JP2561471B2 - Method for producing 5-fluoro-2-nitrophenol - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a method for producing 5-fluoro-2-nitrophenol. More specifically, 2- [4-substituted-7-fluoro-, which is a herbicide described in JP-A No. 61-79486, is disclosed.
2H-1,4-benzoxazin-3 (4H) -one-6-yl] -4,5,6,7-tetrahydro-2H-isoindole-
The present invention relates to a method for producing 5-fluoro-2-nitrophenol, which is an intermediate in producing 1,3-dione.

<Prior Art> Conventionally, as a method for producing 5-fluoro-2-nitrophenol, a method of nitrating 3-fluorophenol with fuming nitric acid (J. Chem. Soc., 1928 , 1880) and 2,4-difluorophenol were used. After reacting nitrobenzene with sodium hydroxide solution, steam distillation under acidic condition
73, No. 3, 513, 1970) is known.

<Problems to be Solved by the Invention> However, the former method has a problem in that 3-fluoro-4-nitrophenol and dinitro 2,4-dinitrophenol, which are different in orientation of nitration, are by-produced. In addition, the latter method has a problem that a separation operation such as steam distillation is necessary because 3-fluoro-4-nitrophenol is by-produced and the yield is not always sufficient. .

<Means for Solving Problems> The inventors of the present invention have diligently studied a method for producing 5-fluoro-2-nitrophenol, and as a result, have determined that 2,4-difluoronitrobenzene and hydroxide are combined with 1,4-dioxane. By reacting in the medium, 5-fluoro- can be easily obtained in high yield and without by-product of 3-fluoro-4-nitrophenol.
The present invention has been accomplished by finding that 2-nitrophenol can be produced.

This reaction is usually carried out at a temperature of 0 to 200 ° C., and hydroxides used include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, calcium hydroxide, barium hydroxide, Examples thereof include tetraalkylammonium hydroxide (eg, benzyltrimethylammonium hydroxide). If necessary, benzyltrimethylammonium chloride, benzyltriethylammonium chloride, tetrabutylammonium bromide,
A phase transfer catalyst such as crown theteres and tris [2- (2-methoxyethoxy) ethyl] amine can also be added. The time required for this reaction is usually 4 hours to 10 days, and the reaction time can be shortened by raising the reaction temperature.

After completion of the reaction, the reaction solution is added to water, extracted with an organic solvent if necessary, and subjected to usual post-treatments such as concentration to obtain 5
-Fluoro-2-nitrophenol can be produced.

<Examples> Next, the present invention will be described in more detail with reference to production examples and comparative examples.

Production Example 32.00 g of sodium hydroxide (flakes, 95% product) and tris [2- (2methoxyethoxy) ethyl] amine
3.20 g was suspended in 200 g of 1,4-dioxane, and 2,4-
31.82 g of difluoronitrobenzene was added, and the mixture was stirred at the same temperature for 32 hours. Water was added to the reaction solution, the aqueous layer was washed with 1,2-dichloroethane, 72 g of concentrated hydrochloric acid was added to the aqueous layer, and the mixture was extracted with 1,2-dichloroethane. The extract was washed with dilute hydrochloric acid, dried and the solvent was distilled off under reduced pressure to obtain 27.61 g of 5-fluoro-2-nitrophenol.

Yield 88% Melting point 35-37 ° C Comparative Example 1 32.00 g of sodium hydroxide (95% product) and 2.28 g of benzyltriethylammonium chloride were dissolved in 200 g of water, and 40
31.82 g of 2,4-difluoronitrobenzene was added at 0 ° C, and the mixture was stirred at the same temperature for 27 hours. 800 g of water was added to the reaction solution, the aqueous layer was washed with 1,2-dichloroethane, 72 g of concentrated hydrochloric acid was added to the aqueous layer, and the mixture was extracted with 1,2-dichloroethane. The extract was washed with diluted hydrochloric acid, dried and the solvent was distilled off under reduced pressure to obtain 27.24 g of a mixture of 5-fluoro-2-nitrophenol and 3-fluoro-4-nitrophenol (mixing ratio 87:13). It was

Comparative Example 2 2.49 g of potassium hydroxide (85.5% product) was dissolved in 47.31 g of water, 1.59 g of 2,4-difluoronitrobenzene was added at 40 ° C., and the mixture was stirred at the same temperature for 22 hours. 40 g of water was added to the reaction solution,
-After washing the aqueous layer with dichloroethane, concentrated hydrochloric acid in the aqueous layer 3.
6 g was added and extracted with 1,2-dichloroethane. The extract was washed with diluted hydrochloric acid, dried and the solvent was distilled off under reduced pressure to obtain 1.26 g of a mixture of 5-fluoro-2-nitrophenol and 3-fluoro-4-nitrophenol (mixing ratio 90:10). It was

Comparative Example 3 2.49 g of potassium hydroxide (85.5% product) and 0.16 g of tetrabutylammonium bromide were added to N, N-dimethylformamide.
The suspension was suspended in 47.31 g, 1,59 g of 2,4-difluoronitrobenzene was added at 40 ° C., and the mixture was stirred at the same temperature for 12 hours. Water 4 in the reaction solution
After adding 0 g and washing the aqueous layer with 1,2-dichloroethane,
Concentrated hydrochloric acid (3.6 g) was added to the aqueous layer, and the mixture was extracted with 1,2-dichloroethane. The extract was washed with diluted hydrochloric acid, dried and the solvent was distilled off under reduced pressure to give a mixture of 5-fluoro-2-nitrophenol and 3-fluoro-4-nitrophenol (mixing ratio 9
0:10) 1.46 g was obtained.

Comparative Example 4 2.49 g of potassium hydroxide (85.5% product) and 0.16 g of tetrabutylammonium bromide were suspended in 47.31 g of toluene, 1.59 g of 2,4-difluoronitrobenzene was added at 40 ° C., and the mixture was stirred at the same temperature for 38 hours. However, the progress of the reaction was slow, and it was confirmed in the liquid chromatogram that only 25% of the mixture of 5-fluoro-2-nitrophenol and 3-fluoro-4-nitrophenol was produced.

Comparative Example 5 2.49 g of potassium hydroxide (85.5% product) and 0.16 g of tetrabutylammonium bromide were added to 47.31 g of 1,2-dichloroethane.
Suspended in 2,4-difluoronitrobenzene 1.5 at 40 ℃
9g was added and stirred at the same temperature for 18 hours, but the reaction progressed slowly,
5-fluoro-2-nitrophenol and 3-fluoro-
The liquid chromatogram confirmed that the mixture of 4-nitrophenol produced only 4%.

<Effects of the Invention> According to the production method of the present invention, 5-fluoro-2-nitrophenol can be produced in a high yield without producing by-product of 3-fluoro-4-nitrophenol.

Front page continued (72) Inventor Nobuaki Tabei 3-1-198 Kasugade, Konohana-ku, Osaka Sumitomo Chemical Co., Ltd. (72) Inventor Yuji Funaki 3-1-1, Kasugade, Konohana-ku, Osaka Sumitomo Chemical Co., Ltd.

Claims (2)

(57) [Claims] 1. A method comprising the steps of adding 1,4-difluoronitrobenzene and hydroxide in the presence or absence of a phase transfer catalyst to give 1,4
-A method for producing 5-fluoro-2-nitrophenol, characterized by reacting in dioxane. 2. A method according to claim 1, wherein a phase transfer catalyst is used.
The production method described in the section.