Preparation method of 9-fluorenone

TLDR: In this paper, a method for the preparation of 9-fluorenone is described. But the method is not suitable for the use of industrial fluorene, benzene series solvent, sodium hydroxide and quaternary ammonium salt, and the solvent is toluene or dimethylbenzene.

Abstract: The invention relates to the technical field of production of an aromatic compound 9-fluorenone, in particular to a preparation method of the 9-fluorenone. The preparation method includes the steps as follows: 1) taking industrial fluorene, benzene series solvent, sodium hydroxide and quaternary ammonium salt, and adding the four components in a four-mouth bottle; 2) stirring the mixture in normal pressure, increasing the temperature to above 90 DEG C, reacting, and introducing air for oxidization; 3) conducting reduced-pressure distillation and allowing concentrate to crystallize, thus obtaining yellow fluorenone crystals; and 4) washing the fluorenone crystals for one time and then drying the fluorenone crystals, thus obtaining the 9-fluorenone product. The benzene series solvent is toluene or dimethylbenzene. Compared with the prior art, the preparation method has the benefits as follows: 1) the reaction temperature is low, the operation is simple and convenient and the reaction conditions are moderate; 2) the cheap sodium hydroxide is taken as a catalyst, so the cost is low; 3) the benzene series solvent can be recycled by reduced-pressure distillation, washing water is little in quantity, treatment is easy and pollution to environment is small; and 4) the gas chromatographic purity of the product is higher than 99.2%, the yield is higher than 86.7% and the production requirements are met.