Preparation of 1,5-difluoro-2,4-dinitrobenzene_Kain Industrial Additive

Overview^[1]

1,5-Difluoro-2,4-dinitrobenzene is an important intermediate in the synthesis of the herbicide flufenacil, which can be etherified, hydrogenated and reduced to form rings, and sequentially combined with propylamine bromide. React with acid anhydride to obtain propargyl flufenate. At the same time, because its structure contains two nitro groups and two fluorine groups, the nitro group is an energetic group, and the fluorine group can be further modified into other energetic groups, so 1,5-difluoro-2, 4-Dinitrobenzene is also an intermediate that can be widely used in the field of energetic materials.

Preparation^[1]

A method for preparing 1,5-difluoro-2,4-dinitrobenzene, which mainly includes the following experimental steps: under magnetic stirring, add 220mL of 98% concentrated sulfuric acid into a 1000mL reaction bottle, and mix with ice. After the water bath is completely cooled, slowly add 220 mL (5.0 mol) of 95% fuming nitric acid, that is, the volume ratio of concentrated sulfuric acid and concentrated nitric acid in the nitrating reagent is 1:1. After the fuming nitric acid is added, continue stirring for 15 minutes in an ice-water bath (the fuming nitric acid is completely dissolved in sulfuric acid), then slowly add 114g (1.0mol) of m-difluorobenzene (the temperature of the system does not change during the dropping process). exceeds 10°C), after the dropwise addition is completed, keep the system in an ice-water bath and continue stirring for 3 hours. Then gradually increase the reaction temperature to room temperature and continue stirring. The reaction was monitored using a TLC plate, in which the developing solvent was ethyl acetate: petroleum ether = 1:20, and Rf = 0.6. It was observed that the raw material point disappeared after 20 hours, and the reaction was completed. Carefully and slowly pour the reaction solution into the stirring ice water. It is found that a large amount of light yellow solid has precipitated. After the precipitation is complete, perform a filtration operation. The filter cake needs to be washed twice with n-hexane and then washed repeatedly with distilled water. to neutrality, collect the filter cake and dry it in the air to obtain 193.95g of beige solid product 1,5-difluoro-2,4-dinitrobenzene, with a yield of 95.1% and a purity of 98.2%.

Main reference materials

[1] CN201611247897.3 Method for preparing 1,5-difluoro-2,4-dinitrobenzene