JPS6024787B2 - Method for producing alkylbenzene hydroperoxide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing alkylbenzene hydroperoxide in good yield by oxidizing an alkylbenzene in which at least one isopropyl group is bonded to a benzene ring using a molecular oxygen-containing gas.

Alkylbenzene in which at least one isopropyl group is bonded to a benzene ring (hereinafter simply referred to as alkylbenzene unless otherwise specified).

), for example, by reacting cumene or cymene with oxygen, the carbon at the Q position of the isopropyl group bonded to the benzene ring has -
It is well known to produce alkylbenzene hydroperoxides, such as cumene hydroperoxide or cymene hydroperoxide, to which a 00-day group is attached. Such alkylbenzene hydroperoxides are extremely useful substances as radical initiators or as intermediates in the production of phenols such as phenol or cresol. In the oxidation process in which alkylbenzene and molecular oxygen-containing gas are reacted, the reaction is stopped before the entire amount of alkylbenzene is oxidized in order to suppress side reactions as much as possible, and then the alkylbenzene hydroperoxide is concentrated by distillation of the oxidation product. The recovered alkylbenzene is mixed with fresh alkylbenzene that has not undergone the oxidation process and recycled to the oxidation process.

Phenols can be produced from the alkylbenzene hydroperoxide produced by the above method, but in this case, a concentrated solution of alkylbenzene hydroperoxide is usually subjected to a cleavage reaction in the presence of an acid catalyst to obtain phenols and acetone, and at the same time recover the alkylbenzene. do. The recovered alkylbenzene, like the alkylbenzene recovered in the alkylbenzene hydroperoxide concentration step, is again recycled to the alkylbenzene oxidation step for producing alkylbenzene hydroperoxide. These recovered alkylbenzenes contain impurities such as created products generated in the oxidation process, by-products generated in the cleavage process of alkylbenzene hydroperoxide, and phenols. The substances created in the oxidation process vary depending on the type of alkylbenzene; for example, when oxidizing cumene, they include dimethylphenyl carbinol and acetophenone, as well as acidic substances such as formic acid, acetic acid, and butyric acid, but the main component is dimethylphenyl. It is carbinol.

Also, in the case of oxidation of cymene, dimethyltolyl carbinol is the main component, and in the case of other alkylbenzenes, a considerable amount of carbinols are produced as by-products. Therefore, if the production of carbinols can be suppressed, alkylbenzene will not be wasted, and the overall yield of alkylbenzene hydroperoxide can be improved. Oxide will be obtained.
Furthermore, when producing phenols by cleavage reaction of alkylbenzene hydroperoxide in the presence of an acid catalyst, the presence of carbinols in the alkylbenzene hydroperoxide causes many complex side reactions and reduces the yield of phenols. cause it to happen. Therefore, the object of the present invention is to suppress the production of carbinols in the oxidation process of alkylbenzene. As a result of intensive studies to achieve the above object, the inventor of the present invention found that the recovered alkylbenzene is brought into contact with an aqueous solution A having a pH of 1.5 or more, and then brought into contact with an aqueous solution B containing 0.1 mole or more of carbonate ions per solution. It was found that this method has a remarkable effect on suppressing the production of created products, especially carbinols, during the oxidation process, and the present invention was completed.

Therefore, the present invention provides a method for producing an alkylbenzene hydroperoxide by oxidizing an alkylbenzene having at least one isopropyl group bonded to a benzene ring using a molecular oxygen-containing gas, and a step of concentrating the alkylbenzene hydroperoxide after the oxidation step. After the alkylbenzene recovered is brought into contact with an aqueous solution A having a pH of 12.5 or more, the alkylbenzene is brought into contact with an aqueous solution B containing 0.1 mol or more of carbonate ions per 1 mol, and then supplied to the alkylbenzene oxidation step. This is a characteristic method for producing alkylbenzene hydroperoxide.

Various methods have been proposed to remove acidic substances from recovered alkylbenzene.

For example, Japanese Patent Publication No. 29-6031 describes a method for completely removing phenol by washing recovered cumene with an aqueous sodium hydroxide solution, and Japanese Patent Publication No. 36-9075,
Samurai Publication No. 36-20012, Japanese Patent Publication No. 42-98, etc. describe a method of washing with alkali to remove acid substances in cumene, but the specific type of alkali is not disclosed. . Although these methods certainly increase the oxidation rate in the oxidation step compared to the case where recovered alkylbenzene is not treated, they are still insufficient in suppressing the production of by-products. For example, in the oxidation of cumene,
Even if the recovered cumene is treated with an aqueous solution with a high concentration of sodium hydroxide or is subjected to intensive purification with a longer washing time, approximately 6% or more of the cumene reacted in the oxidation process still remains as dimethylphenyl carbide. It is wasted in order to generate nol. In the present invention, the alkylbenzene in which at least one isopropyl group is bonded to a benzene ring specifically includes cumene, P-cymene,
Examples include m-cymene, P-diisopropylbenzene, m-diisopropylbenzene, and triisopropylbenzene, but cumene, P-cymene, and m-cymene are preferred, and cumene is particularly preferred.

