orthonym.decomposition.amide_c_locant

Note

Internal API. Names and behaviour may change between releases.

The C-locant of a substituted acetamide assembled from the name of its acid (PB-W).

The acid fragment of an amide split is named as the free acid, and a free acid cites no locant for the group on its one substitutable carbon: ‘chloroacetic acid’, ‘(thiophen-2-yl)acetic acid’. The amide made from it has a nitrogen that can carry a substituent as well, so the same group could stand on the nitrogen and the locant is essential.

(the Blue Book, heading “ Omission of locants”): “Locants are omitted

when no isomer can be generated by moving suffixes and/or prefixes (if any) from their position to another or by interchanging them between two different positions.” The Blue Book’s own amides cite it: ‘2-amino-N-(2,3-dihydroxypropyl)-N-methylacetamide (PIN)’ (:33576), ‘N-carbamoyl-2- phenylacetamide (PIN)’ (:33364). The amide of the acid names printed without the locant (‘(thiophen-2-yl)acetamide’ for ‘2-(thiophen-2-yl)acetamide’) omits one that (:2869) makes essential: “if any locants are essential for defining the structure of the parent structure or of a unit of structure… then all locants must be cited”.

orthonym.decomposition.amide_c_locant.amide_with_c_locant(amide_name, acid_smiles)

amide_name (the acid’s name turned into an amide name) with the locant of the group on C-2 cited, or None when the amide cannot be cited with confidence.

Unchanged: a name that is not a substituted acetamide (‘propanamide’, ‘acetamide’), and one that already begins with a locant (‘2-chloroacetamide’). '2-' + name when the acid has one group on its alpha carbon. None for two or three groups on it (the citation order of several prefixes with a shared locant is not decided here), for a name that begins with a stereodescriptor block, and when the structure of the acid is not at hand: the caller then builds no amide from this split and another producer names the molecule.