JPS632956A - Method for separating dichloronitrobenzene isomers - Google Patents

Abstract

PURPOSE:To separate and to recover a 1,2,3-substitution isomer and a 1,2,4-substitution type isomer in high purity, by treating an isomer mixture of the titled compound by the use of ZSM type zeolite adsorbent. CONSTITUTION:Water of crystallization is preremoved from an isomer mixture of 3,4-dinitrobenzene(DCNB) and 2,3-DCNB, and 2,4-DCNB and 2,6-DCNB obtained by nitration of o- and m-dichlorobenzene and the isomer mixture is brought into contact with a ZSM type zeolite adsorbent at room temperature - 350 deg.C, preferably 100-250 deg.C and separated into a nonadsorbed component and an adsorbed component selectively to give 2,3-DCNB and 2,3-DCNB in high purity.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for separating and purifying isomers of dichloronitrobenzene (hereinafter abbreviated as DCNB), which are useful as intermediates for agricultural chemicals, dyes, and the like.

(Prior art and problems) DCNBs are industrially obtained by nitration of o-, m- and p-dichlorobenzene, but among these, nitration of o- and m-dichlorobenzene is difficult. Each main product obtained by 3. 4-DCNB and 2,4-DCNB are isomers of 2,3-D
It contains CNB or 2.6-DCNB, and it is extremely difficult to separate these isomers individually because the boiling points and freezing points of each isomer are close to each other.

For example, 3 and 4 are useful as pesticide intermediates, respectively.
-12.3-U.S. Patent-32 for separation of DCNB mixture
No. 72875 and the like disclose formulations based on crystallization separation. Also, as a well-known method, 3.4-12.3
There is also a method of treating the mixture with fuming sulfuric acid to decompose it by utilizing the difference in sulfonation rate between -DCNB. but,
With these methods, it is difficult to separate and recover each of the contained isomers with high purity, and it is difficult to say that these methods are industrially or economically advantageous.

(Means for Solving the Problem) In view of the current situation, the inventors of the present invention have conducted extensive research into methods for separating DCNB isomer mixtures, and have surprisingly found that a certain zeolite adsorbent can be used to The present invention has been completed based on the discovery that it is possible to selectively separate and recover each isomer having a specific substitution position by performing adsorption separation using the method.

That is, the present invention provides D represented by the following general formula (T)
Among the isomer mixtures of CNB, 1,2,3-substituted isomer and 1
, 2.4-substituted isomers are selectively adsorbed and separated using a ZSM type zeolite adsorbent.

As the ZSM type zeolite used in the present invention, ZSM-type zeolite described in Japanese Patent Publication No. 46-10064
5 zeolite and zeolites considered to belong to the same series, for example, in addition to the above-mentioned ZSM-5, ZSM-8 described in British Patent No. 1334243, Japanese Patent Publication No. 53-23280 ZSM-11 described in U.S. Patent No. 4001346, ZSt-21 described in U.S. Pat.
ZSM-35 described in JP-A No. 4500, zeolite zeta 1 described in JP-A-51-67299, zeolite zeta-3 described in JP-A-51-67298, etc. is preferred.

Preferably, the zeolite is used in acid form.

Acid type zeolite has H” as a cation in zeolite.
, NlI4'', or a polyvalent cation having a divalent or higher valence such as a rare earth ion. These usually convert at least a portion of a monovalent alkali metal ion such as sodium into a proton, an ammonium cation, or a polyvalent cation. It can be obtained by ion exchange.

Furthermore, it is necessary to remove crystallization water from zeolite before use. Usually, the crystal water content can be reduced at 100°C or higher, preferably 300 to 60°C.
Most of the black water can be removed by heating at 0°C.

The shape of the zeolite used in the present invention may be a powder, a crushed lump, or a molded product obtained by compression molding, extrusion molding, marmerizer, or the like. Furthermore, during molding, a binder such as bentonite or alumina sol can be added if necessary. On a small scale, it can be used from powder; industrially, to avoid pressure loss, a spherical molded product with a diameter of 0.1 to 1 (In) is preferably used.The shape can be freely selected depending on the equipment. can be selected.

S r Ot /to120. The ratio is not particularly limited, and is preferably 10 to 100.

The method of the present invention may be carried out by a batch method using a fixed bed method, which is known as a separation technique, or by a continuous method, but in small-scale cases, a batch method is simpler and requires less operation. It is used because it is easy.

The separation technology of the present invention is basically provided with one or more adsorption chambers filled with an adsorbent, and is carried out in a cycle of adsorption--4=washing-desorption-adsorbent regeneration steps.

That is, the DCNB isomer mixture can be brought into contact with an adsorbent in an adsorption chamber and selectively separated into non-adsorbed components and adsorbed components.

The adsorption temperature of the present invention is from room temperature to 350°C, preferably 10°C.
The temperature ranges from 0 to 250°C.

The adsorption pressure ranges from atmospheric pressure to about 50 kg/cJ, preferably from atmospheric pressure to about 30 kg/cJ.

Further, during adsorption, a substance that does not affect adsorption-desorption may be optionally added to the DCNB isomer mixture as a diluting solvent.

The method for desorption of the adsorbed DCNB isomer after adsorption separation in the present invention is not particularly limited, but steam desorption is preferred.

(Effect of the invention) Thus, according to the method of the present invention, type 1, 2.3 and type 1,
2.4 type and a DCNB isomer mixture with different substitution types are Z
By adsorbing and separating with SM type zeolite, it becomes possible to obtain DCNB of high purity, which has been difficult to achieve in the past.

This is because DCNBs are manufactured industrially by nitration of dichlorobenzenes, and contamination with isomers with different substitution types is unavoidable when using 〇- and m-dichlorobenzenes as raw materials. Considering that, this is an extremely useful effect.

