CN106243027A - A kind of preparation method of 3,6 dichloro 2 picolinic acids - Google Patents
A kind of preparation method of 3,6 dichloro 2 picolinic acids Download PDFInfo
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- CN106243027A CN106243027A CN201610609233.0A CN201610609233A CN106243027A CN 106243027 A CN106243027 A CN 106243027A CN 201610609233 A CN201610609233 A CN 201610609233A CN 106243027 A CN106243027 A CN 106243027A
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- trichloropyridine
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D213/00—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members
- C07D213/02—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members
- C07D213/04—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom
- C07D213/60—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D213/78—Carbon atoms having three bonds to hetero atoms, with at the most one bond to halogen, e.g. ester or nitrile radicals
- C07D213/79—Acids; Esters
- C07D213/803—Processes of preparation
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D213/00—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members
- C07D213/02—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members
- C07D213/04—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom
- C07D213/60—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D213/78—Carbon atoms having three bonds to hetero atoms, with at the most one bond to halogen, e.g. ester or nitrile radicals
- C07D213/79—Acids; Esters
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Abstract
The invention discloses the preparation method of a kind of 3,6 dichloro 2 picolinic acids, by raw material 2,3,6 trichloropyridines are dissolved in acetic acid, and adding catalyst, after intensification, dropping hydrogen peroxide carries out oxidation reaction, after having reacted, filters catalyst, concentrate precipitation, obtain 2,3,6 trichloropyridine nitrogen oxides；Being dissolved in solvent DMF, add Cyanogran. intensification and carry out cyanogenation, after having reacted, precipitation is steamed in rotation, and ethyl alcohol recrystallization obtains 2 cyano group 3,6 dichloropyridine nitrogen oxides；It being mixed with Phosphorous chloride., heat up and carry out deoxygenation, after having reacted, precipitation, resultant product adds in frozen water, separates out solid, filters to obtain 2 cyano group 3,6 dichloropyridines；Being added into ethanolic sodium hydroxide solution, be hydrolyzed reaction, after having reacted, adjusts system pH to 23, and precipitation crystallizes to obtain end product clopyralid.This method total recovery is high, and avoids the generation of a large amount of brine waste of traditional route.
Description
Technical field
The invention belongs to chemical field, be specifically related to a kind of 3, the preparation method of 6-dichloro-2-pyridyl carboxylic acid.
Background technology
Clopyralid is a kind of low-residual new herbicides, can be easy to degraded in soil, and weeding is in extensive range.Pass
The generation method of system is mainly with 2-cyanopyridine for raw material through the step acquisition products such as chlorinated with chlorine, hydrolysis, reduction, tradition
It is low to there is yield in method, and wastewater flow rate is big, and by chlorinated with chlorine, safety factors is low, and the shortcoming such as easy coking in chlorination process.
Traditional route is improved by patent CN200710130919.2, solves easy coking problem in chlorination process,
But 2-cyano group 4 chloro pyridine is hydrolyzed into acid, and follow-up add hydrazine hydrate reduction dechlorination and produce substantial amounts of containing with after salt acid for adjusting pH value
Salt waste water, and the low problem of yield still exists.
Summary of the invention
The invention provides one 3, the preparation method of 6-dichloro-2-pyridyl carboxylic acid, with 2,3,6-trichloropyridines are raw material,
Being aoxidized by nitrogen, cyaniding, deoxidation, hydrolysis waits some row steps to obtain final products, and total recovery is high, and only exists in this technical process
Finally to hydrolyze and regulate in the step of pH value produce outside a certain amount of waste water, all produces without waste water in other steps, it is to avoid passes
The generation of the system a large amount of brine waste of route.
