JPS603290B2 - Method for purifying dihydric phenols - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for purifying resorcin and/or hydroquinone produced via hydroperoxide, and more specifically to a method for purifying resorcin and/or hydroquinone from a decomposition reaction solution of dialkylbenzene dihydroberoxide. A method for purifying resorcinol and/or hydroquinone, which comprises distilling the crude resorcinol and/or hydroquinone at 210°C or lower to remove the tar contained therein. be.

oxidation of dialkylbenzene by dialkylation of benzene to obtain dialkylbenzene dihydroberoxide;
For example, the method is to decompose this under acidic conditions to turn it into ketones, sorcinol, and/or hydroquinone, and then separate and remove the ketones, solvent, and other by-products from the decomposition reaction solution to obtain resorcinol and/or hydroquinone. This is known as the so-called hydroperoxide method.

The present invention relates to improvements in a method for obtaining highly purified resorcinol and/or hydroquinone as the final step in a series of these manufacturing steps.

The dialkylbenzenes targeted by the present invention include diisopropylbenzene, di-Sec-butylbenzene,
These include isopropyl-Sec-butylbenzene, but diisopropylobenzene is the most common, so in the following explanation, diisopropylbenzene will be explained as a representative dialkylbenzene. The ketones contained in the decomposition reaction solution vary depending on the type of alkyl group in the dialkylbenzene that is the oxidation raw material; for example, in the case of isopropyl group, it is acetone, and in the case of Sec-butyl group, it is methyl ethyl ketone.

A solvent is something added to facilitate a decomposition reaction, such as ketones such as acetone, methyl ethyl ketone, methyl isoptyl ketone, and methyl isopropyl ketone, alcohols such as propanol and butanol, benzene, These include aromatic hydrocarbons such as toluene, xylene, and chlorobenzene. Various by-products include inpropylphenol (IPP), isoprobenylphenol (OST), acetylphenol, 2-hydroxy-2-propylphenol, diisoprobenylbenzene, di(2-hydroxy-2-propyl)benzene, 2-hydroxy- These include 2-propylisopropylbenzene, acetylisoprobenylbenzene, 2-hydroxy-2-propyl-acetylbenzene, medityl oxide, diacetone alcohol, and tars generated during decomposition reactions and subsequent processing steps. A method for separating and purifying the target compounds, resorcinol and/or hydroquinone, from the decomposition reaction solution containing various components is to remove light boiling components such as acetone and solvents from the decomposition reaction solution by distillation in advance. After that, it is dissolved in water and extracted with an organic solvent such as toluene to obtain IPP and OS.
T and other created organisms and impurities are transferred to the toluene layer,
Known methods include a so-called extraction method for recovering resorcinol and/or hydroquinone from the aqueous layer, and a method for recrystallizing a decomposition reaction solution from which light boiling components such as acetone and solvent have been removed in advance from toluene. However, these methods require very complicated purification steps, and are not only operationally and economically advantageous, but also may not provide highly pure resorcinol and/or hydroquinone, and are not always fully satisfactory methods. I couldn't say that. Particularly with these methods, the removal of tars is a problem.
It has been very difficult to obtain hydroquinone with a high recovery rate.

For this reason, the present inventors investigated a method of removing tar by distillation from the decomposition reaction liquid from which the vertical moisture had been removed in advance, but found that resorcinol and/or hydroquinone and tars are different from each other. Despite the large difference in boiling point, it is extremely difficult to obtain high-purity resorcinol and/or hydroquinone from which tars have been completely removed under normal distillation conditions.
I learned that it is impossible. However, as a result of further investigation into this distillation method, the present inventors found that the temperature during the distillation operation and the proportion of tar and by-products mixed into the target compound (purity of the target product) are very closely and uniquely related. The inventors discovered that tars can be removed only when distilled under specific conditions, and that the target product can be obtained in high yield with high purity, leading to the present invention. .