In the present invention, recovered alkylbenzene after the oxidation process is cumene obtained by oxidizing alkylbenzene such as cumene or cymene with a molecular oxygen-containing gas and introducing a -00-day group into the carbon at the Q position of the isopropyl group bonded to the benzene ring. 5% by weight of alkylbenzene hydroperoxide such as hydroperoxide, cymene hydroperoxide, etc.
This refers to alkylbenzene separated by distillation from a solution containing alkylbenzene, but this also includes a concentrated solution of alkylbenzene hydroperoxide obtained as a result of the above distillation having a concentration of 60 to 9% by weight, which is subjected to a cleavage reaction in the presence of an acid catalyst. There is no problem even if the alkylbenzene obtained in the process of separating phenol and acetone by distillation from the mixture containing phenols and acetone obtained in the process is mixed.

In the present invention, after the recovered alkylbenzene is brought into contact with an aqueous solution A having a pH of 12.5 or higher, 0 carbonate ions are removed per solution.
．． Contact with aqueous solution B containing 1 mol or more.

In this method for treating recovered alkylbenzene, the order of contact is important. If the order of contact is reversed, the effect of suppressing the formation of by-products in the oxidation step will not be sufficient. Furthermore, if the pH of the aqueous solution A is less than 12.5, the oxidation rate will decrease,
The effect of suppressing the production of by-products is also low, and if the carbonate ions in the aqueous solution B are 0.1 mole per solution, the effect of suppressing the production of by-products is not sufficient. The aqueous solution A in the present invention is p
Although H must be 12.5 or more, it is more preferable that PH is 13 or more.

Such aqueous solution A can be obtained by mixing an appropriate amount of lithium hydroxide, sodium hydroxide, potassium hydroxide, barium hydroxide, etc. with water. Among them, lithium hydroxide, sodium hydroxide and potassium hydroxide are preferably used, and sodium hydroxide is particularly preferably used. Such aqueous solution A has a concentration of 5 to 9 recovered alkylbenzenes.
It is used for 2,000 ℃ in the evening and is kept in contact for 10 minutes to 2 hours at a temperature of room temperature to 10,000 ℃.

The aqueous solution B used in the present invention must contain 0.1 mole or more of carbonate ions per solution, but good results can be obtained if it contains 0.5 mole or more. The form in which carbonate ions exist in water does not necessarily have to be in a free state. Also, p of aqueous solution B
H is preferably 11 or more, more preferably 1
There is no 1, and there are 14. Such aqueous solution B can be obtained by mixing an appropriate amount of a carbonate such as lithium carbonate, sodium carbonate, potassium carbonate, magnesium carbonate, calcium carbonate, barium carbonate, lithium bicarbonate, sodium bicarbonate or potassium bicarbonate with water. . Among them, lithium carbonate, sodium carbonate, potassium carbonate, lithium bicarbonate, sodium bicarbonate, potassium bicarbonate, and the like are preferably used, and sodium carbonate and sodium bicarbonate are particularly preferable. Further, the aqueous solution B may be prepared by mixing an appropriate amount of a strong alkaline substance such as lithium hydroxide, sodium hydroxide, or potassium hydroxide for pH adjustment. A particularly preferred aqueous solution B is a mixture of water and sodium carbonate, or a mixture of water, sodium bicarbonate and sodium hydroxide, so that carbonate ions are present in an amount of 0.5 to 2 gram equivalents per aqueous solution. PH is 11
This is aqueous solution B prepared so as to give No. 14. The aqueous solution B is used for 5 to 2000 t of recovered cumene lk9, and is kept in contact for 10 minutes to 2 hours at a temperature of room temperature to 100 qC.

Even better results can be obtained if the alkylbenzene after contact with aqueous solution B is brought into contact with water.

In this case, 5 to 2,000 hours of water is used for recovered alkylbenzene lk9, and the mixture is brought into contact with the recovered alkylbenzene at room temperature to 10,000 degrees for 1 to 2 hours. The contacting method with each of the above aqueous solutions may be either a batch method or a continuous method, but a continuous method is preferred from an industrial perspective.

