阅读说明：本技术 一种简单、快速安全制备对氨基偶氮苯盐的制备方法 (Simple, rapid and safe preparation method of p-amino azobenzene salt ) 是由 赵鹏 齐帅 杜晓彤 于 2020-12-23 设计创作，主要内容包括：本发明涉及一种简单、快速安全制备对氨基偶氮苯盐的制备方法,本发明方法设计科学合理、操作安全性高,采用一部分苯胺先和盐酸反应,避免了浓盐酸直接加入到苯胺和亚硝酸钠的混合液中,防止反应激烈,造成安全隐患,另外,本发明方法加入的是苯胺盐酸盐而不是盐酸,从而避免了大量亚硝酸的生成,防止了苯胺的氧化,避免反应液变黑。本发明方法采用苯胺部分盐酸化,再滴加入反应液,从而使反应可完全在常温下正常进行,不需要增加冷冻设备,可节约大量开支。(The invention relates to a simple, rapid and safe preparation method of p-amino azobenzene salt, which has scientific and reasonable design and high operation safety, adopts a part of aniline to react with hydrochloric acid first, avoids that concentrated hydrochloric acid is directly added into mixed solution of aniline and sodium nitrite, prevents violent reaction and causes potential safety hazard, and in addition, aniline hydrochloride is added instead of hydrochloric acid, thereby avoiding generation of a large amount of nitrous acid, preventing oxidation of aniline and avoiding blackening of reaction liquid. The method of the invention adopts partial hydrochlorination of aniline, and then dropwise adds reaction liquid, thereby ensuring that the reaction can be completely and normally carried out at normal temperature, without adding refrigeration equipment, and saving a large amount of expenses.)

1. A simple, rapid and safe preparation method of p-amino azobenzene salt is characterized in that: the synthesis process comprises the following steps:

the specific process method comprises the following steps:

preparation of aniline hydrochloride solution

Adding 3-5kg of aniline into a reactor, starting a stirrer, and dripping 1.8-3kg of 36% concentrated hydrochloric acid at room temperature to prepare aniline hydrochloride solution for later use;

respectively adding 6-10kg of aniline, 1.1-1.8kg of sodium nitrite and 1.5-2.5kg of water into another reactor, stirring to prepare a solution, dropwise adding the aniline hydrochloride solution, heating to 50 ℃, and keeping for 4 hours to perform transposition;

thirdly, adding 300-500ml of 40% sodium hydroxide, heating to 70 ℃, immediately pouring into a liquid separating device, standing, separating a water layer, wherein the organic layer is p-aminoazobenzene;

fourthly, evaporating the organic layer under vacuum of 20mmHg at 70-75 ℃ to remove unreacted aniline, and obtaining residual p-aminoazobenzene liquid;

fifthly, keeping the temperature at 130 ℃, dropwise adding the p-aminoazobenzene residue into a 70 ℃ mixed solution prepared from 12-20L of water and 2-5L of 36% concentrated hydrochloric acid, stirring for 2 hours under natural cooling, filtering, and washing with dilute hydrochloric acid for three times to obtain p-aminoazobenzene hydrochloride.

2. The simple, fast and safe preparation method of p-amino azobenzene salt according to claim 1 is characterized in that: aniline in aniline hydrochloride solution: hydrochloric acid: sodium nitrite 9: 2: 1.

3. the process for the simple, rapid and safe preparation of p-aminoazobenzene salt according to claim 1 or 2, characterized in that: the ratio of aniline used for preparing aniline hydrochloride solution to aniline used for mixing with sodium nitrite aqueous solution is 1: 2.

4. the simple, fast and safe preparation method of p-amino azobenzene salt according to claim 1 is characterized in that: the temperature is controlled to be 35 +/-1 ℃.

Technical Field

The invention belongs to the field of chemical synthesis, relates to a preparation method of p-amino azobenzene salt, and particularly relates to a simple, rapid and safe preparation method of p-amino azobenzene salt.

