Fluorene

Fluorene is a polycyclic aromatic hydrocarbon (PAH) with the chemical formula C13H10. It comprises two benzene rings fused to a central five-membered ring, giving a rigid fluorenelike skeleton. The molecule is nonpolar and hydrophobic, with limited water solubility and good solubility in many organic solvents. It is a white crystalline solid that melts around 115–118°C.

Occurrence and production: Fluorene occurs in trace amounts in coal tar and is also manufactured industrially as an intermediate in the production of dyes, resins, and materials used in organic electronics. Industrial preparation often involves the dehydrogenation of dihydrofluorene or related cyclization reactions from suitable precursors under catalytic conditions.

Uses and properties: Fluorene and its derivatives are widely used as building blocks in organic synthesis. The fluorene framework lends itself to a variety of functionalized compounds, including 9,9-diarylfluorenes that have been explored for use in organic light-emitting diodes (OLEDs) and other electronic materials. Fluorene-derived units are also common in dyes and polymers. In peptide synthesis, the fluorenylmethyl motif (such as Fmoc) is used as a protecting group, illustrating the broader utility of fluorene chemistry in synthetic applications.

Safety and handling: Fluorene is of relatively low acute toxicity but can be an irritant to skin, eyes, or respiratory tract with improper handling. It is a non-water-soluble organic solid and should be stored in a cool, well-ventilated area away from oxidizing agents and sources of ignition. Standard laboratory precautions, including gloves and eye protection, are advised when handling fluorene or its derivatives.