CN114455557A - Method for recovering phosphorus oxychloride in chlorination reaction of hydroxyl compound - Google Patents
Method for recovering phosphorus oxychloride in chlorination reaction of hydroxyl compound Download PDFInfo
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- 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
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- C07D239/28—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings having three or more double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, directly attached to ring carbon atoms
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- C07D261/10—Heterocyclic compounds containing 1,2-oxazole or hydrogenated 1,2-oxazole rings not condensed with other rings having two or more double bonds between ring members or between ring members and non-ring members 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
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Abstract
The invention discloses a method for recycling and applying phosphorus oxychloride in a chlorination reaction of a hydroxyl-containing compound, which comprises the steps of reacting phosphorus dichloride and a derivative of phosphoric acid generated after the chlorination reaction with phosphorus pentachloride to regenerate phosphorus oxychloride, so that the generation of phosphorus wastewater is avoided, the post-treatment process of the chlorination reaction is simplified, the effects of simplifying production equipment and reducing the generation of three wastes are achieved, the recycling and applying of the phosphorus oxychloride are realized, the raw material cost is greatly reduced, and the industrial application of the chlorination reaction is facilitated.
Description
Technical Field
The invention belongs to the field of organic synthesis, and particularly relates to a method for recovering phosphorus oxychloride in a chlorination reaction of a hydroxyl compound.
Background
Phosphorus oxychloride is an industrial chemical raw material, is colorless and transparent liquid with pungent odor and garlic smell, is intensely fuming in humid air, reacts with water, and is hydrolyzed into phosphoric acid and hydrogen chloride, and white smoke is generated.
Phosphorus oxychloride is an important chemical raw material and is widely used for producing pesticides, medicines, dyes, phosphate and flame retardants. Phosphorus oxychloride is commonly used as a chlorinating agent to replace hydroxyl groups in organic molecules. Phosphorus oxychloride and hydroxyl are subjected to substitution reaction to generate phosphorus dichloride and phosphoric acid derivatives generally, and the phosphorus dichloride and phosphoric acid derivatives are difficult to separate from products due to strong acidity and high boiling point and can only be added into water together with the products for quenching, and further react with the water to generate phosphoric acid and hydrogen chloride, so that the generated phosphorus-containing wastewater contains a large amount of chloride ions, the phosphorus-containing wastewater is difficult to be further processed into individual phosphate and sodium chloride salts, and the total amount of the phosphate and the sodium chloride salts is large correspondingly. The comprehensive wastewater discharge standard requires that the third-level discharge standard of phosphorus-containing wastewater is that the total phosphorus content is less than 5.0mg/L, so that the problems of high treatment difficulty, high cost and the like exist when the wastewater after the chlorination of phosphorus oxychloride is treated.
Phosphorus oxychloride is generally excessive when the chlorination reaction is carried out, the excessive phosphorus oxychloride can be recovered by distillation after the reaction, but phosphorus dichloride acid and derivatives of phosphoric acid generated by the reaction cannot be separated independently. The usual workup is quenching with water and further reaction with water to form phosphoric acid and hydrogen chloride. For example:
patent CN108191749A discloses a preparation method of flonicamid intermediate 4-trifluoromethyl nicotinic acid, phosphorus oxychloride is adopted in the process of preparing 2, 6-dichloro-3-cyano-4-trifluoromethyl pyridine, the post-treatment scheme is to distill redundant phosphorus oxychloride, the residual liquid is poured into ice water for quenching, and then ethyl acetate is used for multiple extraction. The operation process is complicated, a large amount of heat is easily released in the residual liquid water adding quenching process, and great potential safety hazard exists in industrial amplification; and the phosphorus-containing wastewater contains a large amount of chloride ions and is mixed acid water, the treatment process is complex, and a large amount of equipment is needed.
Patent CN106883185A discloses a method for preparing 4, 6-chloro-2-trifluoromethylpyrimidine, which adopts a method of quenching the reaction solution with water after the reaction is completed when using phosphorus oxychloride to substitute hydroxyl to prepare 4, 6-dichloro-2-trifluoromethylpyrimidine, and the above problems also exist.
