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.