meaning - Why "meth-", "eth-", "prop-", when there is "uni-","di-","tri-"?


In chemistry, the homologous series for hydrocarbons uses the following prefixes:




  • Meth-

  • Eth-

  • Prop-

  • But-

  • Pent-

  • Hex-

  • Hept-

  • Oct-



Why are these prefixes used, instead of just using "uni-", "di-", "tri-"?


I looked up the prefixes, but there is no dictionary record of them. Still, I think "uni-", "di-", "tri-", were invented first.


Is there a specific reason why, instead of using the normal counting prefixes, new prefixes were used or made up, assuming they were made up for this specific purpose?



Answer



Short answer: they were invented to preserve names of organic substances that already were in use. From Wikipedia's article on number prefixes:



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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