JPH08176043A - Method for simultaneously producing high-purity 2-t-butylhydroquinone and 2,5-di-t-butylhydroquinone - Google Patents

Abstract

PURPOSE: To obtain a reaction mixture containing 2-t-butylhydroquinone and 2,5-di-t-butylhydroquinone by butylating hydroquinone with a butylating agent and efficiently and simultaneously obtain both compounds in good yield from the reactional mixture. CONSTITUTION: In this method for producing 2-t-butylhydroquinone and 2,5-di-t- butylhydroquinone by subjecting hydroquinone to butylation reaction in the presence of an acid catalyst, a reaction mixture containing these two compounds is obtained by the butylation reaction and a mixed solvent of methanol and water as a crystallizing solvent is added to the reaction mixture and 2,5-di-t- butylhydroquinone is subjected to separation by crystallization and methanol is distilled away from the resultant mother liquid of crystallization and an aromatic hydrocarbon is added as a solvent for crystallization to the distillation residue to carry out separation of 2-t-butylhydroquinone by crystallization. Thereby, high-purity 2-t-butylhydroquinone and 2,5-di-t-butylhydroquinone can simultaneously be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for simultaneously producing highly pure 2-t-butylhydroquinone and 2,5-di-t-butylhydroquinone. 2-t-butylhydroquinone is widely used as an antioxidant for rubber, plastics, edible oils and fats, a polymerization inhibitor for polymerizable monomers, a photographic agent, a cosmetic additive, and the like. Also,
2,5-di-t-butylhydroquinone is also used as a non-staining antioxidant for plastics, rubbers, lubricating oils and the like.

[0002]

2. Description of the Prior Art 2-t-Butyl hydroquinone and 2,5
-Di-t-butylhydroquinone has conventionally been industrially produced by a method in which hydroquinone is subjected to a butylation reaction using isobutylene or t-butyl alcohol as a butylating agent in the presence of an acid catalyst.

According to such a production method, the butylation reaction of hydroquinone is carried out by the following formula

[0004]

Embedded image

As shown in (1), since the reaction rates of the first butylated reaction and the next butylated reaction are substantially the same, the reaction product obtained by the above butylated reaction is Usually, it is a mixture containing unreacted hydroquinone together with 2-t-butylhydroquinone and 2,5-di-t-butylhydroquinone.

For example, Japanese Unexamined Patent Publication No. 62-81338 describes that hydroquinone is subjected to a butylation reaction using isobutylene in a toluene solvent in the presence of an aqueous phosphoric acid solution. According to this method, The obtained reaction product has a composition shown in Table 1.

[0007]

[Table 1]

As described above, according to the method for carrying out the butylation reaction of hydroquinone using isobutylene or t-butyl alcohol as a butylating agent in the presence of an acid catalyst,
As a reaction product, 2-t-butylhydroquinone and 2,
A mixture containing unreacted hydroquinone is obtained together with 5-di-t-butylhydroquinone. Therefore, in industrial production, usually, from such a reaction mixture,
Required 2-t-butylhydroquinone or 2,5-di-t
-Butyl hydroquinone is separated and used as a product.

However, 2-t-butylhydroquinone and 2,5-di-t-butylhydroquinone are close to each other in physical properties, solubility in various organic solvents, boiling points, etc. Since the compound of (1) also has poor thermal stability, it is necessary to separate a high-purity product from the obtained reaction mixture in good yield by using any conventional separation method conventionally used industrially. Is difficult. For example, JP-A-62-81339
In the publication, the relative volatility of 2-t-butylhydroquinone and 2,5-di-t-butylhydroquinone are both close to 1, and at high temperatures, both compounds undergo thermal decomposition, Further, it is described that the separation by distillation is difficult to industrially adopt because it is markedly colored due to the leakage of a small amount of air.

