JPH0437063B2 - - Google Patents

Abstract

PURPOSE:To separate the titled isomer useful as an intermediate for agricultural chemicals and medicines efficiently in high yield, by bringing a mixture containing >=2 dichlorobenzene isomers into contact with a faujasite type zeolite based adsorbent to adsorb and separate the isomers. CONSTITUTION:A dichloronitrobenzene (hereinafter abbreviated to DCNB) isomer mixture containing at least two or more DCNB isomers is brought into contact with a faujasite type zeolite adsorbent expressed by the formula (M is cation and preferably contains one or more selected from Groups IA, IB and IIA in the periodic table, e.g. Na, K, Ag, Ca, etc.; n is the valence thereof; x=2.5+ or -0.50 for type X and x=3-6 for type Y of the faujasite classified into the types X and Y; y varies with the degree of hydration) at room temperature -350 deg.C under atmospheric pressure -50kg/cm<2>G pressure, adsorbed and separated. The adsorbed and separated isomers are then desorbed with a desorption agent, e.g. 3-8C alcohol or anisole, to separate and give particularly 2, 4-DCNB and 2, 6-DCNB.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to dichloronitrobenzene (hereinafter referred to as
This paper relates to a method for adsorption and separation of isomers (abbreviated as DCNB). [Prior Art] DCNB isomers are important substances as intermediates for agricultural chemicals and medicines. In particular, when using the isomer as a raw material for pharmaceuticals, it is highly purified to reduce side effects other than medicinal effects due to impurities contained in the isomer.
DCNB isomer is required. However, when trying to obtain DCNB isomer by nitration reaction of dichlorobenzene (hereinafter abbreviated as DCB) isomer, for example, 2,
4-DCNB and 2,6-DCNB are 0-DCB
2,3-DCNB and 3,4-DCNB are produced. The boiling points of these DCNB isomers produced by the nitration reaction of DCB are very similar, making it extremely difficult to separate and recover highly pure DCNB isomers by rectification. Furthermore, no economical means for separating and recovering these isomers with high purity has yet been found. [Problems to be Solved by the Invention] An object of the present invention is to adsorb and separate a highly pure DCNB isomer from a DCNB isomer mixture. In particular, 2, produced by nitration of m-DCB,
The objective is to adsorb and separate 4-DCNB and 2,6-DCNB. [Means for Solving the Problems] In order to achieve the above object, the present invention is directed to separating a dichloronitrobenzene isomer mixture containing at least two or more types of dichloronitrobenzene isomers, by separating the isomer mixture from houjasite. This is a method for separating dichloronitrobenzene isomers, which is characterized by bringing the dichloronitrobenzene isomers into contact with a zeolite type adsorbent. The haujasite type zeolite used in the present invention is a crystalline aluminosilicate represented by the following formula. 0.9±0.2M _2/o 0: Al ₂ O ₃ :xSiO ₂ :yH ₂ O Here, M represents a cation, and n represents its valence. The haujasite type zeolite of the above formula is classified into an X type and a Y type, where the X type is represented by x=2.5±0.5, and the Y type is represented by x=3 to 6. Moreover, y varies depending on the degree of hydration. The cation preferably contains at least one selected from Groups A, B, and A of the periodic table, such as sodium, potassium, lithium, silver, calcium, and barium. The cation is preferably selected appropriately depending on the object to be separated. The above-mentioned haujasite-type zeolite used in the present invention is generally first obtained as a powdered synthetic product containing Na cations, and then a binder such as a clay-based material or alumina sol is added to the zeolite powder, and if necessary, a surfactant or other additives are added. After adding and kneading the organic compound, it is molded into an appropriate size and fired. After that, ion exchange with the necessary cations is performed. The ion exchange method for these cations is
It is well known to those skilled in the art with knowledge of the production of crystalline aluminosilicates and is usually carried out by contacting the zeolite with one or more soluble aqueous solutions to be added to the zeolite. sell. The ion exchange temperature is usually preferably from room temperature to 100°C or less, and the contact method may be a batch method or a flow method. Furthermore, before use as an adsorbent, at least a portion of the adsorbed water is released and activated by calcination before use. The technique for adsorptive separation of a DCNB isomer mixture using the method of the present invention may be a so-called chromatography separation method, or a continuous adsorption separation method using a simulated moving bed. Continuous adsorption separation technology using a simulated moving bed is carried out by continuously cycling the following basic operations: adsorption operation, concentration operation, desorption operation, and desorbent recovery operation. (1) Adsorption operation: The DCNB isomer mixture is brought into contact with a zeolite adsorbent of the faujasite type, and strongly adsorbed components are selectively adsorbed. The remaining weakly adsorbed components are recovered along with the desorbent described below as a roughinate stream. (2) Concentration operation: The adsorbent that has selectively adsorbed the strongly adsorbed components is brought into contact with a part of the extract, which will be described later, to drive out the weakly adsorbed components remaining on the adsorbent and remove the strongly adsorbed components. Highly purified. (3) Desorption operation: The