ACD/pKa DB
|
Quickly and accurately
predict the acid-base
ionization constant for
a wide range of organic
compounds.
|
The acid-base ionization/dissociation constant, pKa, is a measure of the tendency of a molecule or ion to keep a proton (H+) at its ionization center(s), and is related to the ionization ability of chemical species.
pKa is the core property of an electrolyte that defines chemical and biological behavior. In biological terms, pKa is important in determining whether a molecule will be taken up by aqueous tissue components or lipid membranes and is related to logP (the partition coefficient). Since water is a very polar solvent (dielectric constant ε20 = 80), facile ionization will increase the likelihood of a species to be taken up into aqueous solution. If a molecule does not readily ionize, it will tend to stay in a non-polar solvent such as cyclohexane (ε20 = 2) or octanol (ε20 = 10). Separation and analytical scientists require an understanding of pKa because it impacts the choice of techniques used to identify and isolate the compound of interest. pKa is also closely related to the concept of pH (the acidity of solution).
ACD/pKa DB uses Hammett equations derived from a library of highly curated compounds to predict aqueous pKa. In addition, two reference databases are available that offer quick look-up of published data—one contains > 31,000 experimental pKa values for approximately 16,000 compounds in aqueous solutions; the other provides experimental data for more than 2000 molecules in non-aqueous solvents. This software is used by the majority of pharmaceutical and API companies worldwide, and has been tested on a broad variety of chemical classes.
Key capabilities of this software include:
- Calculation of apparent, approximate, and exact microscopic constants and single pKa.
- The ability to train the algorithm with experimental measurements to improve predictions for novel/proprietary compounds.
ACD/pKa DB is available as a part of ACD/PhysChem Suite which includes the full range of ACD/Labs physicochemical and molecular property predictors including logP, logD, aqueous solubility, boiling point, sigma and more.
|
