2-Piperidinone 2-Piperidone 5-Pentanolactam 675-20-7 AI3-33342 DELTA-VALEROLACTAM EINECS 211-622-9 NSC 18894 NSC 2305 PIPERIDONE,2- Pentanoic acid, 5-amino-, lactam Piperidon [German] Piperidone-2 [French] Valerolactim alpha-Piperidone