CN109384714B - Process for recovering and process for producing substituted or unsubstituted 2, 3-pyridinedicarboxylic acid - Google Patents
Process for recovering and process for producing substituted or unsubstituted 2, 3-pyridinedicarboxylic acid Download PDFInfo
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- CN109384714B CN109384714B CN201710653039.7A CN201710653039A CN109384714B CN 109384714 B CN109384714 B CN 109384714B CN 201710653039 A CN201710653039 A CN 201710653039A CN 109384714 B CN109384714 B CN 109384714B
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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
- C07D213/80—Acids; Esters in position 3
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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
Abstract
The invention relates to the field of dipicolinic acid, and discloses a recovery method and a production method of substituted or unsubstituted 2, 3-dipicolinic acid. The recovery method comprises the following steps: (1) adding an extraction liquid into a solution containing substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I) for extraction to obtain a raffinate phase and an extract phase; (2) adding alkali liquor into the extraction phase to adjust the extraction phase to be alkaline, and then carrying out oil-water separation to obtain an organic phase and an aqueous phase containing substituted or unsubstituted 2, 3-pyridine dicarboxylic acid salt; (3) adding an acid solution to the aqueous phase to adjust the aqueous phase to acidity, then standing for layering and filtering to obtain a substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I), wherein in formula (1), R1、R2、R3Each independently is H, C1‑C4Alkyl radical, C1‑C4Alkoxy, halogen, hydroxy, nitro or amino. The recovery method of the invention can greatly improve the recovery rate, has better extraction effect, is simple and easy to implement, is beneficial to industrial production,
Description
Technical Field
The invention relates to the field of dipicolinic acid, in particular to a method for recovering and producing substituted or unsubstituted 2, 3-dipicolinic acid.
Background
The substituted or unsubstituted 2, 3-pyridinedicarboxylic acid intermediate is an important intermediate for synthesizing imidazolinone pesticides, the imidazolinone pesticides are imidazolinone herbicides containing pyridine ring, the action mechanism of the imidazolinone herbicides is mainly to inhibit the activity of Acetohydroxy Acid Synthetase (AHAs), influence the biosynthesis of three branched chain amino acids, valine, leucine and isoleucine, and finally destroy the synthesis of protein, and interfere the DNA synthesis and cell division and growth. The herbicide can effectively prevent and control most annual gramineous and broadleaf weeds, such as wild oat, barnyard grass, green bristlegrass, gold green bristlegrass, alopecurus, and the like.
The compound with a substituted or unsubstituted 2, 3-pyridinedicarboxylic acid structure is a key intermediate for synthesizing imidazolone pesticides, such as 2, 3-pyridinedicarboxylic acid, 5-methyl-2, 3-pyridinedicarboxylic acid, 5-ethyl-2, 3-pyridinedicarboxylic acid, 5-methoxymethyl-2, 3-pyridinedicarboxylic acid, and the molecular structure formula of the compound is as follows:
wherein, in the formula (I), R1、R2、R3Each independently is H, C1-C4Alkyl radical, C1-C4Alkoxy, halogen, hydroxy, nitro or amino.
At present, the synthesis method of 2, 3-pyridinedicarboxylic acid mainly uses quinoline or 8-hydroxyquinoline as raw material, and adopts oxidant such as: potassium permanganate, hydrogen peroxide, ozone, sodium chlorate, oxygen and the like are oxidized, or an oxidation method using 2, 3-dialdehyde pyridine or 2-methyl-3-carboxyl pyridine as raw materials is adopted, the product obtained after oxidation is a copper complex or sodium salt of dipicolinic acid, and the product is obtained after alkaline hydrolysis and acidification of the copper complex.
The synthesis method of the 5-methyl-2, 3-pyridinedicarboxylic acid mainly comprises the following steps:
5-methyl-8-hydroxyquinoline quine is used as a raw material, and the oxidation is carried out by a method similar to that of 2, 3-dipicolinic acid to obtain the 5-methyl-2, 3-dipicolinic acid.
US5227491 discloses the condensation of 2-methyl-acrylaldoxime with an amino maleate or a mixture thereof to obtain a 5-methyl-pyridine diester, followed by alkaline hydrolysis to obtain 5-methyl-2, 3-pyridinedicarboxylic acid.
US4723011 and EP0965589 disclose the closed-loop synthesis of 5-ethyl-pyridine diesters from ethylacrolein with 2-chloro-3-oxosuccinic acid diesters in the presence of ammonium salts, followed by alkaline hydrolysis to 5-methyl-2, 3-pyridinedicarboxylic acid.
US4723011 and EP0965589 disclose the synthesis of 5-ethyl-2, 3-pyridinedicarboxylic acid, which is obtained by ring closure synthesis of 5-ethyl-pyridine diester from methacrolein and 2-chloro-3-oxosuccinic acid diester in the presence of ammonium salt, followed by alkaline hydrolysis acidification.
The synthesis method of the 5-methoxymethyl-2, 3-pyridinedicarboxylic acid mainly comprises the following steps:
US5760239A and EP0548532a1 disclose 5-methoxymethyl-2, 3-pyridinedicarboxylic acid obtained by halogenating, salifying, hydrolyzing, methoxylating, and acidifying 5-methyl-2, 3-pyridinedicarboxylic acid as a raw material.
US5281713A discloses the use of 5-methoxymethyl-8-hydroxyquinolinoquine as a starting material for oxidation by a process similar to that for 2, 3-pyridinedicarboxylic acid, followed by acidification to give 5-methoxymethyl-2, 3-pyridinedicarboxylic acid.
The industrial preparation method of 2, 3-pyridine carboxylic acid compounds is characterized by that firstly obtaining sodium carboxylate of product, then making acidification and filtration to obtain target product, according to the difference of substituted group the yield of hydrolyzed acidified product is 70-85%. 2, 3-pyridinedicarboxylic acid still remains in the filtered filtrate, and if the filtrate is directly discharged as waste liquid, the treatment mode is not environment-friendly and causes a great deal of waste.
At present, a large amount of strong polar organic solvents such as n-butanol and n-octanol are industrially adopted to extract and recover 2, 3-pyridine carboxylic acid in filtrate, the method needs a large amount of alcohols as the extraction solvent, and the used alcohols are partially soluble in water, so that the cost is increased, the difficulty in treating wastewater is increased, and the recovery rate is not ideal and is only about 40% when the method is adopted to extract and recover pyridine diacid. Moreover, the problem of incomplete extraction often occurs in the industrial production process, and the wastewater still contains a large amount of organic matters, namely the content of the 2, 3-pyridinedicarboxylic acid is still high and reaches up to 7 percent.
