7-[(1R,2S)-2-[(1E,3S,5S)-3-Hydroxy-5-methyl-1-nonenyl]-5-oxo-3-cyclopenten-1-yl]-2-heptenoic acid

CAS 853998-94-4

This CAS entry describes a prostaglandin-related acid with an unsaturated ketone ring and two defined side chains. A reference catalog lists it as an impurity rather than an active medicine. Studies of limaprost stability give context for a related transformation: loss of the elements of water can produce a double bond in the ring. That chemical change is different from physically drying a sample. A peak observed during storage can help track a change, but a peak and an assigned structure are not the same evidence. The supplied name also leaves one double-bond geometry unspecified. Matching the sample to an appropriate reference therefore matters. The scientific question is which compound formed, not whether the impurity can be treated as the parent medicine.