Page 134 - Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005)

IR-8.1 I N O R G A N I C A C I D S A N D D E R I V A T I V E S

(b) to list the ‘acid’ names that are still acceptable due to common usage and/or because
they are needed i n o rganic nomenclature (see Tables IR-8.1 and IR-8.2).

In addition, Sections IR-8.4 and IR-8.5 deal with a f urther type of names, denoted here as
hydrogen names. T hese names can be viewed as generalizations of common anion n ames
such as ‘hydrogencarbonate’, but they are not necessary for naming completely specified
molecular structures and can be regarded as a s pecial topic.
Thus, this Chapter p rovides several acceptable names for many inorganic acids; it is left
to practitioners t o c hoose the name m ost suitable for a p articular a pplication. In the future,
IUPAC aims to select preferred names for inorganic s pecies, including the acids dealt with
here, just as Ref. 1 d oes for organic species.
Finally, names which do not denote compounds of a d efinite composition, such as
hydrochloric acid, stannic acid, tungstic acid, etc., are outside the scope of the systematic
nomenclature presented here. However, the chemical systems i nvolved can always be
discussed u sing systematic names such as hydrogen chloride, tin(IV) oxide, t ungsten(VI)
oxide, etc.
A f ew examples are given now in order to illustrate some o f t he general remarks above.
In these examples, and in the remainder of this chapter, a lternative formulae are sometimes
provided for clarity in connection w ith the discussion of additive names. These are based on
a p erception of the structures i n q uestion as generalized coordination entities. For
mononuclear entities, this means that the central atom symbol is listed first and then the
ligand symbols in alphabetical order, as prescribed in Section IR-4.4.3.2.

Example:
1. phosphoric acid ¼ H 3 PO 4 or [PO(OH) 3 ]

Based on the structure, t he compound can be named substitutively (Chapter IR-6) as a
5
5
derivative o f t he parent hydride l -phosphane (PH 5 ), leading to the name t rihydroxy-l -
phosphanone, or additively ( Chapter IR-7) as trihydroxidooxidophosphorus.
As opposed to the two last names, the name phosphoric acid does not convey the
structure, b ut does fit into a g eneral pattern whereby the ending ‘ic’ denotes a h igher or the
highest possible o xidation state (compare n itric acid, sulfuric acid). Examples 2 and 3 s how
organic derivatives named on the basis o f p hosphoric acid as the parent.

Examples:

trimethyl phosphate
2. PO(OMe) 3
hexamethylphosphoric triamide
3. PO(NMe 2 ) 3

Each of these t wo compounds could a lso b e n amed substitutively, on the basis of the above
parent hydride, or additively but t he names given here are preferred IUPAC names (see
Section P-67.1 of Ref. 1).
Some organic derivative n ames still contain the word ‘acid’, as in the following
derivatives of arsonic acid (H 2 AsHO 3 or [AsHO(OH) 2 ]).

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