LAUSR

The chain-length dependence of the thermodynamic properties associated with the solid-to-liquid, liquid-to-gas, and solid-to-gas phase equilibria is analyzed and discussed for homologous families of linear α,ω-disubstituted alkanes, R-(CH2)n-R series. A remarkable alternation on the melting properties exhibited by even and odd-numbered alkanes is clearly emphasized in their α,ω-disubstituted derivatives since the even members display increased properties due to their higher crystal packing density. The odd–even effect is also perceived in the values of ΔsubHo and ΔsubSo. Strong hydrogen bonding contributes to high boiling points and ΔvapHo values evidenced by alkane-α,ω-diols. Moreover, the anomalously low values of ΔsubHo and ΔvapHo reported for larger dicarboxylic acids suggest the formation, in the vapor phase, of hydrogen-bonded cyclic structures. Furthermore, the analysis of the ΔfusHo/ΔsubHo and ΔfusSo/ΔsubSo ratios is used to highlight the contribution of functional groups to the cohesive interacti...