In order to solve the problems referred to above, the technical solution used in the present invention is such, a kind of 3, and 6-dichloro-2-pyridyl carboxylic acid
Preparation method, specifically include following steps:
A) by raw material 2,3,6-trichloropyridines are dissolved in solvent acetic acid, and add catalyst, and after intensification, dropping hydrogen peroxide is carried out
Oxidation reaction, after having reacted, filters catalyst, concentrates precipitation, obtain 2,3,6-trichloropyridine nitrogen oxides；
B) by gained 2,3,6-trichloropyridine nitrogen oxides are dissolved in solvent DMF, add Cyanogran. intensification and carry out cyanogenation,
After having reacted, precipitation is steamed in rotation, and ethyl alcohol recrystallization obtains 2-cyano-3,6-dichloropyridine nitrogen oxides；
C) gained 2-cyano-3,6-dichloropyridine nitrogen oxides is mixed with Phosphorous chloride., heat up and carry out deoxygenation, instead
After having answered, the Phosphorous chloride. of removing excess, residue adds in frozen water, separates out solid, filter to obtain 2-cyano group-3,6-dichloro pyrrole
Pyridine；
D) being added to the alkaline solution of ethanol by gained 2-cyano-3,6-dichloropyridine, be hydrolyzed reaction, has reacted
After, adjust system pH to 2-3, precipitation crystallizes to obtain end product clopyralid.
Reaction scheme is as follows:
A) in step, the consumption of described acetic acid and 3-7 times of raw material 2,3,6-trichloropyridine quality, it is preferable that acetic acid
3-5 times of consumption and raw material 2,3,6-trichloropyridine quality.
A) in step, described catalyst is molybdenum sesquioxide or wolframic acid, and consumption is raw material 2,3,6-trichloropyridine quality
1%-10%, the preferably consumption of catalyst is raw material 2, the 3-7% of 3,6-trichloropyridine quality.
A) in step, the consumption of described hydrogen peroxide is raw material 2, and 1.0-1.5 times of the amount of 3,6-trichloropyridine materials is excellent
Selection of land, the consumption of hydrogen peroxide is raw material 2,1.1-1.3 times of the amount of 3,6-trichloropyridine materials.
A) in step, it is warming up to 60-80 DEG C, carries out oxidation reaction.
B), in step, the consumption of described DMF is 2-5 times of 2,3,6-trichloropyridine nitrogen oxide masses, it is preferable that
The consumption of DMF is 3-4 times of 2,3,6-trichloropyridine nitrogen oxide mass.
B), in step, the consumption of described Cyanogran. is the 1.0-1.5 of the amount of 2,3,6-trichloropyridine nitrogen oxides materials
Times, it is preferable that the consumption of Cyanogran. is 1.1-1.3 times of the amount of 2,3,6-trichloropyridine nitrogen oxides materials.
B) in step, it is warming up to 80-120 DEG C, carries out cyanogenation.
C), in step, the consumption of described Phosphorous chloride. is 3-10 times of 2,3,6-trichloropyridine nitrogen oxide masses, excellent
Selection of land, the consumption of Phosphorous chloride. is 4-8 times of 2-cyano-3,6-dichloropyridine nitrogen oxide mass.
C), in step, intensification 60-80 DEG C carries out deoxygenation.
D), in step, the alkaline solution of described ethanol is that the potassium hydroxide of the sodium hydroxide solution of ethanol or ethanol is molten
The consumption of liquid, sodium hydroxide or potassium hydroxide is 2.1-2.5 times of the amount of 2-cyano-3,6-dichloropyridine material, it is preferable that hydrogen
The consumption of sodium oxide or potassium hydroxide is 2.1-2.3 times of the amount of 2,3,6-trichloropyridine nitrogen oxides material.
Beneficial effect: main advantage of the present invention is 2,3,6-trichloropyridines are aoxidized by nitrogen so that the nucleophilic of pyridine 2-position
Ability becomes strong, and chlorine is easier to leave away, and encompassing easily reacts with Cyanogran., and response speed is fast and yield is high；It addition, nitrogen oxidation, cyaniding
Reaction dissolvent is organic solvent, recyclable, does not produce brine waste.
