Very short chain alcohols like methanol ethanol and propanol are
The aromatic ring of thymol 14 decreases the PIT of the SOW system 7 times more than menthol 10, which has the same structure but with a saturated ring. Indeed, more generally, the effect of thymol 14, phenol 15, benzyl alcohol 16, phenethyl alcohol 17 and cuminic alcohol 18 on the PIT decrease is relatively important. Using the partition coefficient between water and 1-octanol (log P) as an indicator tool to compare these family of compounds, we can notice that benzyl alcohol 16, which exhibits the lowest PIT decrease in this series (−14.6 °C/wt.%), has also the lowest affinity for the oil phase (log P = 1.06). Thymol 14, Phenol 15 and cuminic alcohol 18, with higher affinity for the oily phase according their log P, have a stronger impact on PIT. Branched structure of thymol 14 could explain its more pronounced decrease of PIT as it BAY 41-2272 has been established for pelargol 1 compared to decanol. Generally speaking, the difference in polarity between aromatic alcohols and octