1,2,3,4-tetrafluorobenzene

反応条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

実験手順: 1,2,3,4-Tetrafluorobenzene (67.7 g), sodium hydrobromide (20.8 g), and 200 ml of ethyleneglycol are refluxed with good stirring for 3 hours. The reaction mixture is poured into water (800 ml), acidified with 10% hydrochloric acid and then extracted with ether. The ether is washed with dilute sodium hydroxide and water, and then distilled under vacuum to give 2-(2,3,6-trifluorophenoxy) ethanol), b.p. about 100° at 15 min. extracted with ether The ether is washed with dilute sodium hydroxide and water distilled under vacuum

反応条件: temp:200.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

実験手順: In an autoclave having an inner volume of 100 ml, 3.0 g (0.0126 mole) of 3,4,5,6-tetrafluorophthalic acid containing no sulfate ion, 0.5 g (0.0125 mole) of sodium hydroxide, and 50 g of water were placed and heated for reaction at 200° C. for 25 hours. After completion of the reaction, the reaction mixture was cooled to room temperature and extracted with 150 ml of diisopropyl ether. By analyzing this extract by gas chromatography using a 2 m column packed with SE52 and kept at 50° C., the reaction was found to have produced 2.9 mole % of 1,2,3,4-tetrafluorobenzene, 89.1 mole % of trifluorophenol, and substantially no 2,3,4,5-tetrafluorobenzoic acid based on the 3,4,5,6-tetrafluorophthalic acid used as the starting material [pH 2.75 at 25° C. at the time of charging]. After completion of the reaction the reaction mixture was cooled to room temperature extracted with 150 ml of diisopropyl ether this extract by gas chromatography kept at 50° C.

反応条件: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

実験手順: To one liter of concentrated sulfuric acid was added, at 5° C., 100 ml of 1,2,3,4-tetrafluorobenzene. Then a mixture of 100 ml of 70% nitric acid premixed with 200 ml of concentrated sulfuric acid at 0° C. was slowly added. The reaction was stirred at 0° C. for one hour, and then one hour at 25° C. The mixture was poured over ice and extracted with dichloromethane, which was dried and concentrated to give 120 g of a thick residue which was one spot thin layer chromatography. This product was used for the next step without purification. was slowly added one hour at 25° C The mixture was poured over ice extracted with dichloromethane, which was dried concentrated

反応条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

実験手順: 1,2,3,4-Tetrafluorobenzene (67.7 g), sodium hydrobromide (20.8 g), and 200 ml of ethyleneglycol are refluxed with good stirring for 3 hours. The reaction mixture is poured into water (800 ml), acidified with 10% hydrochloric acid and then extracted with ether. The ether is washed with dilute sodium hydroxide and water, and then distilled under vacuum to give 2-(2,3,6-trifluorophenoxy) ethanol), b.p. about 100° at 15 min. extracted with ether The ether is washed with dilute sodium hydroxide and water distilled under vacuum

反応条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

実験手順: 1,2,3,4-Tetrafluorobenzene (67.7 g), sodium hydrobromide (20.8 g), and 200 ml of ethyleneglycol are refluxed with good stirring for 3 hours. The reaction mixture is poured into water (800 ml), acidified with 10% hydrochloric acid and then extracted with ether. The ether is washed with dilute sodium hydroxide and water, and then distilled under vacuum to give 2-(2,3,6-trifluorophenoxy) ethanol), b.p. about 100° at 15 min. extracted with ether The ether is washed with dilute sodium hydroxide and water distilled under vacuum

反応条件: temp:200.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

実験手順: In an autoclave having an inner volume of 100 ml, 3.0 g (0.0126 mole) of 3,4,5,6-tetrafluorophthalic acid containing no sulfate ion, 0.5 g (0.0125 mole) of sodium hydroxide, and 50 g of water were placed and heated for reaction at 200° C. for 25 hours. After completion of the reaction, the reaction mixture was cooled to room temperature and extracted with 150 ml of diisopropyl ether. By analyzing this extract by gas chromatography using a 2 m column packed with SE52 and kept at 50° C., the reaction was found to have produced 2.9 mole % of 1,2,3,4-tetrafluorobenzene, 89.1 mole % of trifluorophenol, and substantially no 2,3,4,5-tetrafluorobenzoic acid based on the 3,4,5,6-tetrafluorophthalic acid used as the starting material [pH 2.75 at 25° C. at the time of charging]. After completion of the reaction the reaction mixture was cooled to room temperature extracted with 150 ml of diisopropyl ether this extract by gas chromatography kept at 50° C.