JP03101661 discloses the catalytic synthesis of 2, 3-pyridinedicarboxylic acid using anhydrous copper sulfate and the recovery of residual pyridinedicarboxylic acid compounds in the filtrate by means of a metal complex formed by copper sulfate and pyridinecarboxylic acid. The total yield of the product is only 76 percent by adopting the method, and the used copper sulfate is completely converted into copper oxide and can not be recycled, so that the recovery cost is higher and the operation process is more complex.
In conclusion, the existing recovery method of substituted or unsubstituted 2, 3-pyridinedicarboxylic acid has the problems of low recovery rate, high recovery cost, complex operation process, poor extraction effect and increased difficulty in wastewater treatment due to the introduction of heavy metal copper. Further, there is no process which combines the industrial production of substituted or unsubstituted 2, 3-pyridinedicarboxylic acids with a low-cost, simple recovery method.
Disclosure of Invention
The invention aims to provide a recovery method and a production method of substituted or unsubstituted 2, 3-pyridinedicarboxylic acid, aiming at overcoming the problems that the recovery rate of substituted or unsubstituted 2, 3-pyridinedicarboxylic acid is low, the recovery cost is high, the operation process is complex, the extraction effect is poor, the introduction of heavy metal copper increases the difficulty of wastewater treatment, and a reasonable and low-cost recovery method is not combined in the industrial production process. By the production method of the present invention, the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid remaining in the filtrate can be recovered sufficiently at low cost.
In order to achieve the above object, the present invention provides a method for recovering substituted or unsubstituted 2, 3-pyridinedicarboxylic acid, wherein the method comprises the steps of:
(1) adding an extraction liquid into a solution containing substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I) for extraction to obtain a raffinate phase and an extract phase;
(2) adding alkali liquor into the extraction phase to adjust the extraction phase to be alkaline, and then carrying out oil-water separation to obtain an organic phase and an aqueous phase containing substituted or unsubstituted 2, 3-pyridine dicarboxylic acid salt;
(3) adding an acid solution into the aqueous phase to adjust the aqueous phase to acidity, then standing for layering and filtering to obtain the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by the formula (I),
wherein, in the formula (1), R1、R2、R3Each independently is H, C1-C4Alkyl radical, C1-C4Alkoxy, halogen, hydroxy, nitro or amino.
Preferably, the method further comprises: adding a solution containing a substituted or unsubstituted 2, 3-pyridinedicarboxylate salt to the extraction phase before adding the lye to the extraction phase in step (3).
In a second aspect, the present invention provides a process for producing a substituted or unsubstituted 2, 3-pyridinedicarboxylic acid, comprising the steps of:
(A) adding an alkali solution to a solution containing substituted or unsubstituted ethyl 2, 3-pyridinedicarboxylate to form a solution containing substituted or unsubstituted 2, 3-pyridinedicarboxylate;
(B) adding an acid solution to the obtained solution containing the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid salt, and filtering to obtain a product cake and a filtrate, wherein the filtrate contains the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I);
(C) adding an extraction liquid into the obtained filtrate for extraction to obtain a raffinate phase and an extract phase;
(D) adding alkali liquor into the extraction phase to adjust the extraction phase to be alkaline, and then carrying out oil-water separation to obtain an organic phase and an aqueous phase containing substituted or unsubstituted 2, 3-pyridine dicarboxylic acid salt;
(E) adding an acid solution into the aqueous phase to adjust the aqueous phase to acidity, then standing for layering and filtering to obtain the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by the formula (I),
wherein, in the formula (I), R1、R2、R3Each independently is H, C1-C4Alkyl radical, C1-C4Alkoxy, halogen, hydroxy, nitro or amino.
Preferably, the method further comprises: adding a solution containing a substituted or unsubstituted 2, 3-pyridinedicarboxylate salt to the extraction phase before adding the lye to the extraction phase in step (D).
The method for recovering the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid can greatly improve the recovery rate, has good extraction effect, and can effectively reduce the content of organic matters in the wastewater. The recovery method is simple and easy to implement, and the extracted wastewater can be directly discharged without biochemical treatment.
The production method can fully recover the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid in the waste liquid, has simple and convenient process method and low cost, and is easy for industrial production.
Drawings
FIG. 1 is a schematic diagram of a process for the recovery of substituted or unsubstituted 2, 3-pyridinedicarboxylic acids according to the present invention;
FIG. 2 is a schematic diagram of the process of the present invention for producing substituted or unsubstituted 2, 3-pyridinedicarboxylic acids.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
The present invention provides a method for recovering substituted or unsubstituted 2, 3-pyridinedicarboxylic acid, as shown in fig. 1, wherein the method comprises the following steps:
(1) adding an extraction liquid into a solution containing substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I) for extraction to obtain a raffinate phase and an extract phase;
(2) adding alkali liquor into the extraction phase to adjust the extraction phase to be alkaline, and then carrying out oil-water separation to obtain an organic phase and an aqueous phase containing substituted or unsubstituted 2, 3-pyridine dicarboxylic acid salt;
(3) adding an acid solution into the aqueous phase to adjust the aqueous phase to acidity, then standing for layering and filtering to obtain the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by the formula (I),
wherein, in the formula (1), R1、R2、R3Each independently is H, C1-C4Alkyl radical, C1-C4Alkoxy radicalHalogen, hydroxy, nitro or amino.
In the present invention, the solution containing the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I) may be waste water containing the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid.
In the present invention, an extraction liquid is used to extract a substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I) from a solution (waste water) containing the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I), and the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid is separated from the solution by complexing the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid with an extraction agent. The extraction liquid comprises an extracting agent and a diluting solvent.
In the invention, the weight percentage of the extractant is 5-35%, preferably 15-20% based on the total weight of the extraction liquid.
In the present invention, in step (1), the molar ratio of the solution containing the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I) to the extractant is 1: (0.5-10).
In the present invention, the extractant may be: trialkylamines and/or trialkylphosphine oxides.
In the present invention, the trialkylamine may be, but is not limited to: tri-n-octylamine, tri-tert-butylamine, trihexylamine, tri-n-pentylamine, tri-n-heptylamine, tri-n-nonylamine, tri-undecylamine, tri-dodecylamine, and tri-tetradecylamine.
In the present invention, the trialkyl phosphine oxide may be, but is not limited to: at least one of trihexylphosphine, trioctylphosphine, triheptylphosphine, dihexyloctylphosphine oxide, dioctylhexylphosphine oxide, dipentylhexylphosphine oxide, dioctylheptylphosphine oxide, diheptylhexylphosphine oxide and diheptylnonylphosphine oxide.
In the present invention, the diluting solvent may be at least one of an ether, an alkane, a chlorine-containing solvent, and a benzene ring-containing solvent.
In the present invention, the ether is at least one selected from the group consisting of diethyl ether, ethylene glycol dimethyl ether, tetrahydrofuran, 1, 4-dioxane, 1, 2-dimethoxyethane, dioxane, and anisole.
