Studies on the Relationship between Olfactory Stimulating Effectiveness and Physico‐Chemical Properties of Odorous Compounds

Abstract

Summary. The relationship between the olfactory stimulating effectiveness and the chemical and physical properties of a number of odorous compounds has been studied. As a measure of the eff iciency has been taken the magnitude of the slow potential evoked in the olfactory mucosa in the frog. Aliphatic alcohols of equimolar concentrations were found to be increasingly stimulating up to a certain maximum with increasing chain length. A similar increase was also found for aldehydes and ketones while in the series of fatty acids the relation between stimulative effect and chain length was less regular. It was further found that the partial vapour pressures for alcohols of equal stimulating power increase approximately linearly Kith the saturated vapour pressures. In terms of thermodynamic activities the alcohols of intermediate chain length are equally stimulating while the lower alcohols are less effective. The relationship between the different molecular parameters and the olfactory stimulative power of the studied compounds is discussed and the similarity between the results obtained in the present investigation and those in studies of olfaction in insects is pointed out.