阅读说明：本技术 一种对碘苯胺及其制备方法 (P-iodoaniline and preparation method thereof ) 是由 *** 刘琳 苗慧 时金彪 项业专 于 2019-10-21 设计创作，主要内容包括：本发明提供了一种对碘苯胺及其制备方法,属于有机合成技术领域,解决了现有对碘苯胺制备方法存在单质碘消耗量过高、反应产生大量硫酸盐导致三废增多的问题。该方法包括以下步骤：步骤1、将苯胺、水按一定比例加入第一反应容器中,然后向第一反应容器中滴加单质碘并搅拌,制备得到第一溶液；将第一溶液冷却至0～20℃,滴加质量浓度为30％的双氧水,取样分析,至苯胺质量百分含量小于0.5％,得到第二溶液；步骤2、向第二溶液中加入亚硫酸钠并搅拌0.4～0.5h,获得第三溶液,对第三溶液进行抽滤,得到棕色结晶；步骤3、将棕色结晶倒入第二反应容器中并进行萃取提纯处理,得到对碘苯胺成品。本发明不仅耗用的单质碘量少和粗品含量高,还避免了产生硫酸盐。(The invention provides p-iodoaniline and a preparation method thereof, belongs to the technical field of organic synthesis, and solves the problems that the consumption of elemental iodine is too high, and a large amount of sulfate is generated in the reaction to cause increase of three wastes in the conventional preparation method of p-iodoaniline. The method comprises the following steps: step 1, adding aniline and water into a first reaction container according to a certain proportion, then dropwise adding elemental iodine into the first reaction container, and stirring to prepare a first solution; cooling the first solution to 0-20 ℃, dropwise adding hydrogen peroxide with the mass concentration of 30%, sampling and analyzing until the mass percentage content of aniline is less than 0.5%, and obtaining a second solution; step 2, adding sodium sulfite into the second solution, stirring for 0.4-0.5 h to obtain a third solution, and performing suction filtration on the third solution to obtain brown crystals; and 3, pouring the brown crystals into a second reaction container, and carrying out extraction and purification treatment to obtain a finished product of the p-iodoaniline. The invention not only consumes less elemental iodine and has high crude product content, but also avoids generating sulfate.)

1. The preparation method of p-iodoaniline is characterized by comprising the following steps:

step 1, adding aniline and water into a first reaction container according to a certain proportion, then dropwise adding an iodine simple substance into the first reaction container, and stirring to prepare a first solution; cooling the first solution to 0-20 ℃, dropwise adding hydrogen peroxide with the mass concentration of 30%, sampling and analyzing until the mass percentage content of aniline is less than 0.5%, and obtaining a second solution;

step 2, adding a reducing agent into the second solution, stirring for 0.4-0.5 h to obtain a third solution, carrying out suction filtration on the third solution, and washing a filter cake with water to obtain brown crystals;

and 3, extracting and purifying the brown crystals obtained in the step 2 to obtain a finished product of the p-iodoaniline.

2. The method for preparing p-iodoaniline according to claim 1, wherein in the step 1, the molar ratio of the iodine to aniline is 0.5-0.6: 1.

3. The method for producing p-iodoaniline of claim 2, wherein in the step 1, the molar ratio of the iodine to aniline is 0.55: 1.

4. The method for preparing p-iodoaniline according to claim 3, wherein in the step 1, the molar ratio of hydrogen peroxide to aniline is 0.5-1: 1.

5. the method for preparing p-iodoaniline of claim 4, wherein in the step 1, the molar ratio of hydrogen peroxide to aniline is 0.74: 1.

6. The method for preparing p-iodoaniline of claim 5, wherein in step 3, the brown crystals are poured into a second reaction vessel, petroleum ether is added into the second reaction vessel, heating and refluxing are carried out, layering is carried out after standing to obtain a supernatant, the supernatant is cooled to below 0 ℃, white-like solid crystals are separated out from the supernatant, and the supernatant is subjected to suction filtration and drying to obtain a finished product of p-iodoaniline.

7. The method for preparing p-iodoaniline according to claim 6, wherein the molar ratio of petroleum ether to p-iodoaniline is 5-10: 1.