Further, conventionally, a reaction mixture containing 2-t-butylhydroquinone and 2,5-di-t-butylhydroquinone was obtained by the butylation reaction of hydroquinone as described above, and either compound was separated from this. However, although various purification methods have been proposed, each of them only describes a method for separating only one of the above-mentioned two compounds from the obtained reaction mixture. In other words, since the separation efficiency of both is poor, one compound must be sacrificed and only the other high-purity product must be separated, and this is the current state of affairs. Therefore, conventionally, by the butylation reaction of hydroquinone,
High-purity 2-t-butylhydroquinone and 2,5-di-t
There is no known method for simultaneously separating -butylhydroquinone and a high yield from a reaction mixture to obtain a product.

2-tert-butylhydroquinone and 2,5-di-t-obtained by the butylation reaction of hydroquinone
From the reaction mixture containing butyl hydroquinone, 2-t
-As a method for separating and purifying butyl hydroquinone,
Various fractional crystallization methods utilizing the difference in solubility of these two compounds in organic solvents have been proposed.

For example, Japanese Patent Application No. 3-236340 discloses a fractional crystallization method which utilizes the difference in the solubility of the above two compounds in toluene. That is, according to this, 2-t-butylhydroquinone and 2,5-di-t-
Toluene was added as a crystallization solvent to a reaction mixture containing butylhydroquinone, and 2,5-di-t-butylhydroquinone having a lower solubility in this solvent was first added to 80%.
It is crystallized at ℃, filtered, and then the crystallization mother liquor is cooled to 40 ℃ to crystallize the desired 2-t-butylhydroquinone, which is then separated. According to this method, the target 2-t-butylhydroquinone can be obtained with a purity of 94 to 99%, but the crystallization recovery rate is 25% based on the produced 2-t-butylhydroquinone. Only ~ 30%.

Further, many extraction and separation methods utilizing the difference in solubility of two compounds in hot water have been proposed. This method utilizes the fact that 2-t-butylhydroquinone has higher solubility in hot water.

For example, in US Pat. No. 2,722,556, hydroquinone is butylated in toluene in the presence of an acid catalyst, and 2-t-butylhydroquinone and 2,5-di-t-butyl are reacted with unreacted hydroquinone. A reaction mixture containing hydroquinone is obtained, first, this reaction mixture is subjected to steam distillation, toluene is distilled off, 2-t-butylhydroquinone is dissolved in hot water, transferred, and then undissolved in hot water. As it is, the suspended crystals of 2,5-di-t-butylhydroquinone are filtered off, and finally, this crystallization mother liquor is cooled to crystallize the desired 2-t-butylhydroquinone. A method of filtering off is described.

Further, in JP-A-62-81340, a reaction mixture containing 2-t-butylhydroquinone and 2,5-dibutylhydroquinone is first subjected to a solid-liquid extraction operation using hot water, and then, The obtained extract was cooled and crystallized, and crude crystals of 2-t-butylhydroquinone were brought into contact with a toluene solvent at room temperature to wash them, and then 2-t-butylhydroquinone thus obtained. The solid content is collected by filtration from the slurry of 1., the resulting cake is dehydrated, and then steam distillation is performed to remove the toluene attached to the cake, and the target 2-t-butylhydroquinone is crystallized from hot water. Is disclosed. According to this method, the content of 2,5-di-t-butylhydroquinone was 0.05%.
It is described below that a food grade high-purity product having a toluene content of several ppm or less can be obtained. However, this method requires 100 parts by weight of hot water for 1 part by weight of 2-t-butylhydroquinone.

That is, in such a solid-liquid extraction method, since the solubility of 2-t-butylhydroquinone in hot water is small (for example, 2% by weight at 70 ° C. and 1% by weight at 40 ° C.), a large amount of heat is generated. Since water must be used, it is not an industrially advantageous method. Japanese Unexamined Patent Publication (Kokai) No. 62-81339 describes a continuous treatment method including the solid-liquid hot water extraction.

