Tetrazole pKa problem

User d1652f6be1

13-10-2016 16:48:37

I am getting very different answers for a tetrazole pKa depending on which neutral tautomer is specified:

> cxcalc pKa "c1[nH]nnn1"

id    apKa1    apKa2    bpKa1    bpKa2    atoms
1    4.81        -0.85    -5.53    2,5,3

> cxcalc pKa "c1n[nH]nn1"

id    apKa1    apKa2    bpKa1    bpKa2    atoms
1    7.34        -1.52    -4.32    3,4,2

So the 1H tautomer is predicted at 4.81, which is about right, but the 2H tautomer is predicted at 7.3, which is clearly very wrong.  Looks like a bug to me, unless I'm doing something stupid....



ChemAxon 2136dd2f4b

14-10-2016 13:47:56


The fix will be available in the next patch release.

User d1652f6be1

14-10-2016 13:54:52

Wow, quick response!  Thanks, look forward to testing....

ChemAxon d51151248d

18-10-2016 11:04:08

Hi Paul, 

I've tested this issue and the fix will be available in version 16.10.31 the next week.