In chemistry, nor- is a prefix that means "next lower homolog".[1][2] Specifically, it refers to compounds in which one or two methyl groups are removed from the parent compound and replaced with hydrogen atoms, or in which a methylene group has been removed from a chain in the parent compound.[2]
Etymology
There are various conflicting accounts as to the origins of the prefix. According to the British pharmacologist John Gaddum, the prefix nor- was first used in 1868 by Matthiessen and Foster in their studies of opianic acid, a compound that contains two methyl groups.[2][3][4] They had used the term "normal opianic acid" to indicate the fully demethylated compound, and using nor- as a contraction of "normal", they referred to this fully demethylated compound as noropianic acid.
Other reports, including an earlier statement by Gaddum himself,[5] have claimed that the prefix nor- is an acronym derived from the German "Nitrogen ohne Radikal" (literally, nitrogen without a radical). Sharma and Woolman independently suggested that this etymology was likely invented by a German pharmacologist as a mnemonic device for students.[2][6] They supported this claim by noting that many compounds using the prefix nor- do not contain nitrogen at all.[2][6] In response to Woolman, Gaddum retracted his support for nor- being a mnemonic device, and apologized for "supporting a false etymological theory."[3]
Examples
Many names of chemicals use the prefix nor-. For example, norepinephrine is the next lower homolog of epinephrine because the methyl group on epinephrine's nitrogen is replaced with a hydrogen atom in norepinephrine. Similarly, the next lower homolog of estrone is norestrone; whereas estrone has a methyl group attached to carbon 18, norestrone instead has a hydrogen atom.
References
- ^ Corfield CE, ed (1943). The Extra Pharmacopoeia. 2 (22 ed.). London: The Pharmaceutical Press.
- ^ a b c d e Sharma B, Satish A, Kumar R (1999). Dictionary of Drugs. Anmol Publications. ISBN 8126118202. http://books.google.com/books?id=3JvArcoG2voC&printsec=frontcover#PPA166.
- ^ a b Gaddum JH (June 1956). "The Prefix 'Nor' in Chemical Nomenclature". Nature 177 (1046). doi:.
- ^ Matthiessen A, Foster GC (1868). "Researches into the chemical constitution of narcotine and of its products of decomposition". Journal of the Chemical Society 358. http://books.google.com/books?id=tKsOAAAAIAAJ&printsec=titlepage&cad=0#PPA39.
- ^ Gaddum JH (February 1953). "Book Review: The Extra Pharmacopoeia". Nature 171 (350). doi:.
- ^ a b Woolman AM (June 1956). "The Prefix 'Nor' in Chemical Nomenclature". Nature 177 (1046). doi:.
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- For more information, see IUPAC nomenclature of organic chemistry.
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