Propoxy

Part of speech: noun, adjective

Definitions

1. A chemical group made of a propyl unit bonded to an oxygen atom, which attaches to a larger molecule as a substituent
2. The univalent radical formed when a propyl group is joined to an oxygen atom, as found in certain organic compounds
3. Describing or containing the OC3H7 group, a substituent built from a three-carbon propyl chain linked through oxygen

Etymology: "Propoxy" is a chemist's building block, a propyl group attached to an oxygen atom, that appears as a substituent in larger molecules. Its two halves come from different corners of chemistry. The "oxy" part comes from oxygen, whose name draws on the Greek "oxys," meaning sharp or acid, because the element was once thought to be the source of acidity. The "propyl" part is more roundabout. It is named after propionic acid, whose name joins the Greek "protos," first, and "pion," fat, because it was the first of the fatty acids. Chemists then built the "-yl" ending for the group derived from it, and the attached "oxy" marks the oxygen link. The same pattern gives "methoxy" and "ethoxy," where the first syllable names the carbon chain.