The discussion centers on the ordering of cations and anions in ionic compound nomenclature, specifically highlighting exceptions in organic compounds like sodium acetate (CH3COONa). While the conventional rule dictates that cations precede anions, this is relaxed for organic salts to maintain clarity regarding the parent structure, such as acetic acid (CH3COOH). In complex compounds, such as ammonium potassium pentanedioate, cations are listed in alphabetical order to avoid confusion. The IUPAC nomenclature provides a systematic approach to these conventions.
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The requirement (of putting the cation first) is relaxed in the case of organic compounds (typically salts of carboxylic acids). The idea is that you want to minimize the modification to notation for the parent structure - in this case CH3COOH.pivoxa15 said:But with some ionic compounds like sodium acetate, it is written with the anion acetate written first. i.e. CH3COONa
Why like this?
bomba923 said:Where did you see sodium acetate written as CH3COONa ?
(with the cation expressed after the anion)
Gokul43201 said:The requirement (of putting the cation first) is relaxed in the case of organic compounds (typically salts of carboxylic acids). The idea is that you want to minimize the modification to notation for the parent structure - in this case CH3COOH.
This clearly does not mean that the cation is always written at the end - for instance, in a dicarboxylic acid with 2 different cations, it would make more sense to write something like KOOC-(CH2)3-COONH4.
Because of the attendant loss of clarity over which is the cation and which the anion, it becomes customary to include the necessary information to elucidate this. So the above compound (Ammonium potassium pentanedioate - it is convention to list the cations in alphabetical order) would best be written as: K+ -OOC-(CH2)3-COO- NH4+
That's sort of the idea, but as Jack Sparrow would say, it's really more of a guideline. It's with the systematic nomenclature that the IUPAC has more elaborate "rules".pivoxa15 said:So with organic compounds, preservation of the notion of the parent structure is more important than keeping witht the rigid rule of naming ionic compounds.