8. the process for producing p-iodoaniline according to claim 1 or 7, wherein in the step 2, the reducing agent is sodium sulfite for reducing unreacted elemental iodine; the chemical reaction equation of the sodium sulfite and the iodine elementary substance is as follows:

Na₂SO₃+I₂+H₂O→Na₂SO₄+2H1。

9. the method for producing p-iodoaniline according to claim 1 or 7, wherein in the step 2, the reducing agent is sodium thiosulfate, and the sodium thiosulfate is used for reducing unreacted iodine; the chemical reaction equation of the sodium thiosulfate and the iodine simple substance is as follows:

2Na₂S₂O₃+I₂＝＝＝＝Na₂S4O₆+2NaI。

10. p-iodoaniline, which is produced by the process for producing p-iodoaniline according to claims 1 to 9 and is useful as an intermediate for pesticides and dyes.

Technical Field

The invention relates to the technical field of organic synthesis, in particular to p-iodoaniline and a preparation method thereof.

Background

The traditional p-iodoaniline preparation method needs excessive elemental iodine to react in the presence of sodium bicarbonate, and the preparation process has the technical defect of overhigh consumption of the elemental iodine; in addition, the preparation method of the p-iodoaniline adopts the process of adding the sulfuric acid to react by adopting the processes of potassium iodide and hydrogen peroxide, so that more sulfate is generated, and three wastes are increased.

Disclosure of Invention

In view of the above analysis, the embodiment of the present invention aims to provide p-iodoaniline and a preparation method thereof, so as to solve the technical problems of the existing p-iodoaniline preparation method that the consumption of elemental iodine is too high, and more sulfates are generated by reaction, which results in increase of three wastes.

The purpose of the invention is mainly realized by the following technical scheme:

on one hand, the invention discloses a preparation method of p-iodoaniline, which comprises the following steps:

step 1, adding aniline and water into a first reaction container according to a certain proportion, then dropwise adding an iodine simple substance into the first reaction container, and stirring to prepare a first solution; cooling the first solution to 0-20 ℃, dropwise adding hydrogen peroxide with the mass concentration of 30%, sampling and analyzing until the mass percentage content of aniline is less than 0.5%, and obtaining a second solution;

step 2, adding a reducing agent into the second solution, stirring for 0.4-0.5 h to obtain a third solution, carrying out suction filtration on the third solution, and washing a filter cake with water to obtain brown crystals;

and 3, extracting and purifying the brown crystals obtained in the step to obtain a finished product of the p-iodoaniline.

Preferably, in the step 1, the molar ratio of the iodine simple substance to the aniline is 0.5-0.6: 1.

Preferably, in step 1, the molar ratio of the iodine element to the aniline is 0.55: 1.

Preferably, in the step 1, the ratio of the hydrogen peroxide to the aniline is 0.5-1: 1.

Preferably, in step 1, the ratio of hydrogen peroxide to aniline is 0.74: 1.

Preferably, in the step 3, the molar ratio of the petroleum ether to the p-iodoaniline is 5-10: 1.

Preferably, in step 2, the reducing agent is sodium sulfite, and the sodium sulfite is used for reducing unreacted iodine elementary substance; the chemical reaction equation of sodium sulfite and iodine elementary substance is as follows:

Na₂SO₃+I₂+H₂O→Na₂SO₄+2H1。

preferably, in step 2, the reducing agent is sodium thiosulfate, and the sodium thiosulfate is used for reducing unreacted iodine simple substance; the chemical reaction equation of the sodium thiosulfate and the iodine simple substance is as follows:

2Na₂S₂O₃+I₂＝＝＝＝Na₂S₄O₆+2NaI

preferably, in step 3, the brown crystals are poured into a second reaction vessel, petroleum ether is added into the second reaction vessel, heating and refluxing are carried out, layering is carried out after standing to obtain a supernatant, the supernatant is cooled to below 0 ℃, white-like solid crystals are separated out from the supernatant, and the supernatant is subjected to suction filtration and drying to obtain the p-iodoaniline finished product.

