You're right to question that! Two compounds with the same hydrophobicity *should* have similar partition coefficients. It's important to remember that the partition coefficient (K) is a measure of how a compound distributes between two immiscible phases, typically an aqueous phase (water) and a non-aqueous phase (often octanol).

Here's why two compounds with the same hydrophobicity *might* seem to have different partition coefficients, even though in theory they shouldn't:

* Measurement Error: Partition coefficients are determined experimentally. There's always some error in the measurement, especially for complex molecules. Small differences in K could be due to experimental variability.

* Different Hydrophobicity Scales: There are various ways to quantify hydrophobicity. Using different scales (like octanol-water partition coefficients vs. other scales) can lead to slightly different interpretations.

* Other Interactions: While hydrophobicity is the primary driver of partitioning, other factors like:

* Hydrogen Bonding: Compounds with hydrogen bond donors or acceptors can interact differently with the aqueous phase, affecting their partitioning.

* Polarizability: The ability of a molecule to respond to an electric field (polarizability) can also influence how it interacts with the phases.

* Shape and Size: Steric effects, like the size and shape of the molecule, can influence how readily it fits into the two phases.

* Intermolecular Forces: Beyond hydrophobicity, other intermolecular forces, like dipole-dipole interactions, can impact partitioning.

Key Takeaway: While hydrophobicity is a major factor, it's not the only one. If two compounds have apparently different partition coefficients despite similar hydrophobicity, look for other possible factors influencing their partitioning behavior.

Let me know if you'd like me to elaborate on any of these points or have specific examples in mind!