Abstract Seven unknown recurring impurities were isolated during the synthesis of Iloperidone process. All six impurities were subsequently synthesized and characterized by FTIR, MS and NMR spectral data. The structures of impurities were confirmed as 1-[4-(3- chloropropoxy)-3-methoxyphenyl] ethanone (4), 1-[4-(3-hydroxypropoxy)-3-methoxy phenyl] ethanone (7), 1-[4-(3-bromopropoxy)-3-methoxyphenyl] ethanone (9), 1, 1'-[4, 4'-(propane- ...