Similarly, patent CN108178748A discloses a method for preparing 4, 6-dichloropyrimidine-5-carbonitrile, which uses phosphorus oxychloride as a chlorinating agent during the halogenation and dehydration reactions, and directly pours the phosphorus oxychloride into water for quenching after the reaction is completed, thereby generating a large amount of phosphorus-containing three wastes, but does not perform further treatment and recovery.
Patent CN111393427A discloses a preparation method of sulfuryl pyraflufen, which adopts phosphorus oxychloride as a chlorinating reagent when preparing chlorodihydroisoxazole, and after the reaction is finished, the product is evaporated out under reduced pressure, and the residual three wastes containing phosphorus are not further treated.
According to the invention, through a great deal of research, it is surprisingly found that after phosphorus oxychloride and hydroxyl are subjected to substitution reaction, the generated phosphorus dichloride acid and phosphoric acid derivative can react with phosphorus pentachloride to regenerate phosphorus oxychloride and hydrochloric acid gas, the reaction enables the phosphorus oxychloride to be regenerated after the chlorination reaction is carried out, and the reaction system only contains the product and the phosphorus oxychloride. The regenerated phosphorus oxychloride can be completely separated from the reaction system through reduced pressure distillation or normal pressure distillation, so that the recovered phosphorus oxychloride can be obtained, and the purity of the recovered phosphorus oxychloride can reach more than 99%. The recovered phosphorus oxychloride can be used for chlorination again, and the effect is not obviously different from that of fresh phosphorus oxychloride.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides a method for recovering phosphorus oxychloride in the chlorination reaction of a hydroxyl compound.
The technical scheme for solving the technical problems is as follows:
the invention provides a method for recovering phosphorus oxychloride in a chlorination reaction of a hydroxyl-containing compound, which is characterized by comprising the following steps of:
(1) carrying out chlorination reaction on the hydroxyl-containing compound and phosphorus oxychloride, and monitoring by HPLC (high performance liquid chromatography) to obtain a reaction solution containing a chlorinated product;
(2) adding phosphorus pentachloride into the reaction liquid in the step (1) to continue reacting to generate phosphorus oxychloride and hydrogen chloride gas, and recovering the phosphorus oxychloride through distillation to obtain residual liquid;
further, the hydroxyl-containing compound has a structural formula of ROH, wherein R is selected from the following groups: c1～C10Alkyl radical, C2～C10Alkenyl radical, C2～C6Alkynyl, C3～C8A cycloalkyl group, an optionally substituted phenyl group, an optionally substituted aromatic heterocyclic group, an optionally substituted furan ring, an optionally substituted pyrrole ring, an optionally substituted thiophene ring, an optionally substituted pyridine ring, an optionally substituted pyrimidine ring, an optionally substituted purine ring, an optionally substituted isoxazole ring, an optionally substituted thiazole ring, an optionally substituted isothiazole ring, an optionally substituted imidazole ring, an optionally substituted pyridazine, an optionally substituted pyrazine, an optionally substituted benzofuran, an optionally substituted benzothiophene, an optionally substituted indole ring, an optionally substituted quinoline, or an optionally substituted isoquinoline;
further, the molar ratio of the hydroxyl-containing compound to the phosphorus oxychloride in the step (1) is 1: 0.1-10, preferably 1: 1-3;
further, the reaction temperature in the step (1) is 50-150 ℃, and preferably 100-120 ℃; the reaction time is 10-40 h, preferably 12-24 h;
further, amine can be added in the step (1) as an acid-binding agent, or the hydroxyl-containing compound and the amine become amine salt and then carry out chlorination reaction; the amine is trimethylamine, triethylamine, tri-n-propylamine, dimethylethylamine, diisopropylethylamine, dimethylaniline, diethylaniline or methyldiethylamine, preferably triethylamine;
further, when the content of the hydroxyl-containing compound is less than 0.5% by HPLC detection in the step (1), the reaction is finished;
further, the molar ratio of the hydroxyl-containing compound to the phosphorus pentachloride is 1: 0.1-10, preferably 1: 1-3;
further, the reaction temperature in the step (2) is 50-150 ℃, and preferably 80-120 ℃; the reaction time is 1-24 h, preferably 3-12 h;
further, the step (2) also comprises the steps of adding the residual liquid into toluene, cooling, filtering, and distilling under reduced pressure to obtain a crude chloro-product;
further, the recovered phosphorus oxychloride can be applied to the chlorination reaction.
