JPH0480016B2 - - Google Patents

Description

[Detailed description of the invention]

(Technical 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 and simultaneously reusing a recovered catalyst. (Prior art) As a method for producing 2,6-di-tert-butylphenol by selectively alkylating the ortho position of phenol with isobutylene, there is a method using an aluminum salt of a phenol as a catalyst (Japanese Patent Publication No. 1973- 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 causes elimination or transfer of the alkyl group, which is particularly noticeable when the alkyl group is a tertiary alkyl group. . According to the prior art, the separation and purification of 2,6-di-tert-butylphenol from the crude product is entirely carried out by distillation, so it is essential to remove the catalyst from the crude product before distillation. be. 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,
40-15013, JP-A No. 55-133324, etc.), all of them have drawbacks such as complicated separation operations and the fact that an oil phase adheres to the separated catalyst residue or that phenol-containing wastewater is generated. (Objects, Structures, and Effects of the Invention) The object of the present 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;
Moreover, it is an object of the present invention to provide a method for economically producing 2,6-di-tert-butylphenol with good yield. As a result of various studies to overcome the drawbacks of the prior art described above, the present inventors have discovered that highly pure 2,6-di-tert-butylphenol can be produced by crystallization without separating the catalyst from the crude product. It was discovered that this crystallized liquid can be re-decomposed and recovered into isobutylene and phenols by thermal decomposition as it is, and that the catalyst in the thermal decomposition residue can be recycled to the reactor and used for circulation. . The present invention was completed based on such new knowledge, and the present invention is based on the 2,6- In a method for separating and purifying 2,6-di-tert-butylphenol from a crude product consisting of di-tert-butylphenol, phenols, and an aluminum component, the crude product is crystallized to obtain 2,6-di-tert-butylphenol. -tert-butylphenol is precipitated as crystals, separated, the crystallized separated liquid is thermally decomposed at a temperature of 120 to 400°C, the catalyst is recovered, and the recovered catalyst is reused. ,6
- Provides a method for producing di-tert-butylphenol. Furthermore, the present invention provides a method for re-decomposing the crystallized separated liquid obtained above into isobutylene and phenols by directly thermally decomposing them, and recovering them, thereby making it possible to effectively utilize the reaction raw materials. It also provides. According to the method of the present invention, highly pure 2,6-di-tert-butylphenol can be obtained by crystallization without removing the catalyst from the crude product, and the catalyst can be repeatedly reused, eliminating the need for large amounts of waste. This method is industrially very advantageous because it does not produce any substances. Of course, the method of the present invention as described above can be carried out industrially very easily. 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. As the method for crystallizing the crude product used in the present invention, any method such as a cooling crystallization method, a high-pressure crystallization method, or a combination thereof may be used, and it does not matter whether it is a batch method or a continuous method. Further, as a method for separating the crystals, any method such as vacuum filtration, pressurization, centrifugation, etc. can be adopted. Through this crystallization and separation, 60% or more of 2,6-di-tert-butylphenol in the crude product can be easily recovered with a purity of 99% or more. Thermal decomposition treatment of the crystallized liquid is carried out at 120-400°C, preferably 150-350°C. The catalyst is dissolved in the crystallization separation liquid while remaining active, and since this catalyst also comes into contact with the decomposition reaction, thermal decomposition proceeds easily and quickly. The decomposition products are mainly isobutylene and phenol, which can be recycled to the reactor and reused. And a small amount of 4-
Alkylphenols such as tert-butylphenol are produced as by-products, and these are also useful as raw materials for many chemical products including synthetic resins and surfactants. The pressure for thermal decomposition may be either normal pressure or increased pressure. The equipment is not particularly limited, and heating and recovery of isobutylene and phenols may be performed continuously using an ordinary distillation column, or the crystallized separated liquid is subjected to distillation after heat treatment in a reaction vessel to recover isobutylene and phenols. The phenols and the catalyst liquid may be separated. The separated catalyst liquid contains phenol and/or 2-tert-
Return to the butylphenol and isobutylene reactor for reuse. If the crystallized separated liquid is not thermally decomposed and is recycled to the reactor as part of the starting material while containing the catalyst, a considerable amount of catalyst is contained in the crystallized separated liquid, that is, about 60 to 70 mol%2. ,6-G-
It seems that tert-butylphenol can be used effectively without being decomposed, but if it is recycled at this stage, it will cause impurities in the reaction system, especially 2,
If the proportion of 4,6-tri-tert-butylphenol increases and the purity of 2,6-di-tert-butylphenol is kept constant, 2,6-di-tert-butylphenol increases.
It may be necessary to reduce the amount of butylphenol crystallized, and recycling at this stage is not necessarily preferable. 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. (Specific Example) An example of the process for producing 2,6-di-tert-butylphenol according to the present invention will be explained with reference to FIG. The charge to the reactor 12 consists of a catalyst liquid from line 10, phenol from line 5, and isobutylene from line 4, and the molar ratio of phenol to isobutylene is preferably 1 to 3, and the concentration of the aluminum salt catalyst is set to the reactor. It is preferably adjusted to a range of 0.1 to 25% by weight based on the phenol charged in No. 12. The reaction temperature is preferably 50
~200°C and reaction pressure are preferably maintained at 2 to 70 atmospheres, and reaction time is preferably 1 to 25 hours. In the figure, the reaction is carried out batchwise and one reactor is shown, but a plurality of reactors can also be used. In the case of a continuous system, two reactors are used;
It is preferable that the first reactor is a high temperature reactor, the second reactor is a low temperature reactor, and a cooler is provided between the two reactors. Even in the case of a batch system, temperature control is easy when multiple reactors are used, and semi-continuous operation is also possible by switching operation. During steady operation, the catalyst liquid is recirculated from the thermal cracking column bottom component line 24 (described later), but only at the start of operation and for replenishment, aluminum from line 7 and phenol from line 6 are sent to the catalyst adjustment tank. Adjust by heating and stirring to 100-200°C in Step 9. The recycled catalyst from the line 24, that is, the recovered catalyst from this reaction system, can be directly returned to the reactor by connecting it to the line 10 without necessarily passing through the catalyst adjustment tank 9. In the method shown in the figure, it is assumed that the reactor 12 is operated batchwise and the thermal decomposition column 22 is operated continuously, so that the catalyst liquid from the line 24 is obtained continuously, so the timing with the reactor 12 is A catalyst adjustment tank 9 is used to adjust the temperature. The reaction product exiting the reactor is supplied to a deisobutylene tower 14 via a line 13. The overhead component (unreacted isobutylene) is recycled to isobutylene tank 1 via line 15. The bottom component is fed through line 16 to crystallizer 17 . The slurry of 2,6-di-tert-butylphenol produced by cooling, pressurizing, etc. in the crystallizer is passed through line 1.
8 and is supplied to the crystal separator 19. The crystals (2,6-di-tert-butylphenol product) are separated from line 20. The crystallized separated liquid is sent from line 21 to heating separation tower 22 (bottom temperature 120-400℃)
is supplied to The bottom component (catalyst) is recycled from line 27 to reactor 12 via catalyst conditioning tank 9. The top components (isobutylene and phenols) pass through line 23 to isobutylene separator 2.
5. The gas component (isobutylene) is recycled to the isobutylene tank 1 via line 26. The phenol component is supplied to a phenol recovery column 28 through a line 27. The overhead component (phenol) is recycled to the phenol tank 2 via line 29. The bottom components (high-boiling point alkylphenols such as 4-tert-butylphenol, 2,4-di-tert-butylphenol, and 2,4,6-tri-tert-butylphenol) exit the system through line 30. being extracted. (Example) The effects of the present invention will be explained below with reference to Examples. Example 1 20 g of phenol and 0.20 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.
cm ² ·G, which decreased as the reaction progressed. 90 minutes after the start of the reaction, the pressure inside the reactor is 5.0.
When the temperature reaches Kg/ ^cm2・G, change the temperature of the oil bath.
The mixture was rapidly cooled to 50°C and reacted for an additional 150 minutes. Thereafter, stirring was stopped, and the reactor was immersed in cold water to be rapidly cooled to release unreacted isobutylene, and then a small amount of seed crystals were added, and the crude product was cooled to 15° C. and crystallized. 22g of 2,6-di-tert-butylphenol crystals with a purity of 99.0% were passed under a nitrogen atmosphere.
was gotten. The compositions of the crude product and the crystallized liquid are shown in Table 1.

