阅读说明：本技术 采用复合离子液体萃取分离2,5-二氯硝基苯的方法 (Method for extracting and separating 2, 5-dichloronitrobenzene by adopting composite ionic liquid ) 是由 陈永乐 黄伟 金汉强 张伟 刘卓 于 2018-08-21 设计创作，主要内容包括：本发明公开了一种采用复合离子液体萃取分离2,5-二氯硝基苯的方法,采用烷基咪唑硫酸氢盐和烷基咪唑硝酸氢盐复合质子型离子液体做萃取剂,该类离子液体具有阴离子簇,能够与硫酸和硝酸形成阴离子氢键。经该类复合离子液体萃取后的2,5-二氯硝基苯具有较低的酸含量和水含量。工艺过程无碱使用,酚类副产物少,废水少,是一类具有工业应用前景的绿色分离工艺。(The invention discloses a method for extracting and separating 2, 5-dichloronitrobenzene by adopting composite ionic liquid, which adopts alkyl imidazole hydrogen sulfate and alkyl imidazole hydrogen nitrate composite proton type ionic liquid as an extracting agent, wherein the ionic liquid has anion clusters and can form anion hydrogen bonds with sulfuric acid and nitric acid. The 2, 5-dichloronitrobenzene extracted by the composite ionic liquid has lower acid content and water content. The process has no alkali, less phenol side product and less waste water, and is one kind of green separation process with industrial application foreground.)

1. A method for extracting and separating 2, 5-dichloronitrobenzene by adopting composite ionic liquid is characterized by comprising the following steps: feeding the crude 2, 5-dichloronitrobenzene prepared by mixed acid or ionic liquid mixed acid catalysis from the bottom lateral line of the extraction tower, feeding the composite ionic liquid extracting agent from the top lateral line of the extraction tower, carrying out countercurrent extraction on the crude 2, 5-dichloronitrobenzene and the composite ionic liquid extracting agent, discharging the pure 2, 5-dichloronitrobenzene obtained by separation from the top of the extraction tower, and discharging the extracted composite ionic liquid extracting agent from the bottom of the extraction tower.

2. The method of claim 1, wherein the composite ionic liquid extractant is a mixture of alkyl imidazole bisulfate and alkyl imidazole bisulfate ionic liquids.

3. The process according to claim 2, characterized in that the alkyl imidazole is: one or two of 1-butyl-3-methylimidazole and 1-ethyl-3-methylimidazole.

4. The method according to claim 1, wherein the anion-cation ratio of the ionic liquid in the composite ionic liquid extractant is as follows: alkyl imidazole: bisulfate =1: 1-3, and the proportion of the alkyl imidazole bisulfate ionic liquid cations and anions is as follows: 1: 1-3.

5. The method according to claim 1, wherein the mass ratio of the alkyl imidazole hydrogen nitrate salt to the alkyl imidazole hydrogen sulfate salt ionic liquid in the composite ionic liquid extractant is as follows: 1: 0.5-3.

6. The method according to claim 1, wherein the volume ratio of the 2, 5-dichloronitrobenzene crude product to the composite ionic liquid extractant is 1: 0.5-5.

7. The method of claim 1, wherein the extraction temperature of the extraction column is 60 to 80 ℃.

8. The method of claim 1, wherein the extraction column is a packed column having a height of 20 to 40 meters.

9. The method of claim 1 or 8, wherein the packing material in the extraction column is selected from one of a ceramic step ring, a ceramic cruciform baffle ring, a ceramic saddle ring and a ceramic saddle ring.

10. The method according to claim 1 or 8, characterized in that the feed positions are: feeding 2, 5-dichloronitrobenzene from the bottom of the tower for 1-3 meters; the distance between the composite ionic liquid extractant and the tower top is 1-3 m.

Technical Field

The invention belongs to the technical field of organic compound separation, and particularly relates to a method for extracting and separating 2, 5-dichloronitrobenzene by adopting composite ionic liquid.

Background

2, 5-dichloronitrobenzene is an important organic intermediate, and is mainly used for synthesizing pesticide herbicides dicamba and quizalofop, ice dye scarlet GG, red base 3GL, red base RC and the like. Can also be used as nitrogen fertilizer synergist for fixing nitrogen and maintaining fertilizer in agriculture. In the industrial process of the paradichlorobenzene nitration, mixed acid is mainly used as a nitrating agent, the crude 2, 5-dichloronitrobenzene obtained by nitration needs to be washed with alkali for many times to remove acid, and then is rectified to remove water and remove impurities, so that the pure 2, 5-dichloronitrobenzene is finally obtained. In the nitration process, the use of inorganic base easily causes the generation of phenol byproducts, and directly influences the subsequent separation of products and the quality of the products. In addition, the process is easy to generate a large amount of waste water, and the environment is seriously polluted. Therefore, it is important to develop a new separation method to solve the problems of the conventional process.

Compared with the organic solvent which is widely used at present, the ionic liquid has the characteristics of low vapor pressure, difficult volatilization, adjustable structure, good solubility to organic matters and inorganic matters and the like, and is widely concerned in the field of liquid-liquid extraction application. It has been found that the higher the charge concentration in the ionic liquid, the more polar the ionic liquid has as a whole. Has good separation effect on the environment with large polarity difference of substances. In addition, studies have also found that the partition coefficients of some organic acids and organic bases having charged groups or strong hydrogen bonds vary with pH, and are optimal when the substance is in a molecular state.

