JPH09188638A - Separation of dihalogenated benzene isomer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separate and recover only a specific dihalogenated benzene isomer at high purity and yield from a mixture of dihalogenated benzene isomers containing at least one fluorine as a substituting group by a specific absorbent. SOLUTION: A mixture of dihalogenated benzene isomers containing at least one fluorine are separated by contacting them with an absorbent containing zeolite. A faujasite-type zeolite is preferable as the zeolite. The faujasite type zeolite means a crystalline aluminosilicate of the formula EM is a cation; (n) is a valence of M; (x)=2.5±0.5 in X-type and (x)=3-6 in Y-type; (y) varies depending on the degree of hydration]. Sr, Ba or Ag is extremely preferable as the cation of the zeotile. Among dihalogenated benzene isomers, generally an o substituted isomer is apt to be absorbed strongly, and accordingly o- dihalogenated benzene is strongly absorbed and can be separated.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for separating and recovering a specific dihalogenated benzene isomer from a dihalogenated benzene isomer mixture containing at least one fluorine as a substituent.

Dihalogenated benzene is a pharmaceutical intermediate or
As a pesticide raw material, it is a useful substance used in various fields of industry.

[0003]

2. Description of the Related Art Dihalogenated benzene is usually synthesized by halogenating benzene. This reaction is usually o, p-oriented, and it is necessary to carry out isomerization after the reaction to obtain the m-form. Therefore, a separation step is indispensable for obtaining a specific isomer from these.

In general, of these dihalogenated benzene isomers, the o-form can be separated by distillation.
Since the isomers and the m-isomer have very different boiling points, it is extremely difficult to separate them by distillation.

JP-A-52-62229 and JP-A-53-105434 disclose a method for separating a p-, m-dichlorobenzene mixture using zeolite. Japanese Patent Publication No. 63-24981 discloses a method of adsorbing and separating m-dichlorobenzene from a mixture of dichlorobenzene isomers using an X-type faujasite containing lithium as an adsorbent. Tokuhei 1
No. 12734 discloses a faujasite type zeolite containing silver and potassium, and JP-A-4-3300.
Japanese Patent Publication No. 25 discloses a method of adsorbing and separating m-dichlorobenzene with a faujasite-type zeolite containing lead and potassium.

US Pat. No. 4,996,380 discloses a method for strongly adsorbing and separating m-dichlorobenzene by using X-type faujasite ion-exchanged with sodium and potassium.

Japanese Patent Publication No. 12732 discloses a method in which 3,4-dihalogenated toluene or 4-halogenated-o-xylene is used as a desorbent for the adsorption separation of a dichlorobenzene isomer mixture.

[0008]

The above methods are all related to the adsorption / separation operation of dichlorobenzene among dihalogenated benzenes, and the separation of dihalogenated benzene containing fluorine as a substituent is not mentioned at all. . However, when one of the substituents is fluorine, its atomic size is almost the same as that of hydrogen, so there is no difference in shape between the disubstituted isomers, and separation by adsorption separation method is extremely difficult. Has been considered. In addition, the dihalogenated benzene containing fluorine differs from the case of not containing fluorine also in the distillation property, and in many cases, the o-form cannot be separated by distillation. Therefore, p
It is necessary to separate a mixture of -body, m-body, o-body,
The methods shown in JP-A-52-62229 and JP-A-53-105434 for separating the p-form and the m-form cannot be applied to dihalogenated benzene containing fluorine. Further, since the adsorption mechanism is completely different, the adsorption order is also different from that of dihalogenated benzene containing no fluorine. In adsorption separation, the most necessary adsorption or non-adsorption in the adsorption sequence is a necessary condition for separation, so if the adsorption sequence is different from the conventional fluorine-free dihalogenated benzene, the conventional technique should be applied. Depending on the situation, it is difficult to separate dihalogenated benzene containing fluorine.

[0009]

The present inventors have found that the difference in the substitution position of fluorine has a great influence on the adsorption property. That is, it is considered that the adsorption of the dihalogenated benzene containing fluorine occurs at the position of fluorine due to the strong negative charge on fluorine. Therefore, in the adsorption of dihalogenated benzene containing fluorine, if the size of the cation contained in the zeolite is appropriate, the adsorption occurs in the form of bridging two cation sites. Therefore, the influence of cation size on the adsorption properties is extremely large.

