Sarcosine ethyl ester hydrochloride is an organic salt derived from the amino acid sarcosine (N-methylglycine). It is a white to off-white crystalline powder with the molecular formula C5H12ClNO2. This compound serves as a versatile building block in organic synthesis, particularly valued for its bifunctional nature containing both an ester group and a secondary amine moiety. Its primary and most significant application is in the pharmaceutical industry as a key intermediate. It is notably used in the synthesis of various active pharmaceutical ingredients (APIs), including certain ACE inhibitors for cardiovascular diseases and other therapeutic agents. The molecule acts as a precursor for introducing the N-methylglycine ethyl ester fragment into more complex molecular architectures. Beyond its role as a pharmaceutical intermediate, sarcosine ethyl ester hydrochloride is also employed in peptide synthesis and as a starting material for the preparation of surfactants and corrosion inhibitors. It should be handled with standard laboratory precautions, avoiding inhalation and contact with skin and eyes.