Purification method for removing 1, 5-dichloro-2, 4-dinitrobenzene and application thereof

Abstract

The invention discloses a purification method for removing 1, 5-dichloro-2, 4-dinitrobenzene, which comprises the following steps: S1, dissolving inorganic strong alkali in water to prepare a dilute alkali aqueous solution; s2, adding a dilute alkali aqueous solution into the crude product containing 1, 5-dichloro-2, 4-dinitrobenzene, stirring for reaction, and controlling the reaction temperature, the reaction pressure and the reaction time; and S3, performing liquid separation after the reaction, removing a water phase, and washing an oil phase with water to obtain a purified product. According to the method, the removal rate of the 1, 5-dichloro-2, 4-dinitrobenzene is high, and the risk of subsequent procedures is reduced. The method is mild in reaction condition, simple and convenient to operate, low in cost, high in safety, green, environment-friendly and suitable for industrial large-scale production.

Description

Technical Field

[0001] The invention relates to a purification method for removing 1,5-dichloro-2,4-dinitrobenzene and application thereof, and relates to C07C, and in particular to the field of carbocyclic compounds. Background Art

[0002] Difluanid is a commonly used herbicide. Difluanid is usually obtained by fluorination and hydrogenation reduction of 2,4-dichloronitrobenzene. 2,4-Dichloronitrobenzene is an important intermediate for chemical products. However, a large number of by-products are usually produced in the process of preparing 2,4-dichloronitrobenzene. The by-products will aggregate during the continuous production process, and there is a potential risk of high-temperature decomposition and explosion. Therefore, it is very important to eliminate 1,5-dichloro-2,4-dinitrobenzene in 2,4-dichloronitrobenzene.

[0003] Chinese invention patent CN202310278902.0 discloses a method for removing 1,5-dichloro-2,4-dinitrobenzene and its application, using metal sulfide and phase transfer catalyst to remove 1,5-dichloro-2,4-dinitrobenzene, with mild reaction conditions, high reaction efficiency and forward reaction, but the cost of metal sulfide and phase transfer catalyst is high. Chen Ben'e, Synthesis Research of 2,4-Dichloronitrobenzene, Journal of Dandong Teachers College [J].Jun.1998.Vol.20,No.2 discloses the synthesis research of 2,4-dichloronitrobenzene, and discloses the use of sodium hydroxide to wash the nitration crude product at 100°C until the dinitrate disappears. However, the removal rate of 1,5-dichloro-2,4-dinitrobenzene by this method is limited, and there is still 1,5-dichloro-2,4-dinitrobenzene residual after three hours of reflux. Chinese invention patent CN201410320916.5 discloses a method for treating m-dinitrobenzene wastewater by catalytic reduction, which requires reaction in an anaerobic simulated reactor, has harsh reaction conditions and high equipment investment costs. Summary of the invention

[0004] In order to improve the removal rate of 1,5-dichloro-2,4-dinitrobenzene in 2,4-dichloronitrobenzene and reduce the purification cost, the first aspect of the present invention provides a purification method for removing 1,5-dichloro-2,4-dinitrobenzene, comprising the following steps:

[0005] S1 dissolves an inorganic strong base in water to prepare a dilute alkaline aqueous solution;

[0006] S2: adding a dilute alkali aqueous solution to the crude product containing 1,5-dichloro-2,4-dinitrobenzene, stirring to react, and controlling the reaction temperature, reaction pressure, and reaction time;

[0007] After the S3 reaction, the liquids are separated, the aqueous phase is discarded, and the oil phase is washed with water to obtain a purified product.

[0008] As a preferred embodiment, the inorganic strong base is selected from one or a combination of lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, francium hydroxide, barium hydroxide, calcium hydroxide, and magnesium hydroxide.

[0009] As a preferred embodiment, the inorganic strong base is selected from sodium hydroxide, potassium hydroxide or a combination of them.

[0010] As a preferred embodiment, the inorganic strong base is sodium hydroxide.

[0011] As a preferred embodiment, the mass concentration of the dilute alkali aqueous solution is 1-5%.

[0012] As a preferred embodiment, the mass concentration of the dilute alkali aqueous solution is 2-4%, preferably, the mass concentration of the dilute alkali aqueous solution is 2-3%, and further preferably, the mass concentration of the dilute alkali aqueous solution is 3%.

[0013] As a preferred embodiment, the mass ratio of the crude product to the dilute alkali aqueous solution is 1:(0.75-1).

[0014] As a preferred embodiment, the mass ratio of the crude product to the dilute alkali aqueous solution is 1:(0.75-0.9), preferably, the mass ratio of the crude product to the dilute alkali aqueous solution is 1:(0.75-0.8), and further preferably, the mass ratio of the crude product to the dilute alkali aqueous solution is 1:0.778.

