1) Perfume ingredient 
Cyclopentanone is a cyclic ketone. ==Preparation and use== Upon treatment with barium hydroxide at elevated temperatures, adipic acid undergoes ketonization to give cyclopentanone. ...
(from the article `chemical compound`) ...or heterocyclic rings; examples of selected aldehydes and ketones are given in Table 29. The simplest aldehyde, formaldehyde, is a gas used ...
C5H8O Molar mass: 84.11642