Method for preparing 2,7-dibromo fluorenone

Abstract

The invention relates to the field of the production of aromatic compound 2,7-dibromo fluorenone and particularly relates to a method for preparing the 2,7-dibromo fluorenone, which is characterized by comprising the following steps of: (1) taking industrial 2,7-dibromo fluorine, a benzene series solvent, potassium hydroxide, quaternary ammonium salts, and adding the constituents in a four-opening bottle; (2) heating to a temperature of 80-90 DEG C for reaction, and inletting air for oxidization; (3) depressurizing and distilling, and obtaining a yellow 2,7-dibromo fluorenone crystal after condensate is crystallized; and (4) carrying out once washing by water, and drying to obtain the product, i.e. the 2,7-dibromo fluorenone. The benzene series solvent is toluene or xylene. Compared with the prior art, the method for preparing the 2,7-dibromo fluorenone has the beneficial effects that: the reaction temperature is low, and the operation is simple and convenient; the low-cost potassium hydroxide is taken as a catalyst, thus, the cost is low; the benzene series solvent can be recovered and recycled through depressurizing and distilling, the amount of washing water is little and the treatment is easy, and the pollution to the environment is little; and the gas-phase chromatographic purity of the product is higher than 99.2%, the yield is higher than 85%, and thus, the production requirements are met.

Description

technical field [0001] The invention relates to the technical field of production of aromatic compound 2,7-dibromofluorenone, in particular to a preparation method of 2,7-dibromofluorenone. Background technique [0002] 2,7-Dibromofluorenone is an additive for photoconductive materials, and can also be used as a raw material for other important fine chemicals, and is widely used in the synthesis and preparation of dyes, photoconductive materials, and luminescent materials. Therefore, the study of its synthesis method has theoretical significance and broad application prospects. [0003] Relevant reports at home and abroad 2, the preparation method of 7-dibromofluorenone mainly contains the following aspects: [0004] In 1971, Borowitz et al. in the United States prepared 2,7-dibromofluorenone by reacting fluorenone and bromine in water, and the yield was only 51% [[J.Org.Chem., 36(4), 553, 1971]; [0005] In 1982, Gallos in Greece, John et al. used F3CCOZBr as a brominatin...

AI Technical Summary

Problems solved by technology

[0005] In 1982, Gallos in Greece, John et al. used F3CCOZBr as a brominating agent to react with fluorenone to obtain 2,7-dibromofluorenone with a yield of 73% [J.Chem.Res., Synop.1982, 6, 150, (Eng)], although this method productive rate improves to some extent, brominating agent F CCOZBr price is higher, causes the cost of product to increase;

[0006] In 1982, Japan's Asahi Glass Co. used fluorene and nibromobutylimide (NBS) to react in acetic acid and hydrobromic acid to generate 2, 7-dibromofluorene, and then 2, 7-dibromofluorene in acetic acid 2,7-dibromofluorenone (JP 58,177,955,1983, Appl.82,160,409,13Apr.1982) is prepared by oxidation with CrO3, the method uses fluorene as a raw material in an organic solvent to prepare 2,7 -Dibromofluorenone, but the oxidation process uses CrO3 as an oxidant, not only the cost of the product is higher, but also unfavorable for environmental protection

Obviously, in the above-mentioned preparation method, there are problems such as low yield, high cost, and difficult separation of reactants.