1670-46-8 2-Acetylcyclopentan-1-one 2-Acetylcyclopentanone 4-07-00-01993 (Beilstein Handbook Reference) AI3-19254 BRN 1857601 Cyclopentanone, 2-acetyl- EINECS 216-797-5 NSC 141181 alpha-Acetylcyclopentanone o-Acetylcyclopentanone