orthonym.rules.halogen_ring_fusion

Note

Internal API. Names and behaviour may change between releases.

A benzene ring fused to a heteromonocycle with a halogen ring atom in the lambda state.

The benziodoxolones and their relatives: 1-methoxy-1λ3,2-benziodoxol-3(1H)-one (PIN)

“Nomenclature based on halogen parent hydrides”, the Blue Book, the example at

:39674) and 1H-1λ3-benziodole (PIN) (:39692). Before this module the fusion producers had no component for a ring halogen, so every such system went unnamed.

The name is the one of a benzoheterocycle, “Heteromonocyclic components fused to a benzene ring” (:11813): “the locant(s) indicating the position(s) of the heteroatom(s) at the front of the name consisting of the fusion prefix ‘benzo’ followed by… a Hantzsch-Widman systematic name… The locants cited correspond to the full bicyclic structure. As in Hantzsch-Widman names, locants are placed in the order corresponding to the order of citation of the heteroatoms in the heterocyclic component. The locant ‘1’ is always assigned to the atom of the heterocyclic component next to a fusion atom… The letter ‘o’ of the ‘benzo’ prefix is elided when followed by a vowel. Indicated hydrogen is placed at the front of the name, when required.”

The lambda symbol of a fused system, “Fused ring systems with skeletal atoms with nonstandard bonding numbers” (:14531) and (:12452), “follows the locant of the atom with the nonstandard bonding number in accordance with the numbering of the fused system”. In a benzo name the locant of the halogen is one of the heteroatom locants at the front, so the symbol sits inside that list: 1λ4,5-benzodithiepine (PIN) and 3H-3λ3,2,4-benziodadioxepine (PIN) (:14549, :14557). The Hantzsch-Widman builder (heterocycles.build_hw_name) already writes that list for a monocycle (1,3λ5-oxaphosphole,; this module gives it the locants of the fusion numbering and puts ‘benzo’ in front of its stem.

Everything else is the rules the other fused producers share: the fusion numbering (fusion_numbering.compute_fused_numbering), the indicated, added and hydro hydrogen of the mancude parent (ring_hydrogen, which counts the halogen with its own bonding number: lambda_convention.ring_lambda_valence) and the assembly of the substituents and the suffix (fused_rings._assemble_fused_heterocycle_name). Scope, everything else is declined (None): two rings, one a benzene ring and the other of five to seven members with a halogen of lambda_convention.FUSED_RING_LAMBDA_HALOGENS; no charged, radical or isotope-labelled ring atom; no ring atom of nonstandard bonding number but those halogens; every heteroatom at a numbered (not a lettered) position.

orthonym.rules.halogen_ring_fusion.benzo_hw_name(mol, hetero_ring, atom_to_locant)

The mancude benzoheterocycle name of the ring system under atom_to_locant: ‘1λ3,2-benziodoxole’, ‘1λ3-benziodole’, ‘3λ3,2,4-benziodadioxepine’. None when a heteroatom has no numbered locant or the Hantzsch-Widman builder has no name for the ring.

orthonym.rules.halogen_ring_fusion.name_halogen_benzo_system(mol)

The name of a benzene ring fused to a heteromonocycle with a halogen ring atom in the lambda state, with its substituents, suffix and hydrogen; None (the caller keeps its own answer) when the system is outside the scope of the module docstring.