CH1012
L1 /
‹#›
L1 /
14
NUMBERING IN ORGANICS
Find the Highest Priority Functional Group (HPFG), numbering is based on the HPFG.
1) For aldehydes, carboxylic acids
(+derivatives) the C=O is always C1.
(+derivatives) the C=O is always C1.
2) For all other cases the HPFG is
given the
lowest possible number in the chain.
lowest possible number in the chain.
3) After this has been done the
numbering
is intended to give the lowest numbering to
any remaining functional groups.
is intended to give the lowest numbering to
any remaining functional groups.
4) After this any chain branches are
given
the lowest numbering. Where there are
options (eg. 1,2-dimethyl or 1,3-dimethyl)
then the lowest sum is chosen.
the lowest numbering. Where there are
options (eg. 1,2-dimethyl or 1,3-dimethyl)
then the lowest sum is chosen.
5) An HPFG attaches to a ring at C1.
