Qualitative understanding of partition preferences
Introduction
Cavity modelRules for partitioningThe cavity model in quantitative termsSelftest
Problems
1) Give a qualitative explanation 2) Estimate the extraction efficiency Answer 3) Assign partition constants to substances Answer 4) Fuel accident Answer 5) Mixture of similar isomeres ... ? Answer 6) Extraction with pentane or diethyl ether? 7) Prediction of partition constants Answer 8) Assign data to substances Answer 
9) Explain saturated vapor pressure 10) Apolar surface
Intermolecular interactions in every day life
FAQ4) Fuel accident
Question:
Fuel was spilled in a traffic accident. The local water supplier is concerned that this fuel may have reached the ground water table. In order to set up a worst-case scenario, you are asked to estimate the fuel /water partition constants of various phenols and anilines, which are known to occur in trace amounts in the fuel. In the literature you can only find the fuel/water partition constants of alkylaromatic compounds, ethers, and ketones (see figure). Can you use this knowledge to estimate the fuel/water partition constants of phenols and anilines whose octanol/water partition coefficients are known? (The fuel is a mixture of alkanes and alkylaromatic compounds and Methyl-tert-butylether (MTBE)).
Answer:
No you cannot. Fuel is a mixture of apolar and monopolar (H-bond accepting) solvents. Octanol is bipolar and can therefore not mimick fuel for H-bond donor compounds that are sensitive to just this property. In the graphic only H-bond accepting chemicals are shown. They are not sensitive to this difference between octanol and fuel. But phenols and anilines are H-bond donating compounds and therefore sensitive to this difference (see figure below).
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