阅读说明：本技术 一种用于染料调色用的2,6-二氨基吡啶的合成方法 (Synthesis method of 2, 6-diaminopyridine for dye toning ) 是由 张青 韩峰 曹家瑞 曹军 于 2021-11-10 设计创作，主要内容包括：一种用于染料调色用的2,6-二氨基吡啶的合成方法,包括吡啶氨基化和纯化两个步骤；其中吡啶氨基化所用原料是吡啶、氨水和羟胺,所用催化剂为氯化亚铜-双(氯化锂)络合物和三氯化六氨合钴；采用二氯甲烷和二甲基亚砜混合液重结晶纯化2,6-二氨基吡啶。该方法在75～95℃,常压条件下制备得到了2,6-二氨基吡啶,2,6-二氨基吡啶产率88.1～91.3%(以吡啶计),纯度98.41～99.76%。(A synthetic method of 2, 6-diaminopyridine used for dye toning comprises two steps of pyridine amination and purification; wherein raw materials used for pyridine amination are pyridine, ammonia water and hydroxylamine, and catalysts used for pyridine amination are cuprous chloride-bis (lithium chloride) complex and hexaammine cobalt trichloride; and recrystallizing and purifying the 2, 6-diaminopyridine by using a mixed solution of dichloromethane and dimethyl sulfoxide. The method prepares the 2, 6-diaminopyridine at the temperature of 75-95 ℃ and under the normal pressure condition, wherein the yield of the 2, 6-diaminopyridine is 88.1-91.3% (calculated by pyridine), and the purity is 98.41-99.76%.)

1. A synthetic method of 2, 6-diaminopyridine used for dye toning is characterized in that: comprises two steps of pyridine amination and purification; wherein raw materials used for pyridine amination are pyridine, ammonia water and hydroxylamine, and catalysts used for pyridine amination are cuprous chloride-bis (lithium chloride) complex and hexaammine cobalt trichloride; recrystallizing and purifying the 2, 6-diaminopyridine by using a mixed solution of dichloromethane and dimethyl sulfoxide;

amination of pyridine, adding 25-28 wt% of ammonia water, hydroxylamine, cuprous chloride-bis (lithium chloride) complex and hexammoniacobalt trichloride into a reaction kettle, stirring at a speed of 2500-4000 rpm, heating at a speed of 1-2 ℃/min, heating to 75-95 ℃, keeping constant temperature, dropwise adding 45-60% of ammonia water and pyridine based on the total mass of hydroxylamine at a speed of 1.50-2.2 kg/min, continuously stirring for reacting at a constant temperature for 4-8 hours after dropwise adding, cooling to 10-15 ℃, precipitating crystals, and filtering to obtain coarse 2, 6-diaminopyridine;

the mass ratio of the ammonia water to the hydroxylamine to the cuprous chloride-bis (lithium chloride) complex to the hexammoniacobalt trichloride is 75-85: 5-10: 3-5: 2-6;

the purification method comprises the steps of dissolving crude 2, 6-diaminopyridine in a mixed solution prepared from dichloromethane and dimethyl sulfoxide according to a mass ratio of 10: 1-2, adding activated carbon, stirring and refluxing for 30-60 minutes at 80-90 ℃, thermally filtering to remove the activated carbon, cooling to 0-5 ℃, precipitating 2, 6-diaminopyridine crystals, washing with deionized water for three times, and drying for 3 hours at 60 ℃ to obtain high-purity 2, 6-diaminopyridine; the adding amount of the crude 2, 6-diaminopyridine is 30-45% of the total mass of the mixed solution of dichloromethane and dimethyl sulfoxide.

2. A process for the synthesis of 2, 6-diaminopyridine for the shading of dyes according to claim 1, which comprises: the particle size of the activated carbon is 300 microns, and the specific surface area is 653.8m²The pore size distribution is 55-79 nanometers, and the adding amount is 1.5-3 percent of the total mass of the mixed solution of the dichloromethane and the dimethyl sulfoxide.

Technical Field

The invention relates to a synthetic method of 2, 6-diaminopyridine for dye toning, belonging to the field of organic synthesis.

