Method for synthesizing aminopyridine with pyridine base mixture as well as separation and purification method of aminopyridine

Abstract

The invention discloses a method for synthesizing aminopyridine with a pyridine base mixture as well as a separation and purification method of the aminopyridine and belongs to the field of fine chemical engineering. According to the method, the pyridine base mixture reacts with sodium amide under proper conditions, then a mixture of 2-amino-4-methylpyridine, 2-aminopyridine and 2-amino-6-methylpyridine is obtained through a hydrolysis reaction, the 2-amino-4-methylpyridine, the 2-aminopyridine and the 2-amino-6-methylpyridine are separated one by one according to different melting points and different boiling points of all the components in the mixture, and the high-purity 2-amino-4-methylpyridine, the high-purity 2-aminopyridine and the high-purity 2-amino-6-methylpyridine are obtained. The synthesizing method and the separation and purification method have the advantages of simple technology, reasonable design, convenience in operation, and the synthesizing method is an environment-friendly synthesizing technology and has the broad application prospect.

Description

technical field

[0001] The invention belongs to the field of fine chemical industry, in particular, relates to a method for synthesizing chemical intermediates, more specifically, relates to a method for synthesizing aminopyridine from a mixture of pyridine bases and a separation and purification method thereof. Background technique

[0002] Pyridine compounds are currently one of the most widely developed and applied varieties of heterocyclic compounds. As an important fine chemical raw material, its derivatives mainly include alkylpyridine, halogenated pyridine, aminopyridine, bromopyridine, picoline , iodopyridine, chloropyridine, nitropyridine, hydroxypyridine, benzylpyridine, ethylpyridine, cyanopyridine, fluoropyridine, dihydropyridine, etc. Among them, pesticides account for about 50% of the total consumption of pyridine series products, feed additives About 30%, medicine and other fields accounted for 20%. Pyridine base compounds are important raw materials for orga...

Examples

Embodiment 1

[0037] like figure 1 Shown, a kind of method is synthesized aminopyridine by pyridine base mixture, and its step is:

[0038] (a) Xylene (does not contain ferric ion and water) is added in the reaction flask, then the pyridine base mixture that is made up of 2-picoline, pyridine and 4-picoline is added in the reaction flask through a constant pressure funnel and stirred evenly, Wherein the mass ratio of xylene to the pyridine base mixture is 2.5:1, 2-picoline accounts for 90% of the total mass, pyridine is 6%, and 4-picoline is 4% in the pyridine base mixture;

[0039] (b) Slowly heating the reaction flask in step (a) to 80° C. for reflux dehydration until no water droplets are generated in the reaction flask;

[0040] (c) After the dehydration reaction in step (b) is finished, it is cooled to room temperature, and sodium amide is added (addition speed is 10g / min) into the reaction flask and stirred evenly, and then micro-reflux reaction is carried out, wherein sodium amide a...

Embodiment 2

[0051] A method for synthesizing aminopyridine from a pyridine base mixture, the steps are:

[0052] (a) Xylene (does not contain iron ion) is added in the reaction flask, then the pyridine base mixture that is made up of 2-picoline, pyridine and 4-picoline is added in the reaction flask through a constant pressure funnel and stirred evenly, wherein two The mass ratio of toluene to the pyridine base mixture is 2:1, and in the pyridine base mixture, 2-picoline accounts for 82% of the total mass, pyridine is 11%, and 4-picoline is 7%;

[0053] (b) Slowly heating the reaction flask in step (a) to 100° C. for reflux dehydration until no water droplets are generated in the reaction flask;

[0054] (c) After the dehydration reaction in step (b) is finished, it is cooled to room temperature, and sodium amide is added in the reaction flask with a speed of 15g / min and stirred evenly, and then micro-reflux reaction is carried out, wherein the mass of sodium amide and pyridine base mixtu...

