CN111454174A - Method for preparing fluorobenzonitrile - Google Patents
Method for preparing fluorobenzonitrile Download PDFInfo
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- CN111454174A CN111454174A CN201910108364.4A CN201910108364A CN111454174A CN 111454174 A CN111454174 A CN 111454174A CN 201910108364 A CN201910108364 A CN 201910108364A CN 111454174 A CN111454174 A CN 111454174A
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- potassium fluoride
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- potassium
- toluene
- fluorobenzonitrile
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- GDHXJNRAJRCGMX-UHFFFAOYSA-N 2-fluorobenzonitrile Chemical compound FC1=CC=CC=C1C#N GDHXJNRAJRCGMX-UHFFFAOYSA-N 0.000 title claims abstract description 42
- 238000000034 method Methods 0.000 title claims abstract description 38
- NROKBHXJSPEDAR-UHFFFAOYSA-M potassium fluoride Chemical compound [F-].[K+] NROKBHXJSPEDAR-UHFFFAOYSA-M 0.000 claims abstract description 400
- 239000011698 potassium fluoride Substances 0.000 claims abstract description 200
- 235000003270 potassium fluoride Nutrition 0.000 claims abstract description 200
- 150000003839 salts Chemical class 0.000 claims abstract description 54
- NHWQMJMIYICNBP-UHFFFAOYSA-N 2-chlorobenzonitrile Chemical compound ClC1=CC=CC=C1C#N NHWQMJMIYICNBP-UHFFFAOYSA-N 0.000 claims abstract description 24
- 238000003682 fluorination reaction Methods 0.000 claims abstract description 22
- 238000004519 manufacturing process Methods 0.000 claims abstract description 10
- 238000004064 recycling Methods 0.000 claims abstract description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 217
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 claims description 104
- 239000001103 potassium chloride Substances 0.000 claims description 52
- 235000011164 potassium chloride Nutrition 0.000 claims description 52
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 34
- 238000005406 washing Methods 0.000 claims description 30
- 238000001816 cooling Methods 0.000 claims description 23
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 21
- 238000002425 crystallisation Methods 0.000 claims description 20
- 230000008025 crystallization Effects 0.000 claims description 20
- 239000007788 liquid Substances 0.000 claims description 20
- 238000000967 suction filtration Methods 0.000 claims description 17
- 238000006243 chemical reaction Methods 0.000 claims description 16
- 239000002994 raw material Substances 0.000 claims description 16
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 claims description 15
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 claims description 12
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 12
- 239000012452 mother liquor Substances 0.000 claims description 12
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 11
- 239000000460 chlorine Substances 0.000 claims description 11
- 229910052801 chlorine Inorganic materials 0.000 claims description 11
- 239000003054 catalyst Substances 0.000 claims description 10
- 238000010438 heat treatment Methods 0.000 claims description 10
- 239000002798 polar solvent Substances 0.000 claims description 10
- 239000000243 solution Substances 0.000 claims description 10
- 238000001694 spray drying Methods 0.000 claims description 10
- NHGXDBSUJJNIRV-UHFFFAOYSA-M tetrabutylammonium chloride Chemical compound [Cl-].CCCC[N+](CCCC)(CCCC)CCCC NHGXDBSUJJNIRV-UHFFFAOYSA-M 0.000 claims description 10
- VZGDMQKNWNREIO-UHFFFAOYSA-N tetrachloromethane Chemical compound ClC(Cl)(Cl)Cl VZGDMQKNWNREIO-UHFFFAOYSA-N 0.000 claims description 10
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 claims description 8
- 238000001914 filtration Methods 0.000 claims description 8
- 239000003960 organic solvent Substances 0.000 claims description 8
- WOWHHFRSBJGXCM-UHFFFAOYSA-M cetyltrimethylammonium chloride Chemical compound [Cl-].CCCCCCCCCCCCCCCC[N+](C)(C)C WOWHHFRSBJGXCM-UHFFFAOYSA-M 0.000 claims description 7
- HXJUTPCZVOIRIF-UHFFFAOYSA-N sulfolane Chemical compound O=S1(=O)CCCC1 HXJUTPCZVOIRIF-UHFFFAOYSA-N 0.000 claims description 7
- WAGFXJQAIZNSEQ-UHFFFAOYSA-M tetraphenylphosphonium chloride Chemical compound [Cl-].C1=CC=CC=C1[P+](C=1C=CC=CC=1)(C=1C=CC=CC=1)C1=CC=CC=C1 WAGFXJQAIZNSEQ-UHFFFAOYSA-M 0.000 claims description 7
- CYSGHNMQYZDMIA-UHFFFAOYSA-N 1,3-Dimethyl-2-imidazolidinon Chemical compound CN1CCN(C)C1=O CYSGHNMQYZDMIA-UHFFFAOYSA-N 0.000 claims description 6
- 238000007738 vacuum evaporation Methods 0.000 claims description 6
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 4
- 239000013078 crystal Substances 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 4
- 239000003495 polar organic solvent Substances 0.000 claims description 4
- 239000011259 mixed solution Substances 0.000 claims description 2
- 230000035484 reaction time Effects 0.000 claims description 2
- 238000000926 separation method Methods 0.000 claims description 2
- 238000011084 recovery Methods 0.000 abstract description 8
- 239000012065 filter cake Substances 0.000 description 37
- 239000000706 filtrate Substances 0.000 description 20
- PCRSJGWFEMHHEW-UHFFFAOYSA-N 2,3,5,6-tetrafluorobenzene-1,4-dicarbonitrile Chemical compound FC1=C(F)C(C#N)=C(F)C(F)=C1C#N PCRSJGWFEMHHEW-UHFFFAOYSA-N 0.000 description 13
- 239000012071 phase Substances 0.000 description 13
- BNBRIFIJRKJGEI-UHFFFAOYSA-N 2,6-difluorobenzonitrile Chemical compound FC1=CC=CC(F)=C1C#N BNBRIFIJRKJGEI-UHFFFAOYSA-N 0.000 description 9
- 238000002360 preparation method Methods 0.000 description 9
- BTBFCBQZFMQBNT-UHFFFAOYSA-N 3,4-difluorobenzonitrile Chemical compound FC1=CC=C(C#N)C=C1F BTBFCBQZFMQBNT-UHFFFAOYSA-N 0.000 description 8
- 239000008346 aqueous phase Substances 0.000 description 8
- 239000000047 product Substances 0.000 description 8
- 239000002699 waste material Substances 0.000 description 8
