American Chemical Society
Teaching Chemical Information:
Tips and Techniques
— March 1998 —
CASREACT: Reaction Searching with Structures
- Step-by-Step Reaction Search Sample
- Drawing the Reaction with STN Express ®
- Assigning the Direction of Reaction and Reaction Roles
- Assigning the Role of Reactant or Reagent to Starting Materials
- Uploading a Reaction Question in CASREACT
- Default Display — FHIT CBIB
Step-by-Step Reaction Search Sample
Q: Are any procedures reported for the preparation of 1,5-diphenyldiazoles using phenyl hydrazine as the precursor? What other reactants, reagents, solvents, or catalysts are needed in the reaction?
Drawing the Reaction with STN Express ®
1. To create a reaction query in STN Express, first enter the structure building menu and build the structures of the reaction participants on the same screen.
2. To add the reaction specifications to the query select RXN icon. Once in the RXN menu, roles are assigned automatically to the participants in the reaction as “Any role.”
Assigning the Direction of Reaction and Reaction Roles
In structure reaction queries you can assign four roles:
- reactant
- product
- reagent
- reactant/reagent
Default roles are assigned when you draw an arrow. The head of the arrow points toward “Product” and away from “Reactant/Reagent.”
The starting materials are given the role of “Reactant/Reagent” because authors are not always consistent in how they distinguish between reactants and reagents. You can be more precise and require that a starting material be defined as a “Reactant.”
Assigning the Role of Reactant or Reagent to Starting Materials
To assign the more precise role of reactant to the starting material(s), select the A→B icon. Place your cursor over any atom in the starting material and select. A menu will appear prompting you to respecify the role of the reaction participant.
Once you have completed the reaction query, SAVE it. STN Express software will then ask you to verify the structure characteristics and the reaction attributes.
Uploading a Reaction Question in CASREACT
Structure searching procedures used in CASREACT are similar to those used with single substance files such as REGISTRY.
Follow these steps:
- Leave Structure Drawing
- Logon to STN
- Enter FILE CASREACT
- Upload the Structure Query. You will be asked to identify the file in which the search will be perfomed. For reaction searches this means CASREACT.
This is what the screen will look like when you upload your reaction query (react1.str).
=> react1.str L1 STRUCTURE UPLOADED => D L1 L1' HAS NO ANSWERS L1 STR
Run a Sample Search on substructure, if one is included.
Review resulting answers from Sample Search.
Refine substructure if needed and re-run the Sample Search.
Run a Full File Search
Display answers
FHIT CBIB format: default display-
First hit reaction (reaction diagram, summary);
Condensed bibliographic information.
Default Display — FHIT CBIB
==> D L3 FHIT CBIB or D L3 1 (since this is the default) L3 ANSWER 1 OF 22 COPYRIGHT 1993 ACS RX(2) OF 2 F+B===>G
RX(2) RCT F 144442-95-5, B 100-63-0 RGT H 110-86-1 Pyridine PRO G 37613-36-8 CA 117(23):233916C Synthesis and anti-inflammatory activity of fluorinated phenyl styryl ketones and N-phenyl-5-substituted aryl-3-p-(fluorophenyl) pyrazolines and pyrazoles. Nargund, L.V.G.; Harisprasad, V.; Reddy, G.R.N. (Coll. Pharm., J.N. Med. Coll., Belgaum 590 010, India). J. Pharm. Sci., 81(9), 892-4 (Eng) 1992. CODEN: JPMSAE. ISSN:0022-3549.