orthonym.validation.spelling.checks_placement

Note

Internal API. Names and behaviour may change between releases.

Spelling checks of where a name places a stereodescriptor and an enclosing mark.

“NAMING OF STEREOISOMERS” (the Blue Book): “In preferred IUPAC names, stereodescriptors are

placed immediately at the front of the part of the name to which they relate. They are placed at the front of the complete name when related to the parent structure; they are cited in parentheses followed by a hyphen. When they relate to substituent groups, they are cited at the front of the corresponding prefix. They are preceded by a numerical or letter locant to describe the position of the stereogenic unit when such locants are present.”

A descriptor with a numerical locant that the parent of its own unit has no position for does not relate to that parent: ‘(1R,4S)-2-(4-methoxyphenyl)-N-{…}ethan-1-amine’ puts the ‘4S’ of a substituent ring before an ethane that has two positions. The check reads the unit’s parent from the name alone (an unbranched carbon chain, a carbocyclic, retained or Hantzsch-Widman monocycle, naphthalene, anthracene:models.ring_or_chain_model()) and abstains on any other parent, so a reader that does not know a parent can only pass it. It does not decide which prefix a descriptor belongs to, only that it is not the unit’s own.

“Parentheses” (the Blue Book): “Parentheses are used around compound and complex

prefixes”. A prefix cited with an N-locant that begins with a numerical locant is such a prefix: ‘N-(2-methoxyethyl)’, never ‘N-2-methoxyethyl’ (the reading of that spelling is ‘N-2’ of a methoxyethyl: 2-methoxyethyl has its own locant). No naming code, no OPSIN.

orthonym.validation.spelling.checks_placement.descriptor_locants_fit_their_unit(mol, name)

A stereodescriptor set at the front of a unit whose parent has fewer positions than a locant of the set,:44643): the descriptor relates to a substituent, and is cited in the unit of that prefix.

orthonym.validation.spelling.checks_placement.n_prefix_with_a_locant_is_enclosed(mol, name)

A prefix of an N-locant that begins with a numerical locant is a compound prefix and takes its enclosing marks,:7232).