- 239000007864 aqueous solution Substances 0.000 description 7
- 238000001704 evaporation Methods 0.000 description 7
- TXRVDQMSXQKAPG-UHFFFAOYSA-N 2,3,5,6-tetrachlorobenzene-1,4-dicarbonitrile Chemical compound ClC1=C(Cl)C(C#N)=C(Cl)C(Cl)=C1C#N TXRVDQMSXQKAPG-UHFFFAOYSA-N 0.000 description 6
- 230000018044 dehydration Effects 0.000 description 6
- 238000006297 dehydration reaction Methods 0.000 description 6
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 description 6
- 238000004321 preservation Methods 0.000 description 6
- 238000010992 reflux Methods 0.000 description 6
- 239000012153 distilled water Substances 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- YOYAIZYFCNQIRF-UHFFFAOYSA-N 2,6-dichlorobenzonitrile Chemical compound ClC1=CC=CC(Cl)=C1C#N YOYAIZYFCNQIRF-UHFFFAOYSA-N 0.000 description 4
- KUWBYWUSERRVQP-UHFFFAOYSA-N 3,4-dichlorobenzonitrile Chemical compound ClC1=CC=C(C#N)C=C1Cl KUWBYWUSERRVQP-UHFFFAOYSA-N 0.000 description 4
- 238000004821 distillation Methods 0.000 description 4
- -1 fluorobenzonitrile compound Chemical class 0.000 description 4
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 3
- 239000001110 calcium chloride Substances 0.000 description 3
- 229910001628 calcium chloride Inorganic materials 0.000 description 3
- 239000000575 pesticide Substances 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 238000003912 environmental pollution Methods 0.000 description 2
- 150000004673 fluoride salts Chemical class 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000002194 synthesizing effect Effects 0.000 description 2
- ZFHGXWPMULPQSE-SZGBIDFHSA-N (Z)-(1S)-cis-tefluthrin Chemical compound FC1=C(F)C(C)=C(F)C(F)=C1COC(=O)[C@@H]1C(C)(C)[C@@H]1\C=C(/Cl)C(F)(F)F ZFHGXWPMULPQSE-SZGBIDFHSA-N 0.000 description 1
- SFKCGRCYGCJPHK-UHFFFAOYSA-N 1,3-dimethylimidazolidin-2-one;methylsulfinylmethane Chemical compound CS(C)=O.CN1CCN(C)C1=O SFKCGRCYGCJPHK-UHFFFAOYSA-N 0.000 description 1
- DLKNOGQOOZFICZ-UHFFFAOYSA-N 2,4,5-trifluorobenzonitrile Chemical compound FC1=CC(F)=C(C#N)C=C1F DLKNOGQOOZFICZ-UHFFFAOYSA-N 0.000 description 1
- UCEMIYHYJURQLB-UHFFFAOYSA-N 3,4,6-trifluorobenzene-1,2-dicarbonitrile Chemical compound FC1=CC(F)=C(C#N)C(C#N)=C1F UCEMIYHYJURQLB-UHFFFAOYSA-N 0.000 description 1
- TYIYMOAHACZAMQ-CQSZACIVSA-N Cyhalofop-butyl Chemical group C1=CC(O[C@H](C)C(=O)OCCCC)=CC=C1OC1=CC=C(C#N)C=C1F TYIYMOAHACZAMQ-CQSZACIVSA-N 0.000 description 1
- 239000005502 Cyhalofop-butyl Substances 0.000 description 1
- 239000005893 Diflubenzuron Substances 0.000 description 1
- 239000005264 High molar mass liquid crystal Substances 0.000 description 1
- HRYILSDLIGTCOP-UHFFFAOYSA-N N-benzoylurea Chemical compound NC(=O)NC(=O)C1=CC=CC=C1 HRYILSDLIGTCOP-UHFFFAOYSA-N 0.000 description 1
- 229940122828 Oxytocin receptor antagonist Drugs 0.000 description 1
- 239000005939 Tefluthrin Substances 0.000 description 1
- 239000003242 anti bacterial agent Substances 0.000 description 1
- 229940088710 antibiotic agent Drugs 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 150000008359 benzonitriles Chemical class 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 1
- 229910001634 calcium fluoride Inorganic materials 0.000 description 1
- UISUNVFOGSJSKD-UHFFFAOYSA-N chlorfluazuron Chemical compound FC1=CC=CC(F)=C1C(=O)NC(=O)NC(C=C1Cl)=CC(Cl)=C1OC1=NC=C(C(F)(F)F)C=C1Cl UISUNVFOGSJSKD-UHFFFAOYSA-N 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- QQQYTWIFVNKMRW-UHFFFAOYSA-N diflubenzuron Chemical compound FC1=CC=CC(F)=C1C(=O)NC(=O)NC1=CC=C(Cl)C=C1 QQQYTWIFVNKMRW-UHFFFAOYSA-N 0.000 description 1
- 229940019503 diflubenzuron Drugs 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 239000000975 dye Substances 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 230000002363 herbicidal effect Effects 0.000 description 1
- 239000004009 herbicide Substances 0.000 description 1
- 239000004973 liquid crystal related substance Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000001007 phthalocyanine dye Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- LISFMEBWQUVKPJ-UHFFFAOYSA-N quinolin-2-ol Chemical compound C1=CC=C2NC(=O)C=CC2=C1 LISFMEBWQUVKPJ-UHFFFAOYSA-N 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- DDVNRFNDOPPVQJ-HQJQHLMTSA-N transfluthrin Chemical compound CC1(C)[C@H](C=C(Cl)Cl)[C@H]1C(=O)OCC1=C(F)C(F)=CC(F)=C1F DDVNRFNDOPPVQJ-HQJQHLMTSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C253/00—Preparation of carboxylic acid nitriles
- C07C253/30—Preparation of carboxylic acid nitriles by reactions not involving the formation of cyano groups
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention relates to a method for producing fluorobenzonitrile, comprising the following steps: (1) the chlorobenzonitrile is subjected to fluorination reaction to prepare fluorobenzonitrile and fluorinated mixed salt; (2) recovering potassium fluoride in the fluorinated mixed salt to obtain recovered potassium fluoride; (3) and (3) recycling potassium fluoride obtained in the step (2) and using the recycled potassium fluoride in the fluorination reaction in the step (1). According to the invention, potassium fluoride is separated and recovered, and the recovered potassium fluoride is used for preparing fluorobenzonitrile, so that the utilization rate of potassium fluoride can be increased to 98.78%; meanwhile, the fluorobenzonitrile process and the potassium fluoride recovery process are matched and used, so that more potassium fluoride can be added in the fluorobenzonitrile production engineering, and the purity of the fluorobenzonitrile can be improved to 99.6%.
Description
Technical Field
The invention belongs to the field of intermediate synthesis, relates to a method for preparing halogenated benzonitrile, and particularly relates to a method for preparing fluorobenzonitrile.
