9thioxanthen9one

9-thioxanthen-9-one, commonly known as thioxanthone, is a heterocyclic ketone that serves as the parent compound of the thioxanthone family. The molecule features a tricyclic aromatic core that includes a sulfur atom and a carbonyl group at the 9-position. This structure gives thioxanthone notable photochemical properties, including absorption in the near-UV region and relatively high triplet energy, which enable its activity as a photosensitizer.

Thioxanthone is a solid at room temperature and is soluble in many organic solvents such as acetone, dichloromethane, and alcohols. In chemical applications, it is valued as a photosensitizer and as a photoinitiator component in UV-curing systems and various photochemical reactions. Upon light irradiation, it can populate triplet states and participate in energy or electron transfer with coinitiators to generate reactive species.

Synthesis routes for 9-thioxanthen-9-one are described in the literature and typically involve oxidation or cyclization steps from thianthrene or related precursors to install the carbonyl functionality and complete the thioxanthone framework. The parent compound also serves as a scaffold for numerous thioxanthone derivatives, which are used to tune photochemical properties for specific applications.

Safety: thioxanthone can be an irritant to skin and eyes and should be handled with appropriate personal protective equipment. It should be stored away from moisture and heat and disposed of according to local regulations.

See also: thioxanthone derivatives, xanthone, photoinitiators.