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GB2058067A - Process for the preparation of fluorinated aromatic compounds - Google Patents

Process for the preparation of fluorinated aromatic compounds Download PDF

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Publication number
GB2058067A
GB2058067A GB8028304A GB8028304A GB2058067A GB 2058067 A GB2058067 A GB 2058067A GB 8028304 A GB8028304 A GB 8028304A GB 8028304 A GB8028304 A GB 8028304A GB 2058067 A GB2058067 A GB 2058067A
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quaternary ammonium
solvent
fluorinated aromatic
aromatic compounds
aliquat
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ISC Chemicals Ltd
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ISC Chemicals Ltd
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C201/00—Preparation of esters of nitric or nitrous acid or of compounds containing nitro or nitroso groups bound to a carbon skeleton
    • C07C201/06—Preparation of nitro compounds
    • C07C201/12—Preparation of nitro compounds by reactions not involving the formation of nitro groups
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C201/00—Preparation of esters of nitric or nitrous acid or of compounds containing nitro or nitroso groups bound to a carbon skeleton
    • C07C201/06—Preparation of nitro compounds
    • C07C201/16—Separation; Purification; Stabilisation; Use of additives

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

Fluorinated aromatic compounds containing at least one other functional group, especially nitro or nitrile, are produced by heating the corresponding chlorinated or brominated compound with an alkali metal fluoride, in a polar aprotic solvent, in the presence of a quaternary ammonium compound, the sum of the carbon atoms of the radicals attached to the nitrogen atom of which is at least 18.

