling crystallization. When you think about it, it is a great advantage that cooling by a refrigerator is unnecessary or significantly reduced. Furthermore, if the liquid phase is further removed while lowering the pressure or at a lower pressure after removing most of the liquid phase during the above separation, this pressure change will cause some of the surface of the crystals contaminated with the mother liquor to remain. The impurity-rich portions dissolved in the small amount of liquid phase or contained in the crystal preferentially melt, sweat, and are released into the liquid phase, which purifies the crystal. It has also been found that crystals of 2,6-di-tert-butylphenol can be obtained. Therefore, if pressure crystallization is performed without removing the catalyst from the crude product, 2,6-di-tert-butyl in the crystallized liquid can reach a concentration that was not possible in the crude product from which the catalyst was removed. The concentration of phenol is reduced and a large amount of 2,6-di-tert- is extracted from the crude product.
A high-purity product can be obtained by precipitating butylphenol crystals, and by combining this with an operation of reducing the pressure or removing the liquid phase at a low pressure, an even higher quality product can be obtained. They discovered that this can be done and completed the present invention. The present invention was completed based on such new findings, and is based on 2,6-dimethylphenol, which is obtained by reacting phenol and/or 2-tert-butylphenol with isobutylene in the presence of an aluminum salt catalyst for phenols. In a method for separating and purifying 2,6-di-tert-butylphenol from a crude product consisting of -tert-butylphenol, phenols and an aluminum component, the crude product is crystallized under pressure without removing the catalyst. 2,6-di-
tert-butylphenol is precipitated as crystals,
2,6-di-tert- consisting of separating this
A method for producing butylphenol is provided. According to the method of the present invention, highly pure 2,6-di-tert-butylphenol can be obtained by crystallizing under pressure without removing the catalyst from the crude product, and the catalyst can be repeatedly recycled. This method is industrially advantageous because it can be used easily and does not generate a large amount of waste. Of course, the method of the present invention as described above can be carried out industrially very easily. Furthermore, since the pressure crystallization of the present invention performs crystallization at a higher temperature than the cooling crystallization, it is advantageous in terms of eutectic composition and has the advantage that a refrigerator is unnecessary or its load can be reduced. Furthermore, the present invention also teaches operating conditions in the above manufacturing process,
The 2,6-di-
It also indicates conditions suitable for preventing the formation of by-products caused by the presence of catalysts when attempting to crystallize tert-butylphenol. Thereby, the 2,6-di-tert obtained by the reaction
- It makes it possible to recover butylphenol with maximum yield. The isobutylene used in the present invention does not need to be pure, and may be a C ₄ mixture after removing butadiene from the C ₄ fraction obtained by naphtha cracking, for example. Since isobutylene is highly reactive, it reacts preferentially even if other olefins are present in the raw materials. The term "aluminum salt catalyst of phenols" as used in the present invention includes a single catalyst of aluminum salt of phenol and a catalyst in combination with other components such as an alkali metal salt of phenol. Aluminum salts of phenols used as catalysts can be derived from a variety of phenols, but are generally phenolic and/or 2-tert-
Preferably it is derived from butylphenol.
Generally, the amount of aluminum salt catalyst used is 0.01 to 30% by weight of the phenol, preferably 0.1 to 25% by weight. If the amount of catalyst used is too small, the reaction will not proceed sufficiently, and if the amount of catalyst used is too large, there will be no particular effect. The molar ratio of isobutylene to phenol and/or 2-tert-butylphenol is usually 0.5 to 5, preferably 1 to 3. If the amount of isobutylene used is too small, the yield of the target product 2,6-di-tert-butylphenol will be low, and if the amount of isobutylene used is too large, the pressure in the reaction system will increase and the amount of unreacted isobutylene will increase. Not only that, but the proportion of 2,4,6-tri-tert-butylphenol, a by-product, increases.
Not only does the selectivity to -di-tert-butylphenol decrease, but also 2,
4,6-tri-tert-butylphenol also crystallizes, or 2,6-di-tert-butylphenol is formed by forming a eutectic with 2,6-di-tert-butylphenol.
- making it difficult to separate butylphenol;
It may cause a decrease in purity. Reaction conditions are 10-300℃, preferably 50-300℃
Several minutes to 10 hours at a temperature of 200℃, preferably 1 to 5 hours
When the starting material is phenol, the reaction is continued until the amount of unreacted phenol is 3% by weight or less, and then further heated to 100℃ or less, preferably 10 to 100℃.
10 minutes to 50 hours, preferably 20 minutes to 20 hours at a temperature of 80℃
Allow time to react. In a high-temperature one-stage reaction, the production rate of 2,6-di-tert-butylphenol cannot exceed the range of 70 to 80 mol% even if the reaction time is increased; however, by changing the reaction temperature as described above, 2
When the reaction is carried out in stages, the production rate of 2,6-di-tert-butylphenol increases to 80 to 90 mol%.
When adopting the separation method by crystallization of the method of the present invention, the recovery rate and purity will be improved if the content of 2,6-di-tert-butylphenol in the raw material to be crystallized is even slightly higher. Contribute greatly. In the present invention, the crude product thus obtained is used as a raw material for crystallization separation without removing the catalyst. Removing the catalyst facilitates the formation of eutectics, lowering the crystallization temperature and producing a large amount of 2,6-di-
