JPS62185033A - Purification of 4,4'-dihydroxydiphenyl ether - Google Patents

Abstract

PURPOSE:To recover the titled high-purity compound expected as a raw material for polymers or organic chemicals in high recovery ratio, by recrystallizing crude crystals of low-purity 4,4'-dihydroxydiphenyl ether using a specific solvent system and carrying out purification. CONSTITUTION:Crude crystals of low-purity 4,4'-dihydroxydiphenyl ether obtained by reaction of hydroquinone are recrystallized and purified using a mixed solvent consisting of a polar solvent, e.g. a 3-9C ketone, e.g. acetone, etc., 1-8C alcohol, 4-8C ether, 3-7C ester and a hydrocarbon solvent which may be substituted by a halogen, e.g. 2-10C aliphatic hydrocarbon, 6-12C aromatic hydrocarbon, e.g. toluene, etc., 5-10C alicyclic hydrocarbon, etc., preferably at room temperature-80 deg.C to afford the aimed compound in a purity as high as >=99% and a recovery ratio as high as >=70%. The weight ratio of the above-mentioned polar solvent to the hydrocarbon solvent which may be substituted by the halogen is 4/6-0.2-9.8.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for purifying 4,4-dihydroxydiphenyl ether, and more particularly, to a method for purifying 4,4'-dihydroxydiphenyl ether using a specific solvent system. .

4.4-Dihydroxydiphenyl ether (hereinafter referred to as DHP)
(sometimes abbreviated as E) is expected to be used as a raw material for polymers or organic drugs. This D HP
E is hydroquinone (another name for 1,4-dihydroxybenvin, hereinafter sometimes abbreviated as IQ) as a raw material.
It is known that V= can be obtained by condensing in the presence of a solid acid catalyst such as synthetic mica, activated clay, montmorillonite, or ion exchange resin. In this condensation reaction, non-aqueous solvents such as xylene and toluene are generally used. For reference, the formula for the synthesis reaction of DHPE is as follows.

Q. Contains a solid acid catalyst and a non-aqueous solvent such as an aromatic hydrocarbon. Various methods have been proposed in the past to separate the target compound, DHPE, from this reaction mixture, but all methods yield DHPE as crude crystals together with various reaction by-products. It is necessary to purify DHPE to increase its purity.

As a conventionally proposed method for purifying DHPH, JP-A-49-55635 discloses a method in which crude crystals of DHPH are recrystallized using xylene as a crystallization solvent. Further, in U.S. Pat. No. 4,306,094, D HP containing unreacted HQ and triphenyl ether is disclosed.
A method is shown in which the crude product of E is washed with warm water to remove IQ, and then recrystallized from a solvent, but the specification does not specifically specify what the recrystallization solvent is. Nothing is shown and the purity of 1q D HP E is unknown.

When attempting to purify D HP E by recrystallizing crude crystals of DI-IPE using xylene, cumene, etc., D
Although HPE can be recovered with a high recovery rate, the purity of recrystallized DHPE is as low as 89-90%, and high-purity D
There is a problem that it is difficult to obtain HPE'&.

The present inventors have made extensive studies to solve the problems associated with the prior art as described above and to obtain highly pure DHPE, and have found that if the crystallization operation is performed using a specific solvent system, The present invention was completed based on these discoveries.

The present invention is intended to solve the problems associated with the prior art as described above. H
The object of the present invention is to provide a method for purifying DHPE that allows PE crystals to be recovered with a high recovery rate.

■Ref. 1 The method for purifying 4,4°-dihydroxydiphenyl ether (DHPE) according to the present invention is to purify 4,4°-dihydroxydiphenyl ether (DHPE) by replacing 1q of low-purity crude DHPE crystals produced by the reaction of hydroquinone with a polar organic solvent and a halogen. It is characterized by recrystallization using a mixed solvent consisting of a good hydrocarbon solvent.

In the method for purifying DHPE according to the present invention, D I-I P
When purifying E crude crystals, recrystallization is performed using a mixed solvent consisting of a polar organic solvent and a hydrocarbon solvent that may be substituted with halogen, resulting in highly pure DHP.
E can be obtained by 17 with a high recovery rate.

The method for purifying D I-I PE according to the present invention will be specifically explained below.

