JPS6052732B2 - Method for producing 2,6-di-t-butylphenol - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing 2,6-di-butylphenol, more specifically, a method for producing 2,6-di-butylphenol, and more specifically, a method for producing 2,6-di-butylphenol, and more specifically, a method for producing 2,6-di-butylphenol, which is produced by removing butadiene from a C4 fraction obtained by thermal decomposition of phenol and naphtha.
That is, the present invention relates to an improved method of producing 2,6-di-butylphenol by reacting a return gas with a return gas in the presence of an orthoalkylation catalyst.

A method for producing 2,6-di-butylphenol by reacting isobutylene and phenol in the presence of an orthoalkylation catalyst such as aluminum triphenoxide is already known (ANGEWAND TECH).
EM1E169, Jahrgang, 0Nr, 22.5
eite699~749, 21, Novem 195
7).

On the other hand, as a mixture containing isobutylene, a fraction obtained by removing butadiene from a Cl fraction obtained by thermal decomposition of naphtha is known, and this fraction usually contains 40 to 50% isobutylene, and other butenes and Contains butane, etc. This mixture is also called a so-called return gas, and is inexpensive and has low industrial value, being used as fuel. (Hereinafter, this mixture will be abbreviated as return gas.
) The present inventor used the above return gas containing isobutylene instead of isobutylene, and used the above return gas containing isobutylene to
When conducting experiments to produce |6-di-butylphenol, it became clear that the rate of production of the target compound was generally quite slow, although it depended on the reaction temperature, amount of catalyst used, etc.

Of course, the rate of production of the target compound increases as the reaction temperature increases, but on the other hand, compounds in which 1-butene is added to phenol, and compounds in which isobutylene is further added to the target compound, -
The disadvantage was that undesirable by-products such as butylphenol were formed. Furthermore, although the rate of production of the target compound can be increased by increasing the amount of catalyst used, it is accompanied by an increase in the cost required for the catalyst, and it is not industrially advisable to rely solely on this method. An unexpected fact is that when increasing the amount of return gas charged and increasing the isobutylene concentration in the reaction system with the intention of accelerating the production rate of the target compound, the present invention has the disadvantage that the production rate of the target compound actually decreases. discovered by someone. This unexpected disadvantage was not observed when using pure isobutylene. These will become clear if you refer to the reference examples below. Therefore, as long as return gas is used as a raw material, 2,6
The slow production rate of -di-t-butylphenol seemed to be a fatal drawback.

However, the present inventors believe that even if the return gas is used as a raw material, if the reaction is carried out under specific new reaction conditions described below, a critical effect will be produced and the above disadvantages will be solved. It has been discovered that 2,6-di-t-butylphenol can be obtained in a short reaction time in good yield and with good selectivity.

That is, according to the present invention, a return gas obtained by removing butadiene from a C4 fraction obtained by thermal decomposition of naphtha is reacted with phenol in the presence of an orthoalkylation catalyst to produce 2,6-di In the method for producing t-butylphenol, the molar ratio of isobutylene to the phenolic compound in the liquid phase in the reaction vessel is maintained at about 0.1 to 2, and 1 mole of the phenolic compound in the liquid phase is maintained at about 0.1 to 2. Compared to that, isobutylene is about 0.007 to 0.0% per minute.
The method is characterized in that the return gas is supplied into the reaction vessel in a proportion of 0.04 molar.

The reason why the object of the present invention can be achieved by such a method is not fully elucidated, but 2-t-butylphenol is rapidly generated by the following reaction (1), and then the target compound is generated very slowly by reaction (). Taking into account the known knowledge that I believe that the specific method allowed the reaction () to proceed faster.

By describing the present invention in more detail below, the objects, advantages, etc. of the present invention will be better understood.

In the present invention, in order to introduce an isobutyl group to the ortho position of phenol, a fraction containing isobutylene obtained by removing butadiene from a C4 fraction obtained by thermal decomposition of naphtha, that is, a return gas, is used as a raw material.

This is also commonly called spent B-B, but it usually contains about 40 to about 50% isobutylene and has a boiling point of about -1
2 to about 0.5°C. In the present invention, when reacting the return gas with phenol, the molar ratio of isobutylene to phenolic compound (isobutylene/phenolic compound) in the liquid phase in the reaction vessel is set at about 0.1 to 2, preferably about 0. The first important requirement is to carry out the reaction while maintaining the ratio between 2 and 1.5, and the second important requirement is that isobutylene is The reaction is carried out while supplying a return gas into the reaction vessel at a ratio of about 0.007 to 0.04 mol, preferably about 0.009 to 0.03 mol per mol. By operating in this way, it is possible to obtain the target compound at a rate that can withstand industrial implementation without using a large amount of catalyst or at high temperatures where large amounts of by-products are produced. Under conditions where the molar ratio of isobutylene to phenolic compound in the liquid phase in the reaction vessel exceeds about 2, in other words, there is an excess amount of return gas in the liquid phase consisting of return gas and phenol. In both cases, the reaction is carried out under conditions where the molar ratio is less than about 0.1, i.e., in the absence of a small amount of return gas in the liquid phase. () is slow, resulting in a disadvantage that the production rate of the target compound is slow or the yield is low.

