I can't find any documentation on ChemProp.

I can't find any documentation on ChemProp.

Following is some information on how ChemProp obtains its values:

Log(p) (partition coefficient for n-octanol/water) - three fragmentation methods are used to predict the log(p) values.

1. Method one is based on 94 atomic contributions evaluated from 830 molecules by least squares analysis. This method works with a standard deviation of 0.47 log(p) units and can handle molecules containing hydrogen, oxygen, nitrogen, sulfur and halogens.

2. Method two is an extension of method one that is based on 120 atomic contributions evaluated from 893 molecules by least squares analysis. In addition to the atoms introduced for method one, it can handle molecules which contain phosphorus and selenium atoms. This method works with a standard deviation of 0.50 log(p) units.

3. The third method is based on 222 atomic contributions calculated from 1868 molecules by least squares analysis. This method allows a calculation of log(p)'s with a standard deviation of 0.43 log(p) units and can handle molecules containing hydrogen, oxygen, nitrogen, sulfur, halogens and phosphorus atoms. If this method is applied to molecules with internal hydrogen bonds, the standard deviation is 0.83 log(p) units.

Henry's Law Constant - the air to water partition coefficient that is expressed as ratio of vapor pressure to water solubility or as a unitless distribution coefficient that can can be evaluated as a ratio of the concentration in air to the concentration in water.

Two methods are used to predict Henry's Law constant, the first is an approach based on the bond contribution method. This method uses 59 bond contribution values and 15 correction factors. The contributions were calculated by least squares analysis using a dataset of 345 chemicals. This method estimates with a mean error of 0.30 units and a standard deviation of 0.45 units and can handle molecules containing carbon, hydrogen, oxygen, nitrogen, sulfur, phosphorus and halogens.

In the second method, Henry's Law constant is estimated from an equation found using linear regression.. Multifunctional compounds were omitted from this study. This method should not be used for compounds where distant polar interaction are present.

Molar refractivity - two fragmentation methods are used to estimate the molar refractivity value. Method one includes 93 atomic contributions evaluated from 504 molecules by using a constrained least squares technique. This method works with a standard deviation 1.27 cm3/mol and can handle molecules containing hydrogen, oxygen, nitrogen, sulfur and halogens.

The second method is an extension of method one that includes 120 atomic contributions evaluated from 538 molecules by using a constrained least squares analysis technique. In addition to the atoms introduced for method one, this method can handle molecules with phosphorus and selenium atoms. This method works with a standard deviation of 0.77 cm3/mol.

Heat of Formation, Gibbs Free Energy, Ideal Gas Thermal Capacity, Freezing Point, Critical Temperature, Critical Pressure, and Critical Volume are estimated using Joback's fragmentation method.

Normal Boiling Point - estimated in K using two methods. The first is by Joback's fragmentation method and the second by the Joback method as modified by Stein. All boiling points are estimated at a pressure of 1 atm.