JPH0694457B2 - Method for oxidizing P-diisopropylbenzene - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for producing p-diisopropylbenzene dihydroperoxide (p-DHP) by oxidizing p-diisopropylbenzene (p-DIPB).

[Prior art]

As a method for oxidizing p-DIPB, Japanese Patent Publication No. 55-44066 discloses a method of converting p-DIPB into p-diisopropylbenzene monohydroperoxide (p-MHP) using molecular oxygen, which is 115% by weight or more. There is disclosed a method of oxidizing to. Although an oxidation temperature of 80 to 120 ° C. is shown here, specifically, a method of changing the oxidation temperature in the middle of the oxidation is not described, and the example shows that the oxidation at a constant temperature is shown. It is only being done.

In general, it is desirable that the yield of p-DHP is high in such an advanced oxidation method.
2-Propyl-α, α-dimethylbenzyl hydroperoxide (p-HHP) also included p-DHP and p-HHP because it can also be converted to hydroquinone by using an oxidizing agent such as hydrogen peroxide. It is desired that the overall yield be high, but in this respect, the specific disclosed method in the above proposal cannot be said to be sufficiently satisfactory.

On the other hand, in JP-A-50-19728, the reaction temperature is 70-110.
A method is disclosed in which the temperature is selected from the temperature range of ° C and the reaction temperature is lowered stepwise as the oxidation of p-DIPB proceeds. However, the method stops the oxidation when the amount of oxidation byproducts other than p-MHP and p-DHP is as small as possible,
After separating p-DHP, it is intended to reuse p-MHP or p-DIPB as a raw material for oxidation again, and thus the yield of p-DHP when oxidized in one stage is low. When this method is applied to the advanced oxidation of p-DIPB as in the previous proposal, the crystal of p-DHP is likely to precipitate, and as a result, a smooth gas-liquid contact reaction cannot be performed. However, it was found that the yield of p-DHP and the like tends to be low.

[Problems to be solved by the invention]

The present inventors attempted to further improve the advanced oxidation technology of p-DIPB, and examined methods for increasing the yield of p-DHP and the total yield of p-DHP and p-HHP together.

[Means / actions for solving problems]

As a result, they have surprisingly found that the above object can be achieved by adopting the following method which should be contrasted with the method recommended in the latter proposal, and have completed the present invention. That is, according to the method of the present invention, in the method of liquid-phase oxidizing p-diisopropylbenzene with molecular oxygen in the presence of an alkaline aqueous solution, the oxidation of p-diisopropylbenzene is started below 100 ° C. The reaction temperature is less than 100 ° C until the reaction rate of p-diisopropylbenzene reaches 70% by arbitrarily combining the warming process and the process of maintaining the reaction temperature constant (A). .

(B) When the reaction rate of p-diisopropylbenzene reaches an arbitrary value of 70 to 95%, the reaction temperature is set to 103 to 1
The temperature is raised to an arbitrary temperature of 10 ° C., and the oxidation is continued while raising the temperature. Thereafter, within the temperature range, the hydroperoxide concentration in the oxidation product (oil layer) is p
-Oxidation to be 120% by weight or more, expressed as% by weight converted to diisopropylbenzene monohydroperoxide, and at least 10% by weight or more higher than the hydroperoxide concentration before heating to any temperature of 103 to 110 ° C. And a method for oxidizing p-diisopropylbenzene, characterized in that

In the present invention, the hydroperoxide concentration in the oxidation product is
Analyze the hydroperoxide groups in the water-removed part of the oil layer (usually iodometry is used),
All are calculated assuming p-MHP.

In the present invention, the liquid phase oxidation of p-DIPB is carried out in the presence of an alkaline aqueous solution. At this time, it is preferable to keep the pH of the aqueous alkaline solution layer at 8 or higher, preferably higher than 9 and lower than 12. If the pH value of the water layer is too low, it is difficult to increase the concentration of hydroperoxide, and if the pH value of the water layer is too high, the amount of by-products increases, which is not preferable in the method of the present invention. Further, if an aqueous solution of too high concentration is used, dissolution loss of hydroperoxide will occur, so it is preferable to use an alkali concentration of about 20% by weight or less. As the alkaline aqueous solution, an aqueous solution of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate or the like can be used. When a 5 wt% sodium hydroxide aqueous solution is used as the alkaline aqueous solution, the amount used is preferably 8 to 50% by weight, more preferably 12 to 40% by weight, based on the total reaction solution. In addition, in this invention, an oil layer means a part which is not a water layer, and oil and p-
Includes any crystalline DIPB oxidation products.

In the method of the present invention, p-DIPB is liquid-phase oxidized with molecular oxygen. As the molecular oxygen, oxygen, air, a mixture of oxygen and nitrogen in an arbitrary ratio, or the like can be used. The reaction pressure is usually
Atmospheric pressure or 10 kg / cm ² .

In the method of the present invention, the oxidation of p-DIPB is carried out at a reaction temperature of less than 100 ° C, preferably 9 ° C, until the reaction rate of p-DIPB reaches 70%.
Oxidation is performed in the temperature range of 0 ° C to less than 100 ° C. When the temperature is lower than 90 ° C, the oxidation rate of p-DIPB is extremely slow, which is not preferable. When the reaction temperature is raised to 100 ° C. or higher before the reaction rate of p-DIPB reaches 70%, the oxidation rate increases, but when the temperature is raised when the reaction rate is low, p-DHP is The overall yield of p-HHP combined is low, and the amount of oxidation by-products such as organic acids that adversely affect the oxidation reaction is increased, which is not preferable.

When the oxidation of p-DIPB is continued, the amount of unreacted p-DIPB in the oil layer decreases and the oxidation products such as p-DHP, p-MHP and p-HHP start to increase. When the reaction rate of DIPB reaches an arbitrary value of 70 to 95%, preferably 80 to 90%, the reaction temperature is raised to an arbitrary temperature of 103 to 110 ° C and the oxidation is continued.

As a method for raising the reaction temperature, the temperature may be raised gradually or rapidly, or may be raised stepwise without any problem, but usually the temperature is raised in the range of 1 to 5 ° C / hr. The reaction temperature in the above range is raised at a rate. After heating, the temperature is usually 10
If the temperature is lower than 3 ° C., the reaction time becomes unnecessarily long and the hydroperoxide concentration obtained is low, and the overall yield is low, which is not preferable.

Further, if the reaction temperature is raised above 110 ° C., the decomposition reaction becomes more dominant than the hydroperoxide formation reaction, so the concentration of hydroperoxide in the oxidation product, which is the object of the present invention, should be increased to 120% by weight or more. Moreover, it becomes difficult to increase the yield of p-DHP and the like.

In carrying out the method of raising the reaction temperature of the present invention to oxidize, the reaction rate of p-DIPB is 103 ° C. before reaching 70%.
When the temperature is raised above the above, it is not preferable for the reason described above. If the reaction rate of p-DIPB usually exceeds 95% and the temperature is raised, the more the timing is delayed, the more the oxidation by-products are generated and accumulated until the temperature rises. It is not preferable because it adversely affects the reaction and, as a result, the overall yield decreases.

In the method of the present invention, after the reaction temperature is raised by the method described above, the oxidation reaction is further continued so that the hydroperoxide concentration in the oxidation product (oil layer) is 120% by weight or more, and
Oxidation is performed to at least 10% by weight or more higher than the hydroperoxide concentration before raising the temperature to any temperature from 1 to 110 ° C. If the reaction is stopped before the hydroperoxide concentration reaches 120% by weight, the content of p-MHP, P-DIPB, etc. in the oxidation product will be high, and such oxidation product will be acid-decomposed. However, it is not preferable because hydroquinone cannot be obtained in high yield. Also, the hydroperoxide concentration should be at least 10% compared to the hydroperoxide concentration before heating to any temperature of 103 to 110 ° C.
If the oxidation is not carried out until the amount becomes higher than the weight%, the efficiency in carrying out the oxidation reaction usually decreases, so it is preferable to carry out the oxidation until the amount becomes higher than at least 10% by weight as in the present invention.

In carrying out the method of the present invention, it is necessary to sufficiently bring the oil layer, the alkaline water layer, and the oxygen-containing gas into contact with each other. Examples of the method include mechanical stirring and liquid phase. Examples thereof include a method of circulating a part of the above with a pump and a method of stirring by blowing an oxygen-containing gas.

