2-Chloromethyl-4-methoxy-3-methylpyridine hydrochloride is a pyridine derivative characterized by a chloromethyl group at the 2-position, a methoxy group at the 4-position, and a methyl group at the 3-position, supplied as its hydrochloride salt. This compound is a white to off-white crystalline powder. This chemical serves as a crucial pharmaceutical intermediate. Its primary and well-documented application is in the synthesis of proton pump inhibitors (PPIs), a major class of drugs used to treat acid-related gastrointestinal disorders. Specifically, it is a key building block in the production of lansoprazole and its analogs. The reactive chloromethyl group is essential for constructing the benzimidazole ring system characteristic of these drugs. As a versatile synthetic building block, it is used in research and development for constructing other complex heterocyclic molecules. Handling requires standard precautions for reactive alkyl halides and acid salts.