Background

The melting point of the 2, 6-diaminopyridine is 119-121 ℃, the crystal is generally white or yellowish needle-shaped or sheet-shaped crystal, and the crystal is easily oxidized and blackened when exposed to air, is mainly used for synthesizing dyes and medicines, and is also an indispensable important intermediate of other fine organic chemical products.

The synthesis method of 2, 6-diaminopyridine is more, and can be divided into four types according to the difference of raw materials. According to the heterogeneous Chichibabin method, amination reaction is carried out on pyridine and sodium amide at high temperature to generate 2, 6-diaminopyridine. In the homogeneous Chichibabin method, pyridine and liquid ammonia react under the action of a catalyst, the two methods have more side reactions, and the purification of 2, 6-diaminopyridine is complex and the yield is generally below 60%. The third method is a cyclization reaction of nitrile substances, such as the cyclization of 3-hydroxyglutaronitrile or pentenenitrile and amine substances under the action of a halogen acid catalyst, and the method has high reaction yield which is more than 90 percent, but the 3-hydroxyglutaronitrile and pentenenitrile take virulent cyanide as a raw material, so that the method has few control and strict sources and high price, and is not suitable for industrial production. The fourth is halopyridine ammonolysis reaction, generally 2, 6-dibromopyridine or 2, 6-dichloropyridine and liquid ammonia are used for replacing halogen with amino to generate 2, 6-aminopyridine at a high temperature of more than 180 ℃ and under a high pressure condition, the reaction condition of the method is harsh, the requirement on equipment is high, the cost is correspondingly high, in addition, side reactions are more in the replacement process, the purification of 2, 6-diaminopyridine is also difficult, and the following two patents disclose the method for preparing 2, 6-diaminopyridine by using halopyridine ammonolysis reaction.

Chinese patent CN102993090A discloses a method for synthesizing 2, 6-diaminopyridine, which comprises introducing liquid ammonia into a high-pressure reaction kettle with 2, 6-dihalogenated pyridine, a solvent and a catalyst, reacting at 200-1000 ℃ to obtain a crude product, and purifying with toluene to obtain 2, 6-diaminopyridine with purity of more than 99%. Chinese patent CN103288720A discloses a high-pressure synthesis method of 2, 6-diaminopyridine, which comprises the steps of taking 2, 6-dichloropyridine as a reaction raw material, introducing liquid ammonia into propylene glycol or glycerol in the presence of a catalyst, reacting at 180-300 ℃ and 5-12 MPa, evaporating the solvent to obtain a crude product, wherein the conversion rate of the 2, 6-diaminopyridine is 96%, the conversion rate of the 2-chloro-6-aminopyridine is 3.5%, and the crude product is refined by toluene to obtain 99% of a target product, namely the 2, 6-diaminopyridine.

Disclosure of Invention

In view of the existing defects, the invention provides a synthesis method of 2, 6-diaminopyridine for dye toning, which realizes the following purposes: the 2, 6-diaminopyridine is synthesized under the conditions of low temperature and normal pressure, the synthesis process is simple to operate, the requirement on equipment is low, the cost is low, and the obtained product has high yield and high purity.

In order to realize the purpose, the invention adopts the following technical scheme:

a synthetic method of 2, 6-diaminopyridine used for dye toning comprises two steps of pyridine amination and purification; wherein raw materials used for pyridine amination are pyridine, ammonia water and hydroxylamine, and catalysts used for pyridine amination are cuprous chloride-bis (lithium chloride) complex and hexaammine cobalt trichloride; and recrystallizing and purifying the 2, 6-diaminopyridine by using a mixed solution of dichloromethane and dimethyl sulfoxide.

The following is a further improvement of the above technical solution:

step (1) pyridine amination

Adding ammonia water, hydroxylamine, cuprous chloride-bis (lithium chloride) complex and hexaammine cobalt trichloride into a reaction kettle, stirring, heating to a constant temperature, dropwise adding pyridine, continuously stirring for reacting for 4-8 hours after dropwise adding is finished, cooling to 10-15 ℃, precipitating crystals, and filtering to obtain crude 2, 6-diaminopyridine;

the concentration of the ammonia water is 25-28 wt%;

the mass ratio of the ammonia water to the hydroxylamine to the cuprous chloride-bis (lithium chloride) complex to the hexammoniacobalt trichloride is 75-85: 5-10: 3-5: 2-6;

the adding amount of the pyridine is 45-60% of the total mass of the ammonia water and the hydroxylamine, and the dropping speed is 1.50-2.2 kg/min;

stirring and heating to a constant temperature, wherein the stirring speed is 2500-4000 rpm, the heating speed is 1-2 ℃/min, and the constant temperature is 75-95 ℃.

