JPS6010015B2 - Purification method of recovered solvent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for purifying a recovered solvent used in producing hydroquinone from p-isoprobenylphenol.

As an industrial method for producing hydroquinone, a method of oxidizing rose-substituted phenols has been proposed (Japanese Patent Publication No. 1983).
-3673 number).

In addition, the present inventors previously proposed an improved method using p-isoprobenylphenol as a starting material for this method (Tokusei No. 50-10692y). The present inventors conducted a more detailed study on these methods and discovered a fact that is extremely important from the viewpoint of process safety when refining the recovered solvent used in the oxidation reaction.

By oxidizing p-isoprobenylphenol,
Hydroquinone and acetone are produced, but acetone is further oxidized to peroxide, a dangerous substance that explodes on impact if removed as a solid. Since water is soluble, this material is included in the reaction solvent phase when separating the reaction mixture. Therefore, in purifying the recovered solvent, it is necessary to remove this dangerous substance. The present inventors have completed the present invention as a result of intensive study on a method for removing this dangerous substance from the recovered solvent.

That is, the method for purifying the recovered solvent according to the present invention involves oxidizing p-isoprobenylphenol in water with hydrogen peroxide or an organic peroxide in the presence of a strong acid in a high boiling point polar solvent that is difficult to oxidize. In a method for refining the high-boiling polar solvent recovered by separating the resulting reaction mixture so that it can be reused as an oxidation reaction solvent, the recovered polar solvent is treated with a substance that produces metal ions that can have two or more valences or pka. value is 1.0
It is characterized by treatment in the presence of the following strong acid.

Hydroquinone is produced as follows using p-isoprobenylphenol as a starting material.

The starting material p-isoprobenylphenol can be cleaved, for example, by heating dihydroxydiphenylpropane to 180°C or higher in the presence of a basic catalyst.
After obtaining a mixture of oligomers of p-isoprobenylphenol, p-isoprobenylphenol, and p-isoprobenylphenol, the phenol is removed from the mixture, and the mixture is further treated at a high temperature of 150 qo or higher, preferably under reduced pressure, in the presence or absence of a basic catalyst. It can be easily obtained by a method in which an oligomer of p-isoprobenylphenol is cleaved by ripening to generate p-isoprobenylphenol. The generated p-isoprobenylphenol is brought into contact with water in a gaseous state or immediately after condensation with a high boiling point polar solvent soluble in bonito to form a p-isoprobenylphenol solution and subjected to an oxidation reaction. Examples of high-boiling polar solvents that are compatible with water include alcohols, esters, and ketones, which have a boiling point of 100 oo at 76 mHg.
The temperature is preferably 150°C or higher and the solubility in water at room temperature is 1% by weight or less, particularly 2% by weight.
The following are preferred. For example, aliphatic alcohols such as heptyl alcohol, n-octyl alcohol, 2-ethylhexanol, inoctyl alcohol, n-nonyl alcohol, isodecanol, tridecanol, butyl acetate, amyl acetate, 2-ethylhexyl acetate, cyclohexyl acetate, diethylene glycol monobutyl ether Examples include esters such as acetate, ketoso compounds such as ethylbutyl ketone, valerone, cyclohexanone, and acetophenone. Hydrogen peroxide and organic peroxide are used as oxidizing agents to convert p-isoprobenylphenol in the solution to hydroquinone.

As an organic peroxide, the general formula R,,R2,R3 is as follows:
It is an alkyl group or an aryl group. ), examples of which include t-butyl hydroperoxide, yumene hydroperoxide, isopropylbenzenehydroperoxide, and the like. These oxidizing agents are used in about equimolar amounts to p-isoprobenylphenol in the solution, usually in a proportion of 90 to 130 mol % relative to p-isoprobenylphenol. The strong acid used as a catalyst for the oxidation reaction preferably has a pKa value of about 1.0 or less, such as sulfuric acid, hydrochloric acid, nitric acid, p-toluenesulfonic acid, and the like. The amount used is 1 to 100 mol% based on p-isoprobenylphenol, especially 3
~30 mol% is preferred. The above strong acid and oxidizing agent are p-isoph.

When mixing with the robenylphenol solution, the reaction system should be kept at a temperature of 25 qo or higher, and the temperature should be kept at 280 qo during the oxidation reaction.
Maintain the temperature at ~5,000 o'clock, preferably from 30 o'clock to 45 o'clock o'clock. The oxidation reaction is thus carried out for a predetermined period of time, and a small amount of undecomposed p-isoprobenylphenol hydro/guoxide and unreacted oxidizing agent remain in the reaction mixture where the reaction has substantially completed. Although it is generally a small amount of 0.5% or less of the hydrogen peroxide fed into the reaction system, in order to remove this residual hydrogen peroxide, sulfur dioxide gas or its aqueous solution is added in an amount equal to or more than the remaining oxidizing agent. do. The reaction mixture thus obtained readily separates into an aqueous phase containing primarily strong acid and a pure polar solvent phase containing primarily hydroquine.