That is, the present invention separates and removes components with a lower boiling point than resorcin and/or hydroquinone from the decomposition reaction solution of dialkylbenzene dihydroberoxide, and then converts crude resorcin and/or hydroquinone into 210qo
The following is a method for purifying resorcinol and/or hydroquinone, which preferably involves performing a distillation operation at 20,000 or less to remove the tar content. or) Hydroquinone can be obtained in good yield.

Note that the temperature conditions in the present invention are not intended to be the distillation temperature (top temperature), but mean that the highest temperature in a series of distillation steps is 210°C or less, which is the highest temperature in normal distillation operations. Refers to the temperature of distillation bottom liquid under certain conditions (hereinafter, this temperature will be briefly explained as bottom liquid temperature).

As described above, the present invention prevents the resorcinol and/or hydroquinone that come out from the bottom from being mixed with by-products having esters and vinyl groups to reduce the purity of the target distillate when the temperature of the bottom liquid exceeds 210q0. The reason for this is that tars are cleaved at temperatures above this temperature, regenerating resorcinol, hydroquinone, and OST and other styrenes, which have lower boiling points than these, and this regenerating product cannot be used to produce the target product. In addition, the distilled OST and other styrenes may react with resorcinol, etc. during condensation to form a tar-like substance, resulting in a decrease in the purity of the target product. This is thought to be due to the fact that these are contained in the crabmeat, and on the other hand, it is thought that at 210 qo or less, the cleavage of such tars is suppressed.

In addition, in the present invention, prior to distillation to remove tars, it is possible to remove from the decomposition reaction solution in advance OST and other styrenes, which are the cause of tar-like formation, and substances that are lighter than resorcinol and hydroquinone. is necessary. This is because when the operation of the present invention is carried out as described above, these light boiling fractions distilled together with the target distillate react with the target distillate again and turn into tar, and the tar is removed from the target distillate. This is because it cannot be completely removed and the object of the present invention cannot be achieved. However, it is not necessary to completely remove these light-boiling components, and a small amount of light-boiling components may remain. This is because if these are in small quantities, they will turn into tar due to the preheater or heating in the column during distillation, becoming so-called tar components, and their incorporation into the distillate as light-boiling components can be avoided. . As a method for removing the grain fraction, methods such as extraction, recrystallization, and distillation can be used alone or in combination.

Further, the present invention restricts only the maximum temperature during distillation of the crude resorcinol and/or hydroquinone, and does not impose any restrictions on the type of distillation.

In other words, distillation can be carried out either batchwise or continuously, and there is no particular restriction on the method of distillation, such as simple distillation, flash distillation, or crab distillation. Since tars may come out on the distillate side, high-purity resorcinol and (
or) if hydroquinone is required, theoretical plates 2 to 5
It is better to use a stage-level rectification format. In addition, when this distillation is carried out in the form of steam distillation, when it is carried out in the presence of other solvents (for example, when extractive distillation or azeotropic distillation is carried out), and when it is carried out in the presence of a third substance (for example, a polymerization inhibitor or antioxidant The effects of the present invention can be exhibited even when carried out in the presence of stabilizers (such as stabilizers, etc.). The present invention is directed to crude resorcinol containing tar, and can be applied regardless of the tar content; however, if the tar content is high, it may be necessary to roughly remove the tar in advance (at this time). (the treatment temperature may be 210 oo or more), it may be more efficient to apply the present invention thereafter.

As described above, the present invention specifies only the processing temperature in implementation, and does not require particularly complicated equipment, complicated operations, or large running costs, and is extremely economical. This is an epoch-making improved technology for resorcinol or (and) hydroquinone purification, as it can be carried out extremely easily and efficiently.

The present invention will be explained below with reference to Examples. However, in the examples, % and parts indicate weight % and parts by weight, respectively.

Examples 1 to 3 m-diisopropylbenzene dihydroberoxide (as impurities, diisopropylbenzene monohydroperoxide, acetylkyumene hydroperoxide, 2-hydroxy-2-prolykyumene hydroperoxide, di(2- Contains hydroxy-2-propyl)benzene.

