CN110818556A - Method for producing high-purity 2-chloro-6-fluorobenzoyl chloride by using waste residues - Google Patents
Method for producing high-purity 2-chloro-6-fluorobenzoyl chloride by using waste residues Download PDFInfo
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Abstract
The invention discloses a method for producing high-purity 2-chloro-6-fluorobenzoyl chloride by using waste residues, which comprises the following steps: adding an organic solvent into the waste residue to dissolve at a reflux temperature, standing for layering, filtering an organic phase, removing the organic solvent and water from the obtained filtrate, and obtaining a dehydrated solid material containing 2-chloro-6-fluorobenzoic acid; adding thionyl chloride or a front-end distillate obtained by rectification in the subsequent step into the solid material, carrying out reflux reaction, and carrying out reduced pressure distillation on the obtained reaction material to obtain a crude product of the 2-chloro-6-fluorobenzoyl chloride; and carrying out reduced pressure rectification on the crude product to respectively obtain a front cut fraction containing thionyl chloride, 4-chloro-2-fluorobenzoyl chloride, a rectification mixture and 2-chloro-6-fluorobenzoyl chloride. The method can obtain high-purity 4-chloro-2-fluorobenzoyl chloride and 2-chloro-6-fluorobenzoyl chloride products.
Description
Technical Field
The invention belongs to the field of fine chemical engineering, relates to a purification technology of a medical intermediate, and particularly relates to a method for producing high-purity 2-chloro-6-fluorobenzoyl chloride by using waste residues.
Background
The 2-chloro-6-fluorobenzaldehyde is a key intermediate of the antibiotic flucloxacillin sodium for human use, and the global annual demand is about 1000 tons. The production route of the 2-chloro-6-fluorobenzaldehyde mainly comprises two production routes, wherein the first route is a process route which takes 3-chloro-2-methylaniline as a raw material, prepares 2-chloro-6-fluorotoluene through diazo and fluoro, and then carries out photochlorination, rectification and hydrolysis; the second method is to take toluene as raw material, prepare 2, 6-dichlorotoluene by chlorination and rectification, then obtain 2-chloro-6-fluorotoluene by fluorination and rectification, and finally obtain the product by a technological route of photochlorination, rectification and hydrolysis.
The two process routes have the advantages respectively, but because the medicine has strict control on impurities, the related impurities of the second production route are difficult to control, the conversion efficiency is very low, and no actual industrial value exists, the production is carried out by the first route at home and abroad at present.
In the photochlorination process of the 2-chloro-6-fluorotoluene, about 3 percent of raw materials are converted into 2-chloro-6-fluorotrichlorobenzyl (converted into 2-chloro-6-fluorobenzoic acid after hydrolysis) in order to control the conversion efficiency, so that the raw materials are lost, and meanwhile, the 2-chloro-6-fluorobenzoic acid is byproduct.
In addition, in the production process of 3-chloro-2-methylaniline, the isomer 5-chloro-2-methylaniline is difficult to completely remove (currently, the process of combining rectification and recrystallization is adopted, and the minimum content can be controlled to be below 0.3 percent), so that the obtained 2-fluoro-6-fluorotoluene contains about 0.3 percent of 4-fluoro-2-fluorotoluene. However, 4-fluoro-2-fluorotoluene has smaller steric hindrance than 2-fluoro-6-fluorotoluene, and methyl groups on the side chain are easier to chlorinate and are all converted into 4-chloro-2-fluorotrichlorobenzyl (converted into 4-chloro-2-fluorobenzoic acid after hydrolysis), so that the quality of 2-chloro-6-fluorobenzaldehyde is not influenced.
Due to the reasons, the content of impurities in the byproduct acid in the production process of the 2-chloro-6-fluorobenzaldehyde is high (the main impurities are the 2-chloro-6-fluorobenzaldehyde, the 4-chloro-2-fluorobenzoic acid, tar, sodium sulfate, sodium chloride and the like), and because a proper refining and purifying method is not available before, the method cannot be applied to commercialization, and a large amount of byproduct acid can only be temporarily stored in a warehouse or treated as hazardous waste, so that the resource waste and the environmental pollution are caused.
Because 2-chloro-6-fluorobenzoic acid is a medical intermediate, customers put strict requirements on product quality, and the specific quality indexes are as follows: the content of the 2-chloro-6-fluorobenzoic acid is more than 99.5 percent, the content of the related single impurity is less than 0.2 percent, the melting point is 156 ℃ and 158 ℃, and the residue is less than 0.5 percent.
In the prior art, in order to solve the technical problems existing in the prior art in the aspect of the refining process of 2-chloro-6-fluorobenzoic acid, the inventor also tries to purify by methods such as a sublimation method, a macroporous resin adsorption method, an acid-base recrystallization method, an extraction method, a methanol recrystallization method and the like, but the methods are unsuccessful, and either low yield, serious pollution or product quality can not meet the requirements.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method for producing high-purity 2-chloro-6-fluorobenzoyl chloride by using waste residues. The method has the advantages of high product yield, high quality and simple process, all the solvents can be recycled, the obtained product has higher added value, and the comprehensive utilization of resources is realized.