The present inventors have diligently studied a method for separating a specific isomer from a dihalogenated benzene isomer mixture in which at least one of the substituents is fluorine, in consideration of the above-mentioned adsorption characteristics, and It was found that the adsorption characteristics can be greatly changed by variously changing the cations contained in the faujasite-type zeolite used as the above, and the present invention has been completed.

That is, the present invention is a method for adsorbing and separating a specific isomer from a dihalogenated benzene isomer mixture, wherein at least one of the substituents is fluorine. Is the way.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The dihalogenated benzene isomer mixture in the present invention includes at least two dihalogenated benzene isomers, and at least one of the substituted halogens is fluorine.

The faujasite-type zeolite used in the method of the present invention is a crystalline aluminosilicate represented by the following formula.

0.9 ± 0.2 M _{2 / n} O: Al ₂ O ₃ : x
SiO ₂ : yH ₂ O Here, M represents a cation, and n represents its valence.
Faujasite-type zeolites are classified into X-type and Y-type. In the X-type, x in the above formula is 2.5 ± 0.5, and in the Y-type, x in the above formula is 3 to 6. Further, y differs depending on the degree of hydration. Faujasite-type zeolite is usually obtained in the form of containing sodium as a cation, but this cation can be replaced by various cations by ion exchange.

The faujasite type zeolite used in the present invention has, as cations, for example, lithium, sodium, potassium, rubidium, cesium, magnesium,
Those containing calcium, strontium, barium, silver, nickel, zinc, chromium, lead and the like can be used.

Dihalogenated benzene usually tends to strongly adsorb o-substituted products, and o-dihalogenated benzene can be separated by strong adsorption. In particular, when the cation radius of the contained cation is larger than 0.12 nm, o-
It has a high selectivity for adsorbing the substitution product and is preferable for separating the o-dihalogenated benzene by strong adsorption. Among them, faujasite type zeolite containing strontium, barium or silver is very preferable.

The cation radius of the cation contained is 0.13.
When it is smaller than nm, the adsorption order becomes weaker in the order of o-, p-, and m-, and m-dihalogenated benzene can be separated without adsorption. Particularly, magnesium, calcium, strontium, lithium and sodium are preferable, and magnesium and sodium are very preferable.

Even more surprisingly, when the ionic radius of the contained cation exceeds 0.13 nm, the adsorption order of the p-form and the m-form is reversed, and the cation having an ionic radius of 0.13 nm or more is zeolite. By including it, p-dihalogenated benzene can be separated without being adsorbed. Particularly, potassium, rubidium, cesium and barium are preferable, and potassium is very preferable.
These metals may contain other metals as long as the effects of the present invention are not impaired.

The metal contained in the faujasite type zeolite usually exists in the form of cation by ion exchange.

These cations are easily incorporated into zeolite by the ion exchange method.

Ion exchange methods for cations are widely known to those skilled in the art having knowledge of the production of crystalline aluminosilicates and usually involve adding an aqueous solution of a soluble salt of one or more cations to be added to the zeolite. It is carried out by contacting the zeolite. This contact may be repeated several times if necessary.

The technique for adsorbing and separating a dihalogenated benzene isomer mixture using the method of the present invention may be a so-called chromatographic preparative method, or an adsorbing and separating method using a continuous simulated moving bed. But it's okay.

The continuous adsorption / separation technique using a simulated moving bed is basically carried out by continuously circulating the following adsorption operation, concentration operation and desorption operation.

(1) Adsorption operation: The dihalogenated benzene isomer mixture comes into contact with the adsorbent of the faujasite-type zeolite, and the weakly adsorbed component is selectively left to adsorb the strongly adsorbed component. The strongly adsorbed component is recovered as an extract component together with a desorbing agent described later. (2) Concentration operation: Raffinate containing a large amount of weakly adsorbed components is further brought into contact with an adsorbent to selectively adsorb strongly adsorbed components, whereby the weakly adsorbed components in the raffinate are highly purified.

(3) Desorption operation: The highly purified weakly adsorbed component is recovered as a raffinate, while the strongly adsorbed component is expelled from the adsorbent by the desorbent and recovered as an extract component together with the desorbent. .

