Abstract
Previous data for the distribution of the n-alkyl carboxylic acids between aqueous buffers and heptane have suggested that the free energy of transfer between the two solvents does not increase with the length of the alkyl chain beyond palmitic acid, indicating a limit to the hydrophobicity of the alkyl chain at a length of about 15 carbon atoms. It is shown in this paper that previous measurements were influenced by unexpectedly strong pH-dependent association of the long-chain acids in the aqueous phase. Under conditions where such association becomes negligible, the free energy of transfer becomes a strictly linear function of alkyl chain length for all acids up to behenic acid (C21H43COOH).
Keywords: fatty acids, lipids, hydrogen bonds
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Selected References
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