UC San Diego

Literature data on partitioning of compounds from the gas phase to a number of amides and from water to the amides has been collected and analyzed through the Abraham solvation equations. The resulting equations are statistically good enough to be used for the prediction of further partition coefficients, and allow deductions to be made about the chemical properties of the amides, as solvents. For example, tertiary amides have no hydrogen bond property at all, secondary amides are rather weak hydrogen bond acids, and primary amides are stronger hydrogen bond acids than are alcohols as solvents. Equations for partitioning from the gas phase to amide solvents can also be used to test if the amides are possible models for a number of biological phases and biological processes. It is shown that no organic solvent is a suitable model for phases such as blood, brain, muscle, liver, heart or kidney, but that a number of rather non-polar solvents are models for fat. N-methylformamide is shown to be the best (and excellent) model for eye irritation and nasal pungency in humans, suggesting that the receptor site in these processes is protein-like.