The desorbent used in the adsorptive separation method of the present invention or the developing agent used in chromatographic fractionation are aromatic hydrocarbons, aliphatic hydrocarbons, ethers, alcohols and halogenated aromatics which can be easily separated by distillation from dihalogenated benzene. Compounds of the family can be used. In particular, alkyl aromatic hydrocarbons such as toluene, xylene, ethylbenzene and diethylbenzene, dialkyl aromatic hydrocarbons and halogenated aromatics such as chlorobenzene, dichlorobenzene and dichlorotoluene are preferable. Among them, the p-form dialkylbenzene increases the adsorptive power of p-dihalogenated benzene when the faujasite-type zeolite containing a cation having an ionic radius of 0.1 to 0.14 nm is used as the adsorbent, and the p-form dialkylbenzene is Can be separated by strong adsorption. In this case, the p-dialkylbenzene has 1 to 1 carbon atoms.
Those having an alkyl group of 5 are preferably used, and p-
Diethylbenzene is particularly preferably used.

The operating conditions for adsorption separation are:
The temperature is room temperature to 350 ° C., preferably 50 to 250 ° C., and the pressure is atmospheric pressure to 5 MPa, preferably atmospheric pressure to 4 MPa. The adsorption separation according to the invention may be in the gas phase or in the liquid phase, but is preferably carried out in the liquid phase in order to reduce the operating temperature and to suppress undesired side reactions of the raw material feed or the desorbent.

[0028]

Next, the method of the present invention will be described with reference to examples.

In the examples, the adsorption characteristic of the adsorbent is represented by the adsorption selectivity (α) of the following equation (1).

[Equation 1] Here, A and B represent any one of dihalogenated benzene isomers.

When the value of the above equation is greater than 1, the A component is selectively adsorbed, and when it is less than 1, the B component is selectively adsorbed. Further, the adsorbent having an α value larger than 1 (or the adsorbent smaller than 1 and close to 0) in the above equation facilitates the adsorption separation of A and B.

Example 1 Y-type faujasite-type zeolite having sodium at the cation site (Tosoh, HSZ-320NAA)
After the granulated product of (Na-Y) is calcined at 500 ° C. for about 1 hour, contact with a 10 wt% aqueous solution of Ba (NO ₃ ) _{2 at} a solid-liquid ratio of 3 at 80 ° C. for 30 minutes is repeated 7 times, A Y-type zeolite ion-exchanged with barium was prepared. About 1.6 g of this adsorbent was calcined at 500 ° C. for about 1 hour and then cooled in a desiccator to give about 2.5 ml of liquid phase mixture.
Fill in a 5 ml autoclave together with 1 at 150 ℃
It was left in contact for a time and left. The composition ratio of the charged liquid phase mixture was p-bromofluorobenzene: m-bromofluorobenzene: o-bromofluorobenzene: n-nonane =
It was 32: 63: 5: 10 (weight ratio). N-nonane was added as an internal standard substance in gas chromatography analysis, and is a substance substantially inactive to the adsorbent under the above experimental conditions. The composition of the liquid phase mixture after being contacted with the adsorbent is analyzed, and the adsorption selectivity α is calculated using the above formula (1).
I asked. The results are shown in Table 1. This system strongly adsorbs o-forms.

(Preparation of zeolite containing various cations)
X used in Examples (excluding Examples 7 and 15)
-Type and Y-type zeolite are Na-X (Tosoh, Zeolum F9), Na-Y (Tosoh, HSZ-320NAA)
Was contacted with a 10 wt% aqueous solution of nitrate of each cation in the same manner as in Example 1 to perform ion exchange. Table 2 shows the relationship between the cation and the salt used.

The AgK-Y used in Example 7 is the same as Example 2.
The KY used in 1. was prepared by contacting it with a 6 wt% silver nitrate aqueous solution at 80 ° C. for 30 minutes once at a solid-liquid ratio of 3. Also,
The AgBa-X used in Example 15 was prepared by contacting the Ba-X used in Example 12 with a 7.7 wt% silver nitrate aqueous solution at 80 ° C. for 30 minutes at a solid-liquid ratio of 3 once.

Examples 2 to 15 Adsorption experiments were conducted in the same manner as in Example 1 using the zeolite prepared by the above method. The results are summarized in Table 1.

It can be seen that all of these strongly adsorb the o-form.

