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SciFinder Scholar | CAS Online | Standard Abbreviations | Index Guide | Guide to CASREACT | Structure Searching with STN Express

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