Detailed description of the invention
In order to deepen the understanding of the present invention, below in conjunction with embodiment, the invention will be further described, this embodiment
It is only used for explaining the present invention, is not intended that limiting the scope of the present invention.
Embodiment 1
The synthesis of 1.2,3,6-trichloropyridine nitrogen oxides
18.4g (0.1mol) 2,3,6-trichloropyridine is dissolved in 70g glacial acetic acid and adds molybdenum trioxide 0.54g, is warming up to 80
DEG C, it being slowly added dropwise hydrogen peroxide (30%) 13.6g (0.12mol), fully react, liquid spectrum is controlled, reaction terminates, filtering catalyst,
Filtrate concentration and recovery acetic acid, obtains 2,3,6-trichloropyridine nitrogen oxides 18.2g, yield 90%.
The synthesis of 2.2-cyano group-3,6-dichloropyridine nitrogen oxides
Take step 1 method and prepare gained 2,3,6-trichloropyridines nitrogen oxides 20.0g (0.1mol), be dissolved in 40.0g DMF,
Adding Cyanogran. 5.9g (0.12mol), be warming up to 80-90 DEG C, fully react, control in liquid spectrum, reaction terminates, after precipitation is steamed in rotation,
With
Ethyl alcohol recrystallization, gained crystal, again through 20ml washing with alcohol, obtains 2-cyano-3,6-dichloropyridine nitrogen oxides
17.6g, yield 92.1%.
The synthesis of 3.2-cyano group-3,6-dichloropyridine
Take 2-cyano-3,6-dichloropyridine nitrogen oxides 20.1g (0.1mol) prepared by step 2 method, with Phosphorous chloride.
78g mixes, and is warming up to 75 DEG C, fully reacts, and controls in liquid spectrum, and reaction terminates, and after the Phosphorous chloride. of removing excess, is added by residue
In frozen water, stirring separates out solid, filters, and solid use water rinses, stand-by, quantitative yield 90.4%.
4. the synthesis of end product clopyralid
Take 2-cyano group-3,6-dichloropyridine wet product (water content 20.1wt%) 21.6g prepared by step 3 method
(0.1mol), join in 60g ethanol, and in system, add 8.4g (0.21mol) sodium hydroxide, be warming up to backflow, fully
Reaction, controls in liquid spectrum, and reaction terminates, and lowers the temperature, adds 30g water, adjust pH to 2-3, be sufficiently stirred for crystallization, mistake after removing part ethanol
Filter, solid water fully rinses, and solid dries to obtain 18.2g, yield 94.8%.
Embodiment 2
The synthesis of 1.2,3,6-trichloropyridine nitrogen oxides
36.8g (0.2mol) 2,3,6-trichloropyridine is dissolved in 145g glacial acetic acid and adds molybdenum trioxide 2.2g, is warming up to 80
DEG C, it being slowly added dropwise hydrogen peroxide (50%) 17.7g (0.26mol), fully react, liquid spectrum is controlled, reaction terminates, filtering catalyst,
Filtrate concentration and recovery acetic acid, obtains 2,3,6-trichloropyridine nitrogen oxides 34.6g, yield 85.5%.
The synthesis of 2.2-cyano group-3,6-dichloropyridine nitrogen oxides
Take step 1 method and prepare gained 2,3,6-trichloropyridines nitrogen oxides 40.0g (0.2mol), be dissolved in 150.5g
DMF, adds Cyanogran. 12.7g (0.26mol), is warming up to 80-90 DEG C, fully reacts, and controls in liquid spectrum, and reaction terminates, and rotation is steamed de-
After molten, with ethyl alcohol recrystallization, gained crystal, through 50ml washing with alcohol, obtains 2-cyano-3,6-dichloropyridine nitrogen oxides
34.5g, yield 90.3%.