Background
The fluorobenzonitrile compound is a very important chemical intermediate and is widely applied to the fields of medicines, pesticides, dyes, high polymer liquid crystal materials and the like. For example, 2,4, 5-trifluorobenzonitrile may be used in the production of oxytocin receptor antagonists; 2, 6-difluorobenzonitrile is an intermediate of benzoylurea pesticides such as diflubenzuron and chlorfluazuron; 3, 4-difluorobenzonitrile is an important intermediate of the selective herbicide cyhalofop-butyl; 2,3,5, 6-tetrafluoroterephthalonitrile is an important intermediate of the pesticides transfluthrin and tefluthrin; the 3,4, 6-trifluoro phthalonitrile can be used for synthesizing quinolone antibiotics, phthalocyanine dyes and liquid crystal materials.
At present, the main method for synthesizing fluorobenzonitrile is to perform fluorination reaction on chlorobenzonitrile and anhydrous potassium fluoride.
CN 102690214A discloses a preparation method of 3, 4-difluorobenzonitrile, which aims to enable the purity of the prepared 3, 4-difluorobenzonitrile to reach 99%, the molar ratio of chlorine in the 3, 4-dichlorobenzonitrile to potassium fluoride in raw materials is 1 (1.1-2), excessive potassium fluoride causes that a large amount of potassium fluoride cannot be effectively utilized, and the generation amount of waste potassium salt is large. CN 108409605A also discloses a preparation method of 3, 4-difluorobenzonitrile, wherein the molar ratio of 3, 4-dichlorobenzonitrile to chlorine to potassium fluoride is 1 (1-1.7), although the addition amount of potassium fluoride is slightly reduced, the potassium fluoride is still excessive, and in order to ensure that the purity of the prepared fluorobenzonitrile is qualified, a large amount of potassium fluoride is still required to be consumed, and a large amount of waste potassium salt is generated.
CN 104151196A discloses a method for preparing 2,3,4,5, 6-pentafluorophenylnitrile, wherein the molar ratio of chlorine to potassium fluoride of 2,3,4,5, 6-pentafluorophenylnitrile in the raw materials is 1 (1.2-1.6), the amount of potassium fluoride added is likewise excessive, a large amount of potassium fluoride which cannot be fully utilized is generated in the process of preparing 2,3,4,5, 6-pentafluorophenylnitrile by the method, and the amount of waste potassium salt is large.
In summary, in the process of preparing fluorobenzonitrile, in order to ensure the purity of fluorobenzonitrile product, the methods in the prior art all consume a large amount of potassium fluoride and generate a large amount of waste potassium salt. Therefore, a method for recovering potassium fluoride in waste potassium salt is developed, and the method for recovering potassium fluoride is matched with the method for preparing fluorobenzonitrile, so that the utilization rate of potassium fluoride can be improved, and the purity of the prepared fluorobenzonitrile can be further improved.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a method for preparing fluorobenzonitrile, wherein a fluorinated mixed salt generated in the preparation process of the fluorobenzonitrile contains potassium fluoride and potassium chloride; meanwhile, the fluorobenzonitrile process and the potassium fluoride recovery process are matched and used, so that more potassium fluoride can be added in the fluorobenzonitrile production engineering, and the purity of the fluorobenzonitrile is further improved.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a method for preparing fluorobenzonitrile, which comprises the following steps:
(1) the chlorobenzonitrile is subjected to fluorination reaction to prepare fluorobenzonitrile and fluorinated mixed salt;
(2) recovering potassium fluoride in the fluorinated mixed salt to obtain recovered potassium fluoride;
(3) the recovered potassium fluoride obtained in the step (2) is used for the fluorination reaction in the step (1);
the fluorinated mixed salt generated in the process of preparing the fluorobenzonitrile is a mixture of potassium chloride and potassium fluoride, and the recovered potassium fluoride with the mass fraction of the potassium fluoride of 85-95 wt.% and the mass fraction of the potassium chloride of 5-15 wt.% can be obtained through recovery treatment. The invention improves the utilization rate of the potassium fluoride, reduces the generation amount of three wastes and lightens the environmental pollution by using the recovered potassium fluoride for preparing the fluorobenzonitrile.
Preferably, the specific steps of the fluorination reaction in the step (1) are as follows:
(a) mixing an aprotic polar solvent, toluene, chlorobenzonitrile and a catalyst to obtain a mixed raw material solution;
(b) heating the mixed raw material liquid, dehydrating and removing methylbenzene;
(c) cooling, adding anhydrous potassium fluoride into the system dehydrated and subjected to toluene removal in the step (b), and reacting after heating;
(d) cooling and filtering after the reaction in the step (c) is finished to obtain filtering mother liquor and fluoridized mixed salt;
(e) and (d) rectifying the suction filtration mother liquor obtained in the step (d) to obtain the fluorobenzonitrile.
Preferably, the structural formula of the chlorobenzonitrile in the step (a) is:
Preferably, the fluorobenzonitrile has the formula:
Preferably, the aprotic polar solvent of step (a) comprises N, N-dimethylformamide, N-dimethylacetamide, dimethylsulfoxide, N-methylpyrrolidone, any one or combination of at least two of 1, 3-dimethyl-2-imidazolidinone or sulfolane, typical but non-limiting combinations include a combination of N, N-dimethylformamide with N, N-dimethylacetamide, a combination of N, N-dimethylacetamide with dimethyl sulfoxide, a combination of N, N-dimethylacetamide, N-methylpyrrolidone with 1, 3-dimethyl-2-imidazolidinone or a combination of N, N-dimethylformamide, N-dimethylacetamide, dimethyl sulfoxide 1, 3-dimethyl-2-imidazolidinone with sulfolane.
Preferably, the catalyst comprises any one or combination of at least two of tetrabutylammonium chloride, hexadecyltrimethylammonium chloride or tetraphenylphosphonium chloride, typical but non-limiting combinations include combinations of tetrabutylammonium chloride with hexadecyltrimethylammonium chloride, tetrabutylammonium chloride with tetraphenylphosphonium chloride or combinations of tetrabutylammonium chloride, hexadecyltrimethylammonium chloride with tetraphenylphosphonium chloride.
The mass ratio of the chlorobenzonitrile to the catalyst is preferably 1 (0.03-0.1), and may be, for example, 1:0.03, 1:0.04, 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09 or 1:0.1, preferably 1 (0.05-0.08).
Preferably, the mass ratio of the chlorobenzonitrile to the aprotic polar solvent is 1 (1-5), and may be, for example, 1:1, 1:2, 1:3, 1:4 or 1:5, preferably 1 (2-4).
Preferably, the mass ratio of the chlorobenzonitrile to toluene is 1 (0.5-0.7), and may be, for example, 1:0.5, 1:0.6 or 1:0.7, preferably 1: 0.6.