[0036]

[Table 1]

[Table 2] Example 16 X-type faujasite-type zeolite having sodium at the cation site (Tosoh, Zeolum F9) (Na-
After firing the granulated product of X) at 500 ° C. for about 1 hour,
Contact with a 10 wt% aqueous solution of (NO ₃ ) ₂
Repeated times, an X-type zeolite ion-exchanged with magnesium (Mg-X) was prepared. About 1.6g of this adsorbent
Was calcined at 500 ° C. for about 1 hour, then cooled in a desiccator, filled into a 5 ml autoclave with about 2.5 ml of the liquid phase mixture, and left to contact at 150 ° C. for 1 hour. The composition ratio of the charged liquid phase mixture was p-bromofluorobenzene: m-bromofluorobenzene: o-bromofluorobenzene: n-nonane = 32: 63: 5: 10.
(Weight ratio). N-nonane was added as an internal standard substance in gas chromatography analysis, and is a substance substantially inactive to the adsorbent under the above experimental conditions.
The composition of the liquid phase mixture after contact with the adsorbent was analyzed, and the adsorption selectivity α was determined using the above formula (1). Table 3 shows the results
Shown in This system is capable of non-adsorbingly separating the m-form.

Example 17 The adsorbent used in Example 16, Mg-X, was packed in a stainless steel column having a length of 1 m and an inner diameter of 4.75 mm, and a desorbent toluene of about 1.8 ml / in an oil bath at 150 ° C.
Flowed at a flow rate of min. Separated raw materials while flowing toluene: p-bromofluorobenzene: m-bromofluorobenzene: o-bromofluorobenzene: toluene: decalin = 30: 70: 100: 10 (% by weight)
About 1.6 ml of a mixture consisting of was introduced into the column inlet. Decalin is an internal standard and is used as a basis for the outflow time, and its adsorption is virtually negligible compared to other components.

The liquid flowing out from the column outlet was analyzed by gas chromatography to find that it was about 4.5 after the introduction.
After a minute, m-bromofluorobenzene began to flow out.
Further, the effluent was analyzed periodically to obtain the outflow curve shown in FIG.

Examples 18 to 36 In the same manner as in Examples 1 and 2 to 15, Ca-X, Sr-
X, Ca-Y, Sr-Y, Li-Y, Na-Y, Ni-
Y, Zn-Y, and Cr-Y were prepared, and adsorption experiments were conducted in the same manner as in Example 1 using the desorbing agents shown in Table 3. The results are shown in Table 3.

[Table 3] Example 37 The same granulated product of Na—Y type zeolite as that used in Example 1 was calcined at 500 ° C. for about 1 hour and then contacted with a 10 wt% aqueous solution of KNO ₃ was repeated 7 times to ionize with potassium. An exchanged Y-type zeolite (KY) was prepared. The same experiment as in Example 1 was conducted using this adsorbent. Table 4 shows the results. This system is capable of separating p-bromofluorobenzene non-adsorptively.

Examples 38 to 45 In the same manner as in Examples 1 and 2 to 15, KY, KX,
Rb-Y, Cs-Y, and Ba-X were adjusted, and an adsorption experiment was conducted in the same manner as in Example 1 using the desorbing agents shown in Table 4. Table 4 shows the results.

[0041]

[Table 4] Examples 46 to 48 Using Y-type faujasite-type zeolite (Na-Y) having sodium at the cation site as an adsorbent,
Example 1 using p-diethylbenzene as the desorbent
The same experiment was performed. However, the composition ratio of the charged liquid phase mixture is p-bromofluorobenzene: m-bromofluorobenzene: o-bromofluorobenzene: p-
Diethylbenzene: n-nonane = 32: 63: 5: 10
It was 0:20 (weight ratio). n-nonane was added as an internal standard substance in gas chromatography analysis,
It is a substance which is substantially inactive to the adsorbent under the above experimental conditions. Furthermore, zeolite (Ca-X, Sr-) in which Na-X is ion-exchanged with calcium or strontium.
A similar experiment was performed using X). Table 5 shows the results.
In this system, p-forms can be separated by strong adsorption.

Comparative Example 1 The same experiment as in Example 1 was conducted using Ca-X used in Example 47 as an adsorbent and no desorbent. Table 5 shows the results. This system strongly adsorbs o-form.

