(Trimethylphosphoranylidene)acetonitrile is a phosphonium ylide reagent widely used in organic synthesis, particularly as a Wittig reagent for the stereoselective formation of α,β-unsaturated nitriles from aldehydes or ketones. This reaction is crucial for constructing carbon-carbon double bonds in complex molecules. It is also employed in the synthesis of phosphorus-containing heterocycles and as a building block in materials science for functionalized polymers with electronic properties. In the pharmaceutical sector, it facilitates the assembly of intricate scaffolds for drug candidates. The 0.5 M solution in THF offers stability, ease of handling, and precise dosing, enhancing its utility in laboratory and industrial applications.