阅读说明：本技术 一种2-硝基-苯胺的制备方法 (Preparation method of 2-nitro-aniline ) 是由 袁相富 于 2020-07-13 设计创作，主要内容包括：本申请公开一种2-硝基-苯胺的制备方法,即在高沸点高极性溶剂作为反应溶剂与无机酸存在的条件下,控制温度为100-140℃将2-硝基-4-磺酸基苯胺进行常压脱磺酸反应,反应结束后减压浓缩去除高沸点高极性溶剂,然后加入水混匀,调pH值为8-10后依次经萃取、洗涤、浓缩干燥得到2-硝基-苯胺,高沸点高极性溶剂反应后可以回收进行再利用。该制备方法在较低的温度范围内进行常压脱磺酸反应,制备过程耗能低,同时产生的废盐少,按每吨2-硝基-苯胺计算,仅产生2.7-3.3吨的硫酸钠,最终得到2-硝基-苯胺产品的纯度(HPLC)大于97%、产率最高可达91%。(The application discloses a preparation method of 2-nitro-aniline, which comprises the steps of carrying out normal-pressure desulfonation reaction on 2-nitro-4-sulfonanilide at 140 ℃ under the condition that a high-boiling point high-polarity solvent is used as a reaction solvent and inorganic acid exists, carrying out reduced pressure concentration to remove the high-boiling point high-polarity solvent after the reaction is finished, then adding water for uniformly mixing, adjusting the pH value to be 8-10, then sequentially carrying out extraction, washing, concentration and drying to obtain the 2-nitro-aniline, wherein the high-boiling point high-polarity solvent can be recycled for reuse after the reaction. The preparation method carries out the normal-pressure desulfonation reaction in a lower temperature range, the energy consumption in the preparation process is low, simultaneously, the generated waste salt is less, only 2.7-3.3 tons of sodium sulfate is generated according to each ton of 2-nitro-aniline, the purity (HPLC) of the finally obtained 2-nitro-aniline product is more than 97%, and the yield can reach 91% at most.)

1. The preparation method of the 2-nitro-aniline is characterized by comprising the following steps:

(1) adding a substrate 2-nitro-4-sulfonanilide into a high-boiling point high-polarity solvent for dissolving, then adding acid, heating the system to 100-140 ℃ for desulfonation reaction, and after the HPLC monitoring reaction is finished, carrying out reduced pressure concentration on the obtained reaction liquid to remove the high-boiling point high-polarity solvent to obtain a concentrate;

The high-boiling point and high-polarity solvent is N-butanol, N-dimethylformamide, N-dimethylacetamide, N-methyl-pyrrolidone, dimethyl sulfoxide, dimethyl sulfone or sulfolane;

the dosage of the high-polarity high-boiling-point solvent is as follows according to the ratio of 2-nitro-4-sulfonanilide: 1g of high-polarity high-boiling-point solvent: 1-10 mL;

the acid is sulfuric acid, hydrochloric acid, acetic acid or phosphoric acid, and the dosage of the acid is as follows according to 2-nitro-4-sulfonic aniline: the molar ratio of the acid is 1: 1.0-1.5;

(2) adding water into the concentrate obtained in the step (1), uniformly mixing, adjusting the pH value to 8-10 by using alkali, sequentially extracting by using ethyl acetate, washing by using saturated alkaline water solution, concentrating and drying to obtain 2-nitro-aniline;

the amount added to the above concentrate is calculated based on the 2-nitro-4-sulfonanilide used to prepare the concentrate in step (1), i.e., 2-nitro-4-sulfonanilide: 1g of water: 2-3 mL.

2. The process for preparing 2-nitro-aniline as claimed in claim 1, wherein the temperature of the desulfonation reaction in step (1) is 120-130 ℃.

3. The process according to claim 2, wherein the high-boiling, highly polar solvent used in step (1) is N, N-dimethylformamide, dimethyl sulfone, dimethyl sulfoxide or sulfolane.

4. The process for producing 2-nitro-aniline according to claim 3, wherein the high-polar high-boiling solvent used in the step (1) is used in an amount of 2-nitro-4-sulfonanilide: 1g of high-polarity high-boiling-point solvent: 5 mL.

5. The process according to claim 4, wherein the acid used in step (1) is acetic acid or phosphoric acid.

6. The process for producing 2-nitro-aniline according to claim 5, wherein the acid is used in the amount of 2-nitro-4-sulfonanilide: the molar ratio of the acid is 1: 1.2.