On the other hand, even if the above molar ratio range is satisfied, if the return gas supply rate deviates from the above-mentioned quantity relationship, similar disadvantages will still result. Note that the phenolic compounds here include phenol, 2-t-butylphenol, 2,6-di-t-
Refers to phenol and phenol derivatives such as butylphenol, 2,4,6-tri-t-butylphenol, 2,4-di-t-butylphenol, and t-butylphenyl ether.

When the present invention is carried out batchwise, the number of moles of the phenolic compound and the number of moles of charged phenol will approximately match. It is recommended that phenol, a return gas, and a catalyst be charged in advance into the reaction vessel as a pre-operation for carrying out the reaction under the above-mentioned reaction conditions of the present invention. Usually, it is preferable to charge the return gas so that isobutylene is charged at a ratio of about 0.5 to 3 moles per mole of phenol. Further, the order in which phenol, return gas, and catalyst are charged is not particularly limited, but rapid mixing of the three at high temperatures should be avoided since this may cause disadvantages such as runaway reaction. To maintain the molar ratio of isobutylene and phenolic compound in the liquid phase in the reaction vessel within the above range, for example, the amount of return gas discharged outside the reaction vessel,
This can be carried out by appropriately adjusting the amount of return gas charged at the initial stage of the reaction.

Then, the pressure corresponding to the molar ratio calculated in advance or experimentally determined based on the equilibrium pressure relationship uniquely determined from the composition and temperature of the liquid phase composed of the phenolic compound and the return gas is set in the reaction vessel. The molar ratio of the liquid phase can be maintained by supplying and discharging return gas so as to maintain it within the liquid phase. Alternatively, the mole ratio may be maintained by directly monitoring the composition of the liquid phase and supplying and discharging the return gas. One embodiment of the present invention will be described with reference to FIG. 1 of the attached drawings. Return gas is supplied to the reaction vessel 4 through line 1, pump 2, and line 3, and return gas is supplied through line 7, valve 8, and line 9. The return gas is then exhausted.

The liquid phase part 6 consisting of a phenolic compound, return gas and a small amount of catalyst is connected to a line 10, a valve 11,
It is sampled through line 12 and analyzed for composition, allowing the molar ratio of isobutylene to phenolic compound in liquid phase 6 to be monitored. A pressure gauge 5 is also provided as required. Examples of the orialkylation catalyst used in the present invention include aluminum phenoxide, magnesium phenoxide, zirconium phenoxide, and aluminum o-t-butyl phenoxide, and among them, the use of aluminum phenoxide is recommended.

The above catalyst is usually about 0.01 to 1 mole of phenol.
The amount used is about 0.07 mol, preferably about 0.02 to 0.05 mol.

Further, the reaction temperature is usually about 70 to 200°C, preferably about 1
The temperature is 120-150℃ until the 2-t-butylphenol concentration reaches the maximum value.
It is preferably carried out at a temperature of 130 to 145°C, and after the 2-t-butylphenol concentration reaches its maximum value, the temperature is 100 to 12°C.
01C1 Preferably, carrying out the reaction at a temperature of 105 to 115 DEG C. is an extremely recommended method because the reaction rate is fast and by-products such as tri-t-butylphenol and 1-butene-added phenol compounds are reduced.

Also, about 5 to 30 kg/CltGl, preferably about 15 to 25
It is carried out under a pressure of kg/C7lfG. The reaction time is about 150 to 40 minutes, but it is recommended that the reaction be terminated when the amount of unreacted phenol in the liquid phase reaches about 6 mol % or less. After the reaction is completed, the return gas is removed, the catalyst is removed from the reaction mixture by a known method, and the target compound 2,6-di-t-butylphenol can be obtained by distillation or the like.

The present invention will be specifically described below with reference to Examples.

Reference example A. B. ．． C In this example, pure isobutylene was used and the molar ratio of isobutylene to phenol was varied from 1.0 to 3.0, and the behavior of the reaction was observed.

That is, phenol, isobutylene, and catalyst are placed in the autoclave 1e, and the reaction temperature is approximately 105 to 120'C.
I reacted with

Aluminum triphenoxide was used as a catalyst, and the amount used was Ae/phenol (molar ratio) = 0.026. Reference example D. ．． E In this example, a return gas having the composition shown in Table 1 is used instead of isobutylene, and the molar ratio of isobutylene to phenol is approximately 2.
Experiments were conducted at a reaction temperature of 135 to 140° C. instead of 3.

The results of the reference example above are shown in Table 2 and Figure 2 (reference example: D
．． ．． Shown in E).

In Figures 2 to 8, the horizontal axis is the reaction time (unit: minutes), the vertical axis is the composition (mol%), and the solid line in the graph is 2,6-
Di-t-butylphenol, the dashed line shows the behavior of 2-t-butylphenol.