Background

The p-aminoazobenzene hydrochloride is columnar crystal, slightly soluble in water, soluble in hydrochloric acid, ethanol, ether, chloroform and benzene, is an azo dye intermediate, and has been widely used for producing acid dyes and disperse dyes. With the rapid development of science and technology, the application of aminoazobenzene hydrochloride, especially reagent grade, is more and more extensive. It can be used as acid-base indicator, nitrite determination, sulfite determination in water and beverage, and methanol and formaldehyde determination in air, water and blood.

In the preparation method of p-amino azobenzene salt in the prior art, sodium nitrite aqueous solution and excessive aniline are added into a reactor, and hydrochloric acid is slowly added for diazotization and para-position transposition under the condition of 30-40O ℃. Since concentrated hydrochloric acid is directly added into the mixed solution of aniline and sodium nitrite at a temperature higher than room temperature, the reaction is violent, and particularly, nitrous acid generated by the reaction of hydrochloric acid and sodium nitrite is not only a diazotization reagent but also a strong oxidizing agent, so that aniline is easily oxidized, and the reaction solution is blackened.

Some researchers have proposed some improvement measures to improve the safety of the original production process and the problem of blackening the reaction liquid: the method mainly changes the feeding mode and sequence, for example, hydrochloric acid and excessive aniline are mixed to form aniline hydrochloride solution, and then sodium nitrite solution is dripped to diazotize the aniline hydrochloride solution. However, aniline hydrochloride is initially present in the reaction medium in large amounts and is therefore prone to premature translocation. In order to inhibit transposition, the sodium nitrite solution must be added dropwise at a lower temperature, so that refrigeration equipment is added in the production process, thereby increasing the investment and energy consumption of the equipment.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a simple, quick and safe preparation method for p-amino azobenzene salt, which can prevent potential safety hazards caused by violent reaction and enables the reaction to be mild and safe.

The technical problem to be solved by the invention is realized by adopting the following technical scheme:

a simple, rapid and safe preparation method of p-amino azobenzene salt comprises the following synthesis processes:

the specific process method comprises the following steps:

preparation of aniline hydrochloride solution

Adding 3-5kg of aniline into a reactor, starting a stirrer, and dripping 1.8-3kg of 36% concentrated hydrochloric acid at room temperature to prepare aniline hydrochloride solution for later use;

respectively adding 6-10kg of aniline, 1.1-1.8kg of sodium nitrite and 1.5-2.5kg of water into another reactor, stirring to prepare a solution, dropwise adding the aniline hydrochloride solution, heating to 50 ℃, and keeping for 4 hours to perform transposition;

thirdly, adding 300-500ml of 40% sodium hydroxide, heating to 70 ℃, immediately pouring into a liquid separating device, standing, separating a water layer, wherein the organic layer is p-aminoazobenzene;

fourthly, evaporating the organic layer under vacuum of 20mmHg at 70-75 ℃ to remove unreacted aniline, and obtaining residual p-aminoazobenzene liquid;

fifthly, keeping the temperature at 130 ℃, dropwise adding the p-aminoazobenzene residue into a 70 ℃ mixed solution prepared from 12-20L of water and 2-5L of 36% concentrated hydrochloric acid, stirring for 2 hours under natural cooling, filtering, and washing with dilute hydrochloric acid for three times to obtain p-aminoazobenzene hydrochloride.

Furthermore, aniline in aniline hydrochloride solution: hydrochloric acid: sodium nitrite 9: 2: 1.

furthermore, the ratio of aniline used for preparing the aniline hydrochloride solution to aniline used for mixing with the sodium nitrite aqueous solution was 1: 2.

and in the step, the temperature is controlled to be 35 +/-1 ℃.