It is not possible to obtain crystals of tert-butylphenol, or the pressure for pressure crystallization cannot be increased, resulting in a decrease in the yield of high-purity 2,6-di-tert-butylphenol crystals, or a decrease in the purity of the product. bring about a decline. Note that the crystallization temperature and the pressure in pressure crystallization have an inverse correlation in terms of the amount of crystals produced, and the use of high pressure has almost the same effect as lowering the crystallization temperature. Therefore, when crystallization is performed in the presence of a catalyst, it is possible to perform crystallization at a lower temperature or higher pressure without the formation of eutectic than when crystallization is performed after removing the catalyst. , crystals of 2,6-di-tert-butylphenol can be obtained in a higher yield with a single step operation. From the viewpoint of eutectic composition, pressure crystallization is one step better than cooling crystallization.
- It is advantageous in that high purity crystals of butylphenol can be obtained in large quantities. Conditions for pressure crystallization of the crude product can be selected from any industrially usable temperature and pressure. One limit is reached by cooling and pressurizing the 2,6-di-tert
- A range in which crystals other than butylphenol crystals are not crystallized, and the other limit is a pressure that can be used industrially. In general, lower temperatures require lower pressures, whereas higher temperatures require higher pressures to achieve a given yield. On the other hand, from the viewpoint of product purity, it is preferable to process at a higher temperature. From these points of view, when processing the crude product, a pressure of 500 to 3000 atmospheres is used, and a temperature of 0 to 100℃ is used.
Can be processed in a temperature range of However, if the temperature is raised too high in the presence of the above catalyst, side reactions such as transfer and elimination of the alkyl group of 2,6-di-tert-butylphenol will occur.
On the contrary, it may reduce the yield. From this point of view, when performing pressure crystallization in the presence of an aluminum salt catalyst of phenols, the temperature is preferably 10 to 70°C, more preferably 20 to 60°C.
It has been found that it is appropriate to process at temperatures ranging from 500 to 3000 atm. After 2,6-di-tert-butylphenol is preferentially crystallized in this manner, the concentrated mother liquor containing coexisting impurities is separated and removed from the crystals under pressure. The mother liquor remaining at the grain boundaries is preferably removed during or after the pressure reduction process. 2,6-di-tert-butylphenol is a solid substance (melting point: 37°C) at room temperature and pressure, but during this pressure reduction process, some of the crystals dissolve in the remaining mother liquor, and some of the crystals contained in the crystals dissolve. The remaining crystals are extremely pure because the impurities in the crystals perspire and ooze out into the mother liquor. Furthermore, in order to purify to a high degree of purity, it is preferable that the separation temperature between the crystals and the mother liquor is 30 to 50°C. Pressure crystallization in a high-pressure container is carried out in a relatively short period of time while rapidly increasing the pressure. Therefore, if the crude product sent to the high-pressure container does not contain some crystals, crystals will form even if the pressure is applied. do not. Therefore, if the crude product does not contain seed crystals, either generate crystals in advance by keeping it at 5 to 30°C for a sufficient time to generate seed crystals prior to pressure crystallization, or A portion of the crude product is separated and cooled to form seed crystals of 2,6-di-tert-butylphenol, and the separated stream containing the seed crystals is then mixed with the remainder of the crude product. Alternatively, it is preferable to add seed crystals in the crude product from the outside. As mentioned above, the melting point of 2,6-di-tert-butylphenol is 37°C at normal pressure, but as the pressure increases, the melting point increases and reaches around 200°C at 3000 atmospheres. The feature of the method of the present invention is that high-purity 2,6-di-
The point is that tert-butylphenol can be crystallized in a high yield. In other words, the 2,6-di-tert- The point is that the proportion of butylphenol can be lowered. (Effects of the Invention) According to the method of the present invention, there is no need for a catalyst removal operation, there is no danger of wastewater pollution, the catalyst can be used repeatedly, there is no problem of catalyst disposal, and compared to purification by distillation, Energy is saved, and compared to cold crystallization no or little cooling energy is required, and the purity or yield of the crystals obtained is improved compared to cold crystallization or pressure crystallization in the absence of a catalyst. . (Example) The present invention will be explained below using Examples and Comparative Examples. Example 1 20 g of phenol and 0.1 g of aluminum pieces were placed in a stainless steel cylindrical pressure-resistant reactor with an inner diameter of 2.5 cm and a capacity of 100 ml, and heated to 160° C. for 10 minutes to prepare a phenol solution of aluminum phenoxide. After cooling, add 27g of isobutylene and heat to 120℃.
The mixture was immersed in an oil bath and reacted with stirring. The pressure inside the reactor is 16-17Kg/at the beginning of the reaction.
The cm ² ·G temperature decreased as the reaction progressed.
90 minutes after the start of the reaction, the pressure inside the reactor was 5.0Kg/
When the temperature reaches cm ²・G, increase the temperature of the oil bath to 50℃.
The mixture was rapidly cooled to 100% and reacted for an additional 150 minutes. After that, stirring was stopped, the reactor was immersed in cold water to quench it, and unreacted isobutylene was released.
The purity was 99.9 as a result of pressurizing to Kg/cm ² , separating the mother liquor at 40℃, and then separating the liquid phase while reducing the pressure.
% of 2,6-di-tert-butylphenol crystals
22.9g was obtained. Table 1 also shows the compositions of the crude product and the crystallized liquid.