Various proposals have hitherto been made for a method for separating and purifying 2,5-di-t-butylhydroquinone from a reaction mixture. For example, Japanese Examined Patent Publication No. 51-33099 proposes a method in which n-hexane or cyclohexane is added to the obtained reaction compound to separate the two compounds. Further, in JP-A-62-81341, the obtained reaction compound is treated with warm water to give 2-t.
A method has been proposed in which, after extracting and removing -butylhydroquinone, the extraction residual liquid is treated with toluene to crystallize 2,5-di-t-butylhydroquinone, followed by separation and purification.
According to this method, the separation and recovery of 2,5-di-t-butylhydroquinone are 95% and the purity thereof is 99.8%.

As described above, the method by distillation is difficult to be industrially adopted, and the method by fractional crystallization is also 2-t-.
Since the difference in solubility between butylhydroquinone and 2,5-di-t-butylhydroquinone in an organic solvent is small, the separation efficiency is poor, and as a result, in order to obtain a highly pure product of any of the conventional compounds, However, many separation and purification processes are required, the manufacturing process is complicated, and the separation yield of the target product is low.

Further, as described above, conventionally, no method has been known which can simultaneously obtain a high-purity product of 2-t-butylhydroquinone and 2,5-di-t-butylhydroquinone.

[0020]

DISCLOSURE OF THE INVENTION The present invention provides a reaction mixture containing 2-t-butylhydroquinone and 2,5-di-t-butylhydroquinone by a butylation reaction of hydroquinone, which is purified and treated. Thus, it is an object of the present invention to provide an industrially useful method capable of efficiently obtaining a highly pure product of the above two compounds together with a high yield.

[0021]

According to the present invention, hydroquinone is subjected to a butylation reaction in an organic solvent in the presence of an acid catalyst to give 2-t-butylhydroquinone and 2,5-di-t-butyl. In the method for producing hydroquinone, a reaction mixture containing these two compounds is obtained, and a mixed solvent of methanol and water is added to this reaction mixture as a crystallization solvent to give 2,5-di-t-butylhydroquinone. It is characterized by performing crystallization separation, then distilling off methanol from the crystallization mother liquor, and adding aromatic hydrocarbon as a crystallization solvent to the distillation residue to crystallize and separate 2-t-butylhydroquinone. A method for simultaneously obtaining high-purity 2-t-butylhydroquinone and 2,5-di-t-butylhydroquinone is provided.

That is, according to the present invention, 2-t-butylhydroquinone has a large solubility in a mixed solvent of methanol and water, while 2,5-di-t-butylhydroquinone is almost soluble. Therefore, by taking advantage of such a large difference in solubility of these two compounds in a mixed solvent of methanol and water, crystallization of 2,5-di-t-butylhydroquinone is performed by using the above mixed solvent as a crystallization solvent. By separating and then using the aromatic hydrocarbon as a crystallization solvent for 2-t-butylhydroquinone, both can be efficiently separated and crystallized.

As described above, the isobutylene or t-butyl alcohol is used as the butylating agent in the presence of an acid catalyst in an organic solvent to carry out the butylation reaction of hydroquinone to give 2-t-butyl hydroquinone and 2 , 5-the-
The method for producing t-butylhydroquinone has already been industrially carried out, and the method of the present invention is not particularly limited by the reaction solvent and catalyst used in the butylation reaction.

As already known, in the above-mentioned butylation reaction, 2-t-butylhydroquinone and 2,5-di-t-butylhydroquinone can be obtained by changing the amount of the butylating agent used relative to hydroquinone. It is possible to adjust the production ratio of the, but the method of the present invention, the amount of butylating agent used in the butylation reaction, and also,
The ratio of 2-t-butylhydroquinone and 2,5-di-t-butylhydroquinone in the obtained reaction mixture is not particularly limited either. However, the method according to the present invention is particularly suitable for the case where unreacted hydroquinone is zero.
~ 20% by weight, 20% of 2-t-butylhydroquinone
80% by weight and 2,5-di-t-butylhydroquinone can be suitably applied to a reaction mixture having a composition in the range of 80 to 5% by weight.