The crude crystals of DHPE purified in the present invention are 1q obtained by dehydrating hydroquinone.

The hydroquinone crude crystals contain high-boiling byproducts such as hydroquinone trimer, hydroquinone polymorph, and unreacted hydroquinone as impurities.

When producing DHPE by dehydrating and trimerizing hydroquinone, synthetic mica, activated clay, montmorillonite,
A solid acid catalyst such as an ion exchange resin or a liquid acid catalyst such as a protonic acid is used. In order to obtain crude crystals of Dl-IPE from the reaction mixture obtained after the reaction, a wide range of conventionally known methods can be employed, and a method discovered by the present inventors can also be employed. That is, the dehydration reaction of hydroquinone is carried out using a water-immiscible solvent, and the resulting unreacted hydroquinone is
6. After removing the solid acid catalyst from the liquid reaction mixture, the reaction mixture is heated to preferably 55°C or higher, more preferably 70°C.
D)- by contacting with water at a temperature of ~90°C to transfer the human monoquinone and DHPE into the aqueous phase, and after separating this aqueous phase, the aqueous phase is preferably cooled to below 50°C.
1q of IPE crude crystals can be obtained. Alternatively, the dehydration dimerization reaction of hydroquinone is carried out using a water-immiscible solvent, and after adding water to the resulting liquid reaction mixture containing unreacted hydroquinone, this is preferably
D HP E crude crystals can also be prepared by maintaining the temperature at ~70'C to precipitate D HP E crude crystals. In addition, in case J1, 1q of DHPE crude crystals can be obtained by carrying out the dehydration di-composition reaction of hydroquinone using a water-immiscible solvent and cooling the liquid reaction mixture containing unreacted hydroquinone as it is. You can also

The DHP E crude crystals that are jqed in this way are (previously)
In addition, since it contains unreacted hydroquinone, hydroquinone triplex, and hydroquinone multi-W isomer, it can be purified by the purification method according to the present invention.

In the present invention, when purifying DHPE crude crystals,
For polarity right, a mixed solvent consisting of a solvent and a hydrocarbon solvent which may be substituted with halogen is used as the crystallization solvent.

The polar organic solvent used in the present invention is in a liquid state,
For example, organic solvents with high 1Φ property of oxygen-containing compounds, such as carbon atoms, alcohols, ethers, Nisdel compounds, among which ketones with 3 to 9 carbon atoms, carbon Alcohols with numbers 1 to 8, carbon numbers 4 to 8
Ethers and esters having 3 to 7 carbon atoms are preferably used.

Specific examples of ketones having 3 to 9 carbon atoms include acetone, methylisobutylketone, methyl ethyl ketone, and methyl ethyl ketone.
-Pentanone, 3-pentanone, 2-hexanone, diisobutyl ketone, etc. are used.

Examples of alcohols having 1 to 8 carbon atoms include methanol, ethanol, isopropanol, butanol, pentanol, hexanol, heptatool, octanol, and the like. As the ether having 4 to 8 carbon atoms, diethyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, dioxane, etc. are used. Further, as the ester having 3 to 7 carbon atoms, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, pentyl acetate, etc. are used.

On the other hand, the hydrocarbon solvent used in the present invention may be substituted with halogen, and may include aliphatic hydrocarbons having 2 to 10 carbon atoms, aromatic hydrocarbons having 6 to 12 carbon atoms, and 5 to 1 carbon atoms.
0 alicyclic hydrocarbons are preferably used.

Specific examples of aliphatic hydrocarbons having 2 to 10 carbon atoms include hexane, heptane, ACtane, decane, 1,2-
Dichloroethane, i,i,2-trichloroethane, etc. are used. Specific examples of aromatic hydrocarbons having 6 to 12 carbon atoms include benzene, chlorobenpine, 0-dichlorobenzene, toluene, xylene, mesitylene,
Ethylbenbin, isopropylbenzene, diisopropylbenzene, etc. are used. Specific examples of the alicyclic hydrocarbon having 5 to 10 carbon atoms include Schiffpentane, cyclohexylline, methylcyclohexane, ethylcyclohexane, and decalin.

