What are the rough pKa values of the two amine groups in carbidopa? Do these amines form a diamine or are they seperate aliphatic amines? I presumed they would have average pKa values for primary (9.4) and secondary amines (10.7), however drugbank says the most basic group in carbidopa has a pKa of around 5.6. I am not sure how either of the amines have a pKa value of around this unless both of them being bonded has an effect.
Any responses would be greatly appreciated as this is help for an assignment due very soon. Many thanks,