benzophenone

Benzophenone, also known as diphenyl ketone, is an organic compound with the formula C13H10O. It features a carbonyl group (C=O) bonded to two phenyl rings (Ph–CO–Ph). The substance is a colorless to white crystalline solid with a melting point around 48–50°C and a boiling point near 305°C. It is poorly soluble in water and soluble in many organic solvents such as ethanol and acetone. The molecule is relatively stable under ordinary conditions and absorbs ultraviolet light due to its conjugated aromatic system.

Industrial production of benzophenone is commonly achieved by Friedel–Crafts acylation of benzene with benzoyl chloride in the presence of a Lewis acid catalyst, such as aluminum chloride, followed by workup to yield the ketone.

Applications and uses of benzophenone are diverse. It is employed as a photoinitiator in UV-curable coatings and inks, where it absorbs UV light and initiates radical polymerization. It also serves as a UV absorber in plastics, coatings, and some cosmetic formulations to reduce UV degradation. In organic synthesis, benzophenone is used as an intermediate and sometimes as a photosensitizer or reagent for various transformations.

Safety and handling considerations include irritation to skin and eyes upon contact; inhalation of dust or vapors should be avoided. It has relatively low acute toxicity but should be handled with appropriate PPE and stored away from heat and light. Environmental concerns center on its persistence in organic media and potential aquatic effects if released in large quantities.

See also: photoinitiators, UV absorbers, Friedel–Crafts acylation.