[Table] Comparative Example 1 A trace amount of seed crystals was added to the same crude product (42 g) that released unreacted isobutylene as in Example 1, and the mixture was heated at 15°C.
The mixture was cooled to crystallization. Then, when the mixture was passed under a nitrogen atmosphere, 21 g of crystals of 2,6-di-tert-butylphenol were obtained. The purity of the crystal was 99.0%. The composition of the crystallization separation liquid (21 g) is shown in Table 2.

[Table] In this comparative example, the amount of crystals obtained was 21.0g
Although the amount of crystals obtained in Example 1 is smaller, the purity is 99.0%, which is the same as Example 1.
It is low compared to This indicates that the selectivity of the separation is low. 2,6-di- in the crystallization separation liquid
The proportion of tert-butylphenol was 73.3 mol%, which is higher than that in Example 1.
Therefore, it is obvious that if the proportion of 2,6-di-tert-butylphenol in the crystallization separation is reduced to the same value as in Example 1, the purity of the obtained crystals will further decrease. . Comparative Example 2 A sample obtained by removing the catalyst from the crude product (42 g) that released unreacted isobutylene, which is exactly the same as in Example 1, was pressurized to 1300 Kg/cm ² in a high-pressure container, the mother liquor was roughly separated at 40°C, and the pressure was reduced. The crystals were purified by further separating the mother liquor, resulting in a purity of 99.7%.
Crystals of 2,6-di-tert-butylphenol
16.0g was obtained. The composition of the crystallized separation liquid (24.4 g) is shown in Table 3.

【table】

[Table] In this comparative example, since crystallization is performed after removing the catalyst, eutectic is more likely to be formed than in Example 1, and the crystallization conditions can be loosened compared to Example 1. It was necessary. The conditions for preventing the formation of eutectic include the degree of pressurization in Example 1.
It had to be kept at 1300 Kg/cm ² which is lower than 1500 Kg/cm ² , and the amount of crystals obtained was therefore significantly reduced.
Along with this, the proportion of 2,6-di-tert-butylphenol in the crystallization separation liquid remains at a high value, and it is recognized that the separation efficiency is lower than in Example 1.

Claims (1)

[Claims] 1. 2,6-di-tert produced by reacting phenol and/or 2-tert-butylphenol with isobutylene at a reaction temperature of 10 to 300°C in the presence of an aluminum salt catalyst of phenols. - A method for producing butylphenol, in which the obtained crude product is heated at 0 to 100 °C for 50 to 100 °C without removing the catalyst.
A method for producing high-purity 2,6-di-tert-butylphenol, which comprises applying pressure to 3,000 atmospheres to precipitate crystals, and separating the remaining liquid phase from the crystals under pressure. 2 The temperature at which the pressure is applied to precipitate crystals is 20 to 60℃.
The manufacturing method according to claim 1, wherein the temperature is .degree. 3 The crude product was kept at 5 to 30°C for a while and 2,6-
Claim 1, characterized in that the crystals are increased by partially generating crystals of di-tert-butylphenol, and then sending the crude product containing the crystals to a high-pressure container and applying pressure. Second
Manufacturing method described in Section. 4. Separate a portion of the crude product, cool it to form seed crystals of 2,6-di-tert-butylphenol, and then combine the separated stream containing the seed crystals with the remainder of the crude product. The manufacturing method according to claim 1 or 2, wherein crystallization is performed by mixing and pressurizing the mixture into a high-pressure container. 5. Crystallization is carried out by adding crystals of 2,6-di-tert-butylphenol as seed crystals to the crude product and then sending it to a high-pressure vessel and pressurizing it, as claimed in claim 1 or 2. The manufacturing method described in. 6. Any one of claims 1 to 5, characterized in that after the liquid phase is separated from the crystals under pressure, the liquid phase is further separated from the crystals while reducing the pressure or at a low pressure. Manufacturing method described.