The IUPAC nomenclature of organic chemistry uses the numerical prefixes derived from Greek, except for the prefix for 9 (as mentioned) and the prefixes from 1 to 4 (meth-, eth-, prop-, and but-), which are not derived from words for numbers.
These prefixes were invented by the IUPAC, deriving them from the pre-existing names for several compounds that it was intended to preserve in the new system:
- methane (via methyl which is in turn from the Greek word for wine),
- ethane (from ethyl coined by Justus von Liebig in 1834),
- propane (from propionic which is in turn from pro- and the Greek word for fat), and
- butane (from butyl which is in turn from butyric which is in turn from the Latin word for butter).
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