The polar organic solvent and the optionally halogen-substituted hydrocarbon solvent as described above are used as a mixture, and the mixing ratio of the polar organic solvent [A] and the hydrocarbon solvent [8] is A/ It is preferable that B (weight ratio) is in the range of 476 to 0.2/9.8. When the mixing ratio A/B is larger than 4/6, the purity of DHPE recovered by recrystallization is good, but it is not preferable because the recovery rate of DHPE becomes too low, whereas when the mixing ratio is 0.2/9. When it is smaller than .8, the recovery rate of DHPE is good, but the obtained D HP
This is not preferable because the purity of E becomes too low.

In the present invention, DHPE has a high purity of 99% or more and 70%
% or more. However, if only polar solvents are used to recrystallize DHPE crude crystals,
Is DHPE recrystallized with a high purity of 99% or higher?
The recovery rate of E would be less than 50%. On the other hand, D H
When recrystallizing crude PE crystals, if only a hydrocarbon solvent is used, DHPE can be recovered with a high recovery rate of 95% or more, but the purity of DHPE is as low as less than 90%.

It is preferable that the crystallization temperature when recrystallizing the D I-I PE crude crystals from the above-mentioned mixed solvent is from room temperature to about 80°C.

Effects of the Invention In the method for manufacturing D1 to IPE according to the present invention, D
When refining HPE crude crystals, recrystallization is performed using a mixed solvent consisting of a polar organic solvent and a halogen-substituted hydrocarbon solvent, resulting in highly pure D.
HPE is obtained with high recovery.

The present invention will be explained below with reference to Examples and Reference Examples, but the present invention is not limited to these Examples and Reference Examples.

First, the present invention will be explained with reference to a method for producing DHPE crude crystals, and then a method for producing DHPE crude crystals will be explained based on a reference example.
A method for purifying crude HPE crystals will be explained.

(1) 1qwt% aqueous suspension of synthetic mica manufactured by Topy Industries, Ltd.
ooq was suspended in 10''' of water, 2000 tnl of 5%-A&(NO3)3 aqueous solution was added with stirring, and the mixture was stirred roughly for 25 minutes, followed by ion exchange into the aluminum mold. The exchanged synthetic mica was collected by centrifugation, thoroughly washed with water, and further dried (40° C., 50 mm)-IQ, 10 hours).

The solid acid catalyst thus prepared was 80 g of aluminum-exchanged synthetic mica (ion exchange rate 45%), 400 q of hydroquinone (HQ), and 2500 mm of mesitylene!
was charged into a 5" four-hole flask, the Dean Stark water bucket trap was removed, and the water produced during the reaction was removed from the thread by azeotropy with mesitylene, while heating and stirring for 2 hours under reflux of mesitylene to dissolve hydroquinone. A trimerization reaction was performed.

(2) After the reaction was completed, the reaction mixture was filtered at 150°C to separate the solid acid catalyst and the reaction liquid. This separated reaction solution 24
2OCl contains unreacted HQ1720, target 4,
4°-dihydroxydiphenylethyl 172g, I
Trimers and other multimers of Q were included in 27CI and mesitylene (1,3,5-trimethylbenzene) as the reaction solvent.

(3) Water 748Q was added to the separated reaction solution, and both layers were vigorously stirred while maintaining the temperature at 90° C., and then separated into an oil layer and an aqueous layer.

The separated aqueous layer was cooled to 50°C while stirring,
The precipitated crystals were separated from this aqueous layer using a Vasquera I type centrifuge kept at 50°C.

When the separated crystals were dried, DI containing no HQ was obtained.
- Crude 4,4°-dihydroxydiphenyl ether consisting of 89.0% IPE, 11.0% HQ tria and other polymers was 146Q4G? is.

1 Reaction mixture obtained in the same manner up to (2) of Reference Example 1 2"1
Add 7/18 g of water to 22Q and gradually lower the humidity while stirring to 50°C. Using a basket centrifuge kept at 50°C, the precipitated crystals were separated from the oil and water layers. .

When the separated crystals were dried, D containing no HQ was obtained.
HPE 88.5%, HQ trimer and other multimers 11
．． 148 g of crude 4,4'-dihydroxydiphenyl ether consisting of 5% were obtained.