Description

SPECIFICATION Process for the production of fluorinated aromatic compounds This invention relates to the production of fluorinated aromatic compounds containing one or two ring-substituted fluorine atoms and at least one other functional group, by the halogen-exchange reaction on the corresponding chlorinated or brominated aromatic compounds by means of an alkali metal fluoride.
Our British patent specification 1,469,700, published 6th April 1977, describes and claims such a process wherein 2-chlorinitrobenzene is heated with an alkali metal fluoride at a temperature of from 230 to 250"C in the presence of tetrahydrothiophen-1 ,1 -dioxide (sulpholane). The preferred quantity of sulpholane is from 0.3 to 0.9 moles per mole of the 2-chloronitrobenzene.
United States patent specification 4,069,262 issued January 17th 1978, describes the same reaction when carried out in the same reaction medium but using finely-divided potassium fluoride and a catalyst for the reaction, chosen from macrocyclic ethers and quaternary ammonium halides. The reaction temperature claimed in from 240 to 250"C. The preferred quaternary ammonium halides mentioned in the specification are tetrabutyl-ammonium chloride, benzyl-trimethyl-ammonium fluoride and benzyl-triethyl-ammonium chloride. The role of the catalyst is apparently to promote the rate of the reaction by enhancing the solubilization of potassium fluoride, and hence the availability of fluoride ions in the reaction medium.
A further United States patent specification 4,140,719, issued February 20th 1979 deals with the preparation of difluoroaniline by the halogen-exchange fluorination of 2,4,5-trichloronitrobenzene using an alkali metal fluoride in an organic solvent and in the presence of certain quaternary complexes of nitrogen arsenic, phosphorus antimony or bismuth having relatively long-chain hydrocarbon substituents, followed by hydrogenation of the product.
The problem of halogen-exchange fluorination of monochloro- or dichloro- nitrobenzenes is made difficult by the requirement for long reaction times to achieve acceptable conversions and the fact that at temperatures above about 200"C, although reaction rates are increased, carbon recovery is reduced due to unknown side-reactions resulting in tarry and carbonaceous materials. There is therefore an incentive to try to increase reaction rates at relatively lower temperatures (preferably between 1000 and 170"C).
We have now found that the above-defined halogen-exchange reactions on mono-chloro and dichloronitrobenzenes can be carried out at an enhanced reaction rate and at a lower temperature if certain quaternary ammonium complexes are present in the reaction mixture.
This invention consists in a process for the production of fluorinated aromatic compounds containing one or two ring-substituted fluorine atoms and at least one other functional group, comprising heating the corresponding chlorinated or brominated aromatic compound with an alkali metal or ammonium fluoride in an aprotic solvent in the presence of a quaternary ammonium compound of general formula;
where X an anion capable of dissociating from the cation and R1, R2, R3, and R4 are monovalent hydrocarbon radicals, chosen from alkyl, alkenyl, alkynyl, aryl, aralkyl and cycloalkyl, wherein the sum of the carbon atoms of these radicals is at least 18, and separating the fluorinated aromatic compound thus produced.
Preferably the functional groups (other than halogen) are nitro- or nitrile-groups which are positioned ortho- or para- to the halogen atoms.
Preferably the alkali metal fluoride is that of potassium or sodium, although caesium fluoride may be used.
Preferably the aprotic solvent is polar e.g. sulpholane or dimethyl sulphoxide but it may be non-polar e.g.
toluene or benzene. Alternatively the aprotic solvent may be constituted by the organic starting material or by an excess of the quaternary ammonium compound.
Preferably the quaternary ammonium compound contains 3 radicals containing from 8 to 12 carbon atoms and one having from 1 to 3 carbon atoms. A more preferred quaternary ammonium compound is sold under the trade-name of "ALIQUAT 336" which has the general formula; n(C8 - C12)3 N+CH3CI The temperature of the reaction is not critical but it is preferred to work between 70" and 220"C, preferably from 1000 to 175"C. Normally the reaction will be carried out, in solution, at or about ambient pressures. The reaction times may be from 2 to 100 hours.
In general, known filtration and distillation techniques may be employed for isolating the products and, if necessary, recovering the solvents for further use. Such techniques are discussed in more detail in British patent specification 1,469,700.
The invention will be further illustrated by reference to the following non-limiting Examples in which Example 1 sets out the general procedure used to fluorinate 2-chloronitrobenzene with potassium fluoride in sulpholane in the presence of "ALIQUAT 336". Examples 2 to 13 illustrate fluorinations according to the invention on a variety of organic substrates and in a variety of solvents, using the quaternary ammonium compounds "ALIQUAT 336" and tetradodecyl ammonium bromide. The reaction temperature was 1300C (unless otherwise specified) and the reaction time was 6 hours.The abbreviations used in Examples 2-13 are as follows: 2-CNB 2-chloronitrobenzene > 99% 4-CNB 4-chloronitrobenzene > 99 /O 2,4-DCNB 2,4-dichloronitrobenzene > 99% 2-CBN 2-chlorobenzonitrile > 99% DMSO Dimethyl sulphoxide > 99% Sulpholane Tetrahydrothiophen-1 ,1 -dioxide > 98% Toluene Toluene > 99.5% KF Potassium fluoride > 97% Aliquat 336 Tricaprylmethylammonium chloride > 99% TDAB Tetradodecylammonium bromide > 99% Where "F" has replaced "C" represents fluoro replacing chloro.
Moles = Moles desired product Formation = x 100% Moles - Moles reactant added x 100% Yield = Moles desired product Moles reactant added-Moles reactant recovered x 100% Moles = Moles desired product+Moles reactant recovered Carbon = Moles reactant added x 10 /O Moles reactant added Recovery wt% = wt% desired product (from g.l.c.) Conversion = Wt% recovered reactant+ wt% desired product The Examples followed by the suffix B are in the absence of quaternary ammonium compounds and are for comparison purposes only (i.e. they are not according to the invention).
Example I 2-chloronitrobenzene (128.7g, 0.82M), sulpholane (68.6g, 0.57M) "ALIQUAT336" (46.6, 0.09M) and KF (50.0g, 0.86M) were heated in a 500 ml 3-neck-flask. The mixture was kept at a temperature of 1 25"C (maximum temperature 1 35"C). The mixture was burnt orange in colour; samples were removed at intervals.