) methyl isobutyl ketone solution was decomposed and neutralized using an acid catalyst. The resulting decomposition reaction solution was distilled under normal pressure and reduced pressure to remove acetone and methyl isobutyl ketone. The aqueous layer obtained was extracted with toluene. This toluene extraction was repeated until the components lower in boiling point than resorcin were completely transferred to the toluene layer. The aqueous layer was concentrated and dehydrated to obtain crude resorcin containing 90.8% of resorcin, 0.2% of m-acetylphenol, and 9.0% of tars. Using 10 parts of this crude resorcin, each was rectified under reduced pressure in a distillation tower with five theoretical plates at the bottom liquid temperature shown in Table 1. The refining was stopped when 90 to 95% of resorcin was distilled off, and the resulting distillate was analyzed, as shown in Table 1. Comparative Examples 1-2 The same procedure as in Example 1 was carried out except that the temperature of the can liquid in Example 1 was changed to the temperature shown in Table 1, and the obtained crab content was analyzed and the results were as shown in Table 1. Ta.

Table 1 Example 4 m/P of diisopropylbenzene dihydroberoxide
-Mixture (as impurities diisopropylbenzene monohydroperoxide, acetylkyumene hydroperoxide, 2-hydroxy-2-propylkyumehyde.

Contains peroxide, di(2-hydroxy-2-propyl)benzene. ) is decomposed with an acid catalyst,
The decomposition reaction solution obtained by the neutralization treatment is distilled at normal pressure or reduced pressure to remove lower boiling components from acetone, resorcinol, and hydroquinone, resulting in 82.7% resorcinol and hydroquinone and 0.0% m·P-acetylphenol. 9%
, and a mixture of crude resorcinol and hydroquinone containing 16.4% of tars. 10 parts of this crude resorcinol and hydroquinone mixture were added to the theoretical plate 1.
Using a frog bag distillation tower, vacuum purification was carried out at a temperature of 190° C. in the can liquid. When 95% of resorcinol and hydroquinone were released, the crab production was stopped and the distillate was analyzed, and the total amount of resorcinol and hydroquinone was 99.4%.
%, m·P-acetylphenol 0.3%, m·P-isoprobenylphenol 0.1%, and tars 0.2%. Example 5 P-diisopropylbenzene dihydroberoxide (impurities include diisopropylbenzene monohydroperoxide, acetylkyumene hydroperoxide, (2-hydroxy-2-propyl)kyumene hydroperoxide, di(2-hydroxy-2-propyl) -propyl)benzene.

) methyl isobutyl ketone solution was decomposed with an acid catalyst and neutralized, the resulting decomposition reaction liquid was distilled to remove most of the acetone and methyl isobutyl ketone, and the distillate liquid was cooled. Crystals were precipitated and separated in a furnace. When the solvent (methyl isobutyl ketone) in the obtained crystals was removed, crude hydroquinone containing 94.2% hydroquinone, 0.2% P-acetylphenol, and 5.6% tars was obtained. . This crude hydroquinone was distilled under reduced pressure in a rice cracker tower with three theoretical plates, with the temperature of the bottom liquid controlled at 200°C. The rectification was stopped when about 95% of hydroquinone had been distilled out, and hydroquinone with a purity of 99.5% was obtained. As impurities, 0.2% of P-acetylphenyl and 0.3% of tars were contained.

[Brief explanation of the drawing]

Figure 1 shows the relationship between the distillation temperature (bottom liquid temperature) (Yokofuji) and the distilled solcin purity (Tatemari). Many 1 drawings

Claims (1)

[Claims] 1 Crude resorcin and () after separating and removing components with a lower boiling point than resorcin and (or) hydroquinone from the decomposition reaction solution of dialkylbenzenedihydroperoxide.
or) A method for purifying resorcinol and/or hydroquinone, which comprises performing a distillation operation on hydroquinone at 210° C. or lower to remove tar contained therein.