On the other hand, the invention also provides p-iodoaniline prepared by the preparation method of the p-iodoaniline, and the p-iodoaniline can be used as an intermediate of pesticides and dyes.

Compared with the prior art, the invention can realize at least one of the following beneficial effects:

a) the preparation method of p-iodoaniline provided by the invention adopts aniline and 0.55 equivalent of iodine to be dropwise added with hydrogen peroxide for reaction, and the hydrogen iodide generated by the reaction is oxidized into iodine to continue to react with aniline, so that a large amount of expensive iodine simple substances are saved. The reaction is carried out in a small amount of water, and finally sodium sulfite is added to destroy excessive iodine simple substance, and the product is obtained by filtration and recrystallization.

b) Compared with the prior art for preparing the p-iodoaniline by adopting halide, the method for preparing the p-iodoaniline directly adopts the iodine simple substance, and because the iodine simple substance is directly used, only a small amount of unreacted iodine simple substance in three wastes generates iodine salt, so that the process has small pollution.

In the invention, the above technical schemes can be combined with each other to realize more preferable combination schemes. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the instrumentalities and combinations particularly pointed out in the written description.

Detailed Description

The preferred embodiments of the present invention will be described in detail below.

The embodiment discloses a preparation method of p-iodoaniline, which comprises the following steps:

step 1, adding aniline and water into a first reaction container according to a certain proportion, adding an iodine simple substance into the first reaction container in batches, and stirring to prepare a first solution; cooling the first solution to 0-20 ℃, dropwise adding hydrogen peroxide with the mass concentration of 30%, sampling and analyzing until the mass percentage content of aniline is less than 0.5%, and obtaining a second solution;

the chemical reaction equation in step 1 is as follows:

in the step 1, the molar ratio of the iodine simple substance to the aniline is 0.5-0.6: 1, especially 0.55:1, because too little iodine simple substance is used to cause incomplete reaction of the aniline, and too much iodine simple substance is used to easily generate multi-iodide. In addition, the ratio of hydrogen peroxide to aniline is 0.5-1: 1, especially 0.74:1, because too little hydrogen peroxide can not completely oxidize the generated hydrogen iodide into iodine simple substance, and too much hydrogen peroxide can easily oxidize the product, and the color of the product becomes dark.

Step 2, adding a reducing agent into the second solution, stirring for 0.4-0.5 h to obtain a third solution, performing suction filtration on the third solution by using a suction filtration instrument, and washing a filter cake with water to obtain brown crystals;

when sodium sulfite is used as the reducing agent, the chemical reaction equation in step 2 is as follows:

Na₂SO₃+I₂+H₂O→Na₂SO₄+2H1

when the reducing agent is sodium thiosulfate, the chemical reaction equation in the step 2 is as follows:

2Na₂S₂O₃+I₂＝＝＝＝Na₂S₄O₆+2NaI

in the step 2, sodium sulfite and sodium thiosulfate are both used for destroying excessive iodine simple substances, the system has darker color due to the existence of excessive iodine simple substances after the hydrogen peroxide is added, and when sodium sulfite or sodium thiosulfate is added and stirred for a period of time, a water layer in the reaction system is almost white along with the reduction of the iodine simple substances; if the amount of sodium bisulfite or sodium thiosulfate added is too small, the product will be darker in color and will produce polyiodides, and the product content will be reduced.

And 3, pouring the brown crystals into a second reaction container, adding a certain amount of petroleum ether into the second container, heating and refluxing for a certain time, standing and layering to obtain a supernatant, cooling the supernatant to below 0 ℃, separating out white-like solid crystals from the supernatant, and performing suction filtration and drying on the supernatant to obtain a finished product of the p-iodoaniline.

The chemical reaction equation in step 3 is as follows:

in the step 3, the molar ratio of petroleum ether to p-iodoaniline is 5-10: 1, petroleum ether is used as a solvent for brown crystals, the product is dissolved in the petroleum ether after heating, the colored byproduct oxide is insoluble, the amount of the petroleum ether is 5-10 times that of the p-iodoaniline, the product cannot be completely dissolved when the amount of the petroleum ether is small, and the product amount in the mother liquor is increased when the amount of the petroleum ether is too large, so that the yield is influenced.