pKa calculations

Quick question on the pKa-related functions... what's the "strongness" index? I've search around for this but can't seem to find an explanation. Also, what values are expected. I know that when I use "1" I get the same value as when I'm using the plugin in Marvin Sketch.

Thanks,

Stephen

Thank you for your question.

Please check this link http://www.chemaxon.com/marvin/help/calculations/pKa.html for detailed information about the pKa calculations. If you have any further question, please do not hesitate to let us know on the forum.

Zsolt Skribanek

Zsolt,

I'm still not sure about the "Strongness" index for the Excel pka functions. The linked page does not mention what it is.

Thanks,

Stephen

Stephen,

does this help?

acidicpKa
apKa Protonation Plugin Group calculates acidic pK_a values the acidic pK_a values

• the atom index / MolAtom object,


• the strongness index as string (e.g. '1' for strongest, '2' for second strongest pK_a),

Note, that the atom index and the strongness index are mutually exclusive. Molecule Context (All)

acidicpKa(0) returns the acidic pK_a of atom 0 of the input molecule acidicpKa("2") returns the second strongest acidic pK_a value

Viktor

That makes sense. Thanks, Viktor.

See also https://www.chemaxon.com/forum/viewpost30715.html#30715

Zsolt