In the present invention, the alkane is at least one selected from kerosene, petroleum ether, pentane, n-hexane, cyclohexane, octane, heptane and 1,2,3, 4-tetrahydronaphthalene.
In the present invention, the chlorine-containing solvent is at least one selected from the group consisting of methyl chloride, methylene chloride, chloroform, carbon tetrachloride, 1, 2-dichloroethane, 1-dichloroethane and chlorobenzene.
In the present invention, the benzene ring-containing solvent is at least one selected from the group consisting of benzene, toluene, monochlorobenzene, dichlorobenzene, trichlorobenzene, fluorobenzene, phenol and methylphenol.
In the invention, in the step (1), the raffinate phase is standard wastewater and can be directly discharged.
In the present invention, in step (2), the lye forms a substituted or unsubstituted 2, 3-pyridinedicarboxylic acid salt with the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid for transferring the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid in the extract phase from the extract phase (i.e., the organic phase) to the aqueous phase. The alkali solution may be an alkali solution conventional in the art, and may be, for example, at least one of a sodium hydroxide solution, a potassium hydroxide solution, a lithium hydroxide solution, a calcium hydroxide solution, a sodium carbonate solution, a calcium carbonate solution, and ammonia water.
In the present invention, in step (2), the pH of the alkalinity is 8 to 14, preferably 10 to 14.
In the present invention, in step (3), the acid solution is reacted with a substituted or unsubstituted 2, 3-pyridinedicarboxylic acid salt to produce a substituted or unsubstituted 2, 3-pyridinedicarboxylic acid, where the acid solution is used for acidification to form a substituted or unsubstituted 2, 3-pyridinedicarboxylic acid, i.e., a target product. The acid solution may be hydrochloric acid, sulfuric acid, phosphoric acid or hydrobromic acid, etc. which are conventional in the art.
In the present invention, in step (3), the acidic pH is 0.5 to 2.4, preferably 0.5 to 1.1.
In a preferred embodiment of the present invention, as shown in the dashed box in fig. 1, the method further comprises: adding a solution containing a substituted or unsubstituted 2, 3-pyridinedicarboxylate salt to the extraction phase before adding the lye to the extraction phase in step (3). Wherein the solution containing the substituted or unsubstituted 2, 3-pyridinedicarboxylate can be obtained by reacting an alkali solution with a substituted or unsubstituted ethyl 2, 3-pyridinedicarboxylate solution, and can be a raw material (substituted or unsubstituted 2, 3-pyridinedicarboxylate) for the next batch production. For example, each time the next batch of raw material is used, the solution of the batch in which the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid remains is combined with the next batch of raw material, and the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid remaining in the filtrate can be recovered sufficiently and inexpensively. Preferably, the concentration of the solution containing the substituted or unsubstituted 2, 3-pyridinedicarboxylate is 10 to 60%, preferably 10 to 40%, more preferably 30 to 40%.
In the present invention, in step (3), an acid solution is added to the aqueous phase to adjust to acidity, followed by standing for layer separation and filtration to obtain a substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I) (product cake, i.e., target product), and a solution (waste water) containing a substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I).
In a preferred case, the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by the formula (I) is 2, 3-pyridinedicarboxylic acid, 5-methyl-2, 3-pyridinedicarboxylic acid, 5-ethyl-2, 3-pyridinedicarboxylic acid, 5-methoxymethyl-2, 3-pyridinedicarboxylic acid,
in a second aspect, the present invention provides a process for producing a substituted or unsubstituted 2, 3-pyridinedicarboxylic acid, as shown in FIG. 2, comprising the steps of:
(A) adding an alkali solution to a solution containing substituted or unsubstituted ethyl 2, 3-pyridinedicarboxylate to form a solution containing substituted or unsubstituted 2, 3-pyridinedicarboxylate;
(B) adding an acid solution to the obtained solution containing the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid salt, and filtering to obtain a product cake and a filtrate, wherein the filtrate contains the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I);
(C) adding an extraction liquid into the obtained filtrate for extraction to obtain a raffinate phase and an extract phase;
(D) adding alkali liquor into the extraction phase to adjust the extraction phase to be alkaline, and then carrying out oil-water separation to obtain an organic phase and an aqueous phase containing substituted or unsubstituted 2, 3-pyridine dicarboxylic acid salt;
(E) adding an acid solution into the aqueous phase to adjust the aqueous phase to acidity, then standing for layering and filtering to obtain the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by the formula (I),
wherein, in the formula (1), R1、R2、R3Each independently is H, C1-C4Alkyl radical, C1-C4Alkoxy, halogen, hydroxy, nitro or amino.
In the present invention, the product cake contains a substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by the formula (I), which is the objective product.
In the present invention, the filtrate refers to a solution (waste water) containing substituted or unsubstituted 2, 3-pyridinedicarboxylic acid produced after the end of the batch production.
In the invention, in the step (C), the raffinate phase is standard wastewater and can be directly discharged.
In the present invention, in a preferred embodiment of the present invention, as shown by the upper left dashed box in fig. 2, the method further comprises: adding a solution containing a substituted or unsubstituted 2, 3-pyridinedicarboxylate salt to the extraction phase before adding the lye to the extraction phase in step (D). Wherein the solution containing the substituted or unsubstituted 2, 3-pyridinedicarboxylate can be obtained by reacting an alkali solution with a substituted or unsubstituted ethyl 2, 3-pyridinedicarboxylate solution, and can be a raw material (substituted or unsubstituted 2, 3-pyridinedicarboxylate) for the next batch production. For example, each time the next batch of raw material is used, the solution of the batch in which the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid remains is combined with the next batch of raw material, and the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid remaining in the filtrate can be recovered sufficiently and inexpensively. Preferably, the concentration of the solution containing the substituted or unsubstituted 2, 3-pyridinedicarboxylate is 10 to 60%, preferably 10 to 40%, more preferably 30 to 40%.
In a preferred case, the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by the formula (I) is 2, 3-pyridinedicarboxylic acid, 5-methyl-2, 3-pyridinedicarboxylic acid, 5-ethyl-2, 3-pyridinedicarboxylic acid, 5-methoxymethyl-2, 3-pyridinedicarboxylic acid,
in the present invention, as shown by the dotted line box at the lower right of FIG. 2, the solution (waste water) containing the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by the formula (I) may be subjected to step C, D, E again, i.e., the steps of addition of an extractant, addition and subtraction, and addition of an acid, to realize industrial recycling.
In the present invention, in the step (A), the substituted or unsubstituted ethyl 2, 3-pyridinedicarboxylate solution and the alkali solution are added in such an amount that the substituted or unsubstituted 2, 3-pyridinedicarboxylate salt can be obtained.