Therefore, according to the method of the present invention, in the butylation reaction of hydroquinone, the amount of the butylating agent is appropriately adjusted, and the ratio of the reaction product is adjusted,
High-purity 2-t-butylhydroquinone and 2,5-di-t
-Butylhydroquinone can also be obtained in the respective desired ratios.

Although not particularly limited, the butylation reaction of hydroquinone suitable in the method of the present invention will be described in detail.

In the method of the present invention, the organic solvent used in the reaction is not particularly limited, but usually, for example, aromatic hydrocarbons such as toluene, xylene, ethylbenzene, mesitylene and cumene, and aromatic hydrocarbons thereof. A mixture of hydrogen and an aliphatic ketone such as diisopropyl ketone, methyl ethyl ketone or methyl isobutyl ketone is preferably used. Of these, xylene alone or a mixed solvent of xylene and methyl isobutyl ketone is preferably used.

The amount of such an organic solvent used in the reaction is not particularly limited in its amount,
Usually, it is used in the range of 200 to 1000 parts by weight with respect to 100 parts by weight of the raw material hydroquinone. It is preferably used in the range of 250 to 400 parts by weight.

In the method of the present invention, the acid catalyst is
Phosphoric acid is preferably used in the form of an aqueous solution. The phosphoric acid aqueous solution preferably has a phosphoric acid concentration of 50 to 85% by weight, particularly preferably 65 to 75% by weight. Such a phosphoric acid aqueous solution is usually 50 to 50 parts by weight with respect to 100 parts by weight of hydroquinone as a raw material.
It is used in the range of 1000 parts by weight, particularly preferably 1
It is used in the range of 00 to 300 parts by weight.

As the butylating agent, either t-butyl alcohol or isobutylene can be used, but isobutylene without reaction-produced water is preferably used. The butylating agent is usually used in the range of 0.7 to 2.5 mol with respect to 1 mol of hydroquinone as a raw material. In particular, in order to obtain a reaction mixture rich in 2-t-butylhydroquinone, the amount of isobutylene used is 0.7
The range of to 1.0 mol is preferable. On the other hand, in order to obtain a reaction mixture rich in 2,5-di-t-butylhydroquinone,
A range of 1.5 to 2.5 mol is preferred.

In the present invention, the butylation reaction of hydroquinone is usually 70 to 100 ° C., preferably 8
It is carried out at a temperature in the range of 5 to 95 ° C. The reaction pressure is
There is no particular limitation, and either normal pressure or pressure may be applied.

According to the present invention, hydroquinone as a raw material is dispersed in a mixture of the above organic solvent and phosphoric acid aqueous solution with stirring, and a predetermined amount of butylating agent, for example, isobutylene is introduced into the mixture to effect butylation. Carry out the reaction. The reaction mixture thus obtained is composed of two liquid layers of a phosphoric acid aqueous layer and an organic layer, and the reaction products 2-t-butylhydroquinone and 2,5-di-t-hydroquinone are unreacted. Dissolved in the above organic layer together with the hydroquinone.

The reaction mixture thus obtained usually contains 0 to 20 unreacted hydroquinone as described above.
% By weight, 20 to 80% by weight of 2-t-butylhydroquinone and 80 to 5% by weight of 2,5-di-t-hydroquinone.

First, the crystallization separation of 2,5-di-t-hydroquinone will be described. After carrying out the butylation reaction of hydroquinone as described above, the reaction mixture obtained is preferably allowed to stand while keeping the temperature at the time of the reaction, and the layers are separated to form a lower phosphoric acid aqueous solution layer. After liquid separation, the acid catalyst remaining in the oil layer is neutralized with a dilute aqueous alkali solution. The phosphoric acid aqueous layer separated here can be reused by circulating it to the butylation reaction step, if necessary.

