No specific rules as deduced from the Wikipedia definition of Partition coefficient:

"In the physical sciences, a partition-coefficient (P) ... is the ratio of concentrations of a compound in a mixture of two immiscible phases at equilibrium. This ratio is therefore a measure of the difference in solubility of the compound in these two phases".

Limits of P values would be zero and infinite but they never occur. In the examples in wikipedia LogP go from 6.4 to -1.16.

In this link (http://www.cyprotex.com/physicochemicalprofiling/physicochemical-properties/pka-and-log-p-determination) you will find more info on "real" limits.

-6 for highly hydrophilic to +6 for highly hydrophobic. This info from onr book in Russian lanquage. If you need, I will give reference. It is front me

this ratio for octanol and water

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For best drug absorbance and bioavailability the drug should have log-p of more than 1, i.e. more lipophilic to diffuse efficiently through the cell membrane, and this also depends on the site of action.

I rememberr that 0-3 is needed for absorption, because more lipofilic substance is left in lipofilic layer of membranes

I have seen this range in a book

pleease Mrs. Hudz send me your reference

for 0-3 or -6 - + 6?

- 6 - +6 I have the book front me

-but 0-3 I must search for this book

Thank you all.

I found in some references that chlorine photosensitiser and fullerene football-like molecules have log P 9 and 19 respectively but these values are calulated using cheminformatics software tools.

At what extent can we predict log P using web tools (without performing experiment) ?

these substances are used as active pharmaceutical ingredients, aren't they?

- 6 - +6 - this range for active pharmaceutical ingredients

thy are used to photoinactivate microorganisms (bacteria). so yes they are used in medecine and pharmaceutical domains (dermatology, dentistry..)