The Chinese naming of the compound of the invention conflicts with the structural formula, and the structural formula is taken as the standard; except for obvious errors in the formula.
The invention has the beneficial effects that:
the invention provides a method for recycling and applying phosphorus oxychloride in chlorination reaction of hydroxyl-containing compounds, which comprises the steps of reacting phosphorus dichloride and derivatives of phosphoric acid generated after the chlorination reaction with phosphorus pentachloride to regenerate phosphorus oxychloride, avoiding generation of phosphorus-containing wastewater, simplifying post-treatment process of the chlorination reaction, simplifying production equipment, reducing generation of three wastes, realizing recycling and applying of phosphorus oxychloride, greatly reducing raw material cost and being more beneficial to industrial application of the chlorination reaction.
Detailed Description
The invention is illustrated but not limited by the following examples. The technical solutions protected by the present invention are all the simple replacements or modifications made by the skilled person in the art.
Example 1: preparation of 2, 6-dichloro-3-cyano-4-trifluoromethylpyridine
1000ml four-mouth bottle was charged with 500g of POCl3305g triethylamine salt of 2, 6-dihydroxy-3-cyano-4-trifluoromethylpyridine, heating to reflux, reacting for 24h, and determining that the content of the raw material 2, 6-dihydroxy-3-cyano-4-trifluoromethylpyridine is less than 0.5 percent by HPLC to be regarded as the completion of the reaction. Cooling to below 30 ℃, slowly adding 416g of phosphorus pentachloride, heating to reflux after the addition is finished, continuing the reaction for 5 hours, separating out a large amount of solids, cooling, distilling under reduced pressure to evaporate 771.0g of phosphorus oxychloride, adding 300g of toluene into the residual liquid, stirring, cooling to room temperature, filtering, removing triethylamine hydrochloride, distilling the mother liquid under reduced pressure, removing the toluene solvent to obtain 236g of crude 2, 6-dichloro-3-cyano-4-trifluoromethylpyridine with the content of 98 percent and the yield of 96 percent. The recovery rate of phosphorus oxychloride is 96%, and its content is 99%.
The application experiment is as follows: the phosphorus oxychloride recovered by the distillation was reused in the experiment for preparing 2, 6-dichloro-3-cyano-4-trifluoromethylpyridine in the same manner as in example 1, and 235g of crude 2, 6-dichloro-3-cyano-4-trifluoromethylpyridine was obtained with 98% content and 95.6% yield. The recovery rate of phosphorus oxychloride is 95%, and its content is 99%.
Example 2: preparation of 2, 6-dichloro-3-cyano-4-trifluoromethylpyridine
1000ml four-mouth bottle was charged with 500g of POCl3305g triethylamine salt of 2, 6-dihydroxy-3-cyano-4-trifluoromethylpyridine, heating to reflux, reacting for 24h, and determining that the content of the raw material 2, 6-dihydroxy-3-cyano-4-trifluoromethylpyridine is less than 0.5 percent by HPLC to be regarded as the completion of the reaction. Cooling to below 30 ℃, slowly adding 312g of phosphorus pentachloride, heating to reflux after the addition is finished, continuing the reaction for 16 hours, separating out a large amount of solids, cooling, distilling under reduced pressure to evaporate 693.5g of phosphorus oxychloride, adding 300g of toluene into the residual liquid, stirring, cooling to room temperature, filtering, removing triethylamine hydrochloride, distilling under reduced pressure the mother liquid, removing the toluene solvent, and rectifying the crude product to obtain 223g of 2, 6-dichloro-3-cyano-4-trifluoromethylpyridine product with the content of 99 percent and the yield of 92.5 percent. The recovery rate of phosphorus oxychloride is 95%, and its content is 99%.