Next, the organic solvent in the neutralized oil layer is distilled off, and the obtained distillation residue (bottom residue) is obtained.
An appropriate amount of a mixed solvent of methanol and water is added as a crystallization solvent, and the above residue is heated and dissolved. Then, the obtained solution was gradually cooled to a predetermined temperature and crystallized 2,5-di-t.
The crude crystals of butylhydroquinone are filtered off. Usually, the crystallization temperature is preferably in the range of 10 to 60 ° C, but particularly 3
The range of 5-40 degreeC is preferable.

The amount of the crystallization solvent used for the 2,5-di-t-hydroquinone is usually 100 to 300 parts by weight, preferably 100 to 300 parts by weight, preferably It is in the range of 150 to 300 parts by weight. In the mixed solvent of methanol and water used as the crystallization solvent, the concentration of methanol is usually preferably 10 to 60% by weight, but the solubility difference between the two compounds is particularly large.
The range of 0 to 50% by weight is preferable.

Methanol concentration in the crystallization solvent is 10% by weight
Or less than 60% by weight, the solubility difference between the two compounds becomes small, the separation efficiency between the two becomes poor, and the product purity and the crystallization recovery rate decrease.
It is industrially disadvantageous.

In the method of the present invention, the solubilities of 2-t-butylhydroquinone and 2,5-di-t-butylhydroquinone in a mixed solvent containing 40% by weight of methanol, which is preferably used as a crystallization solvent, are shown in Table 2. .

[0039]

[Table 2]

Then, the wet crude crystals of 2,5-di-t-butylhydroquinone thus obtained are washed with an organic solvent to remove the mother liquor adhering to the crude crystals. Then, the wet purified crystals of 2,5-di-t-butylhydroquinone thus obtained are placed in a drier and heated and dried at a temperature of 100 ° C. or less for an appropriate time under a reduced pressure of 100 mmHg or less to dry.

The purified crystals of 2,5-di-t-butylhydroquinone thus obtained were white and had a purity of 99.5%.
It is a high-purity product as described above. The crystallization recovery rate is usually 90% or more. The organic solvent used as the washing liquid for the crude crystals is not particularly limited, but it is preferable to use a mixed solvent of methanol and water used as a crystallization solvent in the present invention from the viewpoint of simplifying the process.

To wash the above crude crystals with an organic solvent,
Although it is not particularly limited, for example, a method in which crude crystals of moistened 2,5-di-t-butylhydroquinone are retained on a filter of a filter and sprinkled with a washing solution, or 2,5 An example is a method in which wet crude crystals of di-t-butylhydroquinone are added and held for an appropriate period of time, followed by filtration, and the like, whereby purified wet crystals can be obtained.

The amount of the washing liquid used is usually in the range of 50 to 100 parts by weight with respect to 100 parts by weight of the wet crude crystals of 2,5-di-t-butylhydroquinone. According to the present invention, it is preferable that the crystallization mother liquor and the washing liquid are sent to a solvent recovery step to recover the solvent by distillation. This recovered solvent is preferably recycled and reused.

Next, the crystallization separation of 2-t-butylhydroquinone will be described. As mentioned above, 2,5-di-
Methanol was distilled off from the crystallization mother liquor from which t-butylhydroquinone was collected by filtration, and then aromatic hydrocarbon was added to the obtained kettle residue as a crystallization solvent and heated to dissolve the kettle residue. , Make a homogeneous solution. Then, by cooling this solution, 2-t-butylhydroquinone is crystallized, and this is collected by filtration to obtain a crude crystal.

Here, as the aromatic hydrocarbon which is the crystallization solvent for the 2-t-butylhydroquinone, toluene, xylene, ethylbenzene, or a mixture thereof is preferable. The crystallization solvent is usually the above-mentioned residue 100
It is used in the range of 100 to 300 parts by weight, and preferably in the range of 100 to 150 parts by weight, based on parts by weight. The crystallization temperature is usually in the range of 10 to 50 ° C.