In the present invention, in step (B), the acid solution is reacted with a substituted or unsubstituted 2, 3-pyridinedicarboxylic acid salt to produce a substituted or unsubstituted 2, 3-pyridinedicarboxylic acid, where the acid is used for acidification to form a substituted or unsubstituted 2, 3-pyridinedicarboxylic acid, i.e., the target product. The acid solution can be hydrochloric acid, sulfuric acid, phosphoric acid or hydrobromic acid and the like.
In the present invention, in step (B), the acidic pH is 0.5 to 2.4, preferably 0.5 to 1.1.
In the present invention, in step (B), preferably, the product cake is subjected to purification, for example: and (3) leaching with water, and drying to obtain the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid and a target product.
In the present invention, in step (C), an extraction liquid is used to extract the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I) from the filtrate containing the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I), and the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I) is separated from the filtrate by complexing the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I) with an extraction agent. The extraction liquid comprises an extracting agent and a diluting solvent.
In the present invention, in step (C), the extractant is contained in an amount of 5 to 35% by weight, preferably 15 to 20% by weight, based on the total weight of the extract.
In the present invention, in the step (C), the molar ratio of the solution containing the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by the formula (I) to the extractant is 1: (0.5-10).
In the present invention, in step (C), the extractant may be: trialkylamines and/or trialkylphosphine oxides.
In the present invention, the trialkylamine may be, but is not limited to: tri-n-octylamine, tri-tert-butylamine, trihexylamine, tri-n-pentylamine, tri-n-heptylamine, tri-n-nonylamine, tri-undecylamine, tri-dodecylamine, and tri-tetradecylamine.
In the present invention, the trialkyl phosphine oxide may be, but is not limited to: at least one of trihexylphosphine, trioctylphosphine, triheptylphosphine, dihexyloctylphosphine oxide, dioctylhexylphosphine oxide, dipentylhexylphosphine oxide, dioctylheptylphosphine oxide, diheptylhexylphosphine oxide and diheptylnonylphosphine oxide.
In the present invention, in the step (C), the diluting solvent may be at least one of an ether, an alkane, a chlorine-containing solvent and a benzene ring-containing solvent.
In the present invention, the ether is at least one selected from the group consisting of diethyl ether, ethylene glycol dimethyl ether, tetrahydrofuran, 1, 4-dioxane, 1, 2-dimethoxyethane, dioxane, and anisole.
In the present invention, the alkane is at least one selected from kerosene, petroleum ether, pentane, n-hexane, cyclohexane, octane, heptane and 1,2,3, 4-tetrahydronaphthalene.
In the present invention, the chlorine-containing solvent is at least one selected from the group consisting of methyl chloride, methylene chloride, chloroform, carbon tetrachloride, 1, 2-dichloroethane, 1-dichloroethane and chlorobenzene.
In the present invention, the benzene ring-containing solvent is at least one selected from the group consisting of benzene, toluene, monochlorobenzene, dichlorobenzene, trichlorobenzene, fluorobenzene, phenol and methylphenol.
In the present invention, in step (D), the lye forms a substituted or unsubstituted 2, 3-pyridinedicarboxylic acid salt with the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid for transferring the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid in the extract phase from the extract phase (i.e., the organic phase) to the aqueous phase. The alkali solution may be an alkali solution conventional in the art, and may be, for example, at least one of a sodium hydroxide solution, a potassium hydroxide solution, a lithium hydroxide solution, a calcium hydroxide solution, a sodium carbonate solution, a calcium carbonate solution, and ammonia water.
In the present invention, in step (D), the pH of the alkalinity is 8 to 14, preferably 10 to 14.
In the present invention, in step (E), the acid solution is reacted with a substituted or unsubstituted 2, 3-pyridinedicarboxylic acid salt to produce a substituted or unsubstituted 2, 3-pyridinedicarboxylic acid, where the acid solution is used for acidification to form a substituted or unsubstituted 2, 3-pyridinedicarboxylic acid, i.e., the target product. The acid solution may be an acid solution conventional in the art, and may be, for example, hydrochloric acid, sulfuric acid, phosphoric acid, hydrobromic acid, or the like.
In the present invention, in step (E), the acidic pH is 0.5 to 2.4, preferably 0.5 to 1.1.
In the present invention, in step (E), an acid solution is added to the aqueous phase to adjust to acidity, followed by standing for separation and filtration to obtain a substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I) (product cake, i.e., target product), and a solution (waste water) containing a substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I).
According to one embodiment of the present invention, the method for producing a substituted or unsubstituted 2, 3-pyridinedicarboxylic acid comprises the steps of:
(a) diluting the extractant to obtain an extract, adding the extract into a solution containing substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I), controlling the temperature at 20-100 ℃, heating to 40-100 ℃, stirring, and cooling to room temperature to obtain a raffinate phase and an extract phase containing a complex, wherein the raffinate phase can be directly discharged;
(b) adding the next batch of reaction liquid containing the substituted or unsubstituted 2, 3-pyridine dicarboxylic acid salt into the extraction phase containing the complex, then adding alkali liquor to adjust the pH to 8-14, and stirring for 0.5-3h at 10-60 ℃ to obtain an organic phase and an aqueous phase containing the substituted or unsubstituted 2, 3-pyridine dicarboxylic acid salt.
(c) Heating to 30-40 ℃, adding an acid solution into an aqueous phase containing substituted or unsubstituted 2, 3-pyridinedicarboxylic acid salt to adjust the pH value for the second time, adjusting the pH value to 0.5-2.4, cooling to 20-30 ℃, obtaining a precipitated solid and a solution containing substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I), filtering, collecting the precipitated solid, and purifying the precipitated solid to obtain substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I) (product filter cake, namely target product),
the purification comprises water leaching and drying.
Preferably, the organic phase obtained in step (b) is used as the extract in step (a) in the next secondary production process for recycling.
Preferably, the solution containing the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I) obtained in step (c) is subjected to repeated steps (a), (b) and (c), i.e., industrial recycling is realized.
Preferably, the content of the substituted or unsubstituted 2, 3-pyridinedicarboxylate in the reaction solution of the next batch containing the substituted or unsubstituted 2, 3-pyridinedicarboxylate is 10 to 60%, preferably 10 to 40%, more preferably 30 to 40%.
The invention uses the extracting agent of the invention to extract the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid from the waste water to obtain the complex compound, then adds alkali and acid. The method has the advantages of high recovery rate of the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid, easy operation, avoidance of heavy metal ions entering water body, and reduction of wastewater treatment difficulty.
The method realizes the recycling of the extracting agent, reduces the treatment difficulty of the waste water, is suitable for continuous production and is beneficial to industrial production.
The present invention will be described in further detail by way of examples, but the scope of the present invention is not limited thereto.
