The solubility of silybin in aqueous hydrochloric acid solution has been measured at temperatures range from 293.15 to 313.15 K. Experimental result shows that the solubility increase with the increase of both temperature and pH value. The solubility data was analyzed by a general salt-effect rule and a hydration ionization model.We have found that the salt-effect rule is obeyed for pH less than 3 where silybin is salted out.We have also found that the salt-effect rule is broken for pH greater than 3 where the concentration of hydrogen ion is very low. The break down of salt-effect rule has been explained by employing a model of molecular hydration ionization where quantum chemical calculation was performed to support this model by optimizing the geometries of silybin water complex. Based on this model, the break down of the salt-effect rule is caused by that silybin s acidity increases with the increase of the pH value, which leads to the increase of the solubility at the higher pH regime. The predicted pKa also agrees well with the experimental result.
Compounds
#
Formula
Name
1
C25H22O10
silybin
2
H2O
water
3
ClH
hydrogen chloride
Datasets
The table above is generated from the ThermoML associated json file (link above).
POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied;
the numbers refer to the table of compounds on the left.