The application experiment is as follows: the phosphorus oxychloride recovered by the distillation was reused in the experiment for preparing 2, 6-dichloro-3-cyano-4-trifluoromethylpyridine in the same manner as in example 2, and the obtained 2, 6-dichloro-3-cyano-4-trifluoromethylpyridine had a content of 98% and a yield of 95%. The recovery rate of phosphorus oxychloride is 95%, and its content is 99%.
Example 3: preparation of 4, 6-dichloro-2-trifluoromethylpyrimidine
1000ml four-mouth bottle was charged with 500g of POCl3Cooling 180g of 2-trifluoromethyl-4, 6-dihydroxypyrimidine to below 10 ℃, keeping the temperature low, dropwise adding 102g of triethylamine, slowly heating to reflux after dropwise adding, reacting for 10 hours, and determining that the content of the 2-trifluoromethyl-4, 6-dihydroxypyrimidine serving as a raw material is less than 0.5% by HPLC (high performance liquid chromatography) to finish the reaction. Cooling to below 30 ℃, slowly adding 416g of phosphorus pentachloride, heating to reflux after the addition is finished, continuing the reaction for 5 hours, separating out a large amount of solids, cooling, distilling under reduced pressure to evaporate 768g of phosphorus oxychloride, adding 300g of toluene into the residual liquid, stirring, cooling to room temperature, filtering, removing triethylamine hydrochloride, distilling the mother liquid under reduced pressure, removing the toluene solvent, and rectifying the crude product to obtain 204g of 4, 6-dichloro-2-trifluoromethylpyrimidine product with the content of 99 percent and the yield of 94 percent. The recovery rate of phosphorus oxychloride is 95%, and its content is 99%.
The application experiment is as follows: the phosphorus oxychloride recovered by the distillation was reused in the experiment for preparing 4, 6-dichloro-2-trifluoromethylpyrimidine in the same manner as in example 3, and the obtained 4, 6-dichloro-2-trifluoromethylpyrimidine had a content of 98% and a yield of 94%. The recovery rate of phosphorus oxychloride is 95%, and its content is 99%.
Example 4: preparation of 4, 6-dichloropyrimidine-5-carbonitrile
1000ml four-mouth bottle was charged with 500g of POCl3155g of 4, 6-dihydroxypyrimidine-5-carbaldehyde oxime, cooled to 10 ℃ in an ice bath toAnd then, dropwise adding 101g of triethylamine, slowly heating to reflux after the dropwise adding is finished, reacting for 12 hours, and determining that the content of the 4, 6-dihydroxypyrimidine-5-formaldehyde oxime is less than 0.5 percent through HPLC (high performance liquid chromatography) as the reaction is finished. Cooling to below 30 ℃, slowly adding 624g of phosphorus pentachloride, heating to reflux after the addition is finished, continuing the reaction for 10 hours, separating out a large amount of solids, cooling, distilling under reduced pressure to evaporate 874g of phosphorus oxychloride, adding 300g of toluene into the residual liquid, stirring, cooling to room temperature, filtering, removing triethylamine hydrochloride, distilling the mother liquid under reduced pressure, removing the toluene solvent to obtain 169g of crude 4, 6-dichloropyrimidine-5-carbonitrile with the content of 98 percent and the yield of 97 percent. The recovery rate of phosphorus oxychloride is 91%, and the content is 99%.
The application experiment is as follows: the phosphorus oxychloride recovered by the distillation was reused in the experiment for preparing 4, 6-dichloropyrimidine-5-carbonitrile in the same manner as in example 4, and the obtained 4, 6-dichloropyrimidine-5-carbonitrile had a content of 98% and a yield of 97%. The recovery rate of phosphorus oxychloride is 91%, and the content is 99%.
