CODATA LOGKOW - A databank of evaluated octanol-water partition coefficients (LogP)
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Introducing LOGKOW ©

This databank contains experimental data, retrieved from the literature, on over 20,000 organic compounds (carbon numbers 1 - 130; gases, liquids and solids). Besides partition coefficients, other stored information includes:

  • IUPAC names
  • CAS Registry Numbers
  • pKa values
  • S.M.I.L.E.S. notation
  • experimental conditions of measurement (summarized)
  • recommended Log Kow
  • full bibliography in Chemical Abstracts style

Data may be retrieved from this databank by searching for specific compounds according to chemical formula or CAS Registry number or in "browse" mode. Instructions on how to search the data bank follow next.

Searching the Databank

1. Searching by Chemical Formula

Step 1. Select option Search Formula

Step 2. Enter the formula of the compound, in the usual manner, on one line and using upper and lower case letters as required. The sequence of the letters in the formula is the same as that used in Chemical Abstracts. For example, 4-chloro nitrobenzene is entered as C6H4ClNO2

Carbon comes first, Hydrogen comes second, other elements are in alphabetical order

It is conventional practice to omit "1" when there is only one atom of an element in the molecule; the search program recognizes this convention and also accepts a "1" written explicitly. The following examples illustrate the correct method of entering chemical formulas:

Compound Correct Not Correct
Methane CH4 (or C1H4 Ch4, H4C
Carbon Tetrachloride CCl4 (or C1Cl4) CCL4
Bromobenzene C6H5Br C6H5BR
Nitrobenzene C6H5NO2 C6H5O2N

Ionic or addition compounds are entered according to their actual stoichiometric formulas:

Compound Correct Entry
Ethylamine hydrochloride (C2H7N.HCl C2H8ClN
Tetramethyl ammonium iodide C4H12IN
Sodium Butanoate C4H7NaO2

Step 3:

After having typed in the formula, click on Search. The program will search for the compound. If it cannot find it, a message to this effect will appear. Check to see whether the formula was entered correctly; if correct, the databank does not contain the compound. If the program finds a compound corresponding to the formula, it will display the data for it. If it finds two or more (i. e. isomers) it will display the names of the isomers and you may click on one.

2. Searching by CAS Registry Number

Step 1: Select option Search CAS Registry Number

Step 2: Enter the Registry number as given in Chemical Abstracts. For example, the number 99-06-9 may be entered as is.

3. Searching in the "Browse" mode

This option allows you to scan the Master List of the databank. The compounds are listed by chemical formula in the order used by Chemical Abstracts Compound Index, that is:

  • First, in order of increasing carbon number
  • Then, in order of increasing number of hydrogen atoms
  • Then, in order of increasing number of other elements, in alphabetical order

Step 1: Select option Browse

Step 2: Enter the postion at which you wish to start browsing through the Master List. The entry has the general form CxHy where x and y are integers.


  • C (or C1 or ENTER) starts you at the very beginning of the list.
  • C4 starts you at the beginning of the C4 compounds.
  • C8H13 starts you at the beginning of the C8H13 compounds.

(No elements other that C or H may be specified in this mode.)

In case your entry should correspond to no entry in the Master List, the program will start you at the position closest to your entry.

Display Information

The data for a compound in compact or tabular form. As an example, for 3-Hydroxy benzoic acid, we have:

Display example for 3-Hydroxy benzoic acid

Comments on the information displayed:

pKa Value

This datum is included whenever a value was found in the literature. When several experimental values were found for the same compound, an average value is reported here.


The name of the compound is that assigned by Chemical Abstracts. When the compound could not be found in the Chemical Abstracts Compound Index, a name was provided according to IUPAC naming rules. A determined effort was made to distinguish correctly among stereoisomers, but 100% accuracy cannot always be guaranteed.

SMILES (Simplified Molecular Input Line Entry System)

This is a chemical notation system for specifying the structure of an organic compound. In a shorthand manner, it indicates how the atoms are connected, but does not distinguish stereoisomers. The notation is described in two publications:

  • E. Anderson, G. D. Veith and D. Weininger, "SMILES: a line notation and computerized interpreter for chemical structures", EPA/600/M-87-021, U.S. Environmental Protection Agency, Duluth (1987).
  • D. Weininger, "SMILES, a chemical language and information system. 1. Introduction to methodology and encoding rules", J. Chem. Inf. Comput. Sci. 28(1), 31-36 (1988)


The datum is quoted directly as it was reported in the original publication. If the datum was corrected for ionization by the original authors, this fact is mentioned in the footnote to the datum (an adjoining column). The compiler of LOGKOW © has not himself corrected any data for ionization.

If the original publication listed values for duplicate measurements of the same compound, the compiler reported the mean value here and this fact is mentioned in the footnote.


This gives further information concerning the source of the Log Kow datum, the experimental method, etc.

Ref (Reference)

This gives the code for the source of the data. The references are listed at the end of the display.

Temp (Temperature)

The temperature of the measurement (in degrees Celsius) is given here, or AMB if "ambient" temperature was mentioned in the original publication.

Equil Meth (Equilibration Method)

The method of equilibration of the aqueous and octanol phases is indicated here (all abbreviations used in these columns are explained in the Glossary.

If the method of measurement was an indirect one (i. e. by neither the shake-flask (SF) or generator column (G) method), a short phrase describing the indirect method is given instead of columnar entries.

Anal Meth (Analytical Method)

The method for analyzing for the compound in either or both phases is indicated here (see glossary).

Aq Phase (Aqueous Phase)

This specifies the nature of the aqueous phase used in the measurement. If the aqueous phase was a buffered solution at a specified pH, this is indicated by "pH7.4", etc. Otherwise, see glossary.

Phases Anal (Phases(s) Analyzed)

Indicates whether one or both phases were analyzed quantitatively for the compound (see glossary).

Meth Ref (Method Reference)

If the original publication included a reference to a previous work describing the method of measurement of measurement or analysis, this reference is cited by code here.

Recommended Value

Whenever possible, the compiler has given here the Log Kow value which, in his judgement, is closest to the true value. All recommended data refer to the neutral compound, the only exception being zwitterionic compounds. The criteria used in choosing a Recommended Value are described in the article:

J. Sangster, "Octanol-water partition coefficients of simple organic compounds", J. Phys. Chem. Ref. Data 18(3), 1111 - 1229 (1989).