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Reaction databases are valuable resources when planning synthetic routes. Today's stop on our continuing survey of free chemistry databases and resources on the Web takes us to WebReactions, an organic reaction database. From the about page:

WebReactions introduces a new concept for the retrieval of reactions from a large database in which reactions are indexed instead by the bond changes which occur. When a synthetic chemist thinks of a reaction, he envisions first the making and breaking of bonds at the reaction center as the defining nature of the reaction. Subsequently he considers the effects of surrounding groups, i.e., on rate, hindrance, or resistance to change under the reaction conditions. The WebReactions program mirrors this approach for indexing reaction entries in any database.

WebReactions is organized around the concept of a transformation of one organic structure into another. Each reaction contains the structures of starting materials and products, along with metadata including yield, bibliographical citation, and reaction type. WebReactions contains information on over 390,000 reactions from the primary literature.

The WebReactions search interface is easy to use, although it does take some getting used to. All searching and browsing takes place inside an applet component. Beginning from the search page; (1) click 'Define Reactants' and draw the structure of a reactant; (2) click 'Define Products' and draw the structure of a product; (3) click 'Search Database'. Result sets are browsable by clicking 'Browse Reactions'.

Searches execute remarkably fast, with none that I performed requiring more than a second or two to complete.

Although its possible to linearly scan reactions in a result set, WebReactions has no capability of browsing reactions. For example, each reaction record contains a reaction type identifier. Unfortunately, there's no way to view all reactions of a given type. Likewise, there's no way to easily see all of the reactions a given structure is involved with.

For a quick lookup of known reactions, WebReactions is a good first stop, and may make a good companion to Sigma-Aldrich Reaction Search.

Kudos

• Fast Reaction Search.
• Streamlined interface.
• Primary literature bibliographical data.

Ideas for Improvement

• Hyperlinks to primary literature sources through DOI. Currently only text bibliographical info displayed.
• Browse all reactions of a given reaction type.
• User-submitted reactions.
• Use HTML to display results. The current system causes an error when using the back button.
• One reaction per Web page would make it easier to expose relationships among reactants, products, and reactions.