Example 5: preparation of 4-chloro-1 (2H) -phthalazinone
500g of POCl was added to a 1000ml four-necked flask3Cooling to below 10 ℃ in an ice bath, adding 162g of phthalhydrazide, dropwise adding 101g of triethylamine, slowly heating to reflux after the dropwise adding is finished, reacting for 12h, and determining that the content of the phthalhydrazide serving as a raw material is less than 0.5% by HPLC (high performance liquid chromatography) to finish the reaction. Cooling to below 30 ℃, slowly adding 208g of phosphorus pentachloride, heating to reflux after the addition is finished, continuing the reaction for 5 hours, separating out a large amount of solids, cooling, distilling out 620g of phosphorus oxychloride by reduced pressure distillation, adding 300g of toluene into the residual liquid, stirring, cooling to room temperature, filtering, removing triethylamine hydrochloride, carrying out reduced pressure distillation on the mother liquid, removing the toluene solvent, and obtaining 177g of a crude product of 4-chloro-1 (2H) -phthalazinone with the content of 98 percent and the yield of 96 percent. The recovery rate of phosphorus oxychloride is 95%, and its content is 99%.
The application experiment is as follows: the phosphorus oxychloride recovered by the above distillation was reused in the experiment for preparing 4-chloro-1 (2H) -phthalazinone in the same manner as in example 5, and the obtained 4-chloro-1 (2H) -phthalazinone had a content of 98% and a yield of 96%. The recovery rate of phosphorus oxychloride is 95%, and its content is 99%.
Example 6: preparation of 3-chloro-5, 5-dimethyl-4, 5-dihydroisoxazole
500g of POCl was added to a 1000ml four-necked flask3Cooling to below 10 ℃ in an ice bath, adding 115g of 3-hydroxy-5, 5-dimethyl-4, 5-dihydroisoxazole, adding 101.2g of triethylamine, slowly heating to reflux after the addition is finished, reacting for 12 hours, and determining that the content of the 3-hydroxy-5, 5-dimethyl-4, 5-dihydroisoxazole is less than 0.5 percent by HPLC (high performance liquid chromatography) as the reaction is finished. Cooling to below 30 ℃, slowly adding 208g of phosphorus pentachloride, heating to reflux after the addition is finished, continuing the reaction for 5 hours, separating out a large amount of solids, cooling, distilling under reduced pressure to evaporate 612g of phosphorus oxychloride, adding 300g of toluene into the residual liquid, stirring, cooling to room temperature, filtering, removing triethylamine hydrochloride, distilling the mother liquid under reduced pressure, removing the toluene solvent to obtain 136g of crude 3-chloro-5, 5-dimethyl-4, 5-dihydroisoxazole with the content of 97 percent and the yield of 95 percent. The recovery rate of phosphorus oxychloride is 94%, and the content is 99%.
The application experiment is as follows: the phosphorus oxychloride recovered by the distillation was reused in the experiment for preparing 3-chloro-5, 5-dimethyl-4, 5-dihydroisoxazole in the same manner as in example 6, and the obtained 3-chloro-5, 5-dimethyl-4, 5-dihydroisoxazole had a content of 97% and a yield of 95%. The recovery rate of phosphorus oxychloride is 94%, and the content is 99%.
Comparative example 1: preparation of 2, 6-dichloro-3-cyano-4-trifluoromethylpyridine
2, 6-dihydroxy-3-cyano-4-trifluoromethylpyridine N-methylmorpholine salt (10g, 32.8mmol) and POCl were weighed out3(50g, 326mmol) was added to a 100mL three-necked flask with reflux condenser and the condensate was turned on. Heating to 130 deg.C under nitrogen protection, reflux reacting for 18 hr, stopping heating, cooling to 70 deg.C, distilling under reduced pressure, and recovering unreacted POCl3. Cooling the residual liquid to 0-5 ℃, pouring the residual liquid into an ice-water mixture, adding ethyl acetate to extract for 3 times, and combiningThe organic phase was dried and concentrated to give 6.8g of 2, 6-dichloro-3-cyano-4-trifluoromethylpyridine, yield 86.13%.
