Partition coefficient of a solvent1/ water system might be defined as the ratio of a chemical's concentration in the solvent1 phase to its concentration in the aqueous phase. Solvent 1 is generally octanol. Log of this partition coefficient, log P is used to measure the hydrophobicity.
By the definition, it seems that water should have a logP value of 1. However I have found the logP value in only one place: (Solvent Extraction
Serban Moldoveanu, Victor David, in Modern Sample Preparation for Chromatography, 2015) and the value is -0.65!
One reason could be that organic and aqueous phases of the binary octanol/water system are not pure octanol and pure water.
My question is what is the real logP value of water?
Nilimesh Das
As you yourself wrote in the logP scale, Н2О/octanol are standard substances. Therefore, logP cannot be determined on this scale. You can create another scale, for example, with standard substances D2O/octanol. On this scale, the logP of water can be determined experimentally.
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