Updated information and screen shots of this page created by Matthew Murray.
Exploring Reactions
Search by Drawing a Full Reaction
CAS Draw can be used to search for a full reaction.
Using the Draw Arrow Reaction tool, reactants can be drawn on one side of the arrow and products can be drawn on the other side of the arrow.
CAS Draw will automatically detect whether a substance is a reactant or product, but if there are any issues, use the Add Reaction Role button to change this.
Matching portions of a reaction will be highlighted in blue, denoting where a match for your drawing is.
Partial matches for your reaction drawing can also appear in your results. For example, a benzene ring can be left out of the reactants in the initial search, but the reaction that includes a benzene ring can still be returned in the search results.
In this case, any reactants or products that were not part of the drawing will not be highlighted in blue in the results.
You should still try to be as accurate as possible in your search to attain results that you are looking for.
Search by Natural Language
From the Reactions tab on the main search screen, you can also attempt to use the natural language search algorithm to develop a search. Typing keywords like “synthesis” cues the system to search for reactions in which a specific substance is produced. You can use the name or CAS Registry Number of the substance that you want to make.
This strategy is reasonably sound when you wish to find the synthesis of a specific substance, but it is not the best when you want to locate information about a class of substance or substances where the name may not appear within a database record’s list of synonyms.
In general, it is better to do reaction searches graphically.
Search by Drawing a Partial Reaction
It is also possible to search for only parts of a reaction in CAS Draw.
To do this, draw the reaction arrow as usual, but leave one side of the reaction blank. This will assign a substance the role of either reaction or product depending on what side of the arrow you drew the substance on.
In this example, the reaction search will look for any reaction that has valproic acid as one of the reactants.
Alternatively, drawing a substance without a line will allow you to search for any reaction that contains the drawn substance, either on the reactant or product side.
Note that you cannot search for catalysts or solvents in a reaction in this manner. To do this, instead search for a given substance in the Substance search, and then "Get Reactions."