The invention has the advantages and positive effects that:

1. according to the method, a part of aniline is reacted with hydrochloric acid to prepare aniline hydrochloride, so that the problem that concentrated hydrochloric acid is directly added into a mixed solution of aniline and sodium nitrite is avoided, the potential safety hazard caused by violent reaction is prevented, and the reaction is mild and safe.

2. The invention adds aniline hydrochloride instead of hydrochloric acid, thereby avoiding the generation of a large amount of nitrous acid, preventing the oxidation of aniline, and ensuring that the reaction liquid does not turn black in the whole reaction process.

3. According to the invention, part of aniline reacts with hydrochloric acid to generate aniline hydrochloride, and then the aniline hydrochloride is slowly dripped into the reaction solution, so that a proper concentration of the aniline hydrochloride is maintained, a large amount of accumulation is avoided all the time, the transposition reaction is inhibited from being carried out in advance, and the completeness of the diazotization reaction is ensured.

4. If a large amount of aniline hydrochloride is initially present in the reaction medium, refrigeration equipment is required to reduce the temperature during the diazotization reaction to inhibit the occurrence of translocation reactions. The method of the invention adopts partial hydrochlorination of aniline, and then dropwise adds reaction liquid, thereby ensuring that the reaction can be completely and normally carried out at normal temperature, without adding refrigeration equipment, and saving a large amount of expenses.

5. The method has scientific and reasonable design and high operation safety, adopts a part of aniline to react with hydrochloric acid first, avoids the situation that concentrated hydrochloric acid is directly added into the mixed solution of aniline and sodium nitrite, prevents the reaction from being violent and causes potential safety hazards, and in addition, aniline hydrochloride is added instead of hydrochloric acid, thereby avoiding the generation of a large amount of nitrous acid, preventing the oxidation of aniline and avoiding the blackening of reaction liquid.

Detailed Description

The present invention is further illustrated by the following specific examples, which are intended to be illustrative, not limiting and are not intended to limit the scope of the invention.

The invention provides a simple, rapid and safe preparation method of p-amino azobenzene salt, which comprises the following synthesis processes:

the specific process method comprises the following steps:

1. preparation of aniline hydrochloride solution

4kg of aniline is added into a reactor, a stirrer is started, and 2.4kg of 36% concentrated hydrochloric acid is dripped at room temperature to prepare aniline hydrochloride solution for later use.

2. In another reactor, 8kg aniline, 1.4kg sodium nitrite and 2kg water are respectively added, stirred to prepare a solution, the temperature is controlled to be 35 +/-1 ℃, and the aniline hydrochloride solution is dripped. After the addition, the temperature was raised to 50 ℃ and held for 4 hours to allow the displacement.

3. Then adding 400ml of 40% sodium hydroxide, heating to 70 ℃, immediately pouring into a liquid separating device, standing, separating an aqueous layer, evaporating unreacted aniline from an organic layer under vacuum of 20mmHg at 70-75 ℃, and obtaining a p-aminoazobenzene residual liquid. Keeping the temperature at 130 ℃, dropwise adding the p-aminoazobenzene organic layer residual liquid into a mixed solution of 16L water and 3.4L 36% concentrated hydrochloric acid at 70 ℃, stirring for 2 hours under natural cooling, filtering, and washing with dilute hydrochloric acid for three times to obtain p-aminoazobenzene hydrochloride.

According to the reaction principle, the material mixing ratio is aniline: hydrochloric acid: sodium nitrite 9: 2: 1, the ratio of aniline used for preparing aniline hydrochloride to aniline used for mixing with sodium nitrite is 1: 2.

table 1: aniline: hydrochloric acid: effect of sodium nitrite batch ratio on yield

Aniline: hydrochloric acid: ratio of sodium nitrite to charge	Yield of
		3：2：1	53％
6：2：1	72％
		9：2：1	84％
11：2：1	79％

Although the embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that: various substitutions, changes and modifications are possible without departing from the spirit and scope of the invention and the appended claims, and therefore the scope of the invention is not limited to the embodiments disclosed.