Benzyl chloromethyl ketone is an organic compound with the chemical formula C9H9ClO. It is a colorless to pale yellow liquid that is primarily used in chemical synthesis. This compound features a benzyl group, a chloromethyl group, and a ketone functional group, making it useful in various chemical reactions. In laboratory settings, benzyl chloromethyl ketone serves as a reagent for introducing the chloromethyl group into other organic molecules. Its reactivity allows it to participate in nucleophilic substitution reactions, which are essential in the development of pharmaceuticals and other chemical products.