1. What is logP (Partition Coefficient)?

The partition coefficient (logP) is a measure of how a compound distributes between octanol and water, indicating its hydrophobicity. It's a key parameter in drug discovery and environmental chemistry.

2. How Does the Calculator Work?

The calculator uses ChemAxon's algorithms to predict logP based on molecular structure:

Where:

• \( [compound]_{octanol} \) — Concentration in octanol phase
• \( [compound]_{water} \) — Concentration in water phase

Explanation: The calculation considers molecular fragments, atom contributions, and correction factors based on extensive experimental data.

3. Importance of logP Calculation

Details: logP predicts drug absorption, distribution, metabolism, and toxicity. Compounds with logP between 0-3 are generally considered drug-like.

4. Using the Calculator

Tips: Enter molecular structure as SMILES notation or IUPAC name. Select calculation method (standard or advanced for more accurate results).

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between logP and logD?
A: logP measures neutral species partitioning, while logD accounts for ionization at specific pH (more relevant for ionizable compounds).

Q2: What are typical logP values for drugs?
A: Most oral drugs have logP between 1-3. Values <0 may indicate poor membrane permeability, >5 may indicate poor solubility.

Q3: How accurate are predicted logP values?
A: Typically within ±0.5-1.0 of experimental values, but can vary for complex structures. Experimental measurement is recommended for critical applications.

Q4: Can I calculate logP for mixtures?
A: No, this calculator is for pure compounds only. Mixtures require experimental determination.

Q5: What molecular formats are supported?
A: SMILES, IUPAC names, or drawn structures (if structure drawing tool is implemented).