In order to solve the technical problem, the invention provides a method for producing high-purity 2-chloro-6-fluorobenzoyl chloride by using waste residues, which is characterized by comprising the following steps:
1) adding an organic solvent into the waste residue according to a material-liquid ratio of 1 kg/3-5L, and dissolving at a reflux temperature to obtain a waste residue liquid, wherein the waste residue liquid is as follows: a solution I containing 2-chloro-6-fluorobenzoic acid;
the waste residue is a byproduct waste residue in the production of 2-chloro-6-fluorobenzaldehyde; the waste residue of the production byproduct contains 2-chloro-6-fluorobenzoic acid, 4-chloro-2-fluorobenzoic acid and water;
2) standing and layering the solution I containing the 2-chloro-6-fluorobenzoic acid obtained in the step 1) to respectively obtain an organic phase and a water phase;
filtering the organic phase; the obtained filtrate is called a solution II containing 2-chloro-6-fluorobenzoic acid (the desalted solution II containing 2-chloro-6-fluorobenzoic acid);
the water phase is used as a wastewater solution;
note: the wastewater solution enters a sewage station for biochemical treatment according to the conventional method, and is discharged after reaching the standard;
3) transferring the solution II containing the 2-chloro-6-fluorobenzoic acid into a dehydration kettle to remove organic solvent and water to obtain a dehydrated solid material containing the 2-chloro-6-fluorobenzoic acid; and recovering the organic solvent;
4) under stirring, adding thionyl chloride or a front fraction obtained by rectification in the subsequent step 6) into the solid material containing the 2-chloro-6-fluorobenzoic acid obtained in the step 3), and carrying out reflux reaction for 0.5-2 h;
the sum of the molar weights of the 2-chloro-6-fluorobenzoic acid and the 4-chloro-2-fluorobenzoic acid in the waste residue is as follows: thionyl chloride is 1: 1.3 to 1.5 molar ratio;
note: controlling the reaction time until the sum of the contents of the 2-chloro-6-fluorobenzoic acid and the 4-chloro-2-fluorobenzoic acid in the obtained reaction material is less than 0.5 percent; the front-end distillate obtained by the rectification in the step 6) contains thionyl chloride;
5) distilling the reaction material obtained in the step 4) under reduced pressure (-0.08MPa) to obtain a crude product of the 2-chloro-6-fluorobenzoyl chloride;
6) putting the crude product of the 2-chloro-6-fluorobenzoyl chloride obtained in the step 5) into a rectifying still, and carrying out rectification under reduced pressure (-0.08 MPa);
collecting the fraction below 110 ℃ as a front cut fraction containing thionyl chloride;
collecting the fraction at 110-135 ℃ as 4-chloro-2-fluorobenzoyl chloride;
collecting the fraction with the temperature of over 135-138 ℃ to obtain a rectification mixture;
collecting the fraction at 138-142 ℃ as 2-chloro-6-fluorobenzoyl chloride;
the rest in the rectifying still is the rectification residual liquid.
Note: the front cut, mainly thionyl chloride, also contains not more than 20% of 4-chloro-2-fluorobenzoyl chloride;
the rectification mixture is a mixture of 4-chloro-2-fluorobenzoyl chloride and 2-chloro-6-fluorobenzoyl chloride.
The improvement of the method for producing the high-purity 2-chloro-6-fluorobenzoyl chloride by using the waste residues is as follows:
the organic solvent is benzene, toluene (preferred) or xylene.
The method for producing the high-purity 2-chloro-6-fluorobenzoyl chloride by using the waste residues is further improved as follows:
the waste residue in the step 1) has the following quality indexes: more than 50 percent of 2-chloro-6-fluorobenzoic acid, less than 10 percent of 4-chloro-2-fluorobenzoic acid, less than 3 percent of 2-chloro-6-fluorobenzaldehyde, less than 30 percent of water, less than or equal to 5 percent of sodium sulfate, less than 5 percent of sodium chloride and less than 5 percent of tar impurities.
The method for producing the high-purity 2-chloro-6-fluorobenzoyl chloride by using the waste residues is further improved as follows:
the dehydrated solid material containing 2-chloro-6-fluorobenzoic acid obtained in the step 3) has the moisture content of less than 0.1%.
The method for producing the high-purity 2-chloro-6-fluorobenzoyl chloride by using the waste residues is further improved as follows:
and 5) carrying out reduced pressure distillation at the vacuum degree of about-0.08 MPa and the kettle temperature of less than or equal to 150 ℃ until no liquid is distilled out.
As a further improvement of the method for producing high-purity 2-chloro-6-fluorobenzoyl chloride by using waste residues, the method comprises the following steps of 6):
returning the front fraction (mainly thionyl chloride and not more than 20 percent of 4-chloro-2-fluorobenzoyl chloride) to the step 4) for recycling;
the rectified mixture (the mixture of 4-chloro-2-fluorobenzoyl chloride and 2-chloro-6-fluorobenzoyl chloride) returns to the rectifying still for circular rectification treatment;
and (3) treating the rectification residual liquid (mainly containing 2-chloro-6-fluorobenzoic acid and tar organic impurities) as hazardous waste.
Note: in the step 6), the vacuum degree is controlled to be-0.08 MPa, the reflux ratio is 1:10, the kettle temperature is 150 ℃, sectional recovery is carried out according to the tower top temperature, and gas chromatography detection is combined.
As a further improvement of the method for producing high-purity 2-chloro-6-fluorobenzoyl chloride by using waste residues, in the step 3), the solution II containing 2-chloro-6-fluorobenzoic acid is transferred into a reaction kettle, and is heated (steam heating and distillation can be conducted) so as to evaporate the organic solvent and water (until the organic solvent and the water are evaporated to dryness), thereby obtaining a dehydrated solid material containing 2-chloro-6-fluorobenzoic acid; and recovering the organic solvent.
Compared with the prior art, the invention has the following technical advantages:
the method takes waste residues (mainly byproduct 2-chloro-6-fluorobenzoic acid) obtained by producing thionyl chloride and 2-chloro-6-fluorotolualdehyde as raw materials, and produces high-purity 2-chloro-6-fluorobenzoyl chloride and byproduct 4-chloro-2-fluorobenzoyl chloride through the technical routes of solvent total-dissolution desalting, drying, acyl chlorination (derivatization reaction) and rectification, thereby realizing the comprehensive utilization of resources and generating remarkable economic and social benefits.
The invention realizes the conversion of acid into acyl chloride through derivatization reaction, and is more beneficial to separation and purification.
The high-purity 4-chloro-2-fluorobenzoyl chloride (the content can reach 99.63%) and the high-purity 2-chloro-6-fluorobenzoyl chloride product (the content can reach 99.74%) are obtained by the 2-chloro-6-fluorobenzoyl chloride crude product through a rectification method, the difficult problem of recrystallization separation of 2-chloro-6-fluorobenzoic acid and 4-chloro-2-fluorobenzoic acid is solved, and the side added value is obviously improved, namely, the resource utilization is realized, and the acid chloride value is higher than the acid value.
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The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.
FIG. 1 is a process flow diagram of the method for producing high-purity 2-chloro-6-fluorobenzoyl chloride by using waste residues.
Detailed Description
The invention will be further described with reference to specific examples, but the scope of the invention is not limited thereto:
all% of the following, which are not particularly specified, are mass%. The stirring speed is about 100-300 rpm.
Embodiment 1, a method for producing high-purity 2-chloro-6-fluorobenzoyl chloride by using waste residues, sequentially comprising the following steps:
1) putting 500 kg of waste residues which are a byproduct in the production of 2-chloro-6-fluorobenzaldehyde into a desalting and liquid separating kettle, adding 1500L of methylbenzene, introducing steam to raise the temperature, and dissolving the waste residues in the methylbenzene at a reflux temperature, wherein the obtained waste residue liquid is called as: a solution I containing 2-chloro-6-fluorobenzoic acid;
the quality indexes of the byproduct waste residue in the production of the 2-chloro-6-fluorobenzaldehyde are as follows: 50.3 percent of 2-chloro-6-fluorobenzoic acid, 9.8 percent of 4-chloro-2-fluorobenzoic acid, 0.3 percent of 2-chloro-6-fluorobenzaldehyde, 25.6 percent of water, 5 percent of sodium sulfate, 4.8 percent of sodium chloride and 4.2 percent of tar impurities.