Step (2) purification

Dissolving crude 2, 6-diaminopyridine in a certain amount of mixed solution of dichloromethane and dimethyl sulfoxide, adding a proper amount of activated carbon, stirring and refluxing for 30-60 minutes at the temperature of 80-90 ℃, removing the activated carbon by hot filtration, rapidly cooling to 0-5 ℃, precipitating 2, 6-diaminopyridine crystals, washing with deionized water for three times, and drying at 60 ℃ for 3 hours to obtain high-purity 2, 6-diaminopyridine;

the mixed solution of dichloromethane and dimethyl sulfoxide comprises dichloromethane and dimethyl sulfoxide in a mass ratio of 10: 1-2;

the adding amount of the crude 2, 6-diaminopyridine is 30-45% of the total mass of the mixed solution of dichloromethane and dimethyl sulfoxide;

the particle size of the activated carbon is 300 microns, and the specific surface area is 653.8m²The pore size distribution is 55-79 nanometers, and the adding amount is 1.5-3 percent of the total mass of the mixed solution of the dichloromethane and the dimethyl sulfoxide.

The preferable technical scheme is as follows:

after the dropwise addition in the step (1) is finished, continuously stirring and reacting for 6 hours, and cooling to 13 ℃ to precipitate crystals;

the concentration of the ammonia water is 27 wt%;

the mass ratio of the ammonia water to the hydroxylamine to the cuprous chloride-bis (lithium chloride) complex to the hexaammine cobalt trichloride is 20:2:1: 1;

the addition amount of the pyridine is 52 percent of the total mass of the ammonia water and the hydroxylamine, and the dropping speed is 1.8 kg/min;

stirring and heating to a constant temperature, wherein the stirring speed is 3600 r/min, the heating speed is 1.5 ℃/min, and the constant temperature is 85 ℃;

stirring and refluxing the mixture in the step (2) at the temperature of 85 ℃ for 50 minutes, quickly cooling the mixture to 2 ℃ after the activated carbon is removed by hot filtration, and separating out crystals, namely the finished product of the 2, 6-diaminopyridine;

the mixed solution of dichloromethane and dimethyl sulfoxide comprises dichloromethane and dimethyl sulfoxide in a mass ratio of 20: 3;

the adding amount of the crude 2, 6-diaminopyridine is 40 percent of the total mass of the mixed solution of the dichloromethane and the dimethyl sulfoxide;

the adding amount of the activated carbon is 2 percent of the total mass of the mixed solution of the dichloromethane and the dimethyl sulfoxide.

Compared with the prior art, the invention has the following beneficial effects:

1. preparing 2, 6-diaminopyridine at 75-95 ℃ under normal pressure;

2. the yield of the 2, 6-diaminopyridine is 88.1-91.3% (calculated by pyridine), and the purity is 98.41-99.76%.

Detailed Description

The following description of the preferred embodiments of the present invention is provided for the purpose of illustration and description, and is in no way intended to limit the invention.

Example 1: synthesis method of 2, 6-diaminopyridine for dye toning

The method comprises the following steps:

1. amination of pyridines

Adding 600 kg of 27wt% ammonia water, 60 kg of hydroxylamine, 30 kg of cuprous chloride-bis (lithium chloride) complex and 30 kg of hexammoniacobalt trichloride into a reaction kettle, heating at 3600 r/min stirring rate and 1.5 ℃/min heating rate, keeping the temperature to 85 ℃, dropwise adding 343.2 kg of pyridine at 1.8 kg/min stirring rate, continuously stirring for reacting for 6 hours after dropwise adding, cooling to 13 ℃, precipitating crystals, and filtering to obtain 461.8 kg of crude 2, 6-diaminopyridine;

the content of 2, 6-diaminopyridine in the crude 2, 6-diaminopyridine was 94.3%.

