On 7 May 2010 05:32, Egon Willighagen <egon.willigha...@gmail.com> wrote:
> moving to: cdk-user
>
> Hi Rajarshi,
>
> On Fri, May 7, 2010 at 4:07 AM, Rajarshi Guha <rajarshi.g...@gmail.com> wrote:
>> Take an SDF file with no H's and then call
>> AtomContainerManipulator.convertImplicitToExplicitHydrogens and no H's
>> are added.
>
> SD files do not have info on the number of implicit hydrogens, making
> the field set to UNKNOWN (null). The
> convertImplicitToExplicitHydrogens has nothing to convert yet; I'd
> guess you simply have to calculate the number of implicit hydrogens
> first?
>
>> But if the corresponding SMILES form is read in, and implcit H's are
>> converted to explicit, H's are added.
>
> SMILES on the other hand *does* specify the number of implicit
> hydrogens (implicitly, of course), but it's part of the standard... so
> the SmilesParser does atom type detection, calculate number of
> implicit hydrogens, and actually aromaticity detection too... The
> values now being set, the convert() method has something to convert...
>
> Rajarshi, can you please verify this hypothesis?

My 2c. It's common for 2D SD files in particular to not include
implicit hydrogens. - Noel

> Egon
>
> --
> Post-doc @ Uppsala University
> Proteochemometrics / Bioclipse Group of Prof. Jarl Wikberg
> Homepage: http://egonw.github.com/
> Blog: http://chem-bla-ics.blogspot.com/
> PubList: http://www.citeulike.org/user/egonw/tag/papers
>
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