1. What Is Partition Coefficient?

The partition coefficient (P) is defined as the ratio of concentrations of a compound in a mixture of two immiscible solvents at equilibrium, typically octanol and water. It is a key parameter in pharmacology and environmental chemistry to measure lipophilicity.

2. How Does The Calculator Work?

The calculator uses the partition coefficient formula:

Where:

• \( [octanol] \) — Concentration in octanol phase (mol/L)
• \( [water] \) — Concentration in water phase (mol/L)

Explanation: The logarithm (base 10) of the ratio provides a convenient measure of how a compound distributes between hydrophobic and hydrophilic environments.

3. Importance Of Log P Calculation

Details: Log P is crucial in drug design to predict membrane permeability, bioavailability, and toxicity. It's also used in environmental science to assess the fate of chemicals.

4. Using The Calculator

Tips: Enter concentrations in mol/L for both octanol and water phases. Both values must be positive numbers greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What does a positive log P value indicate?
A: A positive log P indicates the compound is more soluble in octanol (lipophilic), while negative values indicate higher water solubility (hydrophilic).

Q2: What is considered an ideal log P range for drugs?
A: Typically, log P values between 1-3 are considered optimal for good oral bioavailability and membrane permeability.

Q3: How is partition coefficient experimentally determined?
A: Through shake-flask method where the compound is partitioned between equal volumes of octanol and water, then concentrations are measured.

Q4: What are the limitations of log P?
A: It doesn't account for ionization (use log D for pH-dependent partitioning) and may not accurately predict behavior in complex biological systems.

Q5: How does log P relate to drug absorption?
A: Compounds with appropriate log P values (not too high, not too low) generally have better absorption through lipid membranes.