7. the process according to claim 6, wherein the base used in the step (2) is sodium hydroxide, potassium carbonate, sodium hydrogen carbonate or potassium hydrogen carbonate.

8. The process according to claim 7, wherein the pH of the mixture in step (2) is adjusted to 8 to 9 with a base.

9. The process for producing 2-nitro-aniline according to any one of claims 1 to 8, wherein the saturated aqueous alkali solution in the step (2) is a saturated aqueous sodium hydroxide solution, a saturated aqueous sodium carbonate solution, a saturated aqueous potassium hydroxide solution, a saturated aqueous potassium carbonate solution, a saturated aqueous sodium bicarbonate solution or a saturated aqueous potassium bicarbonate solution.

10. The process for producing 2-nitro-aniline according to claim 1, wherein the concentration under reduced pressure in the step (1) is carried out under a vacuum of 5 to 15 mmHg.

Technical Field

The application relates to the field of organic compound synthesis, in particular to a preparation method of 2-nitro-aniline.

Technical Field

The 2-nitro-aniline is a basic chemical raw material in the fine chemical field, and the related production process comprises the steps of carrying out ortho-position nitration after para-position sulfonation on aniline or acetanilide, then carrying out high-temperature desulfonation in a sulfuric acid or hydrochloric acid system, adding a large amount of inorganic base into a reaction system after the reaction is finished to neutralize the acid of the system to be neutral, then extracting a product by using an organic solvent, washing, drying and concentrating to obtain the product.

The biggest drawback of this related production process is the large amount of waste salt produced, which yields at least about 7.5 tons of sodium sulfate per ton of product. In addition, the process needs high temperature of 150 ℃ and 160 ℃, and has certain safety risk besides high energy consumption. If hydrochloric acid is used instead of sulfuric acid, in addition to generating a large amount of waste inorganic salts, the reaction in a pressure kettle is needed to reach the reaction temperature, so that the potential safety hazard is higher.

Disclosure of Invention

In order to overcome the defects in the prior art, the application provides the preparation method of the 2-nitro-aniline, the amount of the waste salt finally generated by the preparation method is low, and the preparation method has the characteristics of relatively low reaction temperature and operation under normal pressure.

Technical principle of the present application

A method for preparing 2-nitro-aniline, wherein the reaction equation of the preparation process is as follows:

taking a high-boiling point high-polarity solvent as a reaction solvent, carrying out normal pressure desulfonation reaction in a temperature range lower than the boiling point of the reaction solvent under the action of inorganic acid, carrying out reduced pressure concentration to remove the high-boiling point high-polarity solvent after the reaction is finished, then adding water for uniformly mixing, adjusting the pH value to be 8-10, then sequentially extracting, washing, concentrating and drying to obtain the 2-nitro-aniline, wherein the high-boiling point high-polarity solvent can be recycled for reuse after the reaction.

Technical scheme of the application

A preparation method of 2-nitro-aniline specifically comprises the following steps:

(1) adding a substrate 2-nitro-4-sulfonanilide into a high-boiling point high-polarity solvent for dissolving, then adding acid, heating the system to 100-140 ℃, preferably 120-130 ℃ for desulfonation reaction, after the HPLC monitoring reaction is finished, preferably carrying out reduced pressure concentration on the obtained reaction liquid under the condition that the vacuum degree is 5-15mmHg so as to remove the high-boiling point high-polarity solvent, obtaining a concentrate, and simultaneously recovering the high-boiling point high-polarity solvent for reuse;

the high-boiling point and high-polarity solvent is N-butanol, N-dimethylformamide, N-dimethylacetamide, N-methyl-pyrrolidone, dimethyl sulfoxide, dimethyl sulfone or sulfolane, and preferably N, N-dimethylformamide, dimethyl sulfone, dimethyl sulfoxide or sulfolane;

the dosage of the high-polarity high-boiling-point solvent is as follows according to the ratio of 2-nitro-4-sulfonanilide: 1g of high-polarity high-boiling-point solvent: 1-10mL, preferably 1 g: calculating the proportion of 5 mL;

the acid is sulfuric acid, hydrochloric acid, acetic acid or phosphoric acid; acetic acid or phosphoric acid is preferred because it is less corrosive, reducing the requirements on equipment;

the dosage of the acid is as follows according to 2-nitro-4-sulfonic aniline: the molar ratio of the acid is 1: 1.0 to 1.5, preferably 1: 1.2;