Comparative example 2: preparation of 4, 6-dichloro-2-trifluoromethylpyrimidine
Adding 144.1g of phosphorus oxychloride into a reaction bottle, stirring, adding 36g of 2-trifluoromethyl-4, 6-dihydroxypyrimidine, stirring, cooling to 5-10 ℃, dropwise adding 55.4mL of triethylamine, heating to 100-105 ℃ after dropwise addition, reacting for 4 hours, controlling the temperature to 0-5 ℃ after the medium-controlled reaction is qualified, adding the reaction solution into ice water, stirring, adding dichloromethane, stirring for layering, adding dichloromethane into the water phase, extracting, combining organic phases, washing, filtering, and drying to obtain a crude product. The crude product was distilled and the product distilled off was collected as a colorless liquid 31.4g, yield 72.4%, HPLC 99.9%.
Comparative example 3: preparation of 4, 6-dichloropyrimidine-5-carbonitrile
850ml of acetonitrile and POCl were added to the reaction flask3(254.60ml, 2.732mol), dropwise adding DIPEA (377.68ml, 2.278mol) at the temperature of 20-30 ℃, after dropwise adding, adding 4, 6-dihydroxypyrimidine-5-formaldehyde oxime (85g, 0.548mol) in batches, after adding, heating to 80-85 ℃, reacting for 3 hours, concentrating under reduced pressure, dropwise adding the concentrated solution into 1.7L of water, and quenching to separate out a product from the water. Washing a filter cake obtained by filtering twice with 170ml of water, dissolving an obtained wet product with 1080ml of EA, decoloring with active carbon at 45-50 ℃, concentrating and drying a filtrate obtained by filtering, pulping with a mixed solvent of EA and DCM, and drying the filter cake obtained by filtering at 45-50 ℃ under reduced pressure to obtain 45.3g of solid with the yield of 47.7%.
Comparative example 4: preparation of 4-chloro-1 (2H) -phthalazinone
Phthalhydrazide (8.1g, 0.05mol) was weighed out and added to POCl3(50mL, 0.25mol), reacting at 110 ℃ for 4H, after the reaction system is cooled, pouring the reaction system into ice water, precipitating white solid, stirring overnight, filtering, drying the filter cake, washing the filter cake with ethyl acetate to finally obtain 8.5g of 4-chloro-1 (2H) -phthalazinone with the yield of 94.4%.
Comparative example 5: preparation of 3-chloro-5, 5-dimethyl-4, 5-dihydroisoxazole
55g of phosphorus oxychloride (0.4mol) are dissolved in 100mL of 1, 2-dichloroethane under nitrogen protection at 25 ℃, 3-hydroxy-5, 5-dimethyl-4, 5-dihydroisoxazole (25g, 0.22mol) is added in portions to the solution and stirred for 5 hours at 25 ℃. Through liquid phase control reaction, after the reaction is finished, the reaction liquid is distilled under reduced pressure to obtain yellow liquid, then the liquid is poured into 100mL of water and extracted by 150mL of dichloroethane for 3 times, an organic phase is collected, and the solvent is removed through reduced pressure distillation to obtain 13g of light yellow liquid with the yield of 45%.
Comparative example 6: preparation of 4, 6-dichloro-2-trifluoromethylpyrimidine
1000ml four-mouth bottle was charged with 500g of POCl3Cooling 180g of 2-trifluoromethyl-4, 6-dihydroxypyrimidine to below 10 ℃, keeping the temperature low, dropwise adding 80g of pyridine, after dropwise adding, slowly heating to reflux, reacting for 10 hours, and detecting by HPLC that the content of the 2-trifluoromethyl-4, 6-dihydroxypyrimidine serving as a raw material is less than 0.5 percent to finish the reaction. Cooling to below 30 ℃, slowly adding 416g of phosphorus pentachloride, heating to reflux after the addition is finished, continuing the reaction for 5 hours, separating out a large amount of solids, cooling, distilling under reduced pressure to evaporate 768g of phosphorus oxychloride, adding 300g of toluene into the residual liquid, stirring, cooling to room temperature, filtering, removing pyridine hydrochloride, distilling the mother liquid under reduced pressure, removing the toluene solvent, and rectifying the crude product to obtain 188g of 4, 6-dichloro-2-trifluoromethylpyrimidine product with the content of 96% and the yield of 87%. The recovery rate of phosphorus oxychloride is 86%, and its content is 98%.