Preferably, the temperature raising in step (b) is 110-.
Preferably, the temperature of said temperature reduction in step (c) is 90-100 ℃, for example 90 ℃, 91 ℃, 92 ℃, 93 ℃, 94 ℃, 95 ℃, 96 ℃, 97 ℃, 98 ℃, 99 ℃ or 100 ℃, preferably 92-98 ℃.
Preferably, the molar ratio of chlorine in the chlorobenzonitrile of step (a) to potassium fluoride of step (c) is 1 (1.2-2.5), and may be, for example, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2 or 1:2.1, preferably 1 (1.5-2.1).
Preferably, the temperature of the reaction in step (c) is 120-250 ℃, such as 120 ℃, 130 ℃, 140 ℃, 150 ℃, 160 ℃, 170 ℃, 180 ℃, 190 ℃, 200 ℃, 210 ℃, 220 ℃, 230 ℃, 240 ℃ or 250 ℃, preferably 160-210 ℃.
Preferably, the reaction time in step (c) is 5-20h, for example 5h, 8h, 10h, 12h, 14h, 16h, 18h or 20h, preferably 8-16 h.
Preferably, the temperature of said temperature reduction in step (d) is 50 ℃ or less, and may be, for example, 20 ℃, 25 ℃, 30 ℃, 35 ℃, 40 ℃, 45 ℃ or 50 ℃, preferably 25 ℃.
Preferably, the specific steps for recovering potassium fluoride in the fluorinated mixed salt in the step (2) are as follows:
(I) washing the fluoridized mixed salt by using an organic solvent, adding water for dissolving, and layering to obtain a lower-layer water phase;
(II) crystallizing the lower-layer water phase obtained in the step (I), and performing suction filtration to obtain potassium chloride crystals and crystallization mother liquor;
(III) spray drying the crystallization mother liquor obtained in the step (II) to obtain the recovered potassium fluoride.
Preferably, the organic solvent of step (I) is a non-polar organic solvent.
Preferably, the non-polar organic solvent comprises any one or a combination of at least two of toluene, carbon tetrachloride, ethyl acetate or dichloromethane, typical but non-limiting combinations include toluene with carbon tetrachloride, carbon tetrachloride with ethyl acetate, toluene, ethyl acetate with dichloromethane or toluene, carbon tetrachloride, ethyl acetate with dichloromethane.
Preferably, the mass ratio of the fluorinated mixed salt to water is (0.4-0.6):1, for example 0.4:1, 0.5:1 or 0.6:1, preferably 0.5: 1.
Preferably, the crystallization in step (II) is vacuum evaporation crystallization.
Preferably, the pressure of the vacuum evaporative crystallization is from-0.08 to-0.1 MPa, and may be, for example, -0.08MPa, -0.085MPa, -0.09MPa, -0.095MPa, -0.097MPa, -0.099MPa or-0.1 MPa, preferably-0.09 MPa.
Preferably, the temperature of the vacuum evaporation crystallization is 30 ℃ to 70 ℃, for example, 30 ℃, 40 ℃, 50 ℃, 60 ℃ or 70 ℃, preferably 50 ℃.
Preferably, the mass fraction of potassium fluoride in the recovered potassium fluoride in step (III) is 85-95 wt.%, for example, 85 wt.%, 86 wt.%, 87 wt.%, 88 wt.%, 89 wt.%, 90 wt.%, 91 wt.%, 92 wt.%, 93 wt.%, 94 wt.%, or 95 wt.%, preferably 88-92 wt.%.
Preferably, the mass fraction of potassium chloride in the recovered potassium fluoride is 5-15 wt.%, for example, may be 5 wt.%, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, 10 wt.%, 11 wt.%, 12 wt.%, 13 wt.%, 14 wt.% or 15 wt.%, preferably 8-12 wt.%.
Preferably, the sum of the mass fractions of potassium chloride and potassium fluoride is 100 wt.%.
As a preferred embodiment of the first aspect of the present invention, there is provided a method comprising the steps of:
(1) mixing an aprotic polar solvent, toluene, chlorobenzonitrile and a catalyst to obtain a mixed raw material liquid, removing water and toluene in the mixed raw material liquid at the temperature of 110-100 ℃, adding anhydrous potassium fluoride at the temperature of 90-100 ℃, reacting for 5-20h at the temperature of 120-250 ℃, cooling to the temperature below 50 ℃, carrying out solid-liquid separation to obtain a fluorinated mixed salt and a suction filtration mother liquid, rectifying the suction filtration mother liquid to obtain fluorobenzonitrile, wherein the mass ratio of the chlorobenzonitrile to the catalyst is 1 (0.03-0.1), the mass ratio of the chlorobenzonitrile to the aprotic polar solvent is 1 (1-5), and the mass ratio of the chlorobenzonitrile to the toluene is 1 (0.5-0.7);
(2) washing fluorinated mixed salt by using a nonpolar organic solvent, adding water for dissolving after washing, dividing the salt into an upper layer and a lower layer, wherein the upper layer is a nonpolar organic solvent layer, the lower layer of water phase is a mixed solution of potassium chloride and potassium fluoride, and vacuum evaporation and crystallization are carried out under 0.09-0.1 MPa to obtain potassium chloride crystals and crystallization mother liquor, and spray drying the crystallization mother liquor to obtain recovered potassium fluoride, wherein the mass fraction of potassium fluoride in the recovered potassium fluoride is 85-95 wt.%, the mass fraction of potassium chloride is 5-15 wt.%, and the sum of the mass fractions of potassium chloride and potassium fluoride is 100 wt.%;
(3) and (3) recovering potassium fluoride obtained in the step (2) and using the recovered potassium fluoride in the step (1) for preparing the fluorobenzonitrile.
The recitation of numerical ranges herein includes not only the above-recited numerical values, but also any numerical values between non-recited numerical ranges, and is not intended to be exhaustive or to limit the invention to the precise numerical values encompassed within the range for brevity and clarity.
Compared with the prior art, the invention has the beneficial effects that:
(1) the fluorinated mixed salt generated in the process of preparing the fluorobenzonitrile is a mixture of potassium chloride and potassium fluoride, and the recovered potassium fluoride with the mass fraction of the potassium fluoride of 85-95 wt.% and the mass fraction of the potassium chloride of 5-15 wt.% can be obtained through recovery treatment;
(2) the method provided by the invention recycles the potassium fluoride, so that the addition amount of the prepared fluorine-substituted benzonitrile potassium fluoride is increased, and the purity of the prepared fluorine-substituted benzonitrile is further increased to 99.6%.
Detailed Description
The technical solution of the present invention is further explained by the following embodiments.
