Fingolimod.HCl

Fingolimod.HCl is a sphingosine analog hydrochloride salt featuring a 19-carbon aliphatic chain with a tertiary amine and a terminal chloride ion. This impurity arises from the alkylation step in Fingolimod synthesis, where incomplete substitution of the phosphate group with a long-chain alkyl moiety results in a chloride-containing byproduct. Structurally, it retains the core sphingoid backbone but lacks the phosphoryl oxygen, substituting it with a chloride ion. This compound serves as an HPLC reference standard for quantifying process-related impurities in Fingolimod drug substance.