ACD/LogP DB

The octanol-water partition coefficient (P) (also referred to as K_ow) is a measure of the propensity of a neutral compound to differentially dissolve in these immiscible phases. It is usually referred to as the logarithmic ratio, logP, and serves as a quantitative descriptor of lipophilicity.

With ACD/LogP DB, you can obtain accurate values of logP (in octanol/water, calculated under standard conditions, at 25°C) and review an extensive library of experimental logP data. Read this application note to see how logP is applied in different research environments (download).

If you are working with compounds that have ionizable groups, it is essential to have a clear understanding of the limitations of logP. The logP value of a substance is most relevant for neutral substances and is useful as a general reference point to help compare overall hydrophobicity trends of compounds. LogP does not account for modifications in the hydrophobicity of ionizable compounds at varying pH. The appropriate descriptor for these compounds is the distribution coefficient, D (also typically used in its logarithmic form, logD). Example: logP vs. logD of Aspirin.

LogD Profile of Aspirin	Profile of the changing species in aqueous solution with pH

The value of logP for Aspirin is only relevant below pH 3. LogD is therefore the appropriate descriptor in the physiologically relevant pH range of 4–8 (oral administration). This reasoning is equally relevant for applications of logP outside the realm of drug discovery, though the pH ranges of interest will vary.

Download our Application note (Lipophilicity Descriptors: Understanding When to Use LogP and LogD)

ACD/LogP DB is available as a part of ACD/PhysChem Suite which includes the full range of ACD/Labs physicochemical and molecular property predictors including logD, pK_a, aqueous solubility, boiling point, sigma, and more.