Structure searching in CAS Online using STN Express:
An introductory workshop

Types of structure searches: Exact search

  • Exact search retrieves substances which match the query exactly
    • All positions in the structure are blocked for further substitution
    • All query rings are isolated
    • No variable nodes are allowed in the query
    • Variable bond values are allowed in the query
    • Retrieves all substances having the same “connection table”
      • Unsubstituted substance
      • Stereoisomers
      • Isotopically labelled substances
      • Radicals
      • Ions
      • Homopolymers
  • Exact search may be used to find corresponding records in other structure searchable files (e.g. CASREACT)
  • Exact search will add hydrogens to all vacant positions
  • Exact search will not permit any other non-hydrogen atoms to be present