JPS6176472A - Production of diphenylene oxide - Google Patents

Abstract

PURPOSE:To obtain the titled little colored compound useful as the raw material of various chemical industries and vermin-repellent, etc., by distilling a coal tar fraction containing the titled compound to effect the concentration of the titled compound to a specific concentration, and recrystallizing the compound using a specific solvent under specific condition. CONSTITUTION:A coal tar fraction containing diphenylene oxide is distilled to increase the diphenylene oxide content to >=60wt%. 1pt. of the concentrated fraction is recrystallized by using 0.5-4pts. of a solvent selected from 5-10C paraffinic hydrocarbons, 5-10C naphthenic hydrocarbons and 1-4C alcohols as the recrystallization solvent at 15-35 deg.C. A high-purity diphenylene oxide resistant to the discoloration with ultraviolet radiation or aging can be prepared by this process in high efficiency. The above recrystallization is carried out preferably in two steps, and the diphenylene oxide content is increased preferably to >=95wt% by the first recrystallization step.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing diphenylene oxide with little coloring, which is useful as a raw material for various chemical industries or as an insect repellent.

[Conventional technology]

Diphenylene oxide, sometimes referred to as dibenzofuran, is a white crystal with a boiling point of 283°C and a melting point of 83°C, and is known to be contained in coal tar.

] - Lutal is generally first separated by distillation into tar oils such as light oil, carpol oil, naphthalene oil, washing oil, an1-herasene oil, etc., and pitch, and then each of these fractions is distilled and distilled as necessary. It is processed through methods such as crystallization and extraction, and is used as a variety of useful products.

The above diphenylene oxide is contained in the distillate from naphthalene oil to pitch, and the cleaning oil contains about 15 to 30%
The content of these fractions is approximately 5 to 10% by weight in Anne I to spiral oil, and these fractions are suitable as raw materials for the production of diphenylene oxide. Since the boiling point range is from 220 to 300 DEG C., the "-Lutal fraction in this range is suitable as a raw material for the production of Schiff I nylene oxide.

When these fractions are subjected to rectification, they can be relatively easily concentrated to a fraction having a diphenylene oxide content of 60% by weight or more. However, these fractions have boiling points close to that of diphenylene oxide! core naphthene, fluoreno,
Many other components are simultaneously contained in large amounts, and it is extremely difficult to produce diphenylene oxide of r'B purity using only the thermothermal method.

As a method to solve this problem, JP-A No. 57-50984 describes a method of continuously crystallizing a diphenylene oxide fraction concentrated by distillation in a melt state to increase the wear marks of diphenylene oxide. There is. In other words, in this method, the diphenylene oxide fraction concentrated by distillation is introduced into a continuous crystallizer. For example, when a vertical crystallizer is used, the mother liquor is taken out from the top of the column and the mother liquor is extracted from the bottom of the column with J. This is a method to efficiently obtain diphenylene oxide by taking and discharging a crystal melt.

(Problems to be Solved by the Invention) However, although diphenylene oxide obtained by such a method has a relatively high purity and has sufficient quality as a raw material for many chemical industries, If this is used as it is or mixed with other ingredients to make a product, it may be colored, which may impair its appearance and reduce its commercial value.

Means and operation for solving problem C] The present invention was created in view of the above points, and it provides a method for producing highly pure diphenylene oxide, and a method for producing diphenylene oxide with little coloring or coloring over time. The present invention provides a method for producing diphenylene oxide with a small degree of Paraffinic hydrocarbon having 5 to 10 carbon atoms, 0.5 to 4 times the phenylene oxide fraction, 5 carbon atoms
Recrystallization is performed at a cooling temperature of 15 to 35°C using one or more recrystallization solvents selected from a group of solvents consisting of ~10 naphthenic hydrocarbons and alcohols having 1 to 4 carbon atoms. This is a method for producing diphenylene oxide.

The raw material used in the present invention is a diphenylene oxide-containing fraction obtained by distilling coal tar.
It is a coal tar fraction of ~300°C.

Such a coal tar fraction containing diphenylene oxide is first concentrated by distillation to a content of 60% by weight or more, preferably 70% by weight or more to obtain a diphenylene oxide fraction. If the diphenylene oxide content of this diphenylene oxide fraction is lower than 60% by weight, the purity and recovery rate of purified diphenylene oxide will decrease, which is undesirable.

Next, the diphenylene 4:cyto fraction is recrystallized using a solvent. The recrystallization solvent used for this purpose includes paraffinic hydrocarbons having 5 to 10 carbon atoms such as n-pentane and n-hexane, naphthenic hydrocarbons having 5 to 10 carbon atoms such as cyclohexane and methylcyclohexane, and methanol. Ethanome, propatool, etc. carbon number 1~
1 selected from a group of solvents consisting of 4 alcohols
A species or two or more solvents are preferred. Among these solvents, alcohols such as methanol and ethanol in particular give good results with respect to coloring. Regarding the amount of solvent used, a larger amount will give better results in terms of coloring, but since the recovery rate will decrease, it is usually 0% for the diphenylene oxide fraction.
．． The amount used is 5 to 4 times, preferably 1 to 3 times, and the cooling temperature is 15 to 35°C, preferably 20 to 35°C.
It is best to do this at 30°C. This recrystallization can be performed by a conventional method, that is, a heating dissolution-cooling crystallization method.