Embodiment 3

[0065] A method for synthesizing aminopyridine from a pyridine base mixture, the steps are:

[0066] (a) Xylene (does not contain iron ion) is added in the reaction flask, then the pyridine base mixture that is made up of 2-picoline, pyridine and 4-picoline is added in the reaction flask through a constant pressure funnel and stirred evenly, wherein two The mass ratio of toluene to the pyridine base mixture is 3:1, 2-picoline accounts for 55% of the total mass, 28% of pyridine, and 17% of 4-picoline in the pyridine base mixture;

[0067] (b) Slowly heating the reaction flask in step (a) to 135° C. for reflux dehydration until no water droplets are produced in the reaction flask;

[0068] (c) After the dehydration reaction in step (b) is finished, it is cooled to room temperature, and sodium amide is added in the reaction flask with a speed of 20g / min and stirred evenly, and then micro-reflux reaction is carried out, wherein the mass of sodium amide and pyridine base mixture T...

technical field

[0001] The invention belongs to the field of fine chemical industry, in particular, relates to a method for synthesizing chemical intermediates, more specifically, relates to a method for synthesizing aminopyridine from a mixture of pyridine bases and a separation and purification method thereof. Background technique

[0002] Pyridine compounds are currently one of the most widely developed and applied varieties of heterocyclic compounds. As an important fine chemical raw material, its derivatives mainly include alkylpyridine, halogenated pyridine, aminopyridine, bromopyridine, picoline , iodopyridine, chloropyridine, nitropyridine, hydroxypyridine, benzylpyridine, ethylpyridine, cyanopyridine, fluoropyridine, dihydropyridine, etc. Among them, pesticides account for about 50% of the total consumption of pyridine series products, feed additives About 30%, medicine and other fields accounted for 20%. Pyridine base compounds are important raw materials for orga...

Examples

Embodiment 1

[0037] like figure 1 Shown, a kind of method is synthesized aminopyridine by pyridine base mixture, and its step is:

[0038] (a) Xylene (does not contain ferric ion and water) is added in the reaction flask, then the pyridine base mixture that is made up of 2-picoline, pyridine and 4-picoline is added in the reaction flask through a constant pressure funnel and stirred evenly, Wherein the mass ratio of xylene to the pyridine base mixture is 2.5:1, 2-picoline accounts for 90% of the total mass, pyridine is 6%, and 4-picoline is 4% in the pyridine base mixture;

[0039] (b) Slowly heating the reaction flask in step (a) to 80° C. for reflux dehydration until no water droplets are generated in the reaction flask;

[0040] (c) After the dehydration reaction in step (b) is finished, it is cooled to room temperature, and sodium amide is added (addition speed is 10g / min) into the reaction flask and stirred evenly, and then micro-reflux reaction is carried out, wherein sodium amide a...

Embodiment 2

[0051] A method for synthesizing aminopyridine from a pyridine base mixture, the steps are:

[0052] (a) Xylene (does not contain iron ion) is added in the reaction flask, then the pyridine base mixture that is made up of 2-picoline, pyridine and 4-picoline is added in the reaction flask through a constant pressure funnel and stirred evenly, wherein two The mass ratio of toluene to the pyridine base mixture is 2:1, and in the pyridine base mixture, 2-picoline accounts for 82% of the total mass, pyridine is 11%, and 4-picoline is 7%;

[0053] (b) Slowly heating the reaction flask in step (a) to 100° C. for reflux dehydration until no water droplets are generated in the reaction flask;

[0054] (c) After the dehydration reaction in step (b) is finished, it is cooled to room temperature, and sodium amide is added in the reaction flask with a speed of 15g / min and stirred evenly, and then micro-reflux reaction is carried out, wherein the mass of sodium amide and pyridine base mixtu...

Embodiment 3

[0065] A method for synthesizing aminopyridine from a pyridine base mixture, the steps are:

[0066] (a) Xylene (does not contain iron ion) is added in the reaction flask, then the pyridine base mixture that is made up of 2-picoline, pyridine and 4-picoline is added in the reaction flask through a constant pressure funnel and stirred evenly, wherein two The mass ratio of toluene to the pyridine base mixture is 3:1, 2-picoline accounts for 55% of the total mass, 28% of pyridine, and 17% of 4-picoline in the pyridine base mixture;

[0067] (b) Slowly heating the reaction flask in step (a) to 135° C. for reflux dehydration until no water droplets are produced in the reaction flask;

[0068] (c) After the dehydration reaction in step (b) is finished, it is cooled to room temperature, and sodium amide is added in the reaction flask with a speed of 20g / min and stirred evenly, and then micro-reflux reaction is carried out, wherein the mass of sodium amide and pyridine base mixture T...

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