Example 1
This example provides a process for preparing a fluorobenzonitrile comprising the steps of:
2250g of N, N-dimethylacetamide, 500g of toluene, 750g of 2, 6-dichlorobenzonitrile and 45g of cetyltrimethylammonium chloride were mixed, the temperature was raised to 120 ℃ with stirring, reflux dehydration was carried out for 2 hours, toluene removal was continued, and 495g of toluene was recovered.
Cooling the system after dehydrating and removing toluene to 90 ℃, adding 518g of anhydrous potassium fluoride and 190.3g of recovered potassium fluoride (the content of the potassium fluoride is 89 wt.%), heating to 160 ℃, carrying out heat preservation reaction for 16 hours, cooling to 40 ℃ after the reaction is finished, carrying out suction filtration, and washing a filter cake once by using 500g of N, N-dimethylacetamide to obtain 913.5g of fluorinated mixed salt; the filtrate was 3338.2g, distilled at-0.1 MPa and collected as a 105 ℃ and 108 ℃ fraction in 97.5% yield, yielding 591.3g of finished 2, 6-difluorobenzonitrile (2, 6-difluorobenzonitrile content 99.5 wt.%).
1500g of toluene is used for washing 913.5g of fluorinated mixed salt filter cake twice, 2000g of water is added into the washed filter cake for dissolving, then the filter cake is transferred into a separating funnel for separating liquid, the upper layer of toluene phase is combined with toluene washing filtrate, the toluene is distilled and recovered under normal pressure, and the recovered toluene can be used for washing the next batch of fluorinated mixed salt; 2851g of lower-layer water phase, evaporating and crystallizing the lower-layer water phase at-0.09 MPa, evaporating 1748g of water (used for dissolving the next batch of fluorinated mixed salt), cooling and filtering, wherein the filter cake is 697.6g of potassium chloride, and the filtrate is 396g of potassium fluoride aqueous solution.
697.6g of potassium chloride filter cake contains 649g of potassium chloride, 13.7g of potassium fluoride and 34.9g of water, 1750g of water is added to dissolve the filter cake, 27.6g of calcium chloride is added, the calcium chloride and the potassium fluoride react to generate calcium fluoride precipitate, and the filtrate is 2454g of fine potassium chloride aqueous solution, distilled at 0.09MPa and 50 ℃, distilled water amount is 1256g (used for dissolving the next batch of potassium chloride filter cake), the mixture is cooled to room temperature for crystallization and suction filtration, the filter cake is fine potassium chloride, and dried at 0.09MPa and 90 ℃ to obtain 456.6g of fine potassium chloride (the content of potassium chloride is 99.5 wt.%, the content of potassium fluoride is less than 10ppm, and the water content is less than 0.5 wt.%); the filtrate was 719g, a saturated aqueous solution of potassium chloride containing a trace amount of calcium chloride, and was used for recovery of the next batch of potassium chloride filter cake.
188.3g of recovered potassium fluoride is obtained after 396g of potassium fluoride solution is subjected to spray drying treatment, through determination, the content of potassium fluoride in the recovered potassium fluoride is 90 wt.%, and the content of potassium chloride is 10 wt.%, and the obtained recovered potassium fluoride is reused for fluorination reaction.
In the preparation method provided in this example, the addition amount of potassium fluoride in the raw material is 11.831mol, 8.677mol of potassium fluoride is consumed in the fluorination reaction, 2.917mol of potassium fluoride is recovered, and the utilization rate of potassium fluoride is 98%.
Example 2
This example provides a process for preparing a fluorobenzonitrile comprising the steps of:
1500g of sulfolane, 420g of toluene, 750g of 3, 4-dichlorobenzonitrile and 60g of tetraphenylphosphonium chloride are mixed, stirred and heated to 130 ℃, reflux dehydration is carried out for 2 hours, toluene is continuously removed, and 415g of toluene is recovered.
Cooling the system after dehydrating and removing toluene to 95 ℃, adding 587g of anhydrous potassium fluoride and 188.3g of recovered potassium fluoride (the content of potassium fluoride is 90 wt.%), heating to 250 ℃, carrying out heat preservation reaction for 15 hours, cooling to 35 ℃ after the reaction is finished, carrying out suction filtration, and washing a filter cake once by using 500g of sulfolane to obtain 964.2g of fluorinated mixed salt; the filtrate was 2620g, distilled at-0.1 MPa and the 95-100 ℃ fraction was collected in a yield of 80.3% to give 486.5g of a finished 3, 4-difluorobenzonitrile (3, 4-difluorobenzonitrile content 99.6 wt.%).
1500g of toluene is used for washing 964.2g of fluorinated mixed salt filter cake twice, 1928g of water is added into the washed filter cake for dissolving, then the filter cake is transferred into a separating funnel for separating liquid, the upper layer of toluene phase is combined with toluene washing filtrate, the toluene is recovered by distillation under normal pressure, and the recovered toluene can be used for washing the next batch of fluorinated mixed salt; 2818g of lower-layer water phase, evaporating and crystallizing the lower-layer water phase at-0.09 MPa, cooling and filtering after 1520g of distilled water (used for dissolving the next batch of fluorinated mixed salt), wherein the filter cake is 564.8g of potassium chloride, and the filtrate is 726.2g of potassium fluoride aqueous solution, and the method for recovering the refined potassium chloride in the embodiment 1 is adopted to recover the refined potassium chloride.
726.2g of potassium fluoride solution is subjected to spray drying treatment to obtain 354.3g of recovered potassium fluoride, the content of potassium fluoride in the recovered potassium fluoride is 93 wt.%, and the content of potassium chloride in the recovered potassium fluoride is 7 wt.%, and the obtained recovered potassium fluoride is reused in the fluorination reaction.
In the preparation method provided in this example, the amount of potassium fluoride added to the raw material was 13.02mol, 7.028mol of potassium fluoride was consumed in the fluorination reaction, 5.672mol of potassium fluoride was recovered, and the utilization rate of potassium fluoride was 97.54%.
Example 3
This example provides a process for preparing a fluorobenzonitrile comprising the steps of:
2200g of dimethyl sulfoxide, 275g of toluene, 550g of tetrachloroterephthalonitrile and 25g of tetraphenylphosphonium chloride are mixed, stirred and heated to 140 ℃, reflux dehydration is carried out for 2 hours, toluene is continuously removed, and 272g of toluene is recovered.
