L-Alanine benzyl ester hydrochloride is a white to off-white crystalline powder. It is a protected derivative of the natural amino acid L-alanine, where the carboxylic acid group is esterified with benzyl alcohol and the amino group is present as a hydrochloride salt. This compound is a chiral building block with a defined (S)-configuration. Its primary application is in peptide synthesis and medicinal chemistry as a key chiral intermediate. The benzyl ester protecting group is stable under standard peptide coupling conditions but can be readily removed by catalytic hydrogenation or other methods, making this compound a versatile reagent for introducing the alanine residue into target molecules. It is widely used in the research and development of pharmaceuticals, bioactive peptides, and other biologically active compounds. As a readily available and enantiomerically pure amino acid derivative, it serves as a fundamental starting material in organic synthesis. Its handling requires standard precautions for laboratory chemicals, and it should be stored in a cool, dry place.