[0015] As a preferred embodiment, the crude product is crude 2,4-dichloronitrobenzene, and the mass concentration of 1,5-dichloro-2,4-dinitrobenzene in the crude 2,4-dichloronitrobenzene is 0.1-1%.

[0016] As a preferred embodiment, the mass concentration of 1,5-dichloro-2,4-dinitrobenzene in the crude 2,4-dichloronitrobenzene is 0.5-1%.

[0017] As a preferred embodiment, the crude 2,4-dichloronitrobenzene is a crude 2,4-dichloronitrobenzene prepared by nitration reaction of m-dichlorobenzene and mixed acid.

[0018] As a preferred embodiment, the reaction temperature of step S2 is greater than 100° C., and the reaction pressure is 0.1-0.3 MPa.

[0019] As a preferred embodiment, the reaction temperature of step S2 is 110-130° C., and the reaction pressure is 0.15-0.25 MPa.

[0020] As a preferred embodiment, the reaction temperature of step S2 is 120-130° C., and the reaction pressure is 0.2-0.25 MPa.

[0021] As a preferred embodiment, the reaction temperature of step S2 is 120-125° C., and the reaction pressure is 0.2 MPa.

[0022] As a preferred embodiment, the reaction time of step S2 is 5-10 h, and the stirring speed is 100-300 rpm.

[0023] As a preferred embodiment, the reaction time of step S2 is 5-8h, and the stirring speed is 200rpm.

[0024] As a preferred embodiment, the reaction time of step S2 is 5-6 hours, and more preferably, the reaction time of step S2 is 6 hours.

[0025] The reaction mechanism of removing 1,5-dichloro-2,4-dinitrobenzene in the present invention is shown in the following reaction equation:

[0026]

[0027] During the experiment, the applicant found that the use of a dilute alkaline solution to remove 1,5-dichloro-2,4-dinitrobenzene and a reaction pressure of 0.1-0.3 MPa can ensure that 1,5-dichloro-2,4-dinitrobenzene is completely removed, and the yield of 2,4-dichloronitrobenzene is relatively high. The possible reason is that the nitro group is a strong electron-withdrawing group, and its inductive effect makes the ortho-para chlorine atoms easily react with water to undergo nucleophilic substitution reactions to generate phenols, and then react with alkali to generate phenol salts and dissolve in the water phase, thereby achieving the removal of 1,5-dichloro-2,4-dinitrobenzene. The applicant further found that water and materials have an azeotropic effect, and the reflux temperature is only 105°C under normal pressure. After reflux for 10 hours, 1,5-dichloro-2,4-dinitrobenzene cannot be completely removed. However, under a reaction pressure of 0.1-0.3 MPa, the material temperature can be further increased to completely hydrolyze 1,5-dichloro-2,4-dinitrobenzene into sodium phenolate, which is dissolved in the water phase for removal. However, if the preferred temperature and pressure are exceeded, a small amount of 2,4-dichloronitrobenzene will be decomposed, which will affect the yield of 2,4-dichloronitrobenzene.

[0028] The second aspect of the present invention provides an application of a purification method for removing 1,5-dichloro-2,4-dinitrobenzene, which is applied to the purification process of crude 2,4-dichloronitrobenzene.

[0029] As a preferred embodiment, the preparation method of the crude 2,4-dichloronitrobenzene is as follows:

[0030] 2eq of m-dichlorobenzene and 5eq of mixed acid were mixed and reacted, and nitration reaction was carried out at 70-75°C. After the reaction was completed, water was added to quench the reaction. The oil phase was washed with water and 5wt% Na2CO3 to recover the unreacted m-dichlorobenzene, thereby obtaining crude 2,4-dichloronitrobenzene.

[0031] As a preferred embodiment, the mixed acid includes 1 eq of 98 wt % nitric acid and 4 eq of 85 wt % sulfuric acid.

[0032] As a preferred embodiment, the purification process of the crude 2,4-dichloronitrobenzene is applied to the preparation process of difluanid technical.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) The purification method for removing 1,5-dichloro-2,4-dinitrobenzene of the present invention uses a dilute alkaline aqueous solution to remove 1,5-dichloro-2,4-dinitrobenzene from 2,4-dichloronitrobenzene, has low removal cost, and does not require the addition of new equipment.

[0035] (2) The purification method for removing 1,5-dichloro-2,4-dinitrobenzene of the present invention uses a dilute alkali aqueous solution to react at 110-130° C. and 0.1-0.3 MPa, which has a high removal rate for 1,5-dichloro-2,4-dinitrobenzene and reduces the risks of subsequent processes.

[0036] (3) The purification method for removing 1,5-dichloro-2,4-dinitrobenzene of the present invention can still achieve further removal of 1,5-dichloro-2,4-dinitrobenzene in 2,4-dichloronitrobenzene containing a low amount of 1,5-dichloro-2,4-dinitrobenzene, achieving a removal rate of no detection by HPLC.