Cooling the system after dehydrating and removing toluene to 92 ℃, adding 532g of anhydrous potassium fluoride and 354.3g of recovered potassium fluoride (the content of the potassium fluoride is 93 wt.%), heating to 180 ℃, carrying out heat preservation reaction for 8 hours, cooling to 30 ℃ after the reaction is finished, carrying out suction filtration, washing a filter cake once by using 500g of dimethyl sulfoxide, and obtaining 1099g of fluorinated mixed salt; the filtrate is 3061g, the distillation is carried out under the pressure of-0.1 MPa, the fraction at the temperature of 75-85 ℃ is collected, 2300g of dimethyl sulfoxide is recovered, the distillation residual liquid is cooled and crystallized, the filtration is carried out, and the filter cake is dried in vacuum to obtain 382.4g of tetrafluoroterephthalonitrile finished product (the content of tetrafluoroterephthalonitrile is 98 wt.%), and the yield is 91%.
1500g of toluene is used for washing 1099g of fluorinated mixed salt filter cake twice, 2100g of water is added into the washed filter cake for dissolving, then the filter cake is transferred into a separating funnel for separating liquid, the upper layer of toluene phase is combined with the toluene washing filtrate, the toluene is distilled and recovered under normal pressure, and the recovered toluene can be used for washing the next batch of fluorinated mixed salt; 3121g of lower aqueous phase, evaporating and crystallizing the lower aqueous phase at-0.09 MPa, evaporating 1630g of water (used for dissolving the next batch of fluorinated mixed salt), cooling, and performing suction filtration, wherein the filter cake is 665.7g of potassium chloride, the filtrate is 818.4g of potassium fluoride aqueous solution, and the method for recovering the refined potassium chloride in the embodiment 1 is adopted to recover the refined potassium chloride.
818.4g of potassium fluoride solution is subjected to spray drying treatment to obtain 389.3g of recovered potassium fluoride, the content of potassium fluoride in the recovered potassium fluoride is 90 wt.%, and the content of potassium chloride in the recovered potassium fluoride is 10 wt.%, and the obtained recovered potassium fluoride is reused in the fluorination reaction.
In the preparation method provided by this example, the addition amount of potassium fluoride in the raw material is 14.828mol, 8.232mol of potassium fluoride is consumed in the fluorination reaction, 6.031mol of potassium fluoride is recovered, and the utilization rate of potassium fluoride is 96.19%.
Example 4
This example provides a process for preparing a fluorobenzonitrile comprising the steps of:
1500g of 1, 3-dimethyl-2-imidazolidinone, 350g of toluene, 500g of tetrachloroterephthalonitrile and 50g of tetraphenylphosphonium chloride are mixed, the mixture is stirred and heated to 150 ℃, reflux dehydration is carried out for 2 hours, toluene is continuously removed, and 346g of toluene is recovered.
Cooling the system after dehydrating and removing toluene to 100 ℃, adding 650.4g of anhydrous potassium fluoride and 292g of recovered potassium fluoride (the content of the potassium fluoride is 90 wt.%), heating to 250 ℃, carrying out heat preservation reaction for 5 hours, cooling to 25 ℃ after the reaction is finished, carrying out suction filtration, and washing a filter cake once by 500g of 1, 3-dimethyl-2-imidazolidinone to obtain 1177.4g of fluorinated mixed salt; 2314g of filtrate is distilled under the pressure of-0.1 MPa, the fraction at 110 ℃ of 100 ℃ is collected, 1630g of 1, 3-dimethyl-2-imidazolidinone is recovered, the distillation residual liquid is cooled and crystallized, is filtered, and the filter cake is dried in vacuum, thus 350.4g of tetrafluoroterephthalonitrile finished product (the content of tetrafluoroterephthalonitrile is 98.3 wt.%) is obtained, and the yield is 92%.
1500g of toluene is used for washing 1177.4g of fluorinated mixed salt filter cake twice, 2050g of water is added into the washed filter cake for dissolving, then the filter cake is transferred into a separating funnel for separating liquid, the upper layer of toluene phase is combined with toluene washing filtrate, the toluene is distilled and recovered under normal pressure, and the recovered toluene can be used for washing the next batch of fluorinated mixed salt; 3115g of lower aqueous phase, evaporating and crystallizing the lower aqueous phase at-0.09 MPa, cooling and filtering after 1470g of distilled water (used for dissolving the next batch of fluorinated mixed salt), wherein the filter cake is 605.6g of potassium chloride, and the filtrate is 1030.5g of potassium fluoride aqueous solution, and the refined potassium chloride is recovered by the method for recovering the refined potassium chloride in example 1.
1030.5g of potassium fluoride solution is subjected to spray drying treatment to obtain 490.2g of recovered potassium fluoride, the content of potassium fluoride in the recovered potassium fluoride is 90 wt.%, and the content of potassium chloride in the recovered potassium fluoride is 10 wt.%, and the obtained recovered potassium fluoride is reused for fluorination reaction.
In the preparation method provided by this example, the addition amount of potassium fluoride in the raw material is 15.718mol, 7.484mol of potassium fluoride is consumed in the fluorination reaction, 7.593mol of potassium fluoride is recovered, and the utilization rate of potassium fluoride is 95.92%.
Example 5
This example provides a process for preparing a fluorobenzonitrile comprising the steps of:
2500g of N, N-dimethylformamide, 300g of toluene, 500g of tetrachloroterephthalonitrile and 15g of cetyltrimethylammonium chloride are mixed, the temperature is raised to 110 ℃ by stirring, reflux dehydration is carried out for 2 hours, the toluene is continuously removed, and 297g of toluene is recovered.
Cooling the system after dehydrating and removing toluene to 98 ℃, adding 772.1g of anhydrous potassium fluoride and 332g of recovered potassium fluoride (the content of the potassium fluoride is 95 wt.%), heating to 120 ℃, carrying out heat preservation reaction for 20 hours, cooling to 20 ℃ after the reaction is finished, carrying out suction filtration, and washing a filter cake once by using 500g of N, N-dimethylformamide to obtain 1386g of fluorinated mixed salt; the filtrate was 3232g, distilled at-0.095 MPa, and 80-90 ℃ fractions were collected, and 2600g of N, N-dimethylformamide was recovered to obtain 341.7g of a tetrafluoroterephthalonitrile finished product (the tetrafluoroterephthalonitrile content was 98.6 wt.%), with a yield of 90%.
1500g of toluene is used for washing 1386g of the fluorinated mixed salt filter cake twice, 2350g of water is added into the washed filter cake for dissolving, then the filter cake is transferred into a separating funnel for separating liquid, the upper layer of toluene phase is combined with toluene washing filtrate, the toluene is distilled and recovered under normal pressure, and the recovered toluene can be used for washing the next batch of fluorinated mixed salt; 3581g of lower aqueous phase, evaporation and crystallization of the lower aqueous phase at-0.09 MPa, 1670g of distilled water (used for dissolving the next batch of fluorinated mixed salt), cooling and suction filtration, wherein the filter cake is 643.4g of potassium chloride, and the filtrate is 1253.5g of potassium fluoride aqueous solution, and the method for recovering the refined potassium chloride in the embodiment 1 is adopted to recover the refined potassium chloride.
