A Comparison of Gas−Hexadecane and Gas−Apolane Partition Coefficients

Abstract

Gas-apolane partition coefficients (L(87)) of 157 nonpolar and polar organic solutes, spanning a wide range of functional groups, dipolarities, and hydrogen-bonding capabilities, are measured by open tubular capillary gas chromatography at 40 °C. The experimental values compare well (R(2) = 0.999) with literature values of log L(87) from packed-column gas chromatography. The log L(87) values are also compared with gas-hexadecane partition coefficients (log L(16)) at 25 °C. A strong linear relationship exists between log L(87) and log L(16) for all solutes (R(2) = 0.994), as well as for chemically relevant subsets of the data. Therefore, unknown L(16) values at 25 °C can be predicted from the corresponding L(87) values, which can be measured on open-tubular or packed columns at higher temperatures, due to the low volatility of apolane. Predicted values of L(16) would be extremely useful, since log L(16) is often the major explanatory parameter in many linear solvation energy relationships.