The application experiment is as follows: the phosphorus oxychloride recovered by the distillation was reused in the experiment for preparing 4, 6-dichloro-2-trifluoromethylpyrimidine in the same manner as in example 3, and the obtained 4, 6-dichloro-2-trifluoromethylpyrimidine had a content of 95% and a yield of 83%. The recovery rate of phosphorus oxychloride is 84%, and its content is 97%.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the inventive concept of the present invention, and these changes and modifications are all within the scope of the present invention.
Claims (10)
1. A method for recovering phosphorus oxychloride in chlorination reaction of hydroxyl-containing compounds is characterized by comprising the following steps:
(1) carrying out chlorination reaction on the hydroxyl-containing compound and phosphorus oxychloride, and monitoring by HPLC (high performance liquid chromatography) to obtain a reaction solution containing a chlorinated product;
(2) adding phosphorus pentachloride into the reaction liquid in the step (1) to continue reacting to generate phosphorus oxychloride and hydrogen chloride gas, and recovering the phosphorus oxychloride through distillation to obtain residual liquid.
2. The method of claim 1, wherein said hydroxyl containing compound has the formula ROH, wherein R is selected from the group consisting of: c1～C10Alkyl radical, C2～C10Alkenyl radical, C2～C6Alkynyl, C3～C8A cycloalkyl group, an optionally substituted phenyl group, an optionally substituted aromatic heterocyclic group, an optionally substituted furan ring, an optionally substituted pyrrole ring, an optionally substituted thiophene ring, an optionally substituted pyridine ring, an optionally substituted pyrimidine ring, an optionally substituted purine ring, an optionally substituted isoxazole ring, an optionally substituted thiazole ring, an optionally substituted isothiazole ring, an optionally substituted imidazole ring, an optionally substituted pyridazine, an optionally substituted pyrazine, an optionally substituted benzofuran, an optionally substituted benzothiophene, an optionally substituted indole ring, an optionally substituted quinoline, or an optionally substituted isoquinoline.
3. The method for recovering phosphorus oxychloride as claimed in claim 1, wherein the molar ratio of the hydroxyl group-containing compound to the phosphorus oxychloride in the step (1) is 1: 0.1-10.
4. The method for recovering phosphorus oxychloride as claimed in claim 1, wherein the reaction temperature in the step (1) is 50-150 ℃; the reaction time is 10-40 h.
5. The method for recovering phosphorus oxychloride as claimed in claim 1, wherein in the step (1), an amine is added as an acid-binding agent, or the hydroxyl-containing compound and the amine are reacted with each other to form an amine salt and then subjected to chlorination reaction; the amine is trimethylamine, triethylamine, tri-n-propylamine, dimethylethylamine, diisopropylethylamine, dimethylaniline, diethylaniline or methyldiethylamine.
6. The method for recovering phosphorus oxychloride as claimed in claim 1, wherein the reaction is terminated when the content of the hydroxyl group-containing compound is less than 0.5% as determined by HPLC in the step (1).
7. The method for recovering phosphorus oxychloride as claimed in claim 1, wherein the molar ratio of the hydroxyl-containing compound to the phosphorus pentachloride is 1: 0.1-10.
8. The method for recovering phosphorus oxychloride as claimed in claim 1, wherein the reaction temperature in the step (2) is 50-150 ℃; the reaction time is 1-24 h.
9. The method for recovering phosphorus oxychloride as recited in claim 1, wherein the step (2) further comprises adding the residual liquid to toluene, cooling, filtering, and distilling under reduced pressure to obtain a crude chlorinated product.
10. The method for recovering phosphorus oxychloride as claimed in claim 1, wherein the recovered phosphorus oxychloride can be used in the chlorination reaction.
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