orthonym.assembly.n_unit_prefix

Note

Internal API. Names and behaviour may change between releases.

The substituent prefix of a hydrazinyl unit and of an imine joined through nitrogen.

A fragment rooted at one of these nitrogen atoms used to be named as a free molecule (‘methylhydrazine’, ‘methanimine’) and a prefix cut from that name by the ring rule of (-ine to -inyl, substituent_naming.parent_to_prefix). The rule is for ring hydrides, and both words are wrong:

• ‘methylhydrazinyl’ does not say which nitrogen the methyl is on. “Citation of locants” (the Blue Book): “if any locants are essential 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”; “Omission of locants” (:2953) leaves them out only where “no isomer can be generated”. A methyl can stand on either nitrogen, so the prefix is ‘2-methylhydrazin-1-yl’ (‘4-(1-acetyl-2-ethylhydrazin-1-yl)benzoic acid (PIN)’, “Substituent groups derived from hydrazides”,:34042; ‘3-(2-carbamoylhydrazin-1-yl)propanoic acid (PIN)’, “Semicarbazides”,:38644).

• ‘methaniminyl’ is a radical. (:40620), Table 7.2 “Suffixes for Radicals of Amines, Imines and Amides” (:40622): ‘-iminyl’ is the suffix of =N•. R-CH=N- joined through nitrogen is the amino prefix with its ylidene, ‘4-{[(4-chlorophenyl)methylidene]amino}aniline (PIN)’

  “Substitutive names for imines”,:26529), ‘4-[(hydrazinylmethylidene)amino]benzoic

  acid (PIN)’ “Prefixes” of the amidrazones,:34513), ‘4-[(diaminomethylidene) amino]butanoic acid (PIN)’,:34282). R-C(=NH)- joined through carbon is an acyl group, ‘methanimidoyl (preferred prefix)’,:26540,:30468); it is not this unit.

The group is read by hetero_group_prefixes.group_shape and joined by compose_group from the names the fragment namer gives its parts. The three steps (read_n_group, principal_group_in, composed_group) are shared with the diazenyl prefix (substituent_naming._diazenyl_prefix). Left to the other routes, which name them as before: a hydrazinyl unit that holds an ylidene (‘ethylidenehydrazinyl’,,:2959) or no substituent, a chain of three nitrogen atoms (a polyazane, ‘tetraazan-1-yl’,,:39015), an N=C bond with a defined geometry, and an ylidene carbon that carries a nitrogen group other than the two amino groups of a guanidine (_plain_ylidene_carbon).

orthonym.assembly.n_unit_prefix.read_n_group(mol, sub_atoms, attach_idx, unstereo_iminyl=False)

(group, parent, shape) of the fragment sub_atoms rooted at the neutral acyclic nitrogen attach_idx and joined by one single bond to the one atom parent outside it (hetero_group_prefixes.group_shape reads the shape), or None. The set-up the diazenyl prefix (substituent_naming._diazenyl_prefix) and n_unit_prefix share.

orthonym.assembly.n_unit_prefix.principal_group_in(mol, group)

True when a principal characteristic group of the molecule has an atom in group (an amidine, a hydrazide or an imine that is the senior class is named as the parent or by its own producer, not as a prefix), and when the perception cannot tell (fail closed).

orthonym.assembly.n_unit_prefix.composed_group(mol, shape, attach_idx, parent_chain)

The prefix hetero_group_prefixes.compose_group joins from the names the fragment namer gives the parts of shape; None when a part has no name, which fails the whole prefix closed.

orthonym.assembly.n_unit_prefix.n_unit_prefix(mol, sub_atoms, attach_idx, parent_chain)

The prefix of the fragment sub_atoms rooted at nitrogen attach_idx and joined to a carbon by a single bond, when it is a substituted hydrazinyl unit (‘2-methylhydrazin-1-yl’) or an imine (‘(methylideneamino)’); None for any other fragment, for a shape the module docstring leaves to the other routes, and when a part has no name, which fails the whole prefix closed.