JPH0446930B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a method for separating a specific bromodichlorobenzene isomer from a bromodichlorobenzene isomer mixture. In particular, 1-brome-3,
5-dichlorobenzene (abbreviated as B3-5DCB) is
It is an important compound in synthetic chemistry, and is used in agricultural products, dyes,
It is useful as an intermediate raw material for pharmaceuticals, etc. <Conventional technology> Conventionally, 1-bromo-
2,4-dichlorobenzene (abbreviated as B2-4DCB)
The catalyst, AlCl ₃ , is removed by water washing from the brominodichlorobenzene isomer mixture obtained by isomerizing the bromine dichlorobenzene, and unreacted m-dichlorobenzene is separated by distillation, and the target product B3-5DCB is isolated and obtained by crystallization. It is known to do so (Japanese Unexamined Patent Publication No. 53-28126). <Problem to be solved by the invention> Bromodichlorobenzene obtained by isomerizing B2-4DCB by acting bromine on m-DCB contains not only the target B3-5DCB but also unreacted m
-DCB, B2-4DCB and by-product 1-brome-2,
There are 6-dichlorobenzene (abbreviated as B2-6DCB) and 1,5-dibromo-2,4-dichlorobenzene (abbreviated as 1-5B2-4DCB). B3−
When attempting to separate and recover 5DCB with high purity and high yield, it is generally preferable to minimize the amount of substances other than the target substance present. In particular, when separation and purification is performed by crystallization, the composition of the mixture supplied to this step must be stable within a certain range. Furthermore, since unreacted m-DCB is a good solvent for bromodichlorobenzene, its presence in large amounts is not preferable in the crystallization separation and recovery method of B3-5DCB. On the other hand, m-DCB, B2-4DCB in the reaction composition
and 1-5B2-4DCB is recycled to the bromination or isomerization reaction step and the target product B3-5DCB
There is no need to separate and recover each component. On the other hand, since B2-6DCB is concentrated and accumulated through recycling, it must be removed from the system at some point. The present inventors have made extensive studies to solve these problems all at once, and as a result, have arrived at the present invention. <Means for solving the problem> 1-bromo-3,5-dichlorobenzene, 1-
1-bromo-2,4-dichlorobenzene from a mixture containing bromo-2,4-dichlorobenzene, 1-bromo-2,6-dichlorobenzene and 1,5-dibromo-2,4-dichlorobenzene isomers.
When adsorbing and separating 3,5-dichlorobenzene,
The present invention relates to a method for separating 1-bromo-3,5-dichlorobenze, which is characterized by using an X-type zeolite substituted with sodium ions as an adsorbent. It is known that a phasiasite-type zeolite is used as a method for separating trihalogenated benzene isomers (Japanese Unexamined Patent Publication No. 1982-219131), but this method only targets identical halogen compounds such as trihalogenated benzene. This is different from the present invention. The mixture containing bromodichlorobenzene isomers in the present invention refers to B3-5DCB, B2-4DCB, B2
Refers to a mixture containing -6DCB and 1-5B2-4DCB. Furthermore, 1-bromo-2,5-dichlorobenzene (abbreviated as B2-5DCB), 1-bromo-2,3
-dichlorobenzene (abbreviated as B2-3DCB) and 1-bromo-3,4-dichlorobenzene (B3-
(abbreviated as 4DCB), the raw material m-DCB may also be included. As the zeolite used in the method of the present invention, a type X zeolite among haujasite type zeolites is used. This is a crystalline aluminosilicate represented by the following formula. (0.9±0.2)M2 _/o :Al2O3:(2.5±0.5) _SiO2 : _{yH2O Here ,} M represents a cation, and N represents its raw material price. Moreover, y varies depending on the degree of hydration. Sodium ions are used as cations in the zeolite used in the present invention. Along with sodium ions, one or more cations including metal ions selected from Groups A, B, and A of the periodic table, ammonium ions, protons, and the like can be used. The ion exchange method for these cations can be carried out by conventional methods, usually by contacting the zeolite with an aqueous solution of soluble salts of one or more cations to be added to the zeolite, or by calcining the zeolite. This is carried out by contacting the zeolite with an aqueous solution of an ammonium salt, which protonates the zeolite. The zeolite adsorbent of the present invention is, for example,