反応条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

実験手順: 19.4 g (0.1 mol) of 2,3,4,5-tetrafluorobenzoic acid are dissolved in 40 g of water, 20 g of a mixture of trialkylamines having 6 to 14 carbon atoms (Hostarex A 327; a commercial product of Hoechst AG) and 0.2 g of copper(I) oxide are added and the pH is adjusted to 7 by addition of 30% strength aqueous sodium hydroxide solution. The decarboxylation is carried out in an autoclave at 155° C. within a period of 4 hours, the evolved carbon dioxide at a pressure of 12 bar being depressurized via a pressure cooler and the distillate passing overhead in this case being collected (cold trap -78° C.). After termination of the reaction, the autoclave is cooled and the 1,2,3,4-tetrafluorobenzene is distilled off by steam at 100° C. and 1.5 l of distillate are obtained, which distillate is combined with the distillate collected previously. The combined distillates are extracted by means of dichloromethane, the organic phase is separated off, dried over magnesium sulfate, filtered and the solvent is removed in vacuo. 10.5 g of crude, slightly yellowish 1,2,3,4-tetrafluorobenzene are obtained, which can be brought to a very high purity by fractional distillation. being collected (cold trap -78° C.) After termination of the reaction the autoclave is cooled the 1,2,3,4-tetrafluorobenzene is distilled off by steam at 100° C. 1.5 l of distillate are obtained collected previously The combined distillates are extracted by means of dichloromethane the organic phase is separated off dried over magnesium sulfate filtered the solvent is removed in vacuo

反応条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

実験手順: DE-A 3 420 796 describes a process for the preparation of 2,3,4,5-tetrafluorobenzene derivatives, in which 2,3,4,5-tetrachlorobenzene derivatives are reacted with potassium fluoride in a solvent at elevated temperature. Using 2,3,4,5-tetrachlorobenzoyl fluoride as starting material and continuously distilling off the mixture of the fluorination products at from 800 to 500 mbar produces, after fractional distillation of the mixture of the fluorination products, the desired 2,3,4,5-tetrafluorobenzoyl fluoride in a yield of only 10% of theory, while significantly more undesired fluorination products are obtained, namely 2,3,4-trifluoro-5-chlorobenzoyl fluoride in a yield of 43% of theory and 2,4-difluoro-3,5-dichlorobenzoyl fluoride in a yield of 14% of theory (see Example 2 in DE-A). If 2,3,4,5-tetrachlorobenzonitrile is used as starting material and the fluorination mixture is subjected to fractional distillation, the ratios are obviously similar, although no information concerning the amounts of the tetrafluoro-, tetrafluorochloro- and difluorodichlorobenzonitriles obtained is given (see Example 5 in DE-A). continuously distilling off the mixture of the fluorination products at from 800 to 500 mbar produces after fractional distillation of the mixture of the fluorination products

反応条件: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

実験手順: To one liter of concentrated sulfuric acid was added, at 5° C., 100 ml of 1,2,3,4-tetrafluorobenzene. Then a mixture of 100 ml of 70% nitric acid premixed with 200 ml of concentrated sulfuric acid at 0° C. was slowly added. The reaction was stirred at 0° C. for one hour, and then one hour at 25° C. The mixture was poured over ice and extracted with dichloromethane, which was dried and concentrated to give 120 g of a thick residue which was one spot thin layer chromatography. This product was used for the next step without purification. was slowly added one hour at 25° C The mixture was poured over ice extracted with dichloromethane, which was dried concentrated

反応条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

実験手順: 1,2,3,4-Tetrafluorobenzene (67.7 g), sodium hydrobromide (20.8 g), and 200 ml of ethyleneglycol are refluxed with good stirring for 3 hours. The reaction mixture is poured into water (800 ml), acidified with 10% hydrochloric acid and then extracted with ether. The ether is washed with dilute sodium hydroxide and water, and then distilled under vacuum to give 2-(2,3,6-trifluorophenoxy) ethanol), b.p. about 100° at 15 min. extracted with ether The ether is washed with dilute sodium hydroxide and water distilled under vacuum