Phenacyltriphenylphosphonium bromide is a specialty chemical primarily used as a Wittig reagent in organic synthesis. It reacts with aldehydes or ketones to form α,β-unsaturated ketones, such as chalcones, by converting the carbonyl group into an alkene. This makes it valuable for synthesizing compounds with potential applications in pharmaceuticals, agrochemicals, and materials science, including certain dyes and pigments derived from enones.