Obtained by the method described in Publication No. 53-28126. According to the method of the present invention, B2-6DCB can be recovered as an extract component from a polyhalogenated benzene mixture containing m-DCB and 1-5B2-4DCB in the bromodichlorobenzene isomer mixture,
The feature is that B3-5DCB can be separated and recovered as a roughinate component. The technique for adsorptive separation of the bromodichlorobenzene isomer mixture using the method of the present invention may be a so-called chromatographic preparative method, or a continuous adsorption separation method using a simulated moving bed. The developing agent or desorbing agent used in these separation methods can be a compound that can be easily separated by distillation from bromdichlorobenzene, m-DCB, and 1-5B2-4DCB, and preferably an alkyl-substituted aromatic compound or a halogen-substituted aromatic compound. are toluene, chlorotoluene, chlorobenzene, ethylbenzene, xylene, m-DCB, etc. These compounds are 2
It may be a mixture of more than one species. When using m-DCB, B2-4DCB and 1-5B2-
It is also possible to recycle it together with 4DCB to the bromination/isomerization reaction step for B3-5DCB production. As for the operating conditions for adsorption separation, the temperature is from room temperature to 350°C, preferably 50 to 250°C, and the pressure is from atmospheric pressure to 50 Kg/cm ² G, preferably 40 Kg/cm ² G.
It is. The adsorption separation according to the present invention may be carried out in the gas phase or in the liquid phase, but is preferably carried out in the liquid phase in order to lower the operating temperature and to suppress undesirable side reactions of the raw material feed or desorbent. Next, the method of the present invention will be explained by giving examples.
In the examples, the adsorption characteristics of the adsorbent are expressed by the adsorption selectivity (α) of the following formula.
αA/B = [weight fraction of A component/weight fraction of B component] S
/ [weight fraction of component A/weight fraction of component B] L where A and B are any one of the bromodichlorobenzene isomers, m-DCB, or 1-5B2-
Indicates any one of 4DCB, S indicates an adsorption phase, and L indicates a liquid phase in equilibrium with the adsorption phase. When the value of the above formula is greater than 1, the A component is selectively adsorbed, and when it is smaller than 1, the B component is selectively adsorbed. Further, the adsorbent whose α value in the above formula is larger than 1 (or smaller than 1 and closer to 0) makes it easier to adsorb and separate A and B. <Example> Hereinafter, the present invention will be specifically explained with reference to Examples. Example 1 Granulated products of Na-X and Na-Y type haujasite zeolites and nitrates in the equivalent ratio of the cations shown in Table 1 to the total cations in the zeolite (for 0.3Ag-K-Y, 30 equivalents) %of
Ion exchange was performed at 90° C. for 2 hours at a solid-liquid ratio of 5 (ml/g) using an aqueous solution (using AgNO ₃ and 70 equivalent % KNO ₃ ). In addition, the partially protonated zeolite was similarly ion-exchanged with an equivalent aqueous solution of ammonium nitrate. After ion exchange, zeolite granules are
Washed 10 times with pure water at 90°C at a solid-liquid ratio of 5 (ml/g),
It was dried at 120°C overnight. The zeolite adsorbent thus prepared was calcined at 500° C. for 2 hours and used immediately before measuring the adsorption selectivity between bromodichlorobenzene isomers. In order to measure the adsorption selectivity between bromodichlorobenzene isomers including m-DCB and 1-5B2-4DCB, two adsorbents were placed in an autoclave with an internal volume of 5 ml.
g and 3 g of the above polyhalogenated benzene mixture
was charged and left at 150°C for 0.5 hour with occasional stirring. The composition of the charged polyhalogenated benzene mixture is m-DCB 10 B2-4DCB 35 B3-5DCB 35 B2-6DCB 5 1-5B2-4DCB 15 weight ratio. Furthermore, as a reference material for gas chromatography analysis, 20 wt % n-nonane was simultaneously added to the polyhalogenated benzene mixture. n-
Nonane is a material that is virtually inert with respect to the adsorption properties of zeolites under the above conditions. The composition of the liquid phase mixture after contact with the adsorbent was analyzed by gas chromatography, and the adsorption selectivity between bromodichlorobenzene isomers was determined.
