[MurpH]

Is there a way to find the pKa of deprotonation of an amine. Everywhere I look, they mention the pKa between the protonated ( R-NH₃⁺) form and the normal one (R-NH₂).

What I am looking for is the second pKa, the one between the normal form (R-NH₂) and the less common deprotonated form (R-NH^-).

Anyone have an idea where i can find this type of information? I triex sciFinder & Beilsthein but they only mention the first pKa... Thanks in advance  

[movies]

Some of that stuff should be on the Evans pKa tables (http://daecr1.harvard.edu/pKa/pKa.html) or the Bordwell pKa tables (http://www.chem.wisc.edu/areas/reich/pkatable/index.htm).

If you can't find it there, you're going to really have to dig to find it.

[Doxorubicin]

Do you think it would be safe to find pKa data on just some generic amine and then assume it would be nearly the same for any amine in the R-NH- form?

Sizable deviations in reported pka values ('normal' amines) for the same compound are quite common and can be as high as 20%...   So the difference in pKa between R-NH- and R'-NH- may be less than measurable.