http://www.chem.ucla.edu/~harding/IGOC/C/common_name.html

Illustrated Glossary of Organic Chemistry

Common name: A nomenclature system useful for naming simple organic
molecules. It often fails for more complex molecules, in which case
systematic or (better yet) IUPAC nomenclature is preferable.

The prefix "n-" (or normal) is used when all carbons form a
continuous, unbranched (linear) chain. If a functional group (such as
an alcohol) is present that functional group is on the end of the
chain. Not to be confused with 'nor', which indicates a missing
methyl group.


   [common_name01]            [common_name02]

Common name: n-pentane    Common name: n-pentanol
 IUPAC name: pentane      IUPAC name: 1-pentanol


The prefix "iso" is used when all carbons except one form a
continuous chain. This one carbon is part of an isopropyl group at
the end of the chain.


     [common_name03]                 [common_name04]

 Common name: isopentane      Common name: isopentyl alcohol
IUPAC name: 2-methylbutane    IUPAC name: 3-methyl-1-butanol


"Iso" can also indicate that the molecule is an constitutional isomer
of another molecule with a common (or trivial) name.


        [common_name05]                     [common_name06]

   Common name: phthalic acid        Common name: isophthalic acid
   IUPAC name: benzene-1,2-di          IUPAC name: benzene-1,3-di
        carboxylic acid                     carboxylic acid


The prefix "neo" is used when all but two carbons form a continuous
chain, and these two carbons are part of a terminal tert-butyl group.


        [common_name07]                     [common_name08]

    Common name: neopentane          Common name: neopentyl alcohol
IUPAC name: 2,2-dimethylpropane       IUPAC name: 2,2-dimethyl-1-
                                                propanol


The prefix "sec" or "s" is used when the functional group is bonded
to a secondary carbon. This prefix is only useful for a four-carbon
chain. It is not applicable with a shorter chain, and it is often
ambiguous when the chain has five or more carbons.

                           [common_name09]
                Common name: sec-butanol (s-butanol)
                        IUPAC name: 2-butanol

The prefix "tert" or "t" is used when the functional group is bonded
to a tertiary carbon.

                           [common_name10]
                Common name: tert-butanol (t-butanol)
                   IUPAC name: 2-methyl-2-propanol

  * Related terms: Isobutylene, isobutyl group, isoelectronic,
    isoleucine, isomer, isomerization, isopentenyl pyrophosphate,
    isoprene, isoprenoid, isopropanol, isopropyl group, isotope, N,
    n-BuLi, neoprene, sec-butyl group, secondary, S, s-BuLi, s-trans,
    t-BuLi, tBDMS group, tBDPS group, tBu, tert-butyl group, tert
    -butoxide, tBuO^-, tBuOH, tert-butanol, tert-BuOH, tert-butyl
    carbocation
  * Wikipedia entry
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