Fluorenone purification

Acetylfluorene melting at 124-126° has been found to give as good results as the pure compound of melting point 128-129°. The submitters report that the over-all yield from fluorene to fluorenone-2-carboxylic add can be improved by the use of the crude product of the acylation (m.p. 113-117°) without purification (p. 4). 

Bis-(4-hydrox5 henyl)-fluorene is commercially synthesized by the reaction of phenol with 9-fluorenone, in the same way as the synthesis of bisphenol A proceeds. Hydrogen chloride, 3-mercaptopropionic acid or methanesulfonic acid are used as catalysts. The condensation reaction of fluorenone and phenol in the presence of gaseous hydrogen chloride proceeds with sufficient speed already by 30°C. ° A high purity monomer can be obtained by a two-step purification process. In the first purification step, the crude 9,9-bis-(4-hydrox5 henyl)-fluorene is refluxed in acetonitrile and recrystallized. In the second step, the product is purified by crystallization from a toluene/isopropanol mixture. 

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