Pyrazolidone

Part of speech: noun

Definitions

1. Any of a class of organic chemical compounds built around a five-membered ring of three carbon atoms and two adjacent nitrogen atoms, with a ketone group
2. A heterocyclic compound family based on the pyrazolidine ring system, used as a basis for certain photographic developers and pharmaceuticals
3. An organic compound containing a saturated pyrazolidine ring bearing a carbonyl group, a member of a chemical family used in industry and research

Etymology: Pyrazolidone belongs to a family of chemical names built in the late 1800s, when German chemists were naming the new ring-shaped compounds they were producing from coal-tar derivatives. The first part, "pyrazole," was coined by the German chemist Ludwig Knorr in 1883 and combines "pyr-," from Greek "pyr" meaning fire, with "azole," a name for a class of five-membered ring compounds containing nitrogen. The "azole" element was itself formed from "azote," the old name for nitrogen, which means "without life" in French, since nitrogen does not support breathing or burning. The ending "-idone" is a chemical suffix marking a ketone-type group, a carbon bonded to oxygen within a ring, and "pyrazolidone" names a saturated ring of this kind. Like many chemical terms, the word is a deliberate technical coinage rather than something that passed through everyday speech, so its parts describe its structure directly.