[Table] The recovery rate of 2,6-di-tert-butylphenol by crystallization was about 64%. 20g of the crystallized separation liquid obtained above (including catalyst)
was placed in a distillation flask and heated to 280°C. As a result, 10g of isobutylene and phenols were collected from the top of the tower.
6.2g was recovered. Table 2 shows the composition of phenols.
It was shown to.

[Table] 4 g of the solution containing the catalyst remaining from the above thermal decomposition reaction was put into the above stainless steel cylindrical pressure-resistant container under a nitrogen atmosphere, and then 20 g of phenol and 27 g
of isobutylene was added and the reaction was carried out in the same manner as above. The reaction solution composition was as shown in Table 3, and it was found that the activity of the catalyst did not decrease at all.

【table】 [Brief explanation of the drawing]

FIG. 1 is a system diagram showing a specific example of the method of the present invention. 1... Isobutylene tank, 2... Phenol tank, 3... Aluminum tank, 9... Catalyst preparation tank, 12... Reactor, 14... Deisobutylene tower, 17... Crystallizer, 19... Crystal separation machine,
22... Thermal decomposition column, 25... Isobutylene separator, 28... Phenol recovery column.

Claims (1)

[Claims] 1. 2,6-
In producing di-tert-butylphenol,
The obtained crude product was crystallized to give 2,6-di-tert-
2,6 characterized in that butylphenol is separated as crystals, the crystallized separated liquid is thermally decomposed at a temperature of 120 to 400°C, isobutylene, phenols, and a catalyst are recovered, and the recovered catalyst is reused. -G-
Method for producing tert-butylphenol.