Once M-U Reference Example 1 (2) was prepared in the same manner as 11, reaction mixture 24
30CI was cooled to room temperature while stirring, and precipitated crystals 351q were separated using a basket centrifuge.

The separated crystals contained 47.8% HQ and 4% DHPE.
It contained 5.6% HQ trimer and 6.6% HQ trimer.

Next, add 2,100 ca of water to the separated crystals and
After heating up to °C and completely melting VN, cool to room temperature.
The precipitated crystals were separated using a basket centrifuge. When the separated crystals were dried, 150 g of crude 4,4°-dihydroxydiphenyl ether was obtained, which consisted of 86.5% DHPE containing no IQ and 13.5% of IQ trimer and other trimer.

Example 1 10q of dry crystals of crude DHPE obtained in Reference Example 1 were mixed with 1 part of acetone and 9 parts of toluene in a solvent 50
After heating to reflux temperature using Q to completely dissolve the crystals, the mixture was cooled to room temperature. The thus precipitated crystals were separated using a bass-cut centrifuge and dried to obtain Di-IPE7.7Q with a purity of 99.5%.

1q of reference example 2 and reference example 3)-I
Dry crystals of PE 10Q were crystallized in the same manner as in Example 1 using solvent 50Q, which was a mixture of 1 part of acetone and 9 parts of toluene: i+iu. The results are shown in Table 1.

Examples 4 to 27 The dry crystals 10C1 of crude DI-IPE obtained in Reference Example 2 and Reference Example 3 were mixed with a polar organic solvent and a hydrocarbon solvent or a halogen-substituted hydrocarbon solvent as shown in Table 2. A crystallization operation was performed in the same manner as in Example 1 using [Solvent 50C]. The results are shown in Table 2. In addition, Example 4
In ~15, the crude DHPE obtained in Reference Example 2 was used,
In Examples 16 to 27, the crude D HP E obtained in Reference Example 3 was used.

DI-iPE8B, 5%, H obtained in the same manner as in Reference Example
Crude D consisting of Q3 solids and 11.5% of other solids
Crystallization of dried HP E crystal 10Q was carried out in the same manner as in Example 1, except that the mixing ratio of acetone and toluene and the amount of solvent used relative to crude D HP E were changed as shown in Table 3. The results are shown in Table 3.

Comparative Examples 1 to 8 15q of dry crystals of crude DHPE obtained in Reference Example 1 were crystallized in the same manner as in Example 1 using 15 g of a polar organic solvent. The results are shown in Table 4.

Comparison ■ Once done in the same manner as in Reference Example 1 (DHPE 88.5%, HQ
10q of dry crystals of crude DHPE consisting of 11.5% of Effi and other polymers were used as a crystallization solvent using the hydrocarbons or halogen-substituted hydrocarbons shown in Table 5. The crystallization operation was carried out in the same manner as in Example 1, with some changes. The results are shown in Table 5.

From the above results, when recrystallizing a DHPE crude product using a mixed solvent consisting of a polar organic solvent and a hydrocarbon solvent that may be substituted with halogen, it is possible to obtain a high 1iiT! It can be seen that DI-IPE of 100% is obtained with a high recovery rate.

Claims (4)

[Claims] (1) Low purity 4 obtained by reaction of hydroquinone,
A method for purifying 4,4'-dihydroxydiphenyl ether, which comprises recrystallizing crude 4'-dihydroxydiphenyl ether crystals using a mixed solvent consisting of a polar organic solvent and a hydrocarbon solvent optionally substituted with halogen. . (2) Claim 1 in which the polar organic solvent is a ketone having 3 to 9 carbon atoms, an alcohol having 1 to 8 carbon atoms, an ether having 4 to 8 carbon atoms, or an ester having 3 to 7 carbon atoms.
The method described in section. (3) The hydrocarbon solvent which may be substituted with halogen is an aliphatic hydrocarbon having 2 to 10 carbon atoms, an aromatic hydrocarbon having 6 to 12 carbon atoms, or an alicyclic hydrocarbon having 5 to 10 carbon atoms. A method according to claim 1. (4) The method according to claim 1, wherein the weight ratio of the polar organic solvent and the optionally halogen-substituted hydrocarbon solvent is 4/6 to 0.2/9.8.