Water solubility, vapor pressure, and activity coefficients of terpenes and terpenoids

Water solubilities, activity coefficients, and vapor pressures of some terp enes and terpenoids were determined from two sets of experiments. The first involved liquid-liquid contacting until saturation of an aqueous layer, wh ich gave solubility and activity coefficient at infinite dilution gamma(inf inity). The second set involved stripping a solute from a nonsaturated aque ous solution by an air stream. This last experiment gave the product gamma( infinity)P degrees from which vapor pressure P degrees was deduced. Reliabi lity of the results was established from predicted P degrees values, and da ta for 12 compounds are now available. Data obtained at 25 degrees C showed low solubilities (0.037-0.22 mmol/L) and high activity coefficients (10(5) -10(6)) for terpenes, whereas oxygenated monoterpenes exhibited solubilitie s 20 orders of magnitude higher, in the range of 2-20 mmol/L and 10(3)-10(4 ) for activity coefficients. Vapor pressures ranged from 100 to 550 Pa for terpenes and from 1 to 130 Pa for terpenoids. Attempts to estimate water so lubility showed that recent equations in the Literature are unable to predi ct this property with an accuracy better than 140%.