Then, in order to remove the mother liquor adhering to the crude crystals, the crude crystals are washed with an organic solvent. In order to wash the crude crystals with an organic solvent, for example, a method of holding the crude crystals of 2-t-butylhydroquinone on a filter filter and sprinkling the washing liquid on the filter as described above, A method in which 2-t-butylhydroquinone crystals are added, and the mixture is stirred and held for an appropriate period of time and then filtered can be exemplified. In this way, wet purified crystals can be obtained.

Here, the washing solution is usually 50 to 50 parts by weight with respect to 100 parts by weight of crude crystals of 2-t-butylhydroquinone.
It is used in the range of 100 parts by weight. The organic solvent used as the cleaning liquid for the crude crystals is not particularly limited, but according to the method of the present invention, it is preferable to use the aromatic hydrocarbon used as the crystallization solvent because the process can be simplified. .

The wet purified crystals of 2-t-butylhydroquinone thus obtained are placed in an ordinary drier and heated at a temperature of 100 ° C. or less for a suitable time under a reduced pressure of 200 mmHg or less to dry. The purified crystals of 2-t-butylhydroquinone thus obtained are white, and the purity is usually 99.5% or more. Further, according to such a method of the present invention, the crystallization recovery rate is usually
90% or more.

Also in this case, the aromatic hydrocarbons in the crystallization mother liquor and the washing liquid can be recovered by distillation and recycled. Further, although unreacted hydroquinone is dissolved in the crystallization mother liquor after the 2-t-butylhydroquinone is collected by filtration, the unreacted hydroquinone can be recovered by usual means such as concentration and extraction. It can be reused as a raw material.

[0050]

As described above, according to the method of the present invention,
Butylation reaction is performed on hydroquinone to obtain a reaction mixture containing 2-t-butylhydroquinone and 2,5-di-t-butylhydroquinone, and a mixed solvent of methanol and water is added to the reaction mixture as a crystallization solvent. In addition, 2,5-
Di-t-butyl hydroquinone was crystallized and separated, and then
Methanol was distilled off from the obtained crystallization mother liquor, and aromatic hydrocarbon was added to the obtained residue as a crystallization solvent to give 2-t.
-By crystallization separation of butylhydroquinone,
High-purity 2-t-butylhydroquinone and 2,5-di-t
-Butyl hydroquinone can be obtained simultaneously.

Moreover, according to the method of the present invention, even if the proportions of 2-t-butylhydroquinone and 2,5-di-t-butylhydroquinone in the reaction mixture change, they are separated and purified separately. Therefore, it is possible to deal with the production side according to the demand trends of both parties, which is industrially useful.

[0052]

The present invention will be described below with reference to examples.
The present invention is not limited to these examples.

Example 1 1 equipped with stirrer, cooler and isobutylene blowing tube
Hydroquinone 100 in a 3-liter flask with a capacity of 1 liter
g (0.91 mol), 100 g of 70% phosphoric acid and 250 g of xylene were charged, and the inside of the flask was replaced with nitrogen, and then the mixture in the flask was heated to 90 ° C. with stirring.

Then, 46 g of isobutylene was added to this mixture.
(0.82 mol) was bubbled in over 3 hours. The reaction solution is
Although it was in the form of a slurry at the initial stage of the reaction, the suspension in the slurry gradually dissolved as the reaction proceeded, and at the end of the reaction, a uniform two-liquid layer consisting of a phosphoric acid layer and an oil layer was formed. A part of this oil layer was collected, neutralized with dibasic sodium phosphate, and then analyzed by gas chromatography to find that the obtained reaction mixture was 13.7% by weight of hydroquinone and 72.2-t-butylhydroquinone. 5% by weight, 2.5
It was 12.3% by weight of di-t-butylhydroquinone and 1.5% by weight of other by-products.