1253.5g of potassium fluoride solution is subjected to spray drying treatment to obtain 622.4g of recovered potassium fluoride, the content of potassium fluoride in the recovered potassium fluoride is 95 wt.% and the content of potassium chloride in the recovered potassium fluoride is 5 wt.% through measurement, and the obtained recovered potassium fluoride is reused for fluorination reaction.
In the preparation method provided by this example, the addition amount of potassium fluoride in the raw material is 18.718mol, 7.484mol of potassium fluoride is consumed in the fluorination reaction, 10.177mol of potassium fluoride is recovered, and the utilization rate of potassium fluoride is 94.35%.
Example 6
2250g of sulfolane, 500g of toluene, 750g of 2, 6-dichlorobenzonitrile and 45g of cetyltrimethylammonium chloride were mixed, the temperature was raised to 120 ℃ with stirring, reflux dehydration was carried out for 2 hours, toluene removal was continued, and 495g of toluene was recovered.
Cooling the system after dehydrating and removing toluene to 90 ℃, adding 607g of anhydrous potassium fluoride, heating to 160 ℃, carrying out heat preservation reaction for 16h, cooling to 40 ℃ after the reaction is finished, carrying out suction filtration, and washing a filter cake once by using 500g of sulfolane to obtain 806g of fluorinated mixed salt; the filtrate was 3343.9g, distilled at-0.1 MPa, and the 105 ℃ and 108 ℃ fractions were collected in a yield of 96.5% to give 588.2g of finished 2, 6-difluorobenzonitrile (2, 6-difluorobenzonitrile content 99 wt.%).
1500g of toluene is used for washing 806g of fluorinated mixed salt filter cake twice, 1950g of water is added into the washed filter cake for dissolving, then the filter cake is transferred into a separating funnel for separating liquid, the upper layer of toluene phase is combined with toluene washing filtrate, the toluene is distilled and recovered under normal pressure, and the recovered toluene can be used for washing the next batch of fluorinated mixed salt; the lower aqueous phase was 2700g, the lower aqueous phase was evaporated at-0.09 MPa for crystallization, 1770g of distilled water (for dissolution of the next batch of mixed fluoride salts) was cooled and filtered, the filter cake was 674.5g of potassium chloride, and the filtrate was 246g of aqueous potassium fluoride solution. The method for recovering the fine potassium chloride in example 1 was used to recover the fine potassium chloride.
246g of potassium fluoride solution is subjected to spray drying treatment to obtain 112.4g of recovered potassium fluoride, the content of potassium fluoride in the recovered potassium fluoride is 85 wt.% and the content of potassium chloride is 15 wt.% through determination, and the obtained recovered potassium fluoride is reused for fluorination reaction.
In the preparation method provided by this example, the addition amount of potassium fluoride in the raw material is 10.448mol, 8.677mol of potassium fluoride is consumed in the fluorination reaction, 1.644mol of potassium fluoride is recovered, and the utilization rate of potassium fluoride is 98.78%.
From examples 1 to 6 provided by the present invention, it is understood that the recovery of potassium fluoride from the fluorinated mixed salt can improve the utilization rate of potassium fluoride.
In example 1, the molar ratio of chlorine to potassium fluoride in 2, 6-dichlorobenzonitrile is 1:1.36, the content of 2, 6-difluorobenzonitrile in the prepared finished 2, 6-difluorobenzonitrile is 99.5 wt.%, the potassium fluoride in the fluorinated mixed salt is recovered, the utilization rate of the final potassium fluoride is 98%, and if the potassium fluoride is not recovered, the utilization rate of the potassium fluoride is only 73.34%.
In example 2, the molar ratio of chlorine to potassium fluoride in 3, 4-dichlorobenzonitrile was 1:1.5, the content of 3, 4-difluorobenzonitrile in the finished 3, 4-difluorobenzonitrile prepared was 99.6 wt.%, the potassium fluoride in the fluorinated mixed salt was recovered, the final utilization rate of potassium fluoride was 97.54%, and if potassium fluoride was not recovered, the utilization rate of potassium fluoride was only 53.98%.
In example 3, the molar ratio of chlorine to potassium fluoride in tetrachloroterephthalonitrile was 1:1.8, the content of tetrafluoroterephthalonitrile in the finished tetrafluoroterephthalonitrile product obtained was 98 wt.%, the potassium fluoride in the fluorinated mixed salt was recovered, the utilization rate of the final potassium fluoride was 96.19%, and if the potassium fluoride was not recovered, the utilization rate of the potassium fluoride was only 55.52%.
In example 4, the molar ratio of chlorine to potassium fluoride in tetrachloroterephthalonitrile was 1:2.1, the content of tetrafluoroterephthalonitrile in the finished tetrafluoroterephthalonitrile product obtained was 98.3 wt.%, the utilization rate of potassium fluoride in the fluorinated mixed salt was recovered, and the utilization rate of potassium fluoride was 95.92% at the end, and if potassium fluoride was not recovered, the utilization rate of potassium fluoride was only 47.61%.
In example 5, the molar ratio of chlorine to potassium fluoride in tetrachloroterephthalonitrile was 1:2.5, the content of tetrafluoroterephthalonitrile in the finished tetrafluoroterephthalonitrile product obtained was 98.6 wt.%, the utilization rate of potassium fluoride in the fluorinated mixed salt was recovered, and the utilization rate of potassium fluoride was 94.35% at the end, and if potassium fluoride was not recovered, the utilization rate of potassium fluoride was only 39.98%.
In example 6, the molar ratio of chlorine to potassium fluoride in 2, 6-dichlorobenzonitrile was 1:1.2, the content of 2, 6-difluorobenzonitrile in the finished 2, 6-difluorobenzonitrile obtained was 99 wt.%, the potassium fluoride in the fluorinated mixed salt was recovered, the final utilization rate of potassium fluoride was 98.78%, and if potassium fluoride was not recovered, the utilization rate of potassium fluoride was only 80.05%.
From examples 1 to 6, it is understood that recycling of potassium fluoride in the mixed fluoride salt can improve the utilization rate of potassium fluoride and reduce the amount of waste potassium salt; in addition, as shown in comparative examples 3 to 5, the purity of the fluorobenzonitrile product can be improved by increasing the addition amount of potassium fluoride in the fluorination reaction, and the recovery rate of potassium fluoride is improved.
