What is the relation of hydrophobic character of solvents with change its solvent polarity and their dipole moments?
Dipole moment (unit Debye) is a measure of polarity. For example, a solvent having a dipole moment of 1.7 D is more polar than a solvent having a dipole moment of 1.2 D.
Lower alcohols, with general formula R-OH where R is alkyl group ( which contain C1, C2, C3), are completely miscible with water (a highly polar solvent).
As the size of the alkyl group R (which is nonpolar or hydrophobic) increases, the solubility of alcohols in water decreases until there is no solubility. An alcohol, such as cetyl alcohol, which contains 16 carbons "together with their hydrogens" , has a large hydrophobic part so it is insoluble in water.
In brief, the higher the polarity of a molecule, the higher of its hydrophilic and the lower of its hydrophobic character.
The less polar the more hydrophobic. LogKow is a useful parameter for this evaluation.
Regards
GB
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