Therefore, in the 500 kg of the waste residue by-produced in the production of 2-chloro-6-fluorobenzaldehyde, the sum of the molar amounts of 2-chloro-6-fluorobenzoic acid and 4-chloro-2-fluorobenzoic acid is 1721.5 mol.
2) Standing and layering the solution I containing the 2-chloro-6-fluorobenzoic acid obtained in the step 1) for about 1 hour, wherein the layering occurs at the moment, the upper layer is an organic phase, and the lower layer is a wastewater solution serving as a water phase;
the organic phase is a toluene solution containing 2-chloro-6-fluorobenzoic acid and 4-chloro-2-fluorobenzoic acid, and also contains a small amount of water;
the wastewater solution is an aqueous solution containing sodium sulfate and sodium chloride;
filtering the organic phase to remove suspended matters in the organic phase, wherein the filter residue is mechanical impurities and impurities, and the obtained filtrate is called a solution II containing 2-chloro-6-fluorobenzoic acid (the desalted solution II containing 2-chloro-6-fluorobenzoic acid);
thus obtaining 1650 liters of desalted solution II containing 2-chloro-6-fluorobenzoic acid and about 180 kilograms of waste water solution;
the wastewater solution enters a sewage station for biochemical treatment according to a conventional mode, and is discharged after reaching the standard, and the treatment is carried out in the following case.
3) 1650 l of the solution II containing the 2-chloro-6-fluorobenzoic acid is transferred into a reaction kettle (dehydration kettle), then steam is introduced for heating (the heating temperature is about 120 ℃), and toluene is distilled and recovered until the toluene and water are evaporated to dryness, so that 315 kg of dehydrated solid material containing the 2-chloro-6-fluorobenzoic acid is obtained, and the moisture of the solid material is 0.06%.
4) About 270 kg of thionyl chloride (2269 mol of thionyl chloride) was added to the solid material containing 2-chloro-6-fluorobenzoic acid obtained in step 3) with stirring, so that the volume of thionyl chloride: (2-chloro-6-fluorobenzoic acid + 4-chloro-2-fluorobenzoic acid) ═ 1.32: 1, starting steam to raise the temperature, carrying out reflux reaction at the reaction temperature of about 80 ℃ for 1 hour, wherein the residual amount of benzoic acid in the obtained reaction material is 0.15 percent (namely, the content of 2-chloro-6-fluorobenzoic acid is about 0.12 percent, and the content of 4-chloro-2-fluorobenzoic acid is about 0.03 percent); the hydrogen chloride and sulfur dioxide generated by the reaction are absorbed by water to obtain hydrochloric acid and sulfurous acid as byproducts, and the byproducts are sold as byproducts after conventional refining treatment.
5) And 4) carrying out reduced pressure distillation on the reaction material obtained in the step 4) (the vacuum degree is about-0.08 MPa, the kettle temperature is not more than 150 ℃), and obtaining 367 kg of a crude product of 2-chloro-6-fluorobenzoyl chloride and 22 kg of distillation residues when no liquid drops exist in a condenser.
6) Putting 367 kg of the crude product of the 2-chloro-6-fluorobenzoyl chloride obtained in the step 5) into a rectifying still, and carrying out reduced pressure rectification (the vacuum degree is controlled to be-0.08 MPa, the reflux ratio is 1:10, and the temperature of the still is 150 ℃);
collecting front fraction when the temperature at the top of the tower is less than 110 ℃, collecting 55 kg of front fraction together, wherein the content of thionyl chloride in the front fraction is 84.82%, the content of 4-chloro-2-fluorobenzoyl chloride is 14.69%, and the balance is other impurities; the front fraction can be returned to the step 4) for recycling;
when the temperature of the tower top is in a 110-135 ℃ region, the weight of the collected fraction is 32 kg, and the fraction is a 4-chloro-2-fluorobenzoyl chloride product, wherein the content of thionyl chloride is 0.08%, the content of 4-chloro-2-fluorobenzoyl chloride is 99.58%, and the content of 2-chloro-6-fluorobenzoyl chloride is 0.34%;
when the temperature of the tower top is in a region of over 135-138 ℃, collecting 48 kg of distillation fraction of the rectification mixture, wherein the content of 4-chloro-2-fluorobenzoyl chloride is 29.58%, the content of 2-chloro-6-fluorobenzoyl chloride is 70.42%, and returning the mixture to the rectification kettle for circular rectification treatment;
when the temperature of the tower top is in a 138-142 ℃ region, the weight of the collected fraction is 218 kg, and the fraction is a 2-chloro-6-fluorobenzoyl chloride product, wherein the content of 4-chloro-2-fluorobenzoyl chloride is 0.28%, the content of 2-chloro-6-fluorobenzoyl chloride is 99.64%, and other impurities are 0.08%;
14 kg of the bottom residue (rectification residue) of the rectification kettle is used as a unit entrusted with hazardous wastes and qualified to be treated, and the following cases are treated in the same way.
In addition: the 48 kg of the rectification mixture is returned to the rectification kettle for cyclic rectification treatment, the rectification treatment parameters are the same, namely, the vacuum degree is controlled to be-0.08 MPa, the reflux ratio is 1:10, and the kettle temperature is 150 ℃;
when the temperature of the tower top is in a 110-135 ℃ region, the weight of the collected fraction is 12 kg, and the fraction is a 4-chloro-2-fluorobenzoyl chloride product, and the detection: the content of 4-chloro-2-fluorobenzoyl chloride is 99.62%, and the content of 2-chloro-6-fluorobenzoyl chloride is 0.36%;
when the temperature of the tower top is in a region of over 135 ℃ to less than 138 ℃, collecting the weight of mixture fraction as 10 kg, and detecting: the content of the 4-chloro-2-fluorobenzoyl chloride is 30.14 percent, the content of the 2-chloro-6-fluorobenzoyl chloride is 69.37 percent, and the mixture returns to the rectifying still for circular rectification treatment;
when the temperature of the tower top is in a region of 138-142 ℃, the weight of the collected fraction is 26 kg, and the fraction is a 2-chloro-6-fluorobenzoyl chloride product, wherein the content of 4-chloro-2-fluorobenzoyl chloride is 0.21%, the content of 2-chloro-6-fluorobenzoyl chloride is 99.71%, and the content of other impurities is 0.08%.