Preparation example 1
Preparation of the next batch of solution containing 5-methyl-2, 3-pyridinedicarboxylic acid sodium salt
147g (1.1mol) of 30% aqueous sodium hydroxide solution was added dropwise to a mixed solution of 122g (0.5mol) of ethyl 5-methyl-2, 3-pyridinedicarboxylate and 50g of water at room temperature, and after 2 hours of addition, the temperature was raised to 80 ℃ and the mixture was stirred for 3 hours while maintaining the temperature. The temperature was reduced to room temperature to obtain 220ml of 5-methyl-2, 3-pyridinedicarboxylic acid sodium salt, and the concentration of 5-methyl-2, 3-pyridinedicarboxylic acid sodium salt in the reaction solution was 35% as measured by an external standard method.
Preparation example 2
Preparation of the next batch of solution containing 5-ethyl-2, 3-pyridinedicarboxylic acid sodium salt
147g (1.1mol) of 30% sodium hydroxide aqueous solution is added dropwise into a mixed solution of 128.1g (0.5mol) of ethyl 5-ethyl-2, 3-pyridinedicarboxylate and 60g of water at room temperature, after 2h addition, the temperature is raised to 50 ℃, and stirring is carried out for 3h under heat preservation. Cooling to room temperature to obtain 248ml of 5-ethyl-2, 3-pyridinedicarboxylic acid sodium salt, wherein the concentration of the 5-ethyl-2, 3-pyridinedicarboxylic acid sodium salt in the reaction solution is 32% by external standard method.
Examples 1-4 are intended to illustrate the recovery process of the present invention.
Example 1
(1) Measurement of 5-methyl-2, 3-pyridinedicarboxylic acid content in solution (wastewater)
350ml of a solution containing 5-methyl-2, 3-pyridinedicarboxylic acid was prepared, and the content of 5-methyl-2, 3-pyridinedicarboxylic acid in the solution was 7.0% as measured by the external standard method.
(2) Recovering 2, 3-pyridinedicarboxylic acid in the solution
40g of trioctylphosphine oxide, 15g of dihexyloctylphosphine oxide and 30g of trihexylphosphine oxide were dissolved in 550ml of kerosene at room temperature to give 570ml of extract (containing 16.2% by weight of the extractant based on the total weight of the extract). 550ml of extract (the molar ratio of the waste water to the extractant is 1: 0.6) is added into 350ml of solution containing 5-methyl-2, 3-dipicolinic acid, the mixture is mixed and stirred, the temperature is raised to 50 ℃, the mixture is stirred for 2h, the temperature is reduced to room temperature, and the mixture is kept stand and layered to obtain 336ml of raffinate and 580ml of extract containing 5-methyl-2, 3-dipicolinic acid trialkyl phosphine oxide complex. The raffinate phase was analyzed by liquid chromatography (Agilent model LC1200) to determine that the content of 5-methyl-2, 3-pyridinedicarboxylic acid was 30ppm, the extraction recovery rate of 5-methyl-2, 3-pyridinedicarboxylic acid was 99%, and the aqueous phase could be directly discharged.
320g (35% concentration, preparation example 1) of the next reaction solution of 5-methyl-2, 3-pyridinedicarboxylic acid sodium salt was added to 580ml of the extract phase at room temperature, and after the addition, sodium hydroxide (30% concentration) was added dropwise, the pH was adjusted to 14, and the mixture was stirred at 20 ℃ for 2 hours, followed by oil-water separation to obtain 550ml of an organic phase and 356g of an aqueous solution containing 5-methyl-2, 3-pyridinedicarboxylic acid sodium salt. 550ml of extract is recovered and used as extract for the next batch production. 356g of an aqueous solution containing sodium 5-methyl-2, 3-pyridinedicarboxylate was heated to 40 ℃, sulfuric acid (30% concentration) was added to adjust the pH to 0.5, the mixture was allowed to stand for delamination and filtration, and the filter cake was rinsed with 50g of water to obtain 90.05g of 5-methyl-2, 3-pyridinedicarboxylic acid, which had a purity of 98% and a yield of 98% as measured by the external standard method. 352ml of a 2, 3-pyridinedicarboxylic acid solution (waste water) containing 5-methyl-2, 3-pyridinedicarboxylic acid was obtained, and the content of 5-methyl-2, 3-pyridinedicarboxylic acid was 6.9% as measured by the external standard method.
Example 2
(1) Measurement of 5-Ethyl-2, 3-pyridinedicarboxylic acid content in solution (wastewater)
390ml of a solution containing 5-ethyl-2, 3-pyridinedicarboxylic acid was prepared, and the content of 5-ethyl-2, 3-pyridinedicarboxylic acid in the wastewater was 8.6% as measured by the external standard method.
(2) Recovery of 2, 3-pyridinedicarboxylic acid from waste water
160g of trioctylamine were dissolved in 600ml of chlorobenzene at room temperature to give 750ml of extract. Adding 750ml of extraction liquid into 390ml of solution containing 5-ethyl-2, 3-pyridinedicarboxylic acid, mixing and stirring, heating to 80 ℃, stirring for 2 hours, cooling to room temperature, standing and layering to obtain 780ml of chlorobenzene solution of 5-ethyl-2, 3-pyridinedicarboxylic acid trioctylamine complex, analyzing the aqueous phase by using liquid chromatography to obtain that the content of 5-ethyl-2, 3-pyridinedicarboxylic acid is 45ppm, the extraction recovery rate of 5-ethyl-2, 3-pyridinedicarboxylic acid is 99 percent, and the aqueous phase can be directly discharged.
To 780ml of the extract phase was added 335g (32% concentration, preparation example 2) of the next batch of 5-ethyl-2, 3-pyridinedicarboxylic acid sodium salt solution at room temperature, and after the addition, 30% sodium hydroxide was added dropwise, the pH was adjusted to 10, and the mixture was stirred at 30 ℃ for 2 hours, followed by oil-water separation to obtain 750ml of an organic phase and 375g of a 5-ethyl-2, 3-pyridinedicarboxylic acid sodium salt-containing aqueous solution. 750ml of extract is recovered and used as extract for the next batch production. 375g of a brine solution containing 5-ethyl-2, 3-dipicolinic acid sodium salt is heated to 30 ℃, hydrochloric acid (with the concentration of 30%) is added to adjust the pH value to 1.1, the mixture is kept stand for layering and filtered, a filter cake is rinsed with 50g of water, 96.5g of 5-ethyl-2, 3-dipicolinic acid is obtained, the purity of the 5-ethyl-2, 3-dipicolinic acid is 99% and the yield is 98.3% as measured by an external standard method. 390ml of a solution (waste water) containing 5-ethyl-2, 3-pyridinedicarboxylic acid was obtained, and the content of 5-ethyl-2, 3-pyridinedicarboxylic acid was 8.4% as measured by the external standard method.
