Partitioning of alkylphenols and alkylphenol polyethoxylates between water and organic solvents

Abstract

Partition coefficients of octylphenol (OP), nonylphenol (NP) and nonylphenol ethoxylates (NPnEO, n = 1–3) were determined for n- octanol water and n- hexane water systems. In the octanol/water system, logarithmic values of the partition coefficients (log K OW) for the phenols were 4.12 and 4.48 for OP and NP, respectively. Slightly lower lipophilicity was found for APnEO with log K OW values of NP1EO, NP2EO and NP3EO around 4.2. The corresponding values in hexane/water system were approximately 0.8 logarithmic units lower but showed essentially the same ratio between NP and NPnEO as it was observed in the octanol water system. An attempt was made to estimate octanol/water partition coefficients for higher OPnEO and NPnEO oligomers. Application of reversed-phase HPLC for this purpose resulted in a significant overestimation. Alternatively, octanol/water partition coefficients for the higher APnEO oligomers were estimated (i) using an equation that correlates log K OW with solubility and (ii) converting the respective iso- octane water partition coefficients to the octanol/water coefficients.