Databases for Chemists and Chemical Engineers

Chemical Abstracts

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

Searching structure query

Choose Logon in top menu bar of STN Express.
Select STN. Script containing CAS account number and password will automatically log you into CAS.
Enter Registry File. Also add cost=plus 3 character codes. Example: cost=cg1
Go to Query in menu bar and select Upload Structure Query.
Type D to display structure so that you can make sure it uploaded correctly.
Type Search at the next Reg File prompt.
- Enter L# assigned to structure query after uploading
- Enter type of search to be performed (Exact, Family, CSS, SSS)
- Always run a Sample search before performing a full file search to verify that your search will go to completion in the full file. A random 5% of the full file is searched.
Note projected iterations and number of answers listed in sample search report.
View some answers from sample search using D SCAN format (free format).
If strategy will not go to completion in full file or if you need to modify strategy to eliminate compounds that are not of interest. Log off and go into Prepare Structure Query in STN Express.
If projections are within system limits and the number of projected compounds seems appropriate, then run Full file search.
After full file search is completed, enter the CA file to find reference citing substances.
- Either AND or use (L) with search terms to limit scope of articles to a particular subject area
  
  Example:
  
  fil ca; s L# and crystal?
  
  fil ca; s L# (l) crystal?
- Search the L# with a /P suffix to identify prepn references.
  
  Example:
  
  fil ca; s L#/p

Tip for displaying results in CA File: Adding HITSTR to display format to see structure diagrams and names of compounds that matched your structure search.