Example 1-1, the toluene recovered by distillation was used in place of the original toluene in example 1, and the rest was the same as in example 1; step 6) the result obtained by the vacuum distillation is basically the same as that of the example 1; i.e. no significant difference.
Example 2, a method for producing high-purity 2-chloro-6-fluorobenzoyl chloride using waste residues, wherein the organic solvent in example 1 is changed from toluene to xylene, and the rest is the same as example 1; the method comprises the following specific steps:
1) putting 500 kg of waste residue by-produced in the production of 2-chloro-6-fluorobenzaldehyde into a desalting and liquid separating kettle, adding 1500L of dimethylbenzene, introducing steam to heat, and dissolving the waste residue in the dimethylbenzene at a reflux temperature to obtain a solution I containing 2-chloro-6-fluorobenzoic acid;
the quality indexes of the byproduct waste residue in the production of the 2-chloro-6-fluorobenzaldehyde are as follows: 50.3 percent of 2-chloro-6-fluorobenzoic acid, 9.8 percent of 4-chloro-2-fluorobenzoic acid, 0.3 percent of 2-chloro-6-fluorobenzaldehyde, 25.6 percent of water, 5 percent of sodium sulfate, 4.8 percent of sodium chloride and 4.2 percent of tar impurities.
2) Standing and layering the solution I containing the 2-chloro-6-fluorobenzoic acid obtained in the step 1) for about 1 hour, wherein layering occurs at the moment, the upper layer is an organic phase, the lower layer is a wastewater solution serving as a water phase,
the organic phase is a xylene solution containing 2-chloro-6-fluorobenzoic acid and 4-chloro-2-fluorobenzoic acid, and also contains a small amount of water;
the wastewater solution is an aqueous solution containing sodium sulfate and sodium chloride;
filtering the organic phase, wherein the filter residue is mechanical impurities and impurities, and the obtained filtrate is called a solution II containing 2-chloro-6-fluorobenzoic acid;
thus 1650 l of desalted solution II containing 2-chloro-6-fluorobenzoic acid and about 180 kg of waste water solution were obtained.
3) Transferring 1650 liters of 2-chloro-6-fluorobenzoic acid-containing solution II into a reaction kettle, introducing steam for heating, distilling and recovering dimethylbenzene until the dimethylbenzene and water are evaporated to dryness, and obtaining 315 kilograms of dehydrated 2-chloro-6-fluorobenzoic acid-containing solid material, wherein the water content of the solid material is 0.38 percent;
4) about 270 kg of thionyl chloride (2269 mol of thionyl chloride) was added to the solid material containing 2-chloro-6-fluorobenzoic acid obtained in the step 3) under stirring, so that the volume ratio of thionyl chloride: (2-chloro-6-fluorobenzoic acid + 4-chloro-2-fluorobenzoic acid) ═ 1.32: 1, starting steam to raise the temperature, carrying out reflux reaction at the reaction temperature of about 80 ℃ for 1 hour, wherein the residual amount of benzoic acid in the obtained reaction material is 0.39 percent (namely, the content of 2-chloro-6-fluorobenzoic acid is about 0.28 percent, and the content of 4-chloro-2-fluorobenzoic acid is about 0.11 percent); the hydrogen chloride and sulfur dioxide generated by the reaction are absorbed by water to obtain hydrochloric acid and sulfurous acid as byproducts, and the byproducts are sold as byproducts after conventional refining treatment.
5) Carrying out reduced pressure distillation on the reaction materials obtained in the step 4), and obtaining 352 kg of crude products of the 2-chloro-6-fluorobenzoyl chloride when no liquid drops exist in a condenser, so as to obtain 29 kg of distillation residues;
6) 352 kg of the crude product of the 2-chloro-6-fluorobenzoyl chloride obtained in the step 5) is put into a rectifying still for vacuum rectification, the vacuum degree is controlled at-0.08 MPa, the reflux ratio is 1:10, and the still temperature is 150 ℃.
Collecting front fraction when the temperature at the top of the tower is less than 110 ℃, collecting 53 kg of front fraction together, wherein the content of thionyl chloride in the front fraction is 81.82%, the content of 4-chloro-2-fluorobenzoyl chloride is 17.72%, and the balance is other impurities; the front fraction can be returned to the step 4) for recycling;
when the temperature of the tower top is 110-135 ℃, the weight of the collected fraction is 30 kg, the fraction is a 4-chloro-2-fluorobenzoyl chloride product, wherein the content of thionyl chloride is 0.07%, the content of 4-chloro-2-fluorobenzoyl chloride is 99.51%, the content of 2-chloro-6-fluorobenzoyl chloride is 0.39%, and the balance is other impurities.
When the temperature of the tower top is in a region of over 135-less than 138 ℃, collecting 46 kg of distillation fraction of the rectification mixture, wherein the content of 4-chloro-2-fluorobenzoyl chloride is 23.51%, the content of 2-chloro-6-fluorobenzoyl chloride is 76.46%, and the balance is other impurities, and returning the mixture to the rectification kettle for cyclic rectification treatment;
when the temperature of the tower top is in a 138-142 ℃ region, the weight of the collected fraction is 214 kg, the fraction is a 2-chloro-6-fluorobenzoyl chloride product, wherein the content of 4-chloro-2-fluorobenzoyl chloride is 0.24%, the content of 2-chloro-6-fluorobenzoyl chloride is 99.57%, and the balance is other impurities;
9 kg of residual liquid at the bottom of the rectifying still.
Example 3, a method for producing high-purity 2-chloro-6-fluorobenzoyl chloride using waste residue, the input amount of thionyl chloride in step 4) was increased from 270 kg to 310 kg, that is, thionyl chloride: (2-chloro-6-fluorobenzoic acid + 4-chloro-2-fluorobenzoic acid) ═ 1.5: 1, the rest is equal to the example 1, and the specific steps are as follows:
steps 1) to 3) are the same as steps 1) to 3) of the example.
4) Adding 310 kg of thionyl chloride into the solid material containing 2-chloro-6-fluorobenzoic acid obtained in the step 3) under stirring, starting steam to heat up, carrying out reflux reaction at the reaction temperature of about 80 ℃, and carrying out reflux reaction for 1h, wherein the residual amount of benzoic acid in the obtained reaction material is 0.06% (namely, the content of 2-chloro-6-fluorobenzoic acid is about 0.04%, and the content of 4-chloro-2-fluorobenzoic acid is about 0.02%); the hydrogen chloride and sulfur dioxide generated by the reaction are absorbed by water to obtain hydrochloric acid and sulfurous acid as byproducts, and the byproducts are sold as byproducts after conventional refining treatment.