Example 3
The procedure of example 1 was followed, except that,
160g of trioctylamine dissolved in 600ml of chlorobenzene gave 750ml of extract which was replaced by 7g of trihexylphosphine oxide and 8g of dioctylheptylphosphine oxide dissolved in 240ml of toluene to give 260ml of extract (containing 5% by weight of the extractant, based on the total weight of the extract).
Instead of adding 550ml of extract (1: 0.6 molar ratio of solution to extractant) to 350ml of solution containing 5-methyl-2, 3-pyridinedicarboxylic acid, 250ml of extract (1: 0.5 molar ratio of solution to extractant) was added to 350ml of solution.
Sodium hydroxide (30% strength) was added dropwise and the pH adjustment to 14 was replaced by adding sodium hydroxide (40% strength) dropwise and the pH was adjusted to 8.
The addition of sulfuric acid (30% strength) to adjust the pH to 0.5 was replaced by the addition of sulfuric acid (20% strength) to adjust the pH to 0.9.
17g of 5-methyl-2, 3-pyridinedicarboxylic acid was obtained, and the purity of 5-methyl-2, 3-pyridinedicarboxylic acid measured by the external standard method was 98% and the yield was 92%. 330ml of 5-methyl-2, 3-pyridinedicarboxylic acid solution (wastewater) was obtained, and the content of 5-methyl-2, 3-pyridinedicarboxylic acid in the secondary wastewater was 4.5% as measured by the external standard method.
Example 4
The procedure of example 1 was followed, except that,
160g of trioctylamine dissolved in 600ml of chlorobenzene gave 750ml of extract which was replaced by 150g of tri-n-pentylamine and 46g of tri (tetradecyl) amine dissolved in 455ml of kerosene to give 580ml of extract (containing 35% by weight of the extractant, based on the total weight of the extract).
To 350ml of a solution containing 5-methyl-2, 3-pyridinedicarboxylic acid 550ml of extract (molar ratio of solution to extractant of 1: 0.6) was added instead of to 350ml of solution 560ml of extract (molar ratio of solution to extractant of 1: 10).
Sodium hydroxide (30% strength) was added dropwise and the pH adjustment to 14 was replaced by adding sodium hydroxide (30% strength) dropwise and the pH was adjusted to 10.
The addition of sulfuric acid (30% strength) to adjust the pH to 0.5 was replaced by the addition of sulfuric acid (30% strength) to adjust the pH to 2.4.
87g of 5-methyl-2, 3-pyridinedicarboxylic acid was obtained, and the purity of 5-methyl-2, 3-pyridinedicarboxylic acid measured by the external standard method was 98% and the yield was 96.5%. 317ml of 5-methyl-2, 3-pyridinedicarboxylic acid solution (wastewater) was obtained, and the content of 5-methyl-2, 3-pyridinedicarboxylic acid in the secondary wastewater was 4.7% as measured by the external standard method.
Example 5
(1) Measurement of 5-methyl-2, 3-pyridinedicarboxylic acid content in solution (wastewater)
350ml of a solution containing 5-methyl-2, 3-pyridinedicarboxylic acid was prepared, and the content of 5-methyl-2, 3-pyridinedicarboxylic acid in the solution was 7.0% as measured by the external standard method.
(2) Recovering 2, 3-pyridinedicarboxylic acid in the solution
40g of trioctylphosphine oxide, 15g of dihexyloctylphosphine oxide and 30g of trihexylphosphine oxide were dissolved in 550ml of kerosene at room temperature to give 570ml of extract (containing 16.2% by weight of the extractant based on the total weight of the extract). 550ml of extract (the molar ratio of the waste water to the extractant is 1: 0.6) is added into 350ml of solution containing 5-methyl-2, 3-dipicolinic acid, the mixture is mixed and stirred, the temperature is raised to 50 ℃, the mixture is stirred for 2h, the temperature is reduced to room temperature, and the mixture is kept stand and layered to obtain 336ml of raffinate and 580ml of extract containing 5-methyl-2, 3-dipicolinic acid trialkyl phosphine oxide complex. The raffinate phase was analyzed by liquid chromatography (Agilent model LC1200) to determine that the content of 5-methyl-2, 3-pyridinedicarboxylic acid was 30ppm, the extraction recovery rate of 5-methyl-2, 3-pyridinedicarboxylic acid was 99%, and the aqueous phase could be directly discharged.
Sodium hydroxide (30% strength) was added dropwise to 580ml of the extract phase at room temperature, the pH was adjusted to 14, and the mixture was stirred at 20 ℃ for 2 hours, followed by oil-water separation to obtain 550ml of an organic phase and 130g of an aqueous solution containing sodium 5-methyl-2, 3-pyridinedicarboxylate. 550ml of extract was recovered. 130g of a sodium salt aqueous solution containing 5-methyl-2, 3-pyridinedicarboxylic acid was heated to 40 ℃, sulfuric acid (30% concentration) was added to adjust the pH to 0.5, the mixture was allowed to stand for delamination and was filtered, and the filter cake was rinsed with 50g of water to obtain 21.0g of 5-methyl-2, 3-pyridinedicarboxylic acid, and the purity of 5-methyl-2, 3-pyridinedicarboxylic acid was 98% as measured by an external standard method, and the yield was 71.1%. 110ml of waste water is obtained, and the content of 5-methyl-2, 3-pyridinedicarboxylic acid is 6.6 percent by external standard method.
Comparative example 1
The procedure of example 1 was followed except that 85g of n-butanol was used as an extractant in place of 40g of trioctylphosphine oxide, 15g of dihexyloctylphosphine oxide and 30g of trihexylphosphine oxide in example 1.
The content of 5-methyl-2, 3-pyridinedicarboxylic acid was found to be 1.5%, and the extraction recovery of 5-methyl-2, 3-pyridinedicarboxylic acid was found to be 74%.
Comparative example 2
The procedure of example 1 was followed except that neither sodium hydroxide nor sulfuric acid was added dropwise after the addition of the extract.
With this method, 5-methyl-2, 3-pyridinedicarboxylic acid could not be obtained.
It can be seen from the results of comparative examples 1 and 2 that the content and yield of 5-methyl-2, 3-pyridinedicarboxylic acid were significantly lower than those of the extractant of the present invention if the extractant of the present invention was not used. Further, when the extraction agent of the present invention is used alone, the target product cannot be obtained without the steps of adding a base and an acid. The invention uses specific extractant and adds acid to fully recover the target product.
