Additivity of vaporization properties in pheromone-like homologous series

Abstract

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 described. The properties hold for the (subcooled) liquid state and include vapour pressure (p sat ) and heat of vaporization ( vap H) at 25 ЊC. An empirical QSPR model for ln p sat and vap H is developed in terms of three easy-to-calculate structural descriptors related to the number of carbon atoms in the chain (n), the functional group characteristics (I) and the double bond position ( ). The model, covering the property ranges of 2 × 10 ؊4 -2 × 10 1 Pa and 60-120 kJ mol ؊1 , explains over 99.8% of the variance in the experimental data sets containing 295 compounds, with standard errors in ln p sat and vap H of about 0.085 ln unit and 0.62 kJ mol ؊1 , respectively. It is recommended as a useful tool in designing pheromones and in fate-modelling applications in the absence of experimental data.

Determination of Vaporization Enthalpies of the Branched Esters from Correlation Gas Chromatography and Transpiration Methods

“…The correlation of the enthalpies of vaporization with the number of C atoms of the esters is a valuable test to check the consistency of the data derived from gas correlation chromatography. Vaporization enthalpies ∆ l g H°m appear to be a good linear function of the number of carbon atoms of the alkanes (Chickos et al, 1997) or aliphatic esters (Koutek et al, 1998). A similar trend was observed for the branched esters studied in this work, as is shown in Figure 2.…”

Vapour pressures and enthalpies of vaporization of a series of δ-lactones

“…The correlation of the enthalpies of vaporization with the number of C-atoms in the series of homologues is another valuable test to check the internal consistency of the experimental results. Vaporization enthalpies D g l H m appear to be a linear function of the number of carbon atoms of the alkanes [11], aliphatic alcohols [12] or aliphatic nitriles [13]. The plot of D g l H m ð298:15 KÞ against the number of C-atoms in the side alkyl chain (N C ) of d-lactones is presented in figure 3.…”

Vapour pressures and enthalpies of vaporization of a series of the linear n-alkyl acetates

“…The correlation of the enthalpies of vaporization with the number of C-atoms in the series of homologues is another valuable test to check the internal consistency of the experimental results. Vapourization enthalpies D g l H m appear to be a linear function of the number of carbon atoms of the alkanes [25] or aliphatic alcohols [26]. The plot of D g l H m ð298:15 KÞ against the number of C-atoms in acetates is presented in figure 2.…”