Aerobic Oxidation of Fluorene to 9-fluorenone by Liquid-phase Catalysis and Separation of 9-fluorenone from Phenanthrene

Abstract

To realize fluorene oxidation to 9-fluorenone with high selectivity in a short time and highly efficient separation of 9-fluorenon from phenathrene, the effect of solvent and catalyst on the oxidation of fluorene to 9-fluorenone, and the type and dosage of quaternary ammonium salt phase transfer agent with the co-existance of phenathrene was investigated. Thereafter, the separation performance of phenanthrene and 9-fluorenone with different solvents was investigated. The results show that, with xylene as solvent, 45% potassium hydroxide aqueous solution as catalyst, tetrabutylammonium bromide as phase transfer agent, fluorene was completely converted into 9-fluorenone within 3 h, and phenanthrene did not participate in the reaction. With methanol, ethanol, and n-butanol as the separation solvents of phenanthrene and 9-fluorenone, cyclohexane and pentane as the refining solvents of 9-fluorenone, the purity of phenanthrene and 9-fluorenone reached above 96%. With anthracene residue as raw material, anthracene and carbazole did not participate the reaction, the purity of phenanthrene and 9-fluorenone was 97.39% and 93.66%, and the yield was 72.04% and 50.85%, respectively.

Keywords

• reaction-separation coupling
• quaternary ammonium salt
• phase-transfer catalysis
• base
• solvent