Mh. Abraham et al., THE DETERMINATION OF SOLVATION DESCRIPTORS FOR TERPENES, AND THE PREDICTION OF NASAL PUNGENCY THRESHOLDS, Journal of the Chemical Society. Perkin transactions. II (Print), (11), 1998, pp. 2405-2411
We have previously put forward two solvation equations for the correla
tion of chemical and biochemical phenomena, including nasal pungency t
hresholds (NPT) in man. In order to make use of these equations, a num
ber of descriptors need to be assigned to any given solute, viz. pi(2)
(H) the dipolarity/polarizability, Sigma alpha(2)(H) and Sigma beta(2)
(H) the overall hydrogen-bond acidity and basicity, and log L-16 where
L-16 is the solute gas;hexadecane partition coefficient. We show that
these descriptors can be obtained from data from a number of processe
s, including gas-liquid chromatography, high performance liquid chroma
tography, gas-water partitions, gas-solvent partitions and water-solve
nt partitions. In this way, the above descriptors have been obtained f
or eleven terpenes, including hydrocarbons, aldehydes, ketones, alcoho
ls and an ether. The pi(2)(H), Sigma alpha(2)(H) and log L-16 descript
ors have also been obtained for a further 21 terpenes, but Sigma beta
2(H) now has to be estimated. Through our previously reported equation
, we have predicted NPT values for the total 32 terpenes. Small hydroc
arbons such as alpha-pinene are predicted to have large NPT values, bu
t aldehydes (cg. geranial) and ketones (e.g. camphor) are predicted to
have moderate values, and alcohols (cg. menthol and borneol) and thei
r acetates are predicted to have very small NPT values.