In conclusion, the fluorinated mixed salt generated in the process of preparing the fluorobenzonitrile is a mixture of potassium chloride and potassium fluoride, and the recovered potassium fluoride with the mass fraction of the potassium fluoride of 85-95 wt.% and the mass fraction of the potassium chloride of 5-15 wt.% can be obtained through recovery treatment, so that the utilization rate of the potassium fluoride is improved to 98.78% by using the recovered potassium fluoride for preparing the fluorobenzonitrile, the generation amount of three wastes is reduced, and the environmental pollution is reduced; the method provided by the invention recycles the potassium fluoride, so that the addition amount of the prepared chlorobenzonitrile potassium fluoride is increased, and the purity of the prepared chlorobenzonitrile is further increased to 99.6%.
The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.
Claims (10)
1. A process for preparing a fluorobenzonitrile, which comprises the steps of:
(1) the chlorobenzonitrile is subjected to fluorination reaction to prepare fluorobenzonitrile and fluorinated mixed salt;
(2) recovering potassium fluoride in the fluorinated mixed salt to obtain recovered potassium fluoride;
(3) and (3) recycling potassium fluoride obtained in the step (2) and using the recycled potassium fluoride in the fluorination reaction in the step (1).
2. The method according to claim 1, wherein the fluorination reaction in step (1) comprises the following steps:
(a) mixing an aprotic polar solvent, toluene, chlorobenzonitrile and a catalyst to obtain a mixed raw material solution;
(b) heating the mixed raw material liquid, dehydrating and removing methylbenzene;
(c) cooling, adding anhydrous potassium fluoride into the system dehydrated and subjected to toluene removal in the step (b), and reacting after heating;
(d) cooling and filtering after the reaction in the step (c) is finished to obtain filtering mother liquor and fluoridized mixed salt;
(e) and (d) rectifying the suction filtration mother liquor obtained in the step (d) to obtain the fluorobenzonitrile.
3. The process of claim 2, wherein the aprotic polar solvent of step (a) comprises any one or a combination of at least two of N, N-dimethylformamide, N-dimethylacetamide, dimethylsulfoxide, N-methylpyrrolidinone, 1, 3-dimethyl-2-imidazolidinone, or sulfolane;
preferably, the catalyst comprises any one or a combination of at least two of tetrabutylammonium chloride, hexadecyltrimethylammonium chloride or tetraphenylphosphonium chloride;
preferably, the mass ratio of the chlorobenzonitrile to the catalyst is 1 (0.03-0.1), preferably 1 (0.05-0.08);
preferably, the mass ratio of the chlorobenzonitrile to the aprotic polar solvent is 1 (1-5), preferably 1 (2-4);
preferably, the mass ratio of the chlorobenzonitrile to the toluene is 1 (0.5-0.7), preferably 1: 0.6.
4. The method according to claim 2 or 3, wherein the temperature of the temperature increase in step (b) is 110-150 ℃, preferably 120-140 ℃.
5. The method according to any one of claims 2 to 4, wherein the temperature of the temperature reduction in step (c) is 90 to 100 ℃, preferably 92 to 98 ℃;
preferably, the mole ratio of chlorine in the chlorobenzonitrile in the step (a) to the potassium fluoride in the step (c) is 1 (1.2-2.5), preferably 1 (1.5-2.1);
preferably, the temperature of the reaction in step (c) is 120-250 ℃, preferably 160-210 ℃;
preferably, the reaction time of step (c) is 5-20h, preferably 8-16 h;
preferably, the temperature of said temperature reduction of step (d) is below 50 ℃, preferably 25 ℃.
6. The method according to any one of claims 1 to 5, wherein the specific steps for recovering potassium fluoride from the fluorinated mixed salt in step (2) are as follows:
(I) washing the fluoridized mixed salt by using an organic solvent, adding water for dissolving, and layering to obtain a lower-layer water phase;
(II) crystallizing the lower-layer water phase obtained in the step (I), and performing suction filtration to obtain potassium chloride crystals and crystallization mother liquor;
(III) spray drying the crystallization mother liquor obtained in the step (II) to obtain the recovered potassium fluoride.
7. The method of claim 6, wherein the organic solvent of step (I) is a non-polar organic solvent;
preferably, the non-polar organic solvent comprises any one of toluene, carbon tetrachloride, ethyl acetate or dichloromethane, or a combination of at least two thereof;
preferably, the mass ratio of the fluorinated mixed salt to water is (0.4-0.6):1, preferably 0.5: 1.
8. The method according to claim 6 or 7, wherein the crystallization in step (II) is vacuum evaporation crystallization;
preferably, the pressure of the vacuum evaporation crystallization is-0.08 to-0.1 MPa, preferably-0.09 MPa.
9. The process according to any one of claims 6 to 8, wherein the mass fraction of potassium fluoride in the recovered potassium fluoride of step (III) is from 85 to 95 wt.%, preferably from 88 to 92 wt.%;
preferably, the mass fraction of potassium chloride in the recovered potassium fluoride is 5-15 wt.%, preferably 8-12 wt.%;
preferably, the sum of the mass fractions of potassium chloride and potassium fluoride is 100 wt.%.
10. A method according to any of claims 1-9, characterized in that the method comprises the steps of:
(1) mixing an aprotic polar solvent, toluene, chlorobenzonitrile and a catalyst to obtain a mixed raw material liquid, removing water and toluene in the mixed raw material liquid at the temperature of 110-100 ℃, adding anhydrous potassium fluoride at the temperature of 90-100 ℃, reacting for 5-20h at the temperature of 120-250 ℃, cooling to the temperature below 50 ℃, carrying out solid-liquid separation to obtain a fluorinated mixed salt and a suction filtration mother liquid, rectifying the suction filtration mother liquid to obtain fluorobenzonitrile, wherein the mass ratio of the chlorobenzonitrile to the catalyst is 1 (0.03-0.1), the mass ratio of the chlorobenzonitrile to the aprotic polar solvent is 1 (1-5), and the mass ratio of the chlorobenzonitrile to the toluene is 1 (0.5-0.7);
(2) washing fluorinated mixed salt by using a nonpolar organic solvent, adding water for dissolving after washing, dividing the salt into an upper layer and a lower layer, wherein the upper layer is a nonpolar organic solvent layer, the lower layer of water phase is a mixed solution of potassium chloride and potassium fluoride, and vacuum evaporation and crystallization are carried out under 0.09-0.1 MPa to obtain potassium chloride crystals and crystallization mother liquor, and spray drying the crystallization mother liquor to obtain recovered potassium fluoride, wherein the mass fraction of potassium fluoride in the recovered potassium fluoride is 85-95 wt.%, the mass fraction of potassium chloride is 5-15 wt.%, and the sum of the mass fractions of potassium chloride and potassium fluoride is 100 wt.%;
(3) and (3) recovering potassium fluoride obtained in the step (2) and using the recovered potassium fluoride in the step (1) for preparing the fluorobenzonitrile.
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