After completion of the reaction, the reaction mixture was allowed to stand and the layers were separated into two layers. After the lower phosphoric acid layer was extracted, the upper oil layer was neutralized by adding 33 g of a 5% aqueous solution of dibasic sodium phosphate and allowed to stand, then the aqueous layer was removed and the resulting oil layer was washed with water. This oil layer was distilled to remove 246 g of xylene. Then, 420 g of a mixture of methanol and water having a concentration of 40% (hereinafter, the mixture of methanol and water is sometimes referred to as methanol water) was added to the residue of the kettle, and the mixture was heated to 80 ° C. and dissolved to obtain a uniform mixture. It was a solution.

Next, this solution was gradually cooled for crystallization. Precipitation of crystals started at 60 ° C. After cooling to 30 ° C., the obtained precipitated crystals were collected by filtration and washed with 40% methanol water. The obtained wet crystals are pressed at a pressure of 20 mmHg.
When dried under reduced pressure at 80 ° C for 4 hours, 2,5-
16 g of white purified crystals of di-t-butylhydroquinone
I got The crystallization recovery rate was 90%. The purity of the obtained crystal was 99.5%, and it contained 0.1% of 2-t-butylhydroquinone. Thus, methanol was recovered by distillation from the crystallization mother liquor from which the 2,5-di-t-butylhydroquinone crystals were separated.

Then, 226 g of xylene was added to the thus obtained kettle residual liquid and the temperature was raised to 80 ° C. to obtain a uniform solution. This solution was gradually cooled to 30 ° C., and the precipitated crystals were collected by filtration and washed with xylene. After washing, the crystals were dried by heating under the conditions of a pressure of 20 mmHg and a temperature of 80 ° C. for 4 hours to give 99 g of white crystals of 2-t-butylhydroquinone.
I got The crystallization recovery rate was 95%. The obtained crystal had a purity of 99.7%, and as an impurity, 2,5-di-t-
It contained 0.1% butyl hydroquinone.

The mother liquor from which 2-t-butylhydroquinone had been separated was separated into two layers, the oil layer containing 5 g of 2-t-butylhydroquinone, and the water layer containing hydroquinone 5
g was included.

Example 2 Hydroquinone (100 g, 0.9) was placed in a 1-liter three-necked flask equipped with a stirrer, a condenser and a gas blowing tube.
1 mol), 70% phosphoric acid 100 g and xylene 250 g
Was charged, the inside of the flask was replaced with nitrogen, and then the mixture in the flask was heated to 90 ° C. with stirring.

Then, 76 g of isobutylene was added to the above mixture.
(1.4 mol) was blown in over 5 hours. The reaction liquid changed from a slurry form to a uniform two-liquid layer consisting of a phosphoric acid layer and an oil layer. A part of this oil layer was collected, neutralized with an aqueous solution of dibasic sodium phosphate, and then analyzed by gas chromatography to find that the reaction mixture contained 0.2% by weight of hydroquinone and 42% by weight of 2-t-butylhydroquinone. 2,5-
It was 55% by weight of di-t-butylhydroquinone and 2.8% by weight of other by-products. After the completion of the reaction, the obtained reaction mixture was kept at the temperature at the time of the reaction, allowed to stand, and separated into layers, and the lower phosphoric acid layer was extracted. Then, 31 g of a 5% aqueous solution of sodium phosphate dibasic was added to the upper oil layer for neutralization,
The layers were separated and the neutralized water layer was extracted.

After removing 245 g of xylene from this oil layer by distillation, 438 g of 40% methanol water was added and the mixture was heated to 80 ° C.
The temperature was raised to a uniform solution. When this solution was gradually cooled, precipitation of crystals started at 71 ° C. After cooling to 30 ° C., the precipitated crystals were collected by filtration and washed with 40% methanol water. The wet crystals thus obtained are subjected to a pressure of 2
Dry for 4 hours under the condition of 0mmHg and temperature 80 ℃, 2.
96 g of white crystals of 5-di-t-butylhydroquinone were obtained. The crystallization recovery of 2,5-di-t-butylhydroquinone was 96%. The purity of the crystal is 99.5%
And contained 0.1% of 2-t-butylhydroquinone.