Furthermore, ZSM type zeolite can be reused for a long period of time, and is highly effective from an industrial standpoint.

Hereinafter, some examples will be given for the purpose of explaining the present invention.

(Example) Reference Example 1 According to the method of Example 1 of Japanese Patent Publication No. 46-10064, S, O790,1wt%, Al1t0,6.1
wt%, Na, 03.3wt%, SIO! /^1203
A ZSM-5 type zeolite powder having a composition of -25.1 was obtained. Next, add 1 Qwt% ammonium nitrate aqueous solution to the solid-liquid ratio of 2. Oj! /kg, and ion exchange was performed five times at 95°C. After washing with water, it was pre-dried at 150°C for 5 hours, and then baked at 500°C for 3 hours.

The results of X-ray analysis of the obtained powder were
-Z SM It was a one-time loss with -5.

Reference Example 2 ZSM-11 type zeolite powder was obtained according to the method described in Examples of Japanese Patent Publication No. 53-23280.

Further, this was treated in the same manner as in Reference Example 1 to obtain H-Z SM-
Type 11 zeolite powder was obtained.

Example 1 8.2 g of the H-ZSM-5 type zeolite powder of Reference Example 1 was packed into a metal column with an inner diameter of 9.8 mm and a length of 16.3 cm, and 2.3-1 and 3.4-DCNB isomers were The mixture was melted by heating to 45°C and introduced at a rate of 50 μβ/min at 200°C under a nitrogen pressure of 2 kg/cJ. The composition of the DCNB isomer mixture introduced at this time was 2°3-/3.
4-=30.0/70.0wt ratio.

Sample the liquid flowing out from the column outlet at predetermined intervals (3
~7 minute intervals), the liquid volume was measured, and the liquid composition was analyzed using a gas chromatograph. The composition of the effluent sampled about 40 minutes after the start of outflow was the same as the composition of the introduced solution, indicating breakthrough. The changes in composition of the effluent so far are shown in Table 1.

Nitrogen gas was then introduced at the same temperature and under a pressure of 3 kg/crA for 30 min to drain-wash the deposited DCNB isomer mixture.

Next, water vapor (mole fraction 0.33) and nitrogen (
6 kg of mixed gas with a mole fraction of 0.67) at the same temperature
/aJ at a rate of 60 mβ/min. The adsorbed 3,4-DCNB was desorbed and flowed out together with water, and the outflow of DCNB was completed after about 40 minutes. The total amount of 3,4-DCNB released due to desorption was 558.6
The concentration of 3.4-DCNB in this total flow rate was 98.8% as determined by gas chromatography analysis.

Now, 3,4-DCNB per unit amount of zeolite (g)
The apparent adsorption capacity of is expressed by the following formula f'. A: Amount of DCNB flowing out in the desorption process (g) B: Concentration of 3.4-DCNB component in the desorption solution (%) Apparent adsorption capacity in this example f' was 6.73%.

Examples 2-3 The column used in Example 1 was further heated to 6 kg at 200"C.
4Qnj of nitrogen gas under the pressure of / cJ! /min for 2 hours to dry-regenerate the adsorbent.

After completion of the regeneration, as in Example I, one cycle consisted of adsorption, cleaning, underwear, and regeneration, and a total of three cycles including Example 1 were repeated. The amount and composition of the non-adsorbed effluent up to breakthrough, the amount and composition of the effluent in the desorption step, and the apparent adsorption capacity f' were as shown in Table 2.

Incidentally, as a result of X-ray analysis of the crystallinity of the zeolite after repeating this cycle three times, no destruction of the crystal structure was observed.

Example 4 Biting-cleaning was carried out using the same equipment and method as in Example 1, except that the H-ZSM-5 type zeolite used in Example 1 was replaced with the H-ZSM-11 type zeolite synthesized in Reference Example 2.
Desorption and regeneration operations were performed.

The results were shown in Table-2.

Example 5 Using the same equipment and method as in Example 1, the raw material to be introduced was 2.6-
12. Replace the isomer mixture of 4-DCNB and change its composition to 2. 6-/2. Adsorption-washing-desorption-regeneration operations were performed at a ratio of 4-=9.2/90°8wt. Table 3 shows the results of analyzing composition changes in the same manner as in Example 1.

Table-1 Table-2 Table-3 Procedures Amendment Book Showa Otsu/Year 7
Mr. Commissioner of the Japan Patent Office 1, Indication of the case, 1928 Patent Application No. 792777, 2, Title of the invention: J-- Relationship to the case Patent applicant postal code 105 Address Toranomon-chome-4-2, Minato-ku, Tokyo 4 Date of amendment order “″”° ”■ Shichinobe〉1 5. Number of inventions increased by amendment None 6 . Add the following to Column 7, Detailed Description of the Invention, Contents of Amendment (1), Line 10, Page 11, of the Specification Subject to Amendment.

``In addition, the B value of the apparent adsorption capacity F' (%) in Table 3 is the 2.4-DCNB component concentration (%) in the desorption solution.
) is shown. j (2) Correct r555.6J in the bottom column of Table-1 on page 12 to ff558.6JI.

(3) Part of Table 2 on page 13 is corrected as follows.

Hodogaya Chemical Industry Co., Ltd.

Claims (1)

[Claims] Dichloronitro represented by the following general formula (I) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (I) Of the isomer mixture of benzene, a 1,2,3-substituted isomer, The mixture with the 1,2,4-substituted isomer, ZS
A method for separating dichloronitrobenzene isomers, which is characterized in that each is selectively adsorbed and separated using an M-type zeolite adsorbent.