For some compounds, such as these, the names given have been widely used although the systematic names end in "-olinone". In view of this, the least hydrogenated forms should be named as "4-oxopyrazole", "5-oxopyrazole", etc. The locant designates the position of the keto group.

This HTML reproduction of Sections A, B and C of IUPAC "Blue Book" is as close as possible to the published version [see Nomenclature of Organic Chemistry, Sections A, B, C, D, E, F, and H, Pergamon Press, Oxford, 1979. Copyright 1979 IUPAC.] If you need to cite these rules please quote this reference as their source.

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