The apparatus was adjusted for steam distillation and water (90cc) added. A total of 70.5g. organics was recovered from 21/2L distillate and 16.89 from 3L. (A total of 87.39 from 51/2L). The distillate came over as a foam-like emulsion (yellow) which formed three layers; 2-fluoronitrobenzene on the bottom, emulsion, then water on top. As the 2-fluoronitrobenzene was removed, so more fell out from the emulsion until no emulsion was left.
The percentage conversion of 2-chloronitrobenzene to 2-fluoronitrobenzene for cumulative reaction times up to 30 hours is shown in the following table: % by gas/liquid Conversion % Cumulative time chromatography 2FNBx100 2FNB 2CINB 2FNB+2CNB 1 hr 2.76 56.14 4.7 3 hrs 10.44 50.90 17.0 5 hrs 13.20 43.87 23.1 7 hrs 17.34 41.41 29.5 9 hrs 20.44 37.23 35.4 11 hrs 23.42 32.72 41.7 13 hrs 25.57 29.55 46.4 15 hrs 27.62 27.43 50.2 17 hrs 29.16 27.08 51.8 19 hrs 30.17 25.14 54.5 26 hrs 30.77 23.17 57.0 30 hrs 39.47 25.23 61.0 Thus conversions of about 60% are achieved after about 30 hrs. at 1250 - 1350C in the presence of ALIQUAT 336.At similar temperatures in the absence of ALIQUAT 336 very much lower conversions are obtained in the same times.
Example 2 509. of 2-chloronitrobenzene was heated with 309. of KF and 1 5g. of ALIQUAT 336 at 130"C for 6 hours. The mole ratio of organics:fluoride:solvent:phase transfer catalyst was 1:1.6:0:0.1. The product was 2fluoronitrobenzene with a carbon recovery of 98.0%, a yield of 97.9% and a formation of 23.6% Example 28 1 50g. of 2-chloronitrobenzene was heated with 80 g of KF at 130"C for 6 hours. The mole ratio of organics:fluoride:solvent:phase transfer catalyst was 1:1.4:0:0. The carbon recovery was 99.0% but yield and formation of desired product were NIL.
Example 3 4-chloronitrobenzene (1009) was heated with KF (40g) in sulpholane (809) in the presence of ALIQUAT 336 (259) at 130"C for 6 hours. The mole ratio of organics:fluoride:solvent: phase transfer catalyst was 1:1:1:0.08. The product was 4-fluoronitrobenzene with a carbon recovery of 86.7% a yield of 74.8% and a formation of 39.4% Example 3B Example 3 was repeated but in the absence, of ALIQUAT 336. The carbon recovery was 97.4% but both formation and yield were NIL.
Example 4 4-chloronitrobenzene (1 00g) was heated with KF (40g) in sulpholane (1209) in the presence of ALIQUAT 336 (259) at 1300C for 6 hours. The mole ratio as expressed in Example 3 was 1:1:1.6:0.08. The chief product was 4-fluoronitrobenzene with a carbon recovery of 86.1%, a yield of 72.2% and a formation of 36.0% Example 4B Example 4 was repeated, but in the absence of ALIQUAT 336. The carbon recovery was 99.0% but both formation and yield were NIL.
Example 5 4-chloronitrobenzene (100g) was heated with KF (409) in sulpholane (809) in the presence of ALIQUAT 336 (409). The mole ratio as previously expressed was 1:1:1:0.12. The product was 4-fluoronitrobenzene with a carbon recovery of 97.0%, a yield of 94.2% and a formation of 42.5%.
Example 5B Examples was repeated but in the absence of the ALIQUAT 336. A carbon recovery of 97.4% was achieved but both yield and formation were NIL.
Example 6 4-chloronitrobenzene (6.4g) was heated with KF (2.4g) in sulpholane (4.88g) in the presence of TDAB (2.59) for 6 hours at 130"C. The mole ratio (as previously expressed) was 1:1:1 :0.08. The product was 4-fluoronitrobenzene with a 99.9% carbon recovery, a yield of 99.5% and a formation of 1.5%.
Example 6B Example 6 was repeated using 1009 of 4-chloronitrobenzene, 40g of KF in 809 of sulpholane but in the absence of TDAB. The mole ratio was 1:1.2:1:0. The carbon recovery was 97.4% but yield and formation were both NIL.
Example 7 2,4-dichloronitrobenzene (100g) was heated with KF (61g) in DMSO (539) in the presence of ALI QUAT 336 (21g) for 6 hours at 1300C. The mole ratio (as expressed above) was 1:2:1:0.08. The products were 2-fluoro-4-chloronitrobenzene and 2,4-difluoronitrobenzene. The carbon recovery was 38.3% and yield was 36.8% and formation 35.9%.
Example 7B Example 7 was repeated in the absence of the ALIQUAT 336. The products were as above with a carbon recovery of 34.2%, a yield of 32.4% and a formation of 31.6% Example 8 2,4-dichloronitrobenzene (1009) was heated with KF (60g) in toluene (1009) in the present of ALIQUAT 336 (219) at 115" for 6 hours. The mole ratio as expressed above was 1:2:1.6:0.08. The product was 2,4-difluoronitrobenzene. The carbon recovery was 48.4%, the yield was 30.3% and the formation was 22.3%.
Example 8B Example 8 was repeated in the absence of ALIQUAT 336. The carbon recovery was 96% with a yield of 27.8% and a formation of 0.01%.
Example 9 2-chloronitrobenzene (1009) was heated with KF (409) in toluene (1009) in the presence of ALIOUAT 336 (25g) for 6 hours at 1 12"C. The mole ratio was 1:1:1.7:0.08. The product was 2-fluoronitrobenzene with a carbon recovery of 99.0%, a yield of 99.0% and a formation of 8.6%.
Example 9B Example 9 was repeated but in the absence of ALIQUAT 336. The carbon recovery was virtually 100% but yield and formation were NIL.
Example 10 2,4-dichloronitrobenzene (96.49) was heated with KF (58.99) in sulpholane (1249) in the presence of ALIQUAT 336 (249) at 100"C for 6 hours. The mole ratio was 1 :2:2:0.09. The products were 2-fluoro-4- chloronitrobenzene and 2,4-difluoronitrobenzene with a carbon recovery of 73.3%, a yield of 57.5% for 2F4CNB and 47.9% for 2,4DFNB and a formation of 36.6% for 2F4CNB and 24.6% for 2,4DFNB.
Example 10B Example 10 was repeated in the absence of ALIQUAT 336. Carbon recovery was 91.0% but yield and formation were NIL.
Example 11 2-chlorobenzonitrile (50g) was heated with KF (22.09) in sulpholane (66.0g) in the presence of ALIQUAT 336 (1 5g) at 130"C for 6 hours. The mole ratio as expressed above was 1:1:1.5:0.08. The product was 2-fluorobenzonitrile with a carbon recovery of 95.2%, a yield of 81.2% and a formation of 7.0%.
Example 1 1B Example 11 was repeated in the absence of ALIQUAT 336. The carbon recovery was 97.0% but both yield and formation were NIL.
Example 12 2-chloronitrobenzene (6.4g) was heated at 130"C for 6 hours with KF (2.4g) in the presence of TDAB (2.59) but in the absence of any other solvent. The mole ratio, as expressed above, was 1:1.2:0:0.08. The product was 2-fluoronitrobenzene with a carbon recovery of 88.2%, a yield of 71.0% and a formation of 10.5%.
Example 128 2-chloronitrobenzene (1 50g) was heated with KF (809) in the absence of solvent or TDAB. The mole ratio was 1:1.1:0:0. The carbon recovery was 99.0% but yield and formation were NIL.
Example 13 2-chloronitrobenzene (1 00g) was heated at 130"C with KF (50g) in the presence of ALIQUAT 336 (50g) but in the absence of any other solvent. The mole ratio was 1:1.4:0:0.15. The product was 2-fluoronitrobenzene with a carbon recovery of 84.7%, a yield of 72.6% and a formation of 40.5%.
Example 13B 2-chloronitrobenzene (1509) was heated with KF (809) in the absence of solvent and ALIQUAT 336. The mole ratio was 1:1.4:0:0. The carbon recovery was 99.0% but both yield and formation were NIL.