The synthesis of 3.2-cyano group-3,6-dichloropyridine
Take 2-cyano-3,6-dichloropyridine nitrogen oxides 40.3g (0.2mol) prepared by step 2 method, with Phosphorous chloride.
240g, is warming up to 75 DEG C, fully reacts, and controls in liquid spectrum, and reaction terminates, and after the Phosphorous chloride. of removing excess, is added to by residue
In frozen water, stirring separates out solid, filters, and solid use water rinses, stand-by, quantitative yield 91.5%.
4. the synthesis of end product clopyralid
Take 2-cyano-3,6-dichloropyridine wet product (water content 22.5%) 44.6g (0.2mol) prepared by step 3 method,
Join in 130g ethanol, and in system, add 18.5g (0.46mol) sodium hydroxide, be warming up to backflow, fully react, liquid
Controlling in spectrum, reaction terminates, and lowers the temperature, adds 50g water, adjust pH to 2-3, be sufficiently stirred for crystallization, filter after removing part ethanol, and solid is used
Water fully rinses, and solid dries to obtain 35.7g, yield 92.9%.
Embodiment 3
The synthesis of 1.2,3,6-trichloropyridine nitrogen oxides
73.6g (0.4mol) 2,3,6-trichloropyridine is dissolved in 300g glacial acetic acid and adds molybdenum trioxide 2.3g, is warming up to 80
DEG C, it being slowly added dropwise hydrogen peroxide (50%) 29.9g (0.44mol), fully react, liquid spectrum is controlled, reaction terminates, filtering catalyst,
Filtrate concentration and recovery acetic acid, obtains 2,3,6-trichloropyridine nitrogen oxides 70.1g, yield 85.6%.
The synthesis of 2.2-cyano group-3,6-dichloropyridine nitrogen oxides
Take step 1 method and prepare gained 2,3,6-trichloropyridines nitrogen oxides 80.0g (0.4mol), be dissolved in 300.0g
DMF, adds Cyanogran. 21.6g (0.44mol), is warming up to 80-90 DEG C, fully reacts, and controls in liquid spectrum, and reaction terminates, and rotation is steamed de-
After molten, by ethyl alcohol recrystallization, gained crystal 100ml washing with alcohol, obtain 2-cyano-3,6-dichloropyridine nitrogen oxides
67.6g, yield 88.5%.
The synthesis of 3.2-cyano group-3,6-dichloropyridine
Take 2-cyano-3,6-dichloropyridine nitrogen oxides 80.5g (0.4mol) prepared by step 2 method, with Phosphorous chloride.
300g, is warming up to 75 DEG C, fully reacts, and controls in liquid spectrum, and reaction terminates, and after the Phosphorous chloride. of removing excess, is added to by residue
In frozen water, stirring separates out solid, filters, and solid use water rinses, stand-by, quantitative yield 90.4%.
4. the synthesis of end product clopyralid
Take 2-cyano-3,6-dichloropyridine wet product (water content 20.5%) 87.1g (0.4mol) prepared by step 3 method,
Join in 250g ethanol, and in system, add 33.6g (0.84mol) sodium hydroxide, be warming up to backflow, fully react, liquid
Controlling in spectrum, reaction terminates, and lowers the temperature, adds 100g water, adjust pH to 2-3, be sufficiently stirred for crystallization, filter, solid after removing part ethanol
Fully rinsing with water, solid dries to obtain 60.2g, yield 91.1%.
The foregoing is only presently preferred embodiments of the present invention, not in order to limit the present invention, all essences in the present invention
Within god and principle, any modification, equivalent substitution and improvement etc. made, should be included within the scope of the present invention.