5) And 4) carrying out reduced pressure distillation on the reaction material obtained in the step 4) until no liquid drop exists in a condenser, thus obtaining 415 kg of crude 2-chloro-6-fluorobenzoyl chloride and 17 kg of distillation residue.
6) Putting 415 kg of the crude product of the 2-chloro-6-fluorobenzoyl chloride obtained in the step 5) into a rectifying kettle, and carrying out vacuum rectification, wherein the vacuum degree is controlled to be-0.08 MPa, the reflux ratio is 1:10, and the kettle temperature is 150 ℃.
Collecting front fraction when the temperature at the top of the tower is less than 110 ℃, collecting 96 kg of front fraction together, wherein the content of thionyl chloride in the front fraction is 88.52%, the content of 4-chloro-2-fluorobenzoyl chloride is 11.45%, and the balance is other impurities; the front fraction can be returned to the step 4) for recycling;
when the temperature of the tower top is in a 110-135 ℃ region, the weight of the collected fraction is 33 kg, and the fraction is a 4-chloro-2-fluorobenzoyl chloride product, wherein the content of thionyl chloride is 0.07%, the content of 4-chloro-2-fluorobenzoyl chloride is 99.63%, and the content of 2-chloro-6-fluorobenzoyl chloride is 0.30%;
when the temperature of the tower top is in a region of over 135-less than 138 ℃, collecting 50 kg of distillation fraction of the rectification mixture, wherein the content of 4-chloro-2-fluorobenzoyl chloride is 20.1%, the content of 2-chloro-6-fluorobenzoyl chloride is 79.67%, and the balance is other impurities, and returning the mixture to the rectification kettle for cyclic rectification treatment;
when the temperature of the tower top is in a 138-142 ℃ region, the weight of the collected fraction is 224 kg, and the fraction is a 2-chloro-6-fluorobenzoyl chloride product, wherein the content of 4-chloro-2-fluorobenzoyl chloride is 0.26%, the content of 2-chloro-6-fluorobenzoyl chloride is 99.66%, and other impurities are 0.08%;
and 12 kg of residual liquid at the bottom of the rectifying still.
Example 4, a method for producing high-purity 2-chloro-6-fluorobenzoyl chloride using waste residues, the thionyl chloride used in step 4) is replaced (converted in terms of content) with the front fraction obtained by the rectification in step 6) of example 1, and the rest is equivalent to example 1, and the following steps are sequentially performed:
steps 1) to 3) are the same as in steps 1) to 3) of the example;
4) adding 318 kg of the front fraction (the content of thionyl chloride is 84.82%) obtained by rectifying in the step 6) in the step 1 into the solid material containing the 2-chloro-6-fluorobenzoic acid obtained in the step 3) under stirring, starting steam, heating, and carrying out reflux reaction at the reaction temperature of about 80 ℃ for 1 hour, wherein the residual amount of the benzoic acid is 0.12% (namely, the content of the 2-chloro-6-fluorobenzoic acid is about 0.09%, and the content of the 4-chloro-2-fluorobenzoic acid is about 0.03%);
the hydrogen chloride and sulfur dioxide generated by the reaction are absorbed by water to obtain by-products of hydrochloric acid and sulfurous acid, and the by-products are sold as by-products after refining treatment.
5) And 4) carrying out reduced pressure distillation on the reaction material obtained in the step 4) until no liquid drop exists in a condenser, thus obtaining 415 kg of crude 2-chloro-6-fluorobenzoyl chloride and 22 kg of distillation residue.
6) Putting 415 kg of the crude product of the 2-chloro-6-fluorobenzoyl chloride obtained in the step 5) into a rectifying kettle, and carrying out vacuum rectification, wherein the vacuum degree is controlled to be-0.08 MPa, the reflux ratio is 1:10, and the kettle temperature is 150 ℃.
When the temperature at the top of the tower is less than 110 ℃, collecting front fraction 58 kg together, wherein the content of thionyl chloride in the front fraction is 82.12%, the content of 4-chloro-2-fluorobenzoyl chloride is 17.88%, and the front fraction can be returned to the step 4) for recycling;
when the temperature of the tower top is in a 110-135 ℃ region, the weight of the collected fraction is 75 kg, and the fraction is a 4-chloro-2-fluorobenzoyl chloride product, wherein the content of thionyl chloride is 0.08%, the content of 4-chloro-2-fluorobenzoyl chloride is 99.58%, and the content of 2-chloro-6-fluorobenzoyl chloride is 0.34%;
when the temperature of the tower top is in a region of over 135-138 ℃, collecting 52 kg of distillation fraction of the rectification mixture, wherein the content of 4-chloro-2-fluorobenzoyl chloride is 29.36 percent, the content of 2-chloro-6-fluorobenzoyl chloride is 70.61 percent, and the balance is other impurities, and returning the mixture to the rectification kettle for cyclic rectification treatment;
when the temperature of the tower top is in a region of 138-142 ℃, the weight of the collected fraction is 218 kg, the fraction is a 2-chloro-6-fluorobenzoyl chloride product, wherein the content of 4-chloro-2-fluorobenzoyl chloride is 0.31%, the content of 2-chloro-6-fluorobenzoyl chloride is 99.59%, and the balance is other impurities;
and 12 kg of residual liquid at the bottom of the rectifying still.
Embodiment 5, a method for producing high-purity 2-chloro-6-fluorobenzoyl chloride using waste residues, wherein the quality of the waste residues by-produced in the production of 2-chloro-6-fluorobenzaldehyde in the step 1) is changed, and the rest is the same as that in embodiment 1, and the specific steps are as follows:
1) putting 500 kg of waste residue by-produced in the production of 2-chloro-6-fluorobenzaldehyde into a desalting and liquid separating kettle, adding 1500L of toluene, introducing steam to heat, and dissolving the waste residue in the toluene at the reflux temperature to obtain a solution I containing 2-chloro-6-fluorobenzoic acid;
the quality indexes of the byproduct waste residue in the production of the 2-chloro-6-fluorobenzaldehyde are as follows: 72.2 percent of 2-chloro-6-fluorobenzoic acid, 8.7 percent of 4-chloro-2-fluorobenzoic acid, 0.7 percent of 2-chloro-6-fluorobenzaldehyde, 12.3 percent of water, 2.2 percent of sodium sulfate, 1.7 percent of sodium chloride and 2.2 percent of tar impurities.