The contacting device can be a commonly used device, such as a container equipped with a pitcher. The thus treated recovered alkylbenzene is fed to an oxidation step.

Usually, at the same time, fresh alkylbenzene that has not gone through the oxidation process is also supplied, but of course, fresh alkylbenzene and recovered alkylbenzene may be mixed in advance, then the above-mentioned contact operation is carried out, and the mixture is supplied to the oxidation process. The method for oxidizing alkylbenzene used in the present invention involves bringing alkylbenzene into contact with a molecular oxygen-containing gas, such as pure oxygen or air, at a temperature of room temperature to 120 qo and under normal pressure or high pressure, to reduce the concentration of alkylbenzene hydroperoxide. After the amount of 5% and 4% by weight was reached, the reaction product was extracted from the reaction tank.

A method of supplying an aqueous alkali solution such as sodium hydroxide or sodium carbonate into a reaction tank in order to avoid the adverse effects of acidic substances created in the oxidation reaction is well known, but even if this method is used in the oxidation step of the present invention, good. In addition, some alkylbenzene hydroperoxide may be present in the recovered alkylbenzene, and this hydroperoxide can serve as an initiator in the oxidation process. Peroxides more remote than 100% may be added as initiators.

The products created in this oxidation process, especially carbinols,
Since the recovered alkylbenzene is treated according to the method of the present invention, the amount is extremely small compared to conventionally known methods. The solution obtained in the oxidation step is usually distilled under reduced pressure to remove all or part of the alkylbenzene to prepare a solution containing 60 to 9% by weight of alkylbenzene hydroperoxide or alkylbenzene hydroperoxide. The recovered alkylbenzene is again brought into contact with the aqueous solution containing the alkali and supplied to the oxidation step. The alkylbenzene hyde mentioned above.

Phenol can be obtained by distilling a mixture of phenols, acetone, and alkylbenzene obtained by cleaving alkylbenzene hydroperoxide with an acid catalyst, such as sulfuric acid, using a solution containing 60% to 90% by weight of peroxide. can. Since the amount of carbinols in the concentrated solution of alkylbenzene hydroperoxide obtained by the method of the present invention is small, complicated reactions during the cleavage reaction are reduced, and phenol can be obtained in good yield. In addition, the alkylbenzene recovered in the phenol recovery process is contacted with the aqueous alkali solution,
Supplied to the oxidation process. With the completion of the present invention as detailed above, the amount of by-products, especially carbinols, produced in the alkylbenzene oxidation process has been significantly reduced, and as a result, the wasteful consumption of alkylbenzene has been reduced. For example, when cumene is oxidized to obtain cumene hydroperoxide, the proportion of the reacted cumeso that was wasted was as much as 6% or more, but according to the method of the present invention, this can be reduced to about 1%. Furthermore, when producing phenols using alkylbenzene hydroperoxide as a raw material, phenols can be obtained in good yield because undesirable side reactions caused by carbinols are reduced. Therefore, the present invention has great industrial value.

The present invention will be specifically explained below using Examples. Example
Oxidation product obtained by oxidizing 1 cumene with molecular oxygen-containing gas (mixture of cumene and cumene hydroperoxide)
70% by weight of reactive cumene obtained by vacuum distillation, 8% by weight of cumene recovered after decomposing the condensed cumene hydroperoxide obtained by the above vacuum distillation into phenol and acetone with sulfuric acid and recovering phenol and acetone. Then, 600 grams of so-called new cumene (22% by weight) which has not undergone the oxidation process of cumene was charged into a glass flask equipped with a dropper and a thermometer, and then 600 grams of aqueous solution A prepared by the following method was charged. , and was vigorously roped for 1 hour at room temperature.

After the drying period, the entire amount of cumene was collected and put into a glass flask equipped with a pestle and a thermometer along with an aqueous solution B60 prepared by the following method and heated for 1 hour. After standing still, 500 tons of cumene was collected, and 500 tons of cumene, 20 tons of di(tert-butyl) peroxide, and 50 tons of an aqueous solution containing 1% by weight of sodium carbonate were added to a thermometer, a thermometer, and a gas blower. A glass reactor equipped with a charging device was charged with 1.6 m of oxygen gas under normal pressure at 90 mm.
A rope reaction was carried out by supplying the solution at a rate of in. After 4 hours, the supply of oxygen was stopped and the product was taken out.

When the composition of the organic phase was analyzed by gas chromatography and iodometry, the amount of cumene hydroperoxide produced was 192 mmol, dimethylphenyl carpi/
The amount of alcohol was 5.4 mmol, and the amount of acetophenone was 1.4 mmol. Therefore, among the reacted cumene, the proportion converted to cumene hydroperoxide was 96.6 mol%, 2.7 mol% for dimethylphenylrubinol, and 0.7 mol% for acetophenone.
Preparation method of aqueous solution A: An aqueous solution with a pH of 14 was prepared by dissolving 40 ml of sodium hydroxide in water and leaving the entire solution overnight.