[0043]

[Table 5] Examples 49, 50 Na-X was used as an adsorbent, and a chlorofluorobenzene isomer mixture (o-: m-: p- =) was used as an isomer mixture.
The adsorption selectivity of the chlorofluorobenzene isomer mixture was examined in the same manner as in Example 1 except that 1: 1: 1) was used. A similar experiment was conducted using K-X as an adsorbent. Table 6 shows the results.

Comparative Examples 2 and 3 The same experiment as in Examples 49 and 50 was conducted except that a bromochlorobenzene isomer mixture was used as the isomer mixture. Table 5 shows the results.

[0045]

[Table 6]

[0046]

EFFECTS OF THE INVENTION According to the present invention, it becomes possible to separate and collect only a specific isomer in a high purity in a high yield from a dihalogenated benzene isomer mixture containing fluorine.

[Brief description of the drawings]

FIG. 1 is a diagram showing a change over time in the outflow amount of each component in Example 17 of the present invention.

Claims (18)

[Claims] 1. When adsorbing and separating a specific dihalogenated benzene isomer from a dihalogenated benzene isomer mixture in which at least one of the substituted halogen groups is fluorine, it is contacted with an adsorbent containing zeolite. Method for separating dihalogenated benzene isomers. 2. The method for separating a dihalogenated benzene isomer according to claim 1, wherein the zeolite is a faujasite type zeolite. 3. The method for separating a dihalogenated benzene isomer according to claim 1 or 2, wherein the substituted halogen groups of the dihalogenated benzene are different from each other. 4. The method for separating a dihalogenated benzene isomer according to claim 3, wherein the dihalogenated benzene is bromofluorobenzene or chlorofluorobenzene. 5. The method for separating dihalogenated benzene isomers according to claim 1, wherein o-dihalogenated benzene is separated by strong adsorption from the mixture of dihalogenated benzene isomers. 6. The method for separating a dihalogenated benzene isomer according to claim 5, which is brought into contact with an adsorbent containing a faujasite-type zeolite containing a cation having an ionic radius of 0.12 nm or more. 7. The method for separating a dihalogenated benzene isomer according to claim 6, wherein the cation is at least one kind of cation selected from strontium, barium and silver. 8. The method for separating a dihalogenated benzene isomer according to claim 5, 6 or 7, wherein the faujasite-type zeolite is Y-type. 9. A dihalogenated benzene isomer mixture,
A non-adsorbed m-dihalogenated benzene is separated by contacting it with an adsorbent containing a faujasite-type zeolite containing a monovalent and / or divalent cation having an ionic radius of 0.13 nm or less. 1 to 4
A method for separating a dihalogenated benzene isomer according to the item 1. 10. The method for separating a dihalogenated benzene isomer according to claim 9, wherein the cation is at least one cation selected from magnesium, calcium, strontium, sodium and lithium. 11. The method for separating a dihalogenated benzene isomer according to claim 9, wherein the zeolite is an X-type zeolite containing magnesium. 12. The method for separating a dihalogenated benzene isomer according to claim 9, wherein the zeolite is a Y-type zeolite containing sodium. 13. A dihalogenated benzene isomer mixture is contacted with an adsorbent containing a faujasite-type zeolite containing cations having an ionic radius of 0.13 nm or more,
The method for separating a dihalogenated benzene isomer according to any one of claims 1 to 4, wherein p-dihalogenated benzene is separated without being adsorbed. 14. The method for separating a dihalogenated benzene isomer according to claim 13, wherein the cation is at least one cation selected from potassium, rubidium, cesium and barium. 15. The method for separating a dihalogenated benzene isomer according to claim 13, wherein the zeolite contains potassium. 16. A dihalogenated benzene isomer mixture is brought into contact with an adsorbent containing a faujasite-type zeolite containing cations having an ionic radius of 0.1 to 0.14 nm, and p-dialkylbenzene is used as a desorbent. The method for separating a dihalogenated benzene isomer according to any one of claims 1 to 4, wherein the p-dihalogenated benzene is separated by strong adsorption. 17. The method for separating a dihalogenated benzene isomer according to claim 16, wherein the zeolite is a Y-type zeolite containing sodium or an X-type zeolite containing calcium and / or strontium. 18. The method for separating a dihalogenated benzene isomer according to claim 17, wherein the p-dialkylbenzene is p-diethylbenzene.