Therefore, in the 500 kg waste residue by-produced in the production of 2-chloro-6-fluorobenzaldehyde, the sum of the molar amounts of 2-chloro-6-fluorobenzoic acid and 4-chloro-2-fluorobenzoic acid is 2317 mol.
2) Standing and layering the solution I containing the 2-chloro-6-fluorobenzoic acid obtained in the step 1) for about 1 hour, wherein layering occurs at the moment, the upper layer is an organic phase, and the lower layer is a wastewater solution serving as a water phase,
the organic phase is a toluene solution containing 2-chloro-6-fluorobenzoic acid and 4-chloro-2-fluorobenzoic acid, and also contains a small amount of water;
the wastewater solution is an aqueous solution containing sodium sulfate and sodium chloride;
filtering the organic phase, wherein the filter residue is mechanical impurities and impurities, and the obtained filtrate is called a solution II containing 2-chloro-6-fluorobenzoic acid;
1700 l of desalted 2-chloro-6-fluorobenzoic acid-containing solution II and about 82 kg of waste water solution were obtained.
3) 1700 liters of 2-chloro-6-fluorobenzoic acid-containing solution II is transferred into a reaction kettle, then steam is introduced for heating, and toluene is recovered by distillation until the toluene and water are evaporated to dryness, so that 418 kg of dehydrated 2-chloro-6-fluorobenzoic acid-containing solid material with the water content of 0.07 percent is obtained.
4) To the solid material containing 2-chloro-6-fluorobenzoic acid obtained in step 3), about 360 kg of thionyl chloride (3025 mol of thionyl chloride) was added under stirring, so that the volume of thionyl chloride: (2-chloro-6-fluorobenzoic acid + 4-chloro-2-fluorobenzoic acid) ═ 1.31: 1, starting steam to raise the temperature, carrying out reflux reaction at the reaction temperature of about 80 ℃ for 1 hour, wherein the residual amount of benzoic acid in the obtained reaction material is 0.19 percent (namely, the content of 2-chloro-6-fluorobenzoic acid is about 0.14 percent, and the content of 4-chloro-2-fluorobenzoic acid is about 0.05 percent); the hydrogen chloride and sulfur dioxide generated by the reaction are absorbed by water to obtain hydrochloric acid and sulfurous acid as byproducts, and the byproducts are sold as byproducts after conventional refining treatment.
5) And 4) carrying out reduced pressure distillation on the reaction material obtained in the step 4) until no liquid drop exists in a condenser, thus obtaining 540 kg of crude product of 2-chloro-6-fluorobenzoyl chloride and 16 kg of distillation residue.
6) 540 kg of the crude product of the 2-chloro-6-fluorobenzoyl chloride obtained in the step 5) is put into a rectifying kettle for vacuum rectification, the vacuum degree is controlled to be-0.08 MPa, the reflux ratio is 1:10, and the kettle temperature is 150 ℃.
Collecting front fraction when the temperature at the top of the tower is less than 110 ℃, collecting 20 kg of front fraction together, wherein the content of thionyl chloride in the front fraction is 86.11%, the content of 4-chloro-2-fluorobenzoyl chloride is 12.96%, and the balance is other impurities; the front fraction can be returned to the step 4) for recycling;
when the temperature of the tower top is in a 110-135 ℃ region, the weight of the collected fraction is 54 kg, and the fraction is a 4-chloro-2-fluorobenzoyl chloride product, wherein the content of thionyl chloride is 0.08%, the content of 4-chloro-2-fluorobenzoyl chloride is 99.53%, and the content of 2-chloro-6-fluorobenzoyl chloride is 0.39%;
when the temperature of the tower top is in a region of over 135-less than 138 ℃, collecting 96 kg of mixture fractions, wherein the content of 4-chloro-2-fluorobenzoyl chloride is 29.58%, the content of 2-chloro-6-fluorobenzoyl chloride is 70.11%, and the balance is other impurities, and returning the mixture to a rectifying still for circular rectification treatment;
when the temperature of the tower top is in a region of 138-142 ℃, the weight of the collected fraction is 351 kg, and the fraction is a 2-chloro-6-fluorobenzoyl chloride product, wherein the content of 4-chloro-2-fluorobenzoyl chloride is 0.18%, the content of 2-chloro-6-fluorobenzoyl chloride is 99.74%, and other impurities are 0.08%;
19 kg of residual liquid at the bottom of the rectifying still.
Comparative example 1, step 1) of example 1, toluene dissolution, separation and desalination were omitted, and the other examples were the same as example 1, specifically as follows:
putting 500 kg of waste residues which are a byproduct in the production of 2-chloro-6-fluorobenzaldehyde into a reaction kettle, adding 270 kg of thionyl chloride under stirring, starting steam to heat up, carrying out reflux reaction at the reaction temperature of about 80 ℃ for 1 hour, and detecting that 2-chloro-6-fluorobenzoic acid does not substantially participate in the reaction and the experiment is interrupted;
the quality indexes of the byproduct waste residue in the production of the 2-chloro-6-fluorobenzaldehyde are as follows: 50.3 percent of 2-chloro-6-fluorobenzoic acid, 9.8 percent of 4-chloro-2-fluorobenzoic acid, 0.3 percent of 2-chloro-6-fluorobenzaldehyde, 25.6 percent of water, 5 percent of sodium sulfate, 4.8 percent of sodium chloride and 4.2 percent of tar impurities.
Because the waste residue as the byproduct of the 2-chloro-6-fluorobenzaldehyde production contains a large amount of water, the water reacts with thionyl chloride to generate hydrogen chloride and sulfur dioxide gas, and the thionyl chloride does not react with the 2-chloro-6-fluorobenzoic acid basically, so that the experiment fails.
Comparative example 2, on the basis of comparative example 1, the following raw material drying procedure is added: drying the waste residue as the byproduct in the production of 2-chloro-6-fluorobenzaldehyde at the temperature of 105-120 ℃, then crushing, and carrying out feeding reaction on the crushed material, wherein the other steps are the same as those in example 1, and the specific steps are as follows:
1) 500 kg of 2-chloro-6-fluorobenzaldehyde production byproduct waste residue (the same as the example 1 byproduct waste residue) is dried at 105-120 ℃ until the water content is 0.29%, and then crushed and screened by a 40-mesh screen for later use.