Preparation method of aqueous solution B Dissolve 106 ml of sodium carbonate in water, make the whole solution 1. ○ An aqueous solution containing 1 mole of carbonate ion per aqueous solution was prepared.

Example 2 In Example 1, the entire amount of the cumene phase that had come into contact with the aqueous solution B was taken out, put into a flask equipped with a thermometer and a cypress, and further stirred vigorously for 1 hour at room temperature. The same operation as in Example 1 was performed except for the addition.

The results are shown in the table. Example 3 In Example 1, 4 tons of sodium hydroxide was used to adjust the pH.
The same operation as in Example 1 was performed except for preparing aqueous solution A of =13.

The results are shown in the table. Examples 4 and 5 In Example 1, 53 and 212 tons of sodium carbonate were used each to contain 0.5 to 2 moles of carbonate ions per 1 kg, and the pH was 11.311.
．． The same operation as in Example 1 was performed except for preparing aqueous solution B named 9.

The results are shown in the table. Example 6 The same procedure as in Example 1 was carried out except for preparing aqueous solution B containing 1 mole of carbonate ions and having a pH of 11.7 using 84 μm of sodium bicarbonate and 40 μm of sodium hydroxide. went.

The results are shown in the table. Example 7 In Example 1, the same operations as in Example 1 were performed except that the oxidation operation was performed as follows.

The results are shown in the table. As the oxidation operation reactor, a stainless steel pressure-resistant autoclave equipped with a basic vessel and a gas blowing device was used, and cumene hydroperoxide was added in place of di(tert-butyl) peroxide, and the pressure was 7k9. The reaction was carried out at a temperature of 112°C for 4 hours while supplying air at a rate of 300N/hr.

Comparative Example 1 The same operations as in Example 1 were performed except that the operation of contacting with the aqueous solution B' was not performed.

The results are shown in the table. Comparative Example 2 In Comparative Example 1, 80 tons of sodium hydroxide was used to
The same operation was performed except for preparing aqueous solution A on HI Buddha.

The results are shown in the table. Comparative Example 3 The same operation as in Example 1 was performed except that the order of contact between cumene and aqueous solutions A and B was reversed.

Comparative Example 4 The same operation as in Example 1 was performed except that the aqueous solution A of the fence 12 was prepared using sodium hydroxide for 0.4 days.

The results are shown in the table. Comparative Example 5 The same operation as in Example 1 was carried out except that 5.3 t of sodium carbonate was used in Example 1, and aqueous solution B containing 0.05 mol of carbonate ions per night and having a pH of 0.7 was prepared.

The results are shown in the table. Table mCHP: cumene hydroperoxide {2'CA: dimethylphenyl carbinol (3-AP
: Acetophenone [4} Carbonate ion content: mol/so

Claims (1)

[Scope of Claims] 1. A method for producing an alkylbenzene hydroperoxide by oxidizing an alkylbenzene in which at least one isopropyl group is bonded to a benzene ring using a molecular oxygen-containing gas, in which the alkylbenzene hydroperoxide is concentrated after the oxidation step. After bringing the alkylbenzene recovered in the step into contact with an aqueous solution A having a pH of 12.5 or more,
A method for producing alkylbenzene hydroperoxide, which comprises contacting with an aqueous solution B containing carbonate ions in an amount of 0.1 mole or more per liter, and supplying the solution to an alkylbenzene oxidation step. 2. The method according to claim 1, characterized in that cumene is used as the alkylbenzene. 3. The method according to claim 1, characterized in that the aqueous solution B is an aqueous solution containing 0.5 mol or more of carbonate ions per liter. 4. The method according to claim 1, wherein an aqueous solution having a pH of 11 to 14 is used as the aqueous solution B. 5. The method according to claim 1, characterized in that aqueous solution B prepared by mixing sodium carbonate and water is used. 6. The method according to claim 1, characterized in that aqueous solution B prepared by mixing sodium bicarbonate, sodium hydroxide, and water is used. 7. The method according to claim 1, characterized in that the aqueous solution A is an aqueous solution having a pH of 13 or more. 8. The method according to claim 1, characterized in that aqueous solution A prepared by mixing sodium hydroxide and water is used. 9. The method according to claim 1, characterized in that after the recovered alkylbenzene is brought into contact with the aqueous solution B, the recovered alkylbenzene is further brought into contact with water.