The oxidation product of p-DIPB obtained by the above-described method of the present invention is obtained as an oxidation reaction mixture containing an alkaline aqueous solution after the completion of the p-DIPB oxidation reaction. It can be subjected to acid decomposition. For example, a water-insoluble solvent is added to the oxidation reaction mixture to dissolve the oil layer portion to form two layers of a solvent layer and an alkaline aqueous solution layer, and then the aqueous layer is separated from the solution of the water-insoluble solvent, for example, sulfuric acid or perchlorine. Hydroquinone can be obtained by acid decomposition using an acid, an inorganic acid such as phosphomolybdic acid, an organic acid such as paratoluenesulfonic acid, or a solid acid such as silica-alumina or a cation exchange resin. In carrying out this acid decomposition, p-HHP or the like in the above-mentioned oxidation product is previously converted into hydrogen peroxide, peracetic acid,
With an oxidant such as ketone hydroperoxide, p-
A method of converting to DHP to increase the p-DHP concentration and then acid-decomposing it may be adopted, or in the oxidation reaction of p-DIPB, the oxidizing agent may be allowed to coexist with acid-decomposing at the same time. The method of performing may be adopted.

〔The invention's effect〕

In the method for oxidizing p-DIPB of the present invention, the reaction proceeds smoothly as compared with the conventional method, and p-DIPB can be highly oxidized to a hydroperoxide concentration of 120% by weight or more. Also, in this case, the yield of p-DHP and p-DHP and p-HHP
It is industrially useful because it is possible to increase the total yield of the above.

〔Example〕

Hereinafter, the method of the present invention will be specifically described with reference to Examples.

Examples 1 to 5 In a reactor equipped with an air blowing sparger at the bottom, an alkaline aqueous solution inlet and a reflux condenser at the top, p
— 100 parts by weight of DIPB and 20 parts by weight of a 1-5% alkaline aqueous solution were charged, the temperature was raised to a predetermined temperature, and then air was pressurized to a predetermined pressure. After that, while blowing air, the first
The batch type oxidation reaction was carried out at the pressures and the first half temperature shown in the table, and when the reaction rate of p-DIPB in the oil phase reached the value in the table, the temperature was raised at 1 to 5 ° C / hr. The temperature was set to the latter half of Table 1 and the reaction was continued. During this period, an alkaline aqueous solution was added continuously or intermittently so as to keep the pH of the aqueous layer at 9 to 12. The reaction conditions and the results are shown in Table 1.

In the table, the p-DHP yield at the end of the reaction and the total yield of p-DHP and p-HHP were calculated by the following formula.

Comparative Example 1 Table 1 shows the results of oxidation performed by the same method as in Examples 1 to 5 under the conditions shown in Table 1 while increasing the reaction temperature in the latter half to 115 ° C.

Comparative Example 2 Table 1 shows the results of oxidation performed in the same manner as in Examples 1 to 5 except that the temperature was raised to 105 ° C at the stage where the reaction rate of p-DIPB did not reach 70%.

Comparative Example 3 Table 1 shows the results of oxidation performed in the same manner as in Examples 1 to 5, except that the reaction rate of p-DIPB was 95% or more and the temperature was raised to 105 ° C.

Comparative Examples 4 to 6 Table 2 shows the results of the same reaction as in Examples 1 to 5 except that the temperature was not raised during the reaction.

Claims (1)

[Claims] 1. A method of liquid-phase oxidizing p-diisopropylbenzene with molecular oxygen in the presence of an aqueous alkaline solution, in which the oxidation of p-diisopropylbenzene is started at less than 100 ° C., and thereafter the temperature rising process and reaction temperature. The reaction temperature is limited to the following by arbitrarily combining the processes for maintaining constant (A) The reaction temperature is below 100 ° C. until the reaction rate of p-diisopropylbenzene becomes 70%, (B) p -When the reaction rate of diisopropylbenzene reaches an arbitrary value of 70 to 95%, the reaction temperature is set to 103 to 1
The temperature is raised to an arbitrary temperature of 10 ° C, and the oxidation is continued while the temperature is raised, and thereafter, the hydroperoxide concentration in the oxidation product (oil layer) is p-diisopropylbenzene within the temperature range (103 to 110 ° C). 120% by weight expressed as% by weight converted to monohydroperoxide
Above, and at least 10% by weight compared to the hydroperoxide concentration before heating to any temperature of 103 to 110 ° C
A method for oxidizing p-diisopropylbenzene, characterized in that the oxidation is continued until the temperature becomes higher.