Monopolar hydrophobic compounds

All together the examples show that monopolar (electrophilic) hydrophobic compounds can cause bitter taste and that the intensity of bitter taste depends on the size and shape of the hydrophobic part of the molecule. 

We start out by considering the effect of such adsorption sites on the isotherms of apolar and weakly monopolar compounds. For these types of sorbates, hydrophobic organic surfaces and/or nanopores of carbonaceous materials are the most likely sites of adsorption. Such hydrophobic surfaces may be present due to the inclusion of particles like coal dust, soots, or highly metamorphosed organic matter (e.g., kerogen). Because of the highly planar aromatic surfaces of these particular materials, it is reasonable to assume that planar hydrophobic sorbates that can maximize the molecular contact with these surfaces should exhibit higher affinities, as compared to other nonplanar compounds of similar hydrophobicity. 

Figure 11.7 Apolar and slightly monopolar organic compound sorption coefficients, K,min (L nr2), observed for exchange between aluminum oxides and aqueous solutions plotted as a function of sor-bate hydrophobicity (as measured by yw) apolar series of chlorobenzenes (squares, Schwarzenbach and Westall, 1981) and aromatic and chloroaromatic compounds (diamonds, Maderet al., 1997).

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