highly purified adsorbent containing strongly adsorbed components is brought into contact with the desorbent, and the highly purified strongly adsorbed components are expelled from the adsorbent and recovered together with the adsorbent as an extract stream. Ru. (4) Desorbent recovery operation: The adsorbent that is essentially adsorbing only the adsorbent is brought into contact with a portion of the roughinate stream, and a portion of the desorbent contained in the adsorbent is recovered as a desorbent recovery stream. be done. As the adsorbent used in the above-mentioned adsorption separation method or the developing agent used in chromatographic separation, a compound that can be easily separated from DCNB by distillation can be used. Examples include alkyl-substituted aromatics, halogen-substituted aromatics, oxygen-containing aromatics, alcohols, ketones, and the like. Preferably _C3 - _C8 alcohol, anisole,
Examples include methylanisole. The type of desorbent or developer is preferably selected appropriately depending on the object to be separated, the combination with the zeolite cation, etc. As for the operating conditions for adsorption separation, the temperature is from room temperature to 350°C, preferably 50 to 250°C,
The pressure is from atmospheric pressure to 50 kg/cm ² ·G, preferably from atmospheric pressure to 40 kg/cm ² ·G. The adsorption separation according to the 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 the adsorbent. [Effects of the Invention] By using a faujasite-type zeolite-type adsorbent, the present invention can separate a target isomer with high purity from a mixture of dichloronitrobenzene isomers, which has been difficult to separate in the past. In particular, it exhibits a remarkable effect in efficiently separating 2,4-DCNB and 2,6-DCNB. [Example] 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 equation (1). α _A/B = (weight fraction of A component/weight fraction of B component) S
/(weight fraction of component A/weight fraction of component B) L(1) Here, A and B indicate one of the DCNB isomers, S is the adsorbed phase, and L is the state in equilibrium with the adsorbed phase. shows the liquid phase in When the value of the above formula is larger 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 1 Alumina sol was added as a binder to zeolite powder of Na-X (SiO ₂ /Al ₂ O ₃ ≒2.5) and Na-Y type (SiO ₂ /Al ₂ O ₃ ≒5.2) at 15 wt% in terms of Al ₂ O ₃
After adding and kneading, a granulated product with a mesh size of 24 to 32% is obtained by extrusion molding. This granulated product is heated to 100℃ for approximately 12
After drying for an hour, it was calcined at 500°C for 1 hour to prepare Na-X and Na-Y type adsorbents. Furthermore, these adsorbents were ion-exchanged four times with a 10 wt% aqueous solution of cationic nitrates shown in Table 1.
Adsorbents shown in Table 1 were prepared. In order to measure the adsorption selectivity of the above adsorbent between DCNB isomers, approximately 2 g of the adsorbent and approximately 3 g of the liquid phase mixture were filled into an autoclave with an internal volume of 5 ml, and the mixture was left at 150°C for 1 hour with occasional stirring. . The composition of the charged liquid phase mixture is mix−
DCNB: n-hexanol: n-nonane = 50:
50:5 [wt ratio], mix-DCNB is a mixture of DCNB isomers, and its composition is 2,4-DCNB:2,
5-DCNB:2,6-DCNB=94.7:0.8:4.5. n-hexanol was used as a solvent for DCNB, and can also be used as an adsorbent in adsorption separation operations using a simulated moving bed. Further, n-nonane was added as an internal standard substance in gas chromatography analysis, and is a substantially inert substance under the above experimental conditions. The composition of the liquid phase mixture after contact with the adsorbent was analyzed by gas chromatography, and the adsorption selectivity α between DCNB isomers was determined. The results are shown in Table 1. Example 2 An experiment was conducted in which n-hexanol, the solvent for DCNB used in Example 1, was replaced with anisole. Other experimental conditions were the same as in Example 1. Table 1 shows the adsorption selectivity between DCNB isomers obtained through experiments. Example 3 A 0.5Ba-K-X adsorbent was prepared by performing ion exchange once with an aqueous solution containing barium nitrate corresponding to 50/2 mol% of the cations contained in the K-X adsorbent prepared in Example 1. . The adsorption selectivity between DCNB isomers of the adsorbent was measured by the method shown in Example 1.
The results are shown in Table 1. Example 4 The K-Y type adsorbent prepared in Example 1 was used with an inner diameter of 4 mm.
After filling a tube with a diameter of 1200 mm in length and sufficiently contacting it with n-hexanol, a mixture of mix-DCNB: n-hexanol = 50:50 [wt ratio] was mixed with approximately 1.3
cc injection followed by n-hexanol at approximately 90 c.c./
hr (20°C) and developed. At this time, the mix developed in the adsorbent-filled tube
Figure 1 shows the results of gas chromatography analysis of the -DCNB effluent at each effluent time. The mix-DCNB used was the same as that used in Example 1. In addition, in Figure 1, 2,6-DCNB and 2,
The plot was made by increasing the concentration of 5-DCNB by 10 times.

【table】

【table】 [Brief explanation of drawings]

FIG. 1 shows the results of gas chromatography analysis of an example of the present invention.

Claims (1)

[Claims] 1. Separation of dichloronitrobenzene isomers, characterized in that when separating a dichloronitrobenzene isomer mixture containing at least two or more types of dichloronitrobenzene isomers, the isomer mixture is brought into contact with a zeolite adsorbent of the Houjasite type. Method.