The results are shown in Table 1. In Table 1, the adsorbents showing only a single cation component represent 98 equivalent % or more of the cations contained in the adsorbent. For example, 0.3Ag
-K-Y indicates that ion exchange was performed with a silver nitrate solution containing 30 equivalent % of the total cations contained in the K-Y type adsorbent and the remainder with a potassium nitrate solution.

[Table] Table 1 shows that according to the method of the present invention, B3-5DCB can be separated and recovered as a roughinate component very efficiently using the Na-X type zeolite adsorbent.
It is clear from this. Example 2 The adsorption selectivity of a liquid mixture containing other bromodichlorobenzene isomer mixtures, which were not included in Example 1, was measured using 0.05Ag-Na-X. The results are shown in Table 2. The composition of the charged bromdichlorobenzene isomer mixture is B2-3DCB/B2-5DCB/B3-
It is an equal mixture of 4DCB/B3-5DCB. Other measurement conditions are the same as in Example 1.

[Table] Table 2 also shows that B3-5DCB can be separated and recovered as a roughinate component. Example 3 B3-5DCB/B2-4DCB/B2-6DCB/m-dichlorobenzene/1-5B2-4DCB=44/30/
A bromine dichlorobenzene isomer mixture consisting of 1/11/14 wt% was adsorbed and separated using a simulated moving bed apparatus schematically shown in FIG. The Na-X type adsorbent prepared in Example 1 was filled into adsorption chambers 1 to 12 each having an internal volume of about 13 ml. line 13
m-dichlorobenzene, a desorbent, from 378
ml/hr, and the above isomer mixture was fed from line 15 at 11.6 ml/hr. An extract stream was withdrawn from line 14 at 149 ml/hr, a roughinate stream was withdrawn from line 16 at 52 ml/hr, and the remaining fluid was withdrawn from line 17. Further, the flow of fluid between the adsorption chambers 1 and 12 is controlled by a bell 18.
is closed. At this time, adsorption chamber 1 was moved to 12, 11 to 10, 8 to 7, and 5 to 4 simultaneously at approximately 150 second intervals (the other adsorption chambers were also moved upward by one adsorption chamber at the same time). . The adsorption temperature was 150°C. B3 in the bromodichlorobenzene isomer mixture contained in the raffinate stream obtained in the above experiment.
The purity of -5DCB was 99.6%, and the recovery rate of B3-5DCB was over 91%. <Effects of the Invention> According to the present invention, specific bromodichlorobenzene can be efficiently separated and recovered with high purity using a zeolite adsorbent from a mixture of bromodichlorobenzene isomers, which contributes to industry. The effect is extremely high. Bromodichlorobenzene is a compound that is useful as an intermediate raw material for agricultural chemicals, medicines, dyes, etc. It opens the door to supplying high-purity products at low cost, and will greatly contribute to related industries.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing an adsorption separation operation using a simulated moving bed, which is an embodiment of the present invention. 1 to 12...Adsorption chamber, 13...Desorbent supply line, 14...Extract extraction line, 1
5... Isomer mixture supply line, 16... Roughinate extraction line, 17... Desorbent recovery line, 18... Valve.

Claims (1)

[Claims] 1 1-bromo-3,5-dichlorobenzene, 1
- 1-bromo from a mixture containing bromo-2,4-dichlorobenzene, 1-bromo-2,6-dichlorobenzene and 1,5-dibromo-2,4-dichlorobenzene isomers. A method for separating 1-bromo-3,5-dichlorobenzene, which comprises using an X-type zeolite substituted with sodium ions as an adsorbent when adsorbing and separating -3,5-dichlorobenzene. 2 As a desorbent, toluene, chlorotoluene, chlorobenzene, ethylbenzene, xylene, m-
Claim 1 using one or more selected from DCB
The method for separating 1-bromo-3,5-dichlorobenzene as described.