ADDITIVITY OF VAPORIZATION PROPERTIES IN PHEROMONE-LIKE HOMOLOGOUS SERIES

A simple method of estimating vaporization properties of normal alkyl and (Z)-and (E)-alkenyl homologous series of pheromone-like acetates, alcohols and aldehydes with 10 to 18 carbon atoms in the chain is desc ribed. The properties hold for the (subcooled) liquid state and includ e vapour pressure (p(sat)) and heat of vaporization (Delta(vap)H) at 2 5 degrees C. An empirical QSPR model for In p(sat) and Delta(vap)H is developed in terms of three easy-to-calculate structural descriptors r elated to the number of carbon atoms in the chain (n), the functional group characteristics (I) and the double bond position (Delta). The mo del, covering the property ranges of 2 x 10(-4)-2 x 10(1) Pa and 60-12 0 kJ mol(-1), explains over 99.8% of the variance in the experimental data sets containing 295 compounds, with standard errors in In p(sat) and Delta(vap)H of about 0.085 In unit and 0.62 kJ mol(-1), respective ly. It is recommended as a useful tool in designing pheromones and in fate-modelling applications in the absence of experimental data.