While attempting registration, Chemical Registration users might sometimes find that the final structure is not the same as the initial structure. Such a change could be a keto-enol transformation or something different.

The reason for the change is that Chemical Registration uses a “Correct Lot Chemistry” correction rule and it calls the "Correct Chemistry" protocol which can be seen under Base extensions. This extension uses the "Check and Normalize Structure" component and it includes a parameter “Apply Transformation Reactions” which is set to True by default.

This step uses a Transformations.rd file located at \\data\Normalization\Transformations\ folder in Pipeline Pilot. Chemical Registration users may not like to register the transformed structure in some situations. If so, there are two workarounds that can be considered:

1. Remove the unwanted transformation reaction from the RD file, save the modified RD file at the same Pipeline Pilot server location, and then attempt registration of this structure.

2. Rather than modifying the Transformations.rd file to remove that particular transformation, users can set the parameter “Apply Transformation Reactions = False” to allow the initial structure to go through.

In both cases, if the change is reversed later, duplicate check in Chemical Registration will not find the original structure during future registrations.

Chemical Registration users are advised to think about both options and then decide how to proceed. It is also strongly recommended that they test the change thoroughly in their DEV or TEST environment of Chemical Registration first, make sure things work OK as expected, and then try it in their PROD environment