(2) Adding water into the concentrate obtained in the step (1), uniformly mixing, adjusting the pH value to 8-10 by using alkali, sequentially extracting for 3 times by using ethyl acetate, combining the obtained extract, washing by using saturated aqueous alkali to the pH value of 8-10, preferably the pH value of 8-9, and then concentrating and drying at the temperature of 40-45 ℃ to obtain 2-nitro-aniline;

the amount of water added to the above concentrate is calculated based on the 2-nitro-4-sulfonanilide used to prepare the concentrate in step (1), i.e., 2-nitro-4-sulfonanilide: 1g of water: 2-3 mL;

the alkali is preferably sodium hydroxide, potassium carbonate, sodium bicarbonate or potassium bicarbonate, and the sodium hydroxide is used for illustration only in the application, but the application of the other alkali is not limited;

the saturated aqueous alkali is a saturated aqueous sodium hydroxide solution or a saturated aqueous sodium carbonate solution, and may be replaced by a saturated aqueous potassium hydroxide solution, a saturated aqueous potassium carbonate solution, a saturated aqueous sodium bicarbonate solution, or a saturated aqueous potassium bicarbonate solution, and in this application, only a saturated aqueous sodium hydroxide solution is exemplified, but the application of the other saturated aqueous alkali is not limited;

the amount of ethyl acetate used in each extraction is calculated based on the 2-nitro-4-sulfonanilide used in the preparation step (1), i.e., 2-nitro-4-sulfonanilide: ethyl acetate was 1 g: 2-4mL, preferably 1 g: 3 mL.

Advantageous technical effects of the present application

According to the preparation method of the 2-nitro-aniline, the normal-pressure desulfonation reaction can be carried out at the temperature of 140 ℃ under the condition that a high-boiling-point high-polarity solvent is used as a reaction solvent and inorganic acid exists, so that the potential safety hazard of high-temperature and pressure kettle operation in the prior art is solved, and meanwhile, the normal-pressure desulfonation reaction can be carried out at the temperature of 140 ℃ under the temperature of 120 ℃ plus, so that the energy consumption in the preparation process is relatively reduced compared with the prior art.

Further, a process for the preparation of 2-nitro-aniline according to the present application, due to the low amount of waste salt produced by the preparation of tons of 2-nitro-aniline, only 2.7 to 3.3 tons of sodium sulfate per ton of 2-nitro-aniline are produced, which yields at least 7.5 tons of sodium sulfate per ton of product and a 56 to 64% reduction in waste salt production compared to the production reported in the prior art documents.

Furthermore, according to the preparation method of the 2-nitro-aniline, the reaction temperature is reduced and does not exceed the boiling point of the organic solvent, so that the safety of the process is ensured, and meanwhile, the used acid is preferably changed into acetic acid and phosphoric acid with lower acidity and corrosivity, so that the production operation is relatively safe, and the requirement on production equipment is reduced.

Drawings

FIG. 1 is a nuclear magnetic hydrogen spectrum of the crude product obtained in example 1;

FIG. 2 is a nuclear magnetic hydrogen spectrum of an outsourced 2-nitro-aniline standard substance.

Detailed description of the invention

The technical solution of the present application is further illustrated by the following specific examples in combination with the accompanying drawings, but the present application is not limited thereto.

The main raw materials, names of reagents, specifications, and information of manufacturers (or suppliers) used in the examples of the present application are as follows:

name (R)	Specification of	Manufacturers or units of supply of raw materials
			Sulfuric acid	98％w/w	National reagents Ltd
Sodium hydroxide	98％w/w	National reagents Ltd
			Sulfuric acid	98％w/w	National reagents Ltd
Acetic acid	98％w/w	National reagents Ltd
			Phosphoric acid	98％w/w	National reagents Ltd
N, N-dimethylformamide	98％w/w	National reagents Ltd
			Dimethyl sulfone	98％w/w	National reagents Ltd
Sulfolane	98％w/w	National reagents Ltd
			2-nitro-4-sulfonanilides	98％w/w	National reagents Ltd

The yield of the 2-nitro-aniline product was calculated by the formula actual crude weight of 2-nitro-aniline product/theoretical weight of 2-nitro-aniline product 100%;

the purity of 2-nitro-aniline in the crude product obtained in each example of the present application was determined using a high performance liquid chromatography detector (instrument used for determination is a high performance liquid chromatography detector, model 1260, manufactured by agilent technologies, inc.), Analytical Chemistry,1967, vol.39, p.315.