In Table 2, the mole percentages of reaction products are expressed relative to the phenol charge. These results show that when a return gas is used, the production rate of the target compound is slow, and even if the concentration of isobutylene in the reaction system is increased, the production rate of the target compound does not increase, but rather slows down. It can be seen that the trend is opposite to that when using .

Example 1 The reactor shown in FIG. 1 was used.

However, the reactor 4 is an 11 stainless steel autoclave. Phenol 159.8y (1.7 mol) and aluminum triphenoxide 0.068 mol were prepared 13
After the temperature was raised to 5 to 140°C, 380y of return gas (corresponding to 3.28 mol of isobutylene) was passed through line 3.
It was supplied in a timely manner.

After the supply is finished, return gas is supplied through line 3 so that isobutylene is supplied at a rate of 0.0115 mol per minute per 1 mol of phenol compound, and the sample sampled through line 12 is analyzed and monitored. At the same time, the return gas was removed from the system by operating the valve 8 so that the molar ratio between isobutylene and the phenolic compound in the liquid phase was maintained at about 0.4 to 1.1. Table 3 shows the composition when the reaction time was 330 minutes (the start of the reaction was defined as the start of the return gas supply).

Furthermore, changes in the composition of 2-t-butylphenol and 2,6-di-t-butylphenol are shown in FIG. Example 2 In Example 1, after the temperature reached 135-140°C, the return gas was 354 Da (equivalent to 28 moles of isobutylene).
After the supply is finished, return gas is supplied so that 0.01 mol of isobutylene is supplied per minute per 1 mol of the phenolic compound, and the isobutylene in the liquid phase is The operation was carried out so that the molar ratio of the phenolic compound was maintained at about 0.2 to 1.0, and the reaction was carried out at 140°C until the reaction time was 80 minutes.
The procedure of Example 1 was repeated except that the reaction was carried out at a temperature of 0.05°C.

The composition when the reaction time was 30 minutes is shown in Table 3, and the changes in the composition of 2-t-butylphenol and 2,6-di-t-butylphenol are shown in FIG.

Comparative Example 1 After raising the temperature in Example 1, 80 y of return gas (corresponding to 0.66 mol of isobutylene) was supplied over 20 minutes, and then 0.0 y of isobutylene was added per 1 mol of the phenol compound per minute. The same procedure as in Example 1 was carried out, except that a return gas was supplied so that 0.029 mol was supplied, and the molar ratio of isobutylene to phenolic compound in the liquid phase was maintained at 0.01 to 0.09.

The composition after 20 reaction times is shown in Table 3, and changes in the composition of 2-t-butylphenol and the target product are shown in Figure 5. Comparative Example 2 In Comparative Example 1, first, 760y of return gas (corresponding to 6.56 mol of isobutylene) was supplied in two parts, and then the molar ratio of isobutylene to phenolic compound in the liquid phase was 2.2. Comparative example 1 except that it is set to ~2.5
operated in the same way.

The results are shown in Table 3, and the changes in composition are shown in FIG. Comparative Example 3 In Example 1, after raising the temperature, 440y of return gas (equivalent to 3.6 mol of isobutylene) was supplied over 20 minutes, and then the return gas supply rate was changed to 1 mol of isobutylene per 1 mol of the phenol compound. is 0.051 per minute
Table 3 shows the results of the same operation as in Example 1 except that the components were supplied in molar proportions.

Further, FIG. 7 shows compositional changes of the target compound and 2-t-butylphenol. Comparative Example 4 In Example 2, after raising the temperature to 135 to 140°C, return gas 189y (equivalent to 1.5 mol of isobutylene) was supplied in two powders, and then isobutylene was added to 1 mol of the phenolic compound. Supplying return gas at a rate of 0.004 mol per minute to
and the molar ratio of isobutylene to phenolic compound is 0.
The operation was performed in the same manner as in Example 2, except for a, which was operated so that the ratio was 2 to 0.8.

The results are shown in Table 3, and compositional changes are shown in FIG. From the above comparative examples, it is clear that the production rate or yield of the target compound is low when the conditions of the present invention are not met.

[Brief explanation of the drawing]

Fig. 1 shows an example of an embodiment of the apparatus used in carrying out the method of the present invention, and Figs. 2 to 8 show the 2-t -Butylphenol and 2,6-di-t-butylphenol show compositional changes.

Claims (1)

[Claims] 1 The return gas obtained by removing butadiene from the C_4 fraction obtained by thermal decomposition of naphtha is reacted with phenol in the presence of an orthoalkylation catalyst. 2
, 6-di-t-butylphenol, the molar ratio of isobutylene to phenolic compound in the liquid phase in the reaction vessel is maintained at about 0.1 to 2, and the liquid phase is The method is characterized in that the return gas is supplied into the reaction vessel so that isobutylene is supplied into the reaction vessel at a rate of about 0.007 to 0.04 mol per minute per 1 mol of the phenolic compound. .