2. Purification of

441.8 kg of crude 2, 6-diaminopyridine is dissolved in 1104.5 kg of mixed solution of dichloromethane and dimethyl sulfoxide, 22.1 kg of activated carbon is added, stirring and refluxing are carried out at the temperature of 85 ℃ for 50 minutes, the temperature is rapidly reduced to 2 ℃ after the activated carbon is removed by thermal filtration, 2, 6-diaminopyridine crystals are separated out, deionized water is used for washing for three times, and drying is carried out at the temperature of 60 ℃ for 3 hours to obtain 432.3 kg of high-purity 2, 6-diaminopyridine;

the mixed solution of dichloromethane and dimethyl sulfoxide comprises dichloromethane and dimethyl sulfoxide in a mass ratio of 20: 3;

the 2, 6-diaminopyridine obtained in example 1 was obtained in a yield of 91.3% (based on pyridine) and a purity of 99.76%.

Example 2:

1. amination of pyridines

Adding 750 kg of 25wt% ammonia water, 50 kg of hydroxylamine, 30 kg of cuprous chloride-bis (lithium chloride) complex and 20 kg of hexammoniacobalt trichloride into a reaction kettle, heating and keeping the temperature to 75 ℃ at a stirring speed of 2500 rpm and a heating speed of 1 ℃/min, dropwise adding 360 kg of pyridine at a speed of 1.5 kg/min, continuously stirring for reacting for 4 hours after dropwise adding, cooling to 10 ℃ to precipitate crystals, and filtering to obtain 490.3 kg of crude 2, 6-diaminopyridine;

the content of 2, 6-diaminopyridine in the crude 2, 6-diaminopyridine was 93.1%.

2. Purification of

490.3 kg of crude 2, 6-diaminopyridine is dissolved in 1634.3 kg of mixed solution of dichloromethane and dimethyl sulfoxide, 24.5 kg of activated carbon is added, stirring and refluxing are carried out at the temperature of 80 ℃ for 30 minutes, the temperature is rapidly reduced to 0 ℃ after the activated carbon is removed by thermal filtration, 2, 6-diaminopyridine crystals are separated out, deionized water is used for washing for three times, and the crystals are dried at the temperature of 60 ℃ for 3 hours to obtain 456.25 kg of high-purity 2, 6-diaminopyridine;

the mixed solution of dichloromethane and dimethyl sulfoxide comprises dichloromethane and dimethyl sulfoxide in a mass ratio of 10: 1;

the 2, 6-diaminopyridine obtained in example 2 was obtained in 90.4% yield (based on pyridine) and in 98.41% purity.

Example 3:

1. amination of pyridines

Adding 850 kg of 25wt% ammonia water, 100 kg of hydroxylamine, 50 kg of cuprous chloride-bis (lithium chloride) complex and 60 kg of hexammoniacobalt trichloride into a reaction kettle, heating at a stirring speed of 4000 rpm and a heating speed of 2 ℃/min, keeping the temperature to 95 ℃, dropwise adding 570 kg of pyridine at a speed of 2.2 kg/min, continuously stirring for reacting for 8 hours after dropwise adding, cooling to 15 ℃, precipitating crystals, and filtering to obtain 781.9 kg of crude 2, 6-diaminopyridine;

the content of 2, 6-diaminopyridine in the crude 2, 6-diaminopyridine was 92.3%.

2. Purification of

490.3 kg of crude 2, 6-diaminopyridine is dissolved in 1089.6 kg of mixed solution of dichloromethane and dimethyl sulfoxide, 32.7 kg of activated carbon is added, stirring and refluxing are carried out at 90 ℃ for 60 minutes, after the activated carbon is removed by thermal filtration, the temperature is rapidly reduced to 5 ℃, 2, 6-diaminopyridine crystals are separated out, deionized water is used for washing for three times, and drying is carried out at 60 ℃ for 3 hours to obtain 699.60 kg of high-purity 2, 6-diaminopyridine;

the mixed solution of dichloromethane and dimethyl sulfoxide comprises dichloromethane and dimethyl sulfoxide in a mass ratio of 5: 1;

the 2, 6-diaminopyridine obtained in example 3 was obtained in 88.1% yield (based on pyridine) and in 99.03% purity.