Further, in order to obtain diphenylene oxide of higher quality, it is preferable to recrystallize the diphenylene oxide fraction in two stages. In the case of purification by two-stage recrystallization, first the diphenylene oxide content is reduced to 95% in the first stage recrystallization.
Refined to 97% by weight or more, preferably 97% by weight,
Then, in the second stage of recrystallization, the diphenylene oxide content was reduced to 99%.
It is purified to % by weight or more, preferably 99.5% by weight or more.

Even when recrystallization is carried out in two stages as described above, the amount of recrystallization in each stage is 0.5 to 4 times, preferably 1 to 3
It is carried out using twice the amount of recrystallization solvent and at a cooling temperature of 15 to 35°C, preferably 20 to 30°C.

The purified diphenylene oxide obtained through the above-mentioned hot-to-recrystallization process is subjected to solid-liquid separation by a conventional method, and then dried to obtain a product.

〔Example〕

Examples 1 to 8 19.0ffl1% of acenaphthene, 56.5% by weight of diphenylene oxide, 1.3% by weight of fluorene, and other component residues obtained by distilling and concentrating a coal tar fraction with a boiling point of 220 to 300°C The coal tar fraction, which is a raw material consisting of
Precise thermal heating was performed under the conditions of mHQ and reflux ratio of 20 to concentrate again to obtain a diphenylene oxide fraction having the component composition shown in Table 1.

Next, 80 to 150 parts by weight of the recrystallization solvent shown in Table 1 was added to 100 parts by weight of the above diphenylene oxide fraction, and the mixture was heated to 60°C to completely dissolve the diphenylene oxide in the recrystallization solvent. and then gradually cooled while stirring.
The mixture was cooled to the cooling temperature shown in the table to precipitate diphenylene oxide crystals.

The precipitated crystals of diphenylene oxide were centrifuged at 2,200 to 3,200 rpm for 2 minutes and dried to obtain purified diphenylene oxide.

Regarding the obtained purified diphenylene oxide, its recovery rate was determined and its component composition was determined using a gas chromatograph. The results are shown in Table 1. J0 Examples 3 and 6 were purified by two-stage recrystallization, and the second recrystallization was performed using the first
The solvents shown in Table 1 were used for 1 part by weight of crystals obtained in the recrystallization stage, and the same method as in the first stage recrystallization was performed. Regarding the purified diphenylene oxide obtained by the second-stage recrystallization, the recovery rate was determined in the same manner as above, and its component composition was determined by gas chromatography. The results are shown in Table 1.

Furthermore, the two-stage recrystallized purified diphenylene oxides obtained in Examples 3 and 6 were subjected to an ultraviolet irradiation test in which they were irradiated for 20 hours with a 100W high-pressure mercury lamp.As a result, no coloring occurred and the product passed the ultraviolet irradiation test. It turns out that there is something. Note that most of the impurities in the two-step recrystallized purified diphenylene oxide were fluorene.

〔Effect of the invention〕

By using the production method of the present invention, it is possible to obtain diphenylene oxide with less coloring at an efficiency of +a, which is less colored by the front side of ultraviolet rays, and which is less likely to become colored over time. Can be done. Therefore, such Schiff-nylene oxide exhibits an excellent effect of not deteriorating the quality of products used as it is or mixed with other substances.

Claims (2)

[Claims] (1) The coal tar portion containing diphenylene oxide is distilled and concentrated to a diphenylene oxide content of 60% by weight or more, and then the carbon number 5 is 0.5 to 4 times the amount of the obtained diphenylene oxide fraction. Using one or more recrystallization solvents selected from a group of solvents consisting of paraffinic hydrocarbons having ~10 carbon atoms, naphthenic hydrocarbons having 5 to 10 carbon atoms, and alcohols having 1 to 4 carbon atoms. Cooling temperature 1
A method for producing diphenylene oxide, which comprises recrystallizing at 5 to 35°C. (2) A diphenylene oxide fraction with a diphenylene oxide content of 60% by weight or more, a paraffinic hydrocarbon having 5 to 10 carbon atoms, and a paraffinic hydrocarbon having 5 to 10 carbon atoms in an amount of 0.5 to 4 times the amount of the diphenylene oxide fraction. -10 naphthenic hydrocarbons and alcohols having 1 to 4 carbon atoms using one or more recrystallization solvents at a cooling temperature of 15 to 35°C. The method for producing diphenylene oxide according to claim 1, wherein the diphenylene oxide content is adjusted to 95% by weight or more by recrystallization, and then a second recrystallization is performed.