[0037] (4) By using the purification method for removing 1,5-dichloro-2,4-dinitrobenzene of the present invention, 2,4-dichloronitrobenzene does not need to be distilled and separated, and can be directly used in subsequent processes after dehydration. The preparation process is simple and avoids the risk of explosion caused by high material temperature in conventional distillation and separation methods.

[0038] (5) The purification method for removing 1,5-dichloro-2,4-dinitrobenzene of the present invention adopts a dilute alkali aqueous solution with a mass concentration of 1-5%, and the mass ratio of the crude product to the dilute alkali aqueous solution is 1: (0.75-1). The removal rate of 1,5-dichloro-2,4-dinitrobenzene is high, the reaction conditions are mild, the operation is simple, the cost is low, the safety is high, and it is green and environmentally friendly, and is suitable for large-scale industrial production. DETAILED DESCRIPTION

[0039] Example 1

[0040] A purification method for removing 1,5-dichloro-2,4-dinitrobenzene comprises the following steps:

[0041] S1 dissolves an inorganic strong base in water to prepare a dilute alkaline aqueous solution;

[0042] S2: adding a dilute alkali aqueous solution to the crude product containing 1,5-dichloro-2,4-dinitrobenzene, stirring to react, and controlling the reaction temperature, reaction pressure, and reaction time;

[0043] After the S3 reaction, the liquids are separated, the aqueous phase is discarded, and the oil phase is washed with water to obtain a purified product.

[0044] The inorganic strong base is sodium hydroxide. The mass concentration of the dilute alkali aqueous solution is 3%.

[0045] The mass ratio of the crude product to the dilute alkali aqueous solution is 180g:140g.

[0046] The crude product is crude 2,4-dichloronitrobenzene, and the mass concentration of 1,5-dichloro-2,4-dinitrobenzene in the crude 2,4-dichloronitrobenzene is 0.79%.

[0047] The preparation method of the crude 2,4-dichloronitrobenzene is as follows:

[0048] 2 eq of m-dichlorobenzene was mixed with 5 eq of mixed acid for reaction, and nitration reaction was carried out at 75°C. After the reaction was completed, water was added to quench the mixture. The oil phase was washed with water and 5 wt% Na2CO3 to recover the unreacted m-dichlorobenzene, thereby obtaining crude 2,4-dichloronitrobenzene.

[0049] The mixed acid includes 1 eq of 98 wt % nitric acid and 4 eq of 85 wt % sulfuric acid.

[0050] The reaction temperature of step S2 is 125° C. and the reaction pressure is 0.2 MPa.

[0051] The reaction time of step S2 is 6 hours, and the stirring speed is 200 rpm.

[0052] The purified product was subjected to HPLC quantitative analysis, and the results showed that 1,5-dichloro-2,4-dinitrobenzene was not detected in 2,4-dichloronitrobenzene after 1,5-dichloro-2,4-dinitrobenzene.

[0053] Example 2

[0054] A purification method for removing 1,5-dichloro-2,4-dinitrobenzene comprises the following steps:

[0055] S1 dissolves an inorganic strong base in water to prepare a dilute alkaline aqueous solution;

[0056] S2: adding a dilute alkali aqueous solution to the crude product containing 1,5-dichloro-2,4-dinitrobenzene, stirring to react, and controlling the reaction temperature, reaction pressure, and reaction time;

[0057] After the S3 reaction, the liquids are separated, the aqueous phase is discarded, and the oil phase is washed with water to obtain a purified product.

[0058] The inorganic strong base is sodium hydroxide. The mass concentration of the dilute alkali aqueous solution is 3%.

[0059] The mass ratio of the crude product to the dilute alkali aqueous solution is 180g:135g.

[0060] The crude product is crude 2,4-dichloronitrobenzene, and the mass concentration of 1,5-dichloro-2,4-dinitrobenzene in the crude 2,4-dichloronitrobenzene is 0.5%.

[0061] The preparation method of the crude 2,4-dichloronitrobenzene is as follows:

[0062] 2 eq of m-dichlorobenzene was mixed with 5 eq of mixed acid for reaction, and nitration reaction was carried out at 75°C. After the reaction was completed, water was added to quench the mixture. The oil phase was washed with water and 5 wt% Na2CO3 to recover the unreacted m-dichlorobenzene, thereby obtaining crude 2,4-dichloronitrobenzene.

[0063] The mixed acid includes 1 eq of 98 wt % nitric acid and 4 eq of 85 wt % sulfuric acid.

[0064] The reaction temperature of step S2 is 120° C. and the reaction pressure is 0.2 MPa.

[0065] The reaction time of step S2 is 5 h, and the stirring speed is 200 rpm.