2) Putting the dried waste residue obtained in the step 1) into a reaction kettle, adding 270 kg of thionyl chloride under stirring, starting steam to heat up, and carrying out reflux reaction at the reaction temperature of about 80 ℃ for 1h, wherein the residual amount of benzoic acid in the obtained reaction material is 4.32%;
the hydrogen chloride and sulfur dioxide generated by the reaction are absorbed by water to obtain by-products of hydrochloric acid and sulfurous acid, and the by-products are sold as by-products after refining treatment.
3) Carrying out reduced pressure distillation on the reaction material obtained in the step 2) (the vacuum degree is about-0.08 MPa, the kettle temperature is not more than 150 ℃), and obtaining 332 kg of crude 2-chloro-6-fluorobenzoyl chloride when no liquid drops exist in a condenser, thus obtaining 102 kg of distillation residues;
4) putting 332 kg of the crude product of the 2-chloro-6-fluorobenzoyl chloride obtained in the step 3) into a rectifying kettle, and carrying out vacuum rectification, wherein the vacuum degree is controlled to be-0.08 MPa, the reflux ratio is 1:10, and the kettle temperature is 150 ℃.
When the temperature at the top of the tower is lower than 110 ℃, collecting front fraction of 54 kg together, wherein the content of thionyl chloride in the front fraction is 84.16 percent, the content of 4-chloro-2-fluorobenzoyl chloride is 15.33 percent, and the balance is other impurities; the front fraction can be returned to the step 4) for recycling;
when the temperature at the top of the tower is in the region of 110-135 ℃, the weight of the collected fraction is 28 kg, the fraction is a 4-chloro-2-fluorobenzoyl chloride product, wherein the content of thionyl chloride is 0.12%, the content of 4-chloro-2-fluorobenzoyl chloride is 98.68%, the content of 2-chloro-6-fluorobenzoyl chloride is 1.16%, and the balance is other impurities;
when the temperature of the tower top is in a region of over 135-138 ℃, collecting 44 kg of distillation fraction of the rectification mixture, wherein the content of 4-chloro-2-fluorobenzoyl chloride is 29.31%, the content of 2-chloro-6-fluorobenzoyl chloride is 70.67%, and the balance is other impurities, and returning the mixture to the rectification kettle for cyclic rectification treatment;
when the temperature at the top of the column is in the region of 138 ℃ and 142 ℃, the weight of the collected fraction is 165 kg, and the fraction is a 2-chloro-6-fluorobenzoyl chloride product, wherein the content of 4-chloro-2-fluorobenzoyl chloride is 1.59 percent, the content of 2-chloro-6-fluorobenzoyl chloride is 97.88 percent, and other impurities are 0.53 percent;
41 kg of residual liquid at the bottom of the rectifying still.
The product yield can not reach the level of example 1, the amount of dangerous solid waste is obviously increased, and the product quality can not reach the requirement specified by the customer (the content is more than 99 percent required by the conventional customer, and the maximum single impurity content is not more than 0.5 percent).
The dosage of thionyl chloride of comparative example 3, step 4) was reduced from 270 kg to 200 kg, i.e. thionyl chloride: (2-chloro-6-fluorobenzoic acid + 4-chloro-2-fluorobenzoic acid) ═ 1:1, the other steps are the same as the example 1, and the specific steps are as follows:
steps 1) to 3) are the same as steps 1) to 3) of example 1;
4) adding 200 kg of thionyl chloride into the solid material containing 2-chloro-6-fluorobenzoic acid obtained in the step 3) under stirring, starting steam to heat, and carrying out reflux reaction at the reaction temperature of about 80 ℃ for 1h, wherein the residual amount of benzoic acid in the obtained reaction material is 5.6%;
the hydrogen chloride and sulfur dioxide generated by the reaction are absorbed by water to obtain by-products of hydrochloric acid and sulfurous acid, and the by-products are sold as by-products after refining treatment.
5) And 4) carrying out reduced pressure distillation on the reaction materials obtained in the step 4) until no liquid drops exist in a condenser, thus obtaining 298 kg of crude products of 2-chloro-6-fluorobenzoyl chloride and 42 kg of distillation residues.
The conversion rate of raw materials of comparative example 3 is obviously reduced, the product yield does not reach the level of example 1, and the amount of dangerous solid wastes is obviously increased.
Comparative example 4, the toluene (as organic solvent) was replaced by methanol, the other procedure was identical to example 1, and the specific procedure was as follows:
1) 500 kg of waste residue (same as example 1) which is a byproduct in the production of 2-chloro-6-fluorobenzaldehyde is put into a desalting and liquid separating kettle, 1500L of methanol is added, steam is introduced, the temperature is raised, and the waste residue is dissolved in the methanol at the reflux temperature to obtain a solution I containing 2-chloro-6-fluorobenzoic acid.
2) And standing the solution I containing the 2-chloro-6-fluorobenzoic acid obtained in the step 1) for at least 1 hour, but not generating a layering phenomenon, and directly filtering to obtain 1800 liters of desalted solution II containing the 2-chloro-6-fluorobenzoic acid and 12 kilograms of waste residues.
And after the waste residues are dissolved in water, the waste residues enter a sewage station for biochemical treatment, and are discharged after reaching the standard.
3) Transferring 1800 liters of 2-chloro-6-fluorobenzoic acid-containing solution II into a reaction kettle, then introducing steam for heating, distilling and recovering methanol until methanol and water are evaporated to dryness to obtain 378 kilograms of dehydrated 2-chloro-6-fluorobenzoic acid-containing solid material, wherein the water content of the solid material is 4.76%;
the methanol was recovered by distillation in 1620 liters and had a water content of 16.25%.
4) Under stirring, 270 kg of thionyl chloride is added into 378 kg of the solid material containing 2-chloro-6-fluorobenzoic acid obtained in the step 3), steam is started to heat up, reflux reaction is carried out, the reaction temperature is about 80 ℃, the reflux reaction is carried out for 1h, and at the moment, the residual amount of benzoic acid in the obtained reaction material is 5.98%;
the hydrogen chloride and sulfur dioxide generated by the reaction are absorbed by water to obtain by-products of hydrochloric acid and sulfurous acid, and the by-products are sold as by-products after refining treatment.
5) And 4), carrying out reduced pressure distillation on the reaction material obtained in the step 4) until no liquid drop exists in a condenser, thus obtaining 287 kg of a crude product of the 2-chloro-6-fluorobenzoyl chloride and 94 kg of distillation residue.
6) 287 kg of crude 2-chloro-6-fluorobenzoyl chloride product obtained in the step 5) is put into a rectifying still for vacuum rectification, the vacuum degree is controlled to be-0.08 MPa, the reflux ratio is 1:10, and the still temperature is 150 ℃.
