Used as a Lewis acid catalyst in organic synthesis, including Friedel-Crafts alkylation and acylation of aromatic compounds, chlorination reactions, and the production of dyes and pharmaceuticals. Employed as an intermediate in the manufacturing of flame retardants when combined with halogenated compounds, enhancing fire resistance in plastics and textiles. Used in the glass and ceramics industry to increase opacity. Utilized in analytical chemistry for detecting vitamin A and related compounds through the Carr-Price reaction, where it forms a blue complex with vitamin A. Also serves in the electronics industry for the production of semiconductor materials and in the refining of lead and tin alloys.