Production example 1
1) Preparation of 5-methyl-2, 3-pyridinedicarboxylic acid
At room temperature, 147g (1.1mol) of 30% sodium hydroxide aqueous solution is dripped into a mixed solution of 122g (0.5mol) of 5-methylpyridine-2, 3-dicarboxylic acid ethyl ester and 50g of water, the temperature is raised to 80 ℃ after 2h addition, the temperature is kept and the stirring is carried out for 3h, the reaction is finished, the concentration of 5-methylpyridine-2, 3-dicarboxylic acid sodium salt in the reaction solution is 35%, the temperature is lowered to 40 ℃, 30% sulfuric acid is slowly dripped into the reaction solution after 3h addition, the pH value is adjusted to 1.5, the filtration is carried out, a filter cake is rinsed by 50g of water, and the filter cake is dried to obtain 75.0g of 5-methyl-2, 3-pyridinedicarboxylic acid, the content is 98.5%, and the yield is 82%. 418g of a filtrate was obtained, in which the content of 5-methyl-2, 3-pyridinedicarboxylic acid was 7.0% and the volume of the filtrate was 350 ml.
2) Preparation of trialkylphosphine 5-methyl-2, 3-pyridinedicarboxylic acid complex
Dissolving 40g of trioctyl phosphine oxide, 15g of dihexyloctyl phosphine oxide and 30g of trihexyl phosphine oxide in 550ml of kerosene at room temperature to obtain 570ml of extract (based on the total weight of the extract, the weight percentage of the extractant is 16.2%), mixing 550ml of extract with 350ml of filtrate, stirring, heating to 50 ℃, stirring for 2h, cooling to room temperature, standing and layering to obtain 580ml of kerosene solution of 5-methylpyridine-2, 3-dicarboxylic acid trialkyl phosphine oxide complex, wherein the content of 5-methylpyridine-2, 3-dicarboxylic acid is 30ppm in aqueous phase analysis, and the extraction recovery rate of 5-methyl-2, 3-pyridinedicarboxylic acid is more than 99%.
3) Dissociating and recovering 5-methyl-2, 3-pyridinedicarboxylic acid trialkyl phosphine oxide complex
At room temperature, 580ml of kerosene solution of 5-methyl-2, 3-pyridinedicarboxylic acid trialkyl phosphine oxide complex is added into 320g (the concentration is 35%) of 5-methylpyridine-2, 3-dicarboxylic acid sodium salt solution of the next batch, 30% of sodium hydroxide is dripped after the addition is finished, the pH is adjusted to 14, the stirring is carried out for 2h, oil-water separation is carried out, 550ml of extractant solution is recovered, and the extractant solution is used for complexing extraction of the acidification filtrate of the next batch. 356g of 5-methyl-2, 3-pyridinedicarboxylic acid sodium salt aqueous solution is obtained, the temperature is increased to 40 ℃, the pH value is adjusted to 1.5 by acidification, the mixture is kept stand, layered and filtered, and a filter cake is leached by 50g of water, the content of 5-methyl-2, 3-pyridinedicarboxylic acid is 90.05g, the yield is 98 percent. 422g of filtrate was obtained, wherein the content of 5-methyl-2, 3-pyridinedicarboxylic acid was 6.9%, and the volume of the filtrate was 352 ml.
Production example 2
1) Preparation of 5-ethyl-2, 3-pyridinedicarboxylic acid
At room temperature, 147g (1.1mol) of 30% sodium hydroxide aqueous solution is dripped into a mixed solution of 128.1g (0.5mol) of 5-ethyl pyridine-2, 3-dicarboxylic acid ethyl ester and 60g of water, after 2h of addition, the temperature is raised to 50 ℃, the temperature is kept and the stirring is carried out for 3h, the reaction is finished, at the moment, the concentration of 5-ethyl pyridine-2, 3-dicarboxylic acid sodium salt in the reaction solution is 32%, the temperature is lowered to 20 ℃, 30% sulfuric acid is slowly dripped into the reaction solution, after 2h of addition, the pH value is adjusted to 1.1, the filtration is carried out, the filter cake is rinsed by 50g of water, and the filter cake is dried to obtain 77.8g of 5-ethyl pyridine-2, 3-dicarboxylic acid with the content of 99. 453g of filtrate was obtained, in which the content of 5-ethyl-2, 3-pyridinedicarboxylic acid was 8.6% and the volume of the filtrate was 390 ml.
2) Preparation of 5-ethyl-2, 3-pyridinedicarboxylic acid trioctylamine complex
Dissolving 160g of trioctylamine in 600ml of chlorobenzene at room temperature to obtain 750ml of extractant solution, mixing and stirring the extractant solution and 390ml of filtrate obtained in the previous step, heating to 80 ℃, stirring for 2 hours, cooling to room temperature, standing and layering to obtain 780ml of chlorobenzene solution of the 5-ethyl-2, 3-pyridinedicarboxylic acid trioctylamine complex, wherein the content of 5-ethyl-2, 3-pyridinedicarboxylic acid is 45ppm in aqueous phase analysis, and the extraction recovery rate of 5-ethyl-2, 3-pyridinedicarboxylic acid is more than 99%.
3) Dissociating 5-ethyl-2, 3-pyridinedicarboxylic acid trioctylamine complex and recovering
At room temperature, 780ml of chlorobenzene solution of 5-ethyl-2, 3-pyridinedicarboxylic acid trioctylamine complex is added into 335g (the concentration is 32%) of 5-ethyl-2, 3-pyridinedicarboxylic acid sodium salt solution of the next batch, 30% of sodium hydroxide is dripped after the addition is finished, the pH is adjusted to 12, the stirring is carried out for 2h, oil-water separation is carried out, 750ml of extractant solution is recovered, and the extractant solution is used for complexing extraction of the acidification filtrate of the next batch. 375g of 5-ethyl-2, 3-pyridinedicarboxylic acid sodium salt aqueous solution is obtained, the temperature is raised to 20 ℃, the pH value is adjusted to 1.1 by acidification, the mixture is kept stand for layering and is filtered, the filter cake is leached by 50g of water, 96.5g of 5-ethyl-2, 3-pyridinedicarboxylic acid, the content is 99 percent, and the yield is 98.3 percent. 455g of filtrate is obtained, wherein the content of the 5-ethyl-2, 3-pyridinedicarboxylic acid is 8.4 percent, and the volume of the filtrate is 390 ml.
As can be seen by comparing the examples and comparative examples, the recovery of 2, 3-pyridinedicarboxylic acid was greater than 99% and the purity was greater than 98.5% using the process of the present invention. The content of organic matters in the extracted wastewater, namely 2, 3-dipicolinic acid is less than 50 ppm. The method of the invention can realize the recycling of the extracting agent without introducing heavy metal ions, is simple and easy to operate, is suitable for continuous production, has low product purification cost and is beneficial to industrial production.
