how do you calculate pKa
pKa=2.86
pKa = 15
It is around pKa=13
Doxofylline Pka value is about 9.8.
pKa (dissociation constant) is variable with temperature.
The pka of a protonated ether (the conjugate acid) is about -3.5
The pKa of sulfonic acid is < 0
pKa of methanol is 15.5 see this pdf for more information about pka-values: http://chemweb.unp.ac.za/chemistry/Physical_Data/pKa_compilation.pdf
pKa of drug can be determined from Handerson Hasselbatch equation., when conc. of salt become equal to acid i.e. at equivalence point when pH=pka then in H-H equn, pH=pka
pKa = -log KapKa = -log 5.4x10^-10pKa = 9.27
The conjugate acid is Hydrogen (H2), the pKa of which is 35.