Claims (8)
1. one kind 3, the preparation method of 6-dichloro-2-pyridyl carboxylic acid, it is characterised in that specifically include following steps:
A) by raw material 2,3,6-trichloropyridines are dissolved in solvent acetic acid, and add catalyst, and after intensification, dropping hydrogen peroxide aoxidizes
Reaction, after having reacted, filters catalyst, concentrates precipitation, obtain 2,3,6-trichloropyridine nitrogen oxides；
B) by gained 2,3,6-trichloropyridine nitrogen oxides are dissolved in solvent DMF, add Cyanogran. intensification and carry out cyanogenation, reaction
After complete, precipitation is steamed in rotation, and ethyl alcohol recrystallization obtains 2-cyano-3,6-dichloropyridine nitrogen oxides；
C) gained 2-cyano-3,6-dichloropyridine nitrogen oxides is mixed with Phosphorous chloride., heat up and carry out deoxygenation, reacted
After, precipitation, residue adds in frozen water, separates out solid, filter to obtain 2-cyano-3,6-dichloropyridine；
D) being added to the alkaline solution of ethanol by gained 2-cyano-3,6-dichloropyridine, be hydrolyzed reaction, after having reacted,
Adjusting system pH to 2-3, precipitation crystallizes to obtain end product clopyralid.
The preparation method of the most according to claim 1 a kind of 3,6-dichloro-2-pyridyl carboxylic acid, it is characterised in that a) step
In, the consumption of described acetic acid and 4-7 times of raw material 2,3,6-trichloropyridine quality.
The preparation method of the most according to claim 1 a kind of 3,6-dichloro-2-pyridyl carboxylic acid, it is characterised in that a) step
In, described catalyst is molybdenum sesquioxide or wolframic acid, and consumption is raw material 2, the 1%-10% of 3,6-trichloropyridine quality.
The preparation method of the most according to claim 1 a kind of 3,6-dichloro-2-pyridyl carboxylic acid, it is characterised in that a) step
In, the consumption of described hydrogen peroxide is raw material 2,1.0-1.5 times of the amount of 3,6-trichloropyridine materials.
The preparation method of the most according to claim 1 a kind of 3,6-dichloro-2-pyridyl carboxylic acid, it is characterised in that b) step
In, the consumption of described DMF is 2-5 times of 2,3,6-trichloropyridine nitrogen oxide masses.
The preparation method of the most according to claim 1 a kind of 3,6-dichloro-2-pyridyl carboxylic acid, it is characterised in that b) step
In, the consumption of described Cyanogran. is 1.0-1.5 times of the amount of 2,3,6-trichloropyridine nitrogen oxides materials.
The preparation method of the most according to claim 1 a kind of 3,6-dichloro-2-pyridyl carboxylic acid, it is characterised in that c) step
In, the consumption of described Phosphorous chloride. is 3-10 times of 2-cyano-3,6-dichloropyridine nitrogen oxide mass.
The preparation method of the most according to claim 1 a kind of 3,6-dichloro-2-pyridyl carboxylic acid, it is characterised in that d) step
In, the consumption of described sodium hydroxide is 2.1-2.5 times of the amount of 2-cyano-3,6-dichloropyridine material.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112110853A (en) * | 2020-09-23 | 2020-12-22 | 海南梵圣生物科技有限公司 | Method for synthesizing 3-hydroxy-2-picolinic acid and derivatives thereof |
| CN113912533A (en) * | 2021-11-23 | 2022-01-11 | 西安凯立新材料股份有限公司 | Method for preparing 3, 6-dichloropicolinic acid |
| CN115093399A (en) * | 2022-07-29 | 2022-09-23 | 武汉工程大学 | Preparation method of anti-gout drug topiroxostat |
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| CN113912533A (en) * | 2021-11-23 | 2022-01-11 | 西安凯立新材料股份有限公司 | Method for preparing 3, 6-dichloropicolinic acid |
| CN115093399A (en) * | 2022-07-29 | 2022-09-23 | 武汉工程大学 | Preparation method of anti-gout drug topiroxostat |
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| CN106243027B (en) | 2019-03-05 |
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