[0066] The purified product was subjected to HPLC quantitative analysis, and the results showed that 1,5-dichloro-2,4-dinitrobenzene was not detected in 2,4-dichloronitrobenzene after 1,5-dichloro-2,4-dinitrobenzene.

[0067] Comparative Example 1

[0068] A purification method for removing 1,5-dichloro-2,4-dinitrobenzene comprises the following steps:

[0069] S1 dissolves an inorganic strong base in water to prepare a dilute alkaline aqueous solution;

[0070] S2: adding a dilute alkali aqueous solution to the crude product containing 1,5-dichloro-2,4-dinitrobenzene, stirring to react, and controlling the reaction temperature, reaction pressure, and reaction time;

[0071] After the S3 reaction, the liquids are separated, the aqueous phase is discarded, and the oil phase is washed with water to obtain a purified product.

[0072] The inorganic strong base is sodium hydroxide. The mass concentration of the dilute alkali aqueous solution is 3%.

[0073] The mass ratio of the crude product to the dilute alkali aqueous solution is 180g:135g.

[0074] The crude product is crude 2,4-dichloronitrobenzene, and the mass concentration of 1,5-dichloro-2,4-dinitrobenzene in the crude 2,4-dichloronitrobenzene is 0.79%.

[0075] The preparation method of the crude 2,4-dichloronitrobenzene is as follows:

[0076] 2 eq of m-dichlorobenzene was mixed with 5 eq of mixed acid for reaction, and nitration reaction was carried out at 75°C. After the reaction was completed, water was added to quench the mixture. The oil phase was washed with water and 5 wt% Na2CO3 to recover the unreacted m-dichlorobenzene, thereby obtaining crude 2,4-dichloronitrobenzene.

[0077] The mixed acid includes 1 eq of 98 wt % nitric acid and 4 eq of 85 wt % sulfuric acid.

[0078] The reaction temperature of step S2 is 100° C. and the reaction pressure is 0.1 MPa.

[0079] The reaction time of step S2 is 10 h, and the stirring speed is 200 rpm.

[0080] The purified product was subjected to HPLC quantitative analysis, and the results showed that the residual amount of 1,5-dichloro-2,4-dinitrobenzene in 2,4-dichloronitrobenzene after 1,5-dichloro-2,4-dinitrobenzene was 0.006 wt %.

Claims

1. A purification method for removing 1,5-dichloro-2,4-dinitrobenzene, characterized in that: The following steps are involved: S1 dissolves an inorganic strong base in water to prepare a dilute alkaline aqueous solution; S2: adding a dilute alkali aqueous solution to the crude product containing 1,5-dichloro-2,4-dinitrobenzene, stirring to react, and controlling the reaction temperature, reaction pressure, and reaction time; After the S3 reaction, the liquids are separated, the aqueous phase is discarded, and the oil phase is washed with water to obtain a purified product.

2. The purification method for removing 1,5-dichloro-2,4-dinitrobenzene according to claim 1, characterized in that: The inorganic strong base is selected from one or a combination of lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, francium hydroxide, barium hydroxide, calcium hydroxide and magnesium hydroxide.

3. The purification method for removing 1,5-dichloro-2,4-dinitrobenzene according to claim 1, characterized in that: The mass concentration of the dilute alkali aqueous solution is 1-5%.

4. The purification method for removing 1,5-dichloro-2,4-dinitrobenzene according to claim 1, characterized in that: The mass ratio of the crude product to the dilute alkali aqueous solution is 1:(0.75-1).

5. The purification method for removing 1,5-dichloro-2,4-dinitrobenzene according to claim 1, characterized in that: The crude product is crude 2,4-dichloronitrobenzene, and the mass concentration of 1,5-dichloro-2,4-dinitrobenzene in the crude 2,4-dichloronitrobenzene is 0.1-1%.

6. The purification method for removing 1,5-dichloro-2,4-dinitrobenzene according to claim 5, characterized in that: The crude 2,4-dichloronitrobenzene is prepared by nitration reaction of m-dichlorobenzene and mixed acid.

7. The purification method for removing 1,5-dichloro-2,4-dinitrobenzene according to claim 5, characterized in that: The reaction temperature of step S2 is greater than 100° C., and the reaction pressure is 0.1-0.3 MPa.

8. The purification method for removing 1,5-dichloro-2,4-dinitrobenzene according to claim 5, characterized in that: The reaction time of step S2 is 5-10 hours, and the stirring speed is 100-300 rpm.

9. An application of the purification method for removing 1,5-dichloro-2,4-dinitrobenzene according to any one of claims 1 to 8, characterized in that: Applied to the purification process of crude 2,4-dichloronitrobenzene.

10. Application of the purification method for removing 1,5-dichloro-2,4-dinitrobenzene according to claim 9, characterized in that: The purification process of the crude 2,4-dichloronitrobenzene is applied to the preparation process of difluanid technical.

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