When the temperature at the top of the tower is less than 110 ℃, collecting no front fraction;
when the temperature of the tower top is in a 110-135 ℃ region, the weight of the collected fraction is 28 kg, and the fraction is a 4-chloro-2-fluorobenzoyl chloride product, wherein the content of thionyl chloride is 0.03%, the content of 4-chloro-2-fluorobenzoyl chloride is 99.58%, and the content of 2-chloro-6-fluorobenzoyl chloride is 0.39%;
when the temperature of the tower top is in a region of over 135-less than 138 ℃, collecting 50 kg of distillation fraction of the rectification mixture, wherein the content of 4-chloro-2-fluorobenzoyl chloride is 32.44%, the content of 2-chloro-6-fluorobenzoyl chloride is 67.40%, and the balance is other impurities, and returning the mixture to the rectification kettle for cyclic rectification treatment;
when the temperature at the top of the tower is in the region of 138 ℃ and 142 ℃, the weight of the collected fraction is 195 kg, and the fraction is a 2-chloro-6-fluorobenzoyl chloride product, wherein the content of 4-chloro-2-fluorobenzoyl chloride is 0.24 percent, the content of 2-chloro-6-fluorobenzoyl chloride is 99.57 percent, and other impurities are 0.19 percent;
and 14 kg of residual liquid at the bottom of the rectifying still.
Compared with the example 1, the conversion rate of raw materials and the recovery rate of products are obviously reduced, the consumption of thionyl chloride is higher, and the waste residue is obviously increased.
Finally, it is also noted that the above-mentioned lists merely illustrate a few specific embodiments of the invention. It is obvious that the invention is not limited to the above embodiments, but that many variations are possible. All modifications which can be derived or suggested by a person skilled in the art from the disclosure of the present invention are to be considered within the scope of the invention.
Claims (7)
1. The method for producing the high-purity 2-chloro-6-fluorobenzoyl chloride by using the waste residues is characterized by comprising the following steps of:
1) adding an organic solvent into the waste residue according to a material-liquid ratio of 1 kg/3-5L, and dissolving at a reflux temperature to obtain a waste residue liquid I containing 2-chloro-6-fluorobenzoic acid;
the waste residue is a byproduct waste residue in the production of 2-chloro-6-fluorobenzaldehyde, and the byproduct waste residue in the production comprises 2-chloro-6-fluorobenzoic acid, 4-chloro-2-fluorobenzoic acid and water;
2) standing and layering the solution I containing the 2-chloro-6-fluorobenzoic acid obtained in the step 1) to respectively obtain an organic phase and a water phase;
filtering the organic phase to obtain a filtrate II containing 2-chloro-6-fluorobenzoic acid;
the water phase is used as a wastewater solution;
3) transferring the solution II containing the 2-chloro-6-fluorobenzoic acid into a dehydration kettle to remove organic solvent and water to obtain a dehydrated solid material containing the 2-chloro-6-fluorobenzoic acid; and recovering the organic solvent;
4) under stirring, adding thionyl chloride or a front fraction obtained by rectification in the subsequent step 6) into the solid material containing the 2-chloro-6-fluorobenzoic acid obtained in the step 3), and carrying out reflux reaction for 0.5-2 h;
the sum of the molar weights of the 2-chloro-6-fluorobenzoic acid and the 4-chloro-2-fluorobenzoic acid in the waste residue is as follows: thionyl chloride is 1: 1.3 to 1.5 molar ratio;
5) carrying out reduced pressure distillation on the reaction material obtained in the step 4) to obtain a crude product of the 2-chloro-6-fluorobenzoyl chloride;
6) putting the crude product of the 2-chloro-6-fluorobenzoyl chloride obtained in the step 5) into a rectifying still for vacuum rectification;
collecting the fraction below 110 ℃ as a front cut fraction containing thionyl chloride;
collecting the fraction at 110-135 ℃ as 4-chloro-2-fluorobenzoyl chloride;
collecting the fraction with the temperature of over 135-138 ℃ to obtain a rectification mixture;
collecting the fraction at 138-142 ℃ as 2-chloro-6-fluorobenzoyl chloride;
the rest in the rectifying still is the rectification residual liquid.
2. The method for producing high-purity 2-chloro-6-fluorobenzoyl chloride by using waste residues as claimed in claim 1, wherein the method comprises the following steps:
the organic solvent is benzene, toluene or xylene.
3. The method for producing high-purity 2-chloro-6-fluorobenzoyl chloride by using waste residues as claimed in claim 2, wherein the method comprises the following steps:
the waste residue in the step 1) comprises the following components in percentage by mass: more than 50 percent of 2-chloro-6-fluorobenzoic acid, less than 10 percent of 4-chloro-2-fluorobenzoic acid, less than 3 percent of 2-chloro-6-fluorobenzaldehyde, less than 30 percent of water, less than or equal to 5 percent of sodium sulfate, less than 5 percent of sodium chloride and less than 5 percent of tar impurities.
4. The method for producing high-purity 2-chloro-6-fluorobenzoyl chloride by using waste residues as claimed in any one of claims 1 to 3, wherein the method comprises the following steps: the dehydrated solid material containing 2-chloro-6-fluorobenzoic acid obtained in the step 3) has the moisture content of less than 0.1%.
5. The method for producing high-purity 2-chloro-6-fluorobenzoyl chloride by using waste residues as claimed in claim 4, wherein the method comprises the following steps:
and 5) carrying out reduced pressure distillation at the vacuum degree of about-0.08 MPa and the kettle temperature of less than or equal to 150 ℃ until no liquid is distilled out.
6. The method for producing high-purity 2-chloro-6-fluorobenzoyl chloride by using waste residues according to any one of claims 1 to 5, which is characterized by comprising the following steps of 6):
the front fraction is returned to the step 4) for recycling;
the rectification mixture returns to the rectification kettle for circular rectification treatment.
7. The method for producing high-purity 2-chloro-6-fluorobenzoyl chloride by using waste residues as claimed in any one of claims 1 to 5, wherein the method comprises the following steps: in the step 3), heating the solution II containing the 2-chloro-6-fluorobenzoic acid to evaporate the organic solvent and water to obtain a dehydrated solid material containing the 2-chloro-6-fluorobenzoic acid; and recovering the organic solvent.
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| CN113861007A (en) * | 2021-11-07 | 2021-12-31 | 浙江大洋生物科技集团股份有限公司 | Method for treating distillation residue of 2-chloro-6-fluorobenzaldehyde |
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