I've been trying to find information on in default Strongest Acidic and Strongest Basic pKa calculated in instant jchem when you add a new chemical terms field. Are the default pKa's macroconstants or microconstants? Everywhere I've looked has told mostly told me about Marvin and instead of instant jchem. The Instant JChem user guide hasn't been clear either.
I'm using the Instant JChem version 188.8.131.52.
As chemical calculations are done by invoking Chemical Terms functions in Instant JChem you should look at the Chemical Terms manual. Here is the list of all available functions:
I give you the solution for your problem besides just giving a link to the manual. To calculate the strongest acidic/basic pKa you should use the
Please note that the number must be specified with single/double quotation marks; otherwise it works as an atom index, and it calculates the pKa of that atom. The default pKas are macroconstants.
I hope this helps,