The Preparation Of Fluorenone From Catalytic Oxidation Of Fluorene:A Green Technological Study

This paper prepared fluorenone from the phase transfer oxidation of fluorene, used xylene and water as solvent, alkali as catalyst, quaternary ammonium salt as phase transfer reagent, air as oxidant, the temperature of water bath was50℃, the catalyst was40%NaOH aqueous solution, phase transfer reagent was tetra-butyl ammonium chloride, xylene solvent and ratio of xylene/water was5:1, the molar ratio of fluorene and phase transfer reagents was100:1, the stirring speed was300r/min, ventilation rate was300*2mL/min. Under this condition, conversion yield of fluorene was100%, product yield of fluorenone and water was100%with no other by-products.Determined the solubility of fluorene and fluorenone in the xylene, built a new system to prepare fluorenone from four-phase phase transfer catalytic oxidation of fluorene. By optimizing the conditions, conversion yield of fluorene can be100%when the addition of fluorene was3times as saturated solution system. This method can reduce the use of xylene, improve the utilization of equipment.In the system of suspend reaction, this paper proposed once crystallization and twice crystallization based on the difference of post treatment. Once crystallization was simple, and pure fluorenone can be acquired in twice crystallization, the yield was70%. Twice crystallization can meet the requirement of pure fluorenone.Designed recycle technology of solvent, catalyst and phase transfer reagent based on the post treatment, achieved the reuse of raw material.Studied the purification of fluorenone, and proposed recrystallization in industrial alcohol, xylene and cyclohexane. The yield of recrystallization in cyclohexane was higher than80%.Determined eutectic phase diagram of fluorene and fluorenone, the lowest melting point was about70℃, the molar ratio of fluorene and fluorenone was50%:50%. Proposed a new system to prepare fluorenone from the phase transfer oxidation of fluorene, and used eutectic as organic phase, alkali liquor as water phase. Conversion yield of fluorene was100%. Achieved a new technology can prepare large amounts of fluorenone from few fluorenone, meanwhile, avoided the use of solvent. Merged the new reaction technology and recrystallization can simply the recycle of raw material and purification of fluorenone.Combined three production technology based on the characteristics of reaction, separation and purification, can meet different requirements.Determined constitute of industrial fluorene; the material balance of each component of reactants and products reveals:the reaction of four-phase transfer oxidation of fluorene and phase transfer oxidation of eutectic was green reaction. Conversion yield of fluorene was100%, product yield of fluorenone and water was100%with no other by-products. The impurities in fluorene had no change and no influence of reaction.