The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (21)
1. A process for recovering substituted or unsubstituted 2, 3-pyridinedicarboxylic acids, comprising the steps of:
(1) adding an extraction liquid into a solution containing substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I) for extraction to obtain a raffinate phase and an extract phase;
(2) adding alkali liquor into the extraction phase to adjust the extraction phase to be alkaline, and then carrying out oil-water separation to obtain an organic phase and an aqueous phase containing substituted or unsubstituted 2, 3-pyridine dicarboxylic acid salt;
(3) adding an acid solution into the aqueous phase to adjust the aqueous phase to acidity, then standing for layering and filtering to obtain the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by the formula (I),
wherein, in the formula (1), R1、R2、R3Each independently is H, C1-C4Alkyl radical, C1-C4Alkoxy, halogen or nitro, or a salt thereof,
the extraction liquid comprises an extracting agent and a diluting solvent, the extracting agent is trialkylamine and/or trialkylphosphine oxide,
the trialkylamine is at least one of tri-n-octylamine, tri-n-heptylamine and tri-n-nonylamine,
the trialkyl phosphine oxide is at least one of trihexyl phosphine oxide, trioctyl phosphine oxide, triheptyl phosphine oxide and dihexyl octyl phosphine oxide,
based on the total weight of the extraction liquid, the weight percentage of the extraction agent is 5 percent to 35 percent,
the diluting solvent is at least one of diethyl ether, kerosene, petroleum ether, benzene, toluene, monochlorobenzene, dichlorobenzene and trichlorobenzene,
the molar ratio of the solution containing the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I) to the extractant is 1: (0.5-10).
2. The recovery method according to claim 1, wherein the extractant is contained in an amount of 15 to 20 wt% based on the total weight of the extract.
3. The recovery method according to claim 1, wherein, in the step (2), the alkali solution is at least one of a sodium hydroxide solution, a potassium hydroxide solution, a lithium hydroxide solution, a sodium carbonate solution, and ammonia water.
4. The recovery method according to claim 3, wherein, in the step (2), the alkaline pH value is 8 to 14.
5. The recovery method according to claim 4, wherein, in the step (2), the alkaline pH value is 10 to 14.
6. The recovery method according to claim 1, wherein, in the step (3), the acid solution is hydrochloric acid, sulfuric acid, phosphoric acid or hydrobromic acid.
7. The recovery method according to claim 6, wherein, in the step (3), the acidic pH is 0.5 to 2.4.
8. The recovery method according to claim 7, wherein, in the step (3), the acidic pH is 0.5 to 1.1.
9. The recovery method according to any one of claims 1 to 8, wherein the method further comprises: adding a solution containing a substituted or unsubstituted 2, 3-pyridinedicarboxylate salt to the extraction phase before adding the lye to the extraction phase of step (2).
10. A process for producing a substituted or unsubstituted 2, 3-pyridinedicarboxylic acid, comprising the steps of:
(A) adding an alkali solution to a solution containing substituted or unsubstituted ethyl 2, 3-pyridinedicarboxylate to form a solution containing substituted or unsubstituted 2, 3-pyridinedicarboxylate;
(B) adding an acid solution to the obtained solution containing the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid salt, and filtering to obtain a product cake and a filtrate, wherein the filtrate contains the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I);
(C) adding an extraction liquid into the obtained filtrate for extraction to obtain a raffinate phase and an extract phase;
(D) adding alkali liquor into the extraction phase to adjust the extraction phase to be alkaline, and then carrying out oil-water separation to obtain an organic phase and an aqueous phase containing substituted or unsubstituted 2, 3-pyridine dicarboxylic acid salt;
(E) adding an acid solution into the aqueous phase to adjust the aqueous phase to acidity, then standing for layering and filtering to obtain the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by the formula (I),
wherein, in the formula (1), R1、R2、R3Each independently is H, C1-C4Alkyl radical, C1-C4Alkoxy, halogen or nitro, or a salt thereof,
the extraction liquid comprises an extracting agent and a diluting solvent, the extracting agent is trialkylamine and/or trialkylphosphine oxide,
the trialkylamine is at least one of tri-n-octylamine, tri-n-heptylamine and tri-n-nonylamine,
the trialkyl phosphine oxide is at least one of trihexyl phosphine oxide, trioctyl phosphine oxide, triheptyl phosphine oxide and dihexyl octyl phosphine oxide,
based on the total weight of the extraction liquid, the weight percentage of the extraction agent is 5 percent to 35 percent,
the diluting solvent is at least one of diethyl ether, kerosene, petroleum ether, benzene, toluene, monochlorobenzene, dichlorobenzene and trichlorobenzene,
the molar ratio of the solution containing the substituted or unsubstituted 2, 3-pyridinedicarboxylic acid represented by formula (I) to the extractant is 1: (0.5-10).
11. The method of claim 10, wherein the method further comprises: adding a solution containing a substituted or unsubstituted 2, 3-pyridinedicarboxylate salt to the extraction phase before adding the lye to the extraction phase in step (D).
12. The process of claim 10 or 11, wherein in step (B), the acid solution is hydrochloric acid, sulfuric acid, phosphoric acid, or hydrobromic acid.
13. The process of claim 12, wherein in step (B), the acidic pH is 0.5-2.4.
14. The process of claim 13, wherein in step (B), the acidic pH is 0.5-1.1.
15. The method of claim 10, wherein the extractant is present in an amount of 15% to 20% by weight, based on the total weight of the extract.
16. The method according to claim 10 or 11, wherein, in step (D), the alkali solution is at least one of a sodium hydroxide solution, a potassium hydroxide solution, a lithium hydroxide solution, a sodium carbonate solution, and ammonia water.
17. The method of claim 16, wherein in step (D), the alkaline pH is 8-14.
18. The method of claim 17, wherein in step (D), the alkaline pH is 10-14.
19. The process of claim 10 or 11, wherein in step (E), the acid solution is hydrochloric acid, sulfuric acid, phosphoric acid, or hydrobromic acid.
20. The process of claim 19, wherein in step (E), the acidic pH is 0.5-2.4.
21. The process of claim 20, wherein in step (E), the acidic pH is 0.5-1.1.
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| JP2004189651A (en) * | 2002-12-10 | 2004-07-08 | Sumikin Air Water Chemical Inc | Method for producing 2,3-pyridinedicarboxylic acid |
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| CN1057455A (en) * | 1990-06-15 | 1992-01-01 | 美国氰胺公司 | Prepare pyridine-2 by dichloro succinate dialkyl ester, the method for 3-dicarboxylic acid dialkyl esters and derivative thereof |
| JP2004189651A (en) * | 2002-12-10 | 2004-07-08 | Sumikin Air Water Chemical Inc | Method for producing 2,3-pyridinedicarboxylic acid |
| CN101781245A (en) * | 2009-06-26 | 2010-07-21 | 上海海事大学 | New method for synthesizing substitutional pyridine-3-carboxylic acid and analogue |
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