orthonym.rules.ring_position_kinds

Note

Internal API. Names and behaviour may change between releases.

Kinds of substitutable position of a free ring or a parent hydride, for the writers of a ring prefix and of an ionic or amine suffix.

orthonym.rules.ring_position_kinds.one_kind_of_ring_position(mol, ring_atoms)

(the Blue Book): “The locant is omitted in monosubstituted symmetrical parent hydrides or parent compounds where there is only one kind of substitutable hydrogen” – ‘oxiranyl’ (:18929, ‘(oxiranylmethoxy)silane (PIN)’), not ‘oxiran-2-yl’. Read on the ring as its own parent hydride: the ring atoms and ring bonds alone (implicit hydrogens recomputed), positions = the ring atoms that carry hydrogen there. A ring that cannot be read this way counts as having more than one kind, so the caller cites the locant,:2869).

A position that carries an isotope label (a labelled ring atom, or an isotopic hydrogen on one) is its own kind of position, so the licence does not apply to a labelled ring:

Letter and/or numeral locants (:44208): “When locants are needed for defining

the structure of the parent structure or of a unit of structure as defined by its appropriate enclosing marks, then all locants must be cited for the parent structure or that structural unit” – the labelled ring cites its free-valence locant. The label is read from mol and from the labelled molecule that the isotope path declares while it names the label-free skeleton.

orthonym.rules.ring_position_kinds.one_kind_of_substitutable_position(parent)

(the Blue Book): “The locant is omitted in monosubstituted symmetrical parent hydrides or parent compounds where there is only one kind of substitutable hydrogen”. parent is the parent hydride or parent compound as one molecule, ring or chain: every atom that carries a hydrogen is of one kind (one symmetry class), so a suffix cited on it needs no locant (‘benzenaminide (PIN)’,:41057). A parent that carries other groups, or that has two kinds of position, is not, and the caller cites the locant ,:2869).