Claims (17)

1. A process for the production of fluorinated aromatic compounds containing one or two ringsubstituted fluorine atoms and at least one other functional group, comprising heating the corresponding chlorinated or brominated aromatic compound with an alkali metal or ammonium fluoride in an aprotic solvent in the presence of a quaternary ammonium compound of general formula
where X- is an anion capable of dissociating from the cation and R1, R2, R3 and R4 are monovalent hydrocarbon radicals, chosen from alkyl, alkenyl, aryl, aralkyl and cyclo-alkyl, wherein the sum of the numbers of carbon atoms of these radicals is at least 18, followed by separating the fluorinated aromatic compound produced.
2. A process as claimed in claim 1 in which the functional groups are either nitro - or nitrile groups.
3. A process as claimed in claims 1 or 2 in which the alkali metal fluoride is that of potassium.
4. A process as claimed in claims 1,2 or3 in which the aprotic solvent is polar.
5. A process as claimed in claim 4 in which the solvent is sulpholane or dimethyl sulphoxide.
6. A process as claimed in claims 1,2 or 3 in which the aprotic solvent is non-polar
7. A process as claimed in claim 6 in which the solvent is benzene or toluene.
8. A process as claimed in claims 1, 2 or 3 in which the solvent is constituted by an excess of the quaternary ammonium compound.
9. A process as claimed in claim 1 in which the quaternary ammonium compound contains 3 radicals containing from 8 to 12 carbon atoms and one having from 1 to 3 carbon atoms.
10. A process as claimed in claim 9, in which the quaternary ammonium compound is "ALIQUAT 336" as hereinbefore defined.
11. A process as claimed in any one preceding claim in which the reaction temperature is between 70 and 220"C.
12. A process as claimed in claim 11 in which the reaction temperature is between 100" and 175"C.
13. A process as claimed in claim 1 in which the mixture is heated for a period between 1/2 and 100 hours.
14. A process as claimed in claim 1 in which the products are separated by steam distillation of the reaction product.
15. A process for the production of fluorinated aromatic compounds substantially as hereinbefore described with reference to Example 1.
16. A process for the production of fluorinated aromatic compounds substantially as herein before described with reference to any one of the Examples 2 to 13.
17. Afluorinated aromatic compound prepared by a process according to any one preceding claim.
GB8028304A 1979-09-08 1980-09-02 Process for the preparation of fluorinated aromatic compounds Withdrawn GB2058067A (en)

