IUPAC nomenclature of compounds containing one or more functional groups

IUPAC names for compounds carrying one or more functional groups build on everything already established for the underlying hydrocarbon skeleton, adding the functional group itself in as a prefix and/or a suffix, using a fixed set of modified names for each functional group listed out in Table 14.9 (for example -COOH becomes the prefix 'carboxy-' or the suffix '-oic acid'; -OH becomes the prefix 'hydroxy-' or the suffix '-ol'; and so on). For a MONOFUNCTIONAL compound (exactly one functional group present), the longest carbon chain that actually CONTAINS that functional group is chosen as the parent chain, and it is numbered so as to give the functional-group-bearing carbon the LOWEST possible locant; the parent hydrocarbon's name is then modified with that functional group's appropriate suffix, with its locant number stated explicitly ONLY when that locant is not simply '1' by default -- so CH3-CH2-CH2-COOH is 'butanoic acid' (no locant needed, since -COOH is always understood to sit at C-1) and CH3-CH2-C≡N is 'propanenitrile' (likewise no locant needed), but CH3-CO-CH2-CH2-CH3 genuinely needs its locant and is 'pentan-2-one' (since a ketone group could otherwise sit at more than one internal position on a five-carbon chain), whereas CH3-CO-CH2-CH3 needs none and is simply 'butanone' (since on a four-carbon chain a ketone group can only ever be at C-2 anyway). Where a particular functional group can ONLY ever be expressed as a prefix (never as a suffix at all), the whole compound is instead named as a substituted parent alkane carrying that group as an ordinary substituent at its own specified locant -- for example H3C-CH2-CH2-NO2 is '1-nitropropane' and CH3-CH(OCH3)-CH3 is '2-methoxypropane'. POLYFUNCTIONAL compounds (genuinely two or more functional groups present, whether identical or different) require one further step first: ONE of the functional groups present must be chosen as the single PRINCIPAL functional group (which alone gets to be expressed as the suffix), while every other functional group present is demoted to being cited merely as a prefix substituent. Which group gets to be principal is decided by a fixed priority order, from highest to lowest: $-COOH > -SO_3H > -COOR > -COCl > -CONH_2 > -CN > -CHO > C{=}O > -OH > -NH_2 > C{=}C > -C{\equiv}C-$. Three rules then finish the naming of any mono- or poly-functional compound: (i) the longest chain that contains the single (or the chosen principal) functional group becomes the parent chain -- with the one special case that an ETHER is always named as an 'alkoxyalkane', choosing the LARGER of its two attached alkyl groups as the parent chain -- and that parent chain is numbered to give the lowest possible locant to the functional-group carbon; …