Matuszek team published a reference to a composition containing [ (HSO) in 2014₄)(H₂SO₄)_x]^-The article of proton type ionic liquid of anion cluster is characterized in that stable hydrogen bonds can be formed between anions, so that the ionic liquid has strong acidity of inorganic acid and phase separation performance of the ionic liquid. But as the selected cation is pyridine, the formed partial proton type ionic liquid has high melting point and is slightly inferior to the liquid ionic liquid in storage and operation.

Disclosure of Invention

The invention selects the novel compound proton type ionic liquid with anion clusters. The proton type ionic liquid with anion cluster is a compound type proton ionic liquid chamber with anion cluster, wherein the cation is alkyl imidazole, and the anion is bisulfate or bisulfateIs liquid at room temperature, soluble in water and insoluble in 2, 5-dichloronitrobenzene. The compound type proton ionic liquid has unique effect in inorganic acid extraction. On one hand, the water in the 2, 5-dichloronitrobenzene can be extracted by utilizing the phase separation characteristic and the water absorption of the ionic liquid; on the other hand, [ (HSO)₄)(H₂SO₄)_x]^-And [ (NO)₃)(HNO₃)_x]^-The hydrogen bonding of the two anion clusters adsorbs the free H in the crude 2, 5-dichloronitrobenzene₂SO₄And HNO₃. The extraction process can realize alkali-free washing of 2, 5-dichloronitrobenzene, avoid generation of phenol products and generation of a large amount of waste water, and meet the development requirement of greening chemical production at present.

The main technical scheme of the invention is as follows: the method for extracting and separating 2, 5-dichloronitrobenzene by adopting the composite ionic liquid is characterized by comprising the following steps: feeding the crude 2, 5-dichloronitrobenzene prepared by mixed acid or ionic liquid mixed acid catalysis from the bottom lateral line of the extraction tower, feeding the composite ionic liquid extracting agent from the top lateral line of the extraction tower, carrying out countercurrent extraction on the crude 2, 5-dichloronitrobenzene and the composite ionic liquid extracting agent, discharging the pure 2, 5-dichloronitrobenzene obtained by separation from the top of the extraction tower, and discharging the extracted composite ionic liquid extracting agent from the bottom of the extraction tower.

The method of the invention provides a new extraction and separation process of 2, 5-dichloronitrobenzene by taking composite proton type ionic liquid as an extracting agent. The method comprises the following specific steps: the extraction is carried out in a filler extraction tower, the composite ionic liquid and the 2, 5-dichloronitrobenzene are fed at a certain volume ratio and a certain temperature, the composite ionic liquid is fed at the side line of the top of the tower, the 2, 5-dichloronitrobenzene is fed at the side line of the bottom of the tower, and the two are subjected to alternate countercurrent extraction. After extraction, 2, 5-dichloronitrobenzene is extracted from the top of the tower and enters a next-stage rectifying tower for rectification treatment, and finally, a pure 2, 5-dichloronitrobenzene product is obtained. And discharging the composite ionic liquid from the bottom of the tower, and returning the composite ionic liquid to the extraction tower for continuously extracting the 2, 5-dichloronitrobenzene after flash evaporation and water removal.

According to the method for extracting and separating 2, 5-dichloronitrobenzene by using the composite proton type ionic liquid, the adopted composite proton type ionic liquid is a mixture of alkyl imidazole hydrogen sulfate and alkyl imidazole hydrogen nitrate.

The alkyl imidazole is: one or two of 1-butyl-3-methylimidazole and 1-ethyl-3-methylimidazole.

According to the method for extracting and separating 2, 5-dichloronitrobenzene by using the composite proton type ionic liquid, the anion-cation ratio of the ionic liquid in the composite ionic liquid extracting agent is as follows: alkyl imidazole: bisulfate =1: 1-3, and the proportion of the alkyl imidazole bisulfate ionic liquid cations and anions is as follows: 1: 1-3.

According to the method for extracting and separating 2, 5-dichloronitrobenzene by using the composite proton type ionic liquid, the mass ratio of the alkyl imidazole hydrogen nitrate to the alkyl imidazole hydrogen sulfate ionic liquid in the composite ionic liquid extracting agent is as follows: 1: 0.5-3.

According to the method for extracting and separating the 2, 5-dichloronitrobenzene by using the composite proton type ionic liquid, the volume ratio of the 2, 5-dichloronitrobenzene crude product to the composite ionic liquid extractant is 1: 0.5-5.

In the method for extracting and separating 2, 5-dichloronitrobenzene by using the composite proton type ionic liquid, in the reaction step, the extraction temperature of the extraction tower is 60-80 ℃.

In the method for extracting and separating 2, 5-dichloronitrobenzene by using the composite proton type ionic liquid, in the reaction step, the extraction tower is a packed tower, and the height of the tower is 20-40 m.

The packing in the extraction tower is one of a ceramic stepped ring, a ceramic cross partition ring, a ceramic abnormal saddle ring and a ceramic rectangular saddle ring.

In the above method for extracting and separating 2, 5-dichloronitrobenzene by using composite proton type ionic liquid, in the reaction step, the feeding positions are as follows: feeding 2, 5-dichloronitrobenzene from the bottom of the tower for 1-3 meters; the distance between the composite ionic liquid extractant and the tower top is 1-3 m.

Technical effects of the invention

The invention adopts the composite proton type ionic liquid as the extracting agent, has good extracting effect and strong water absorption. In the process, water H can be extracted simultaneously₂SO₄And HNO₃The method has no alkalization in the realization process, avoids the generation of phenol byproducts and the generation of wastewater, has green and environment-friendly process, and is a green new process with great competitive advantage。

Detailed Description

The invention is further illustrated by the following examples.