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS617217A (en) * 1984-06-20 1986-01-13 Shinakita Kasei Kk Novel method for preparating fluorinated aromatic compound
US4642398A (en) * 1986-01-06 1987-02-10 Mallinckrodt, Inc. Preparation of fluoronitrobenzene compounds in dispersion of potassium fluoride
US4642399A (en) * 1984-11-29 1987-02-10 Mallinckrodt, Inc. Method for producing fluoronitrobenzene compounds
US4849552A (en) * 1986-01-06 1989-07-18 Mallinckrodt, Inc. Preparation of fluoroaromatic compounds in dispersion of potassium fluoride
US4927980A (en) * 1986-01-06 1990-05-22 Mallinckrodt Inc. Catalytic method for producing fluoroaromatic compounds using branched alkyl pyridinium salts
US4973772A (en) * 1987-02-07 1990-11-27 Mallinckrodt, Inc. Catalytic method for producing fluoroarmatic compounds using substituted pyridinium salts
US4973771A (en) * 1986-01-06 1990-11-27 Mallinckrodt, Inc. Phase transfer catalysts
EP0523671A3 (en) * 1991-07-17 1993-03-03 Hoechst Aktiengesellschaft Process for the preparation of chlorofluoronitrobenzenes
CN108586257A (en) * 2018-05-03 2018-09-28 浙江解氏新材料股份有限公司 A kind of novel processing step of p-fluoronitrobenzene
EP3786143A1 (en) 2019-08-27 2021-03-03 Fujian Yongjing Technology Co., Ltd. Process for preparing fluorobenzene derivatives and benzoic acid hypofluorite derivatives

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS617217A (en) * 1984-06-20 1986-01-13 Shinakita Kasei Kk Novel method for preparating fluorinated aromatic compound
JPH0676343B2 (en) 1984-06-20 1994-09-28 株式会社トーケムプロダクツ Novel method for producing fluorinated aromatic compounds
US4642399A (en) * 1984-11-29 1987-02-10 Mallinckrodt, Inc. Method for producing fluoronitrobenzene compounds
WO1987004151A1 (en) * 1986-01-06 1987-07-16 Mallinckrodt, Inc. Preparation of fluoroaromatic compounds in dispersion of potassium fluoride
US4849552A (en) * 1986-01-06 1989-07-18 Mallinckrodt, Inc. Preparation of fluoroaromatic compounds in dispersion of potassium fluoride
US4927980A (en) * 1986-01-06 1990-05-22 Mallinckrodt Inc. Catalytic method for producing fluoroaromatic compounds using branched alkyl pyridinium salts
US4973771A (en) * 1986-01-06 1990-11-27 Mallinckrodt, Inc. Phase transfer catalysts
US4642398A (en) * 1986-01-06 1987-02-10 Mallinckrodt, Inc. Preparation of fluoronitrobenzene compounds in dispersion of potassium fluoride
US4973772A (en) * 1987-02-07 1990-11-27 Mallinckrodt, Inc. Catalytic method for producing fluoroarmatic compounds using substituted pyridinium salts
EP0523671A3 (en) * 1991-07-17 1993-03-03 Hoechst Aktiengesellschaft Process for the preparation of chlorofluoronitrobenzenes
US5463148A (en) * 1991-07-17 1995-10-31 Hoechst Aktiengesellschaft Process for the preparation of chlorofluoronitrobenzenes
CN108586257A (en) * 2018-05-03 2018-09-28 浙江解氏新材料股份有限公司 A kind of novel processing step of p-fluoronitrobenzene
EP3786143A1 (en) 2019-08-27 2021-03-03 Fujian Yongjing Technology Co., Ltd. Process for preparing fluorobenzene derivatives and benzoic acid hypofluorite derivatives
US11299445B2 (en) 2019-08-27 2022-04-12 Fujian Yongjing Technology Co., Ltd Process for preparing fluorobenzene derivatives and benzoic acid hypofluorite derivatives

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