Methanol was distilled off from the mother liquor after separating the 2,5-di-t-butylhydroquinone. 226 g of xylene was added to the obtained residual liquid in the kettle and the temperature was adjusted to 80 ° C.
Up to a uniform solution, then add this solution to 30
After cooling to ℃, the precipitated crystals were collected by filtration and washed with xylene. The wet purified crystals thus obtained were subjected to pressure 2
When dried for 4 hours under conditions of 0 mmHg and a temperature of 80 ° C., 68 g of white crystals of 2-t-butylhydroquinone were obtained. The crystallization recovery rate was 90%. Further, the purity of the obtained purified crystal was 99.5%, and as an impurity, 2,5-
It contained 0.2% of di-t-butylhydroquinone.

Comparative Example 1 Hydroquinone (100 g, 0.9) was placed in a one-liter three-necked flask equipped with a stirrer, a cooler and a gas blowing tube.
1 mol), 70% phosphoric acid 100 g and xylene 250 g
Was charged, the inside of the flask was replaced with nitrogen, and the temperature was raised to 90 ° C. with stirring. Then, 60 g (1.07 mol) of isobutylene was blown into the mixture in the flask over 4 hours.

With the progress of the reaction, the mixture changed from a slurry state to a uniform two-liquid layer consisting of two layers of a phosphoric acid layer and an oil layer. A part of this oil layer was collected, neutralized with an aqueous solution of dibasic sodium phosphate, and then analyzed by gas chromatography. As a result, the obtained reaction mixture was found to contain 1.8% by weight of hydroquinone and 74% of 2-t-butylhydroquinone. % By weight, 2.5
-Di-t-butylhydroquinone 21.7% by weight and other by-products 2.5% by weight.

After the reaction was completed, the obtained reaction mixture was allowed to stand still, the layers were separated, and the lower phosphoric acid layer was extracted. Then
To the upper oil layer, 30 g of a 5% aqueous solution of dibasic sodium phosphate was added, neutralized, and then separated, and the neutralized water layer was extracted. The oil layer was heated to 90 ° C. and gradually cooled to 70 ° C., and the precipitated crystals were collected by filtration and washed with xylene. The wet crystals are placed under a pressure of 20 mmHg and a temperature of 80 ° C. for 4 minutes.
When dried for 24 hours, 24 g of 2,5-di-t-butylhydroquinone crystals were obtained. The purity of the 2,5-di-t-butylhydroquinone crystal was 96%. 2-t-butylhydroquinone 3.2 was added as an impurity in the crystals.
% Was included.

The crystallization mother liquor after the 2,5-di-t-butylhydroquinone was collected by filtration was further cooled to 0 ° C., and the precipitated crystals were collected by filtration and washed with xylene. When the wet crystals were dried under a pressure of 20 mmHg and a temperature of 80 ° C., 116 g of 2-t-butylhydroquinone crystals were obtained.
I got The purity of this 2-t-butylhydroquinone crystal was 90.1%, and it contained 7.0% of 2,5-di-t-butylhydroquinone and 1.0% of hydroquinone as impurities.

Claims (3)

[Claims] 1. A method for producing 2-t-butylhydroquinone and 2,5-di-t-butylhydroquinone by subjecting hydroquinone to an butylation reaction in an organic solvent in the presence of an acid catalyst, A reaction mixture containing two compounds was obtained, and a mixed solvent of methanol and water was added to this reaction mixture as a crystallization solvent to crystallize and separate 2,5-di-t-butylhydroquinone. After distilling off methanol from the mother liquor, aromatic hydrocarbon is added to the distillation residue as a crystallization solvent to crystallize and separate 2-t-butylhydroquinone.
A method for simultaneously obtaining butyl hydroquinone and 2,5-di-t-butyl hydroquinone. 2. A mixed solvent of methanol and water is 10 to 60.
The method of claim 1 having a methanol concentration in the range of weight percent. 3. The method according to claim 1, wherein the aromatic hydrocarbon is at least one selected from toluene, xylene and ethylbenzene.