Next, the high-boiling polar solvent phase from which the strong acid has been removed is brought into contact with hot water for extraction. It contains soprobenylphenol, oligomers of p-isoprobenylphenol that are produced as by-products in the oxidation process, its oxides (ketones), benzoquinone, etc.If this is extracted using hot water, it can be extracted with hot water. Hydroquinone and acetone can be extracted and separated in the polar solvent phase, and benylphenol oligomers, their oxides, benzoquinone, etc. can be extracted and separated, respectively. It was discovered that this polar solvent phase also contained acetone peroxide, which is extremely dangerous.In the method of the present invention, this recovered solvent is mixed with a specific organic peroxide. It is processed in the presence of decomposable substances.

Substances that can decompose the specific organic peroxide used in the present invention include substances that generate metal ions that can have two or more valences, such as cobalt, manganese, nickel, chromium, copper, and vanadium ions. Specifically, examples include halides and hydroxides of these metals, and strong acids having a pKa value of about 1.0 or less, such as sulfuric acid and hydrochloric acid.

The amount of catalyst used is sufficient. The treatment temperature is appropriately selected depending on the type of catalyst, the amount of catalyst, the decomposition time of the organic peroxide, etc., but it is preferable to increase the decomposition efficiency by heating.

Further, L. Although this treatment may be carried out before a purification step such as distillation, it is more advantageous in terms of the process to carry out the treatment of the present invention while purifying by distillation. According to the method of the present invention, dangerous explosive substances contained in the recovered solvent can be completely decomposed and removed, making it possible to safely reuse the recovered solvent.

The present invention will be specifically explained below using examples.

Example 1'11 Production of p-isoprobenylphenol solution: 8 p-isoprobenylphenol monomers
%, cleavage product of dephenolated bisphenol A containing 85% linear dimer, 7% trimer or higher polymers 500
The water was charged into the distillation pot.

The temperature inside the pot was raised from 150 quarts to 240 quarts while heating under reduced pressure to extract p-isoprobenylphenol.

A short filling section was provided at the inlet of the cooling tube, and 1000 g of n-octanol was continuously charged from the upper inlet of the filling section.

Considering the distillation rate of p-isoprobenylphenol, the charging rate is approximately 2% for the distilled p-isoprobenylphenol.
The solvent was charged at a rate that doubled the volume. The distillate was absorbed and dissolved in a solvent in the packed column and taken out as an oct/al solution into a receiver. The octanol solution taken out was 1470 ml (
As a result of measuring the composition of the sample (concentration 32%) by gas chromatography and thin layer chromatography, the presence of oligomers including dimers other than p-isoprobenylphenol was not observed. The amount of p-isoprobenylphenol in the octanol solution is equivalent to 470 mg, which gives a cleavage yield of 94%. ■ Production of hydroquinone: 500 g of the obtained p-isoprobenylphenol solution,
30% hydrogen peroxide 134.0% and 60% sulfuric acid water 31
．． 19 were added simultaneously and continuously to the flask and mixed over a period of about 5 hours while maintaining the temperature at about 320°C.

The reaction was exothermic, and the internal temperature was maintained at 30°C while cooling. After the dripping was finished, I worshiped the lantern for another hour.

The hydrogen peroxide concentration and p-isoprobenylphenol hydroperoxide concentration in the reaction system are each 0.0.
3% and 0.05%. Next, 0.61 liters of sulfur dioxide gas (1.1 $ sonic weight of remaining peroxide) was added to decompose the remaining peroxide.

The reaction solution was allowed to stand and was separated into two phases, which were then separated into an aqueous phase and an organic phase. The organic phase was extracted 5 times with 900° portions of water at an extraction temperature of 60°.

The aqueous extracts containing hydroquinone and acetone were combined, acetone was recovered by distillation under normal pressure, and then concentrated under reduced pressure. After cooling, the crystallized hydroquinone was separated and dried through an oven, resulting in a purity of 99.2%.
Hydroquinone 1 with melting point 172.60-172.9qo
25.3 pm. After extracting hydroquinone and acetone, 0.07 g of cupric chloride was added to the organic phase and heated at 115-118°C for 30 minutes.

Claims (1)

[Claims] 1. A high-boiling polar compound recovered by separating the reaction mixture obtained by oxidizing p-isopropenylphenol with hydrogen peroxide or an organic peroxide in the presence of a strong acid in a high-boiling polar solvent that is sparingly soluble in water. In a method for refining a solvent so that it can be reused as an oxidation reaction solvent, the recovered polar solvent is treated with a substance that produces metal ions having two or more valences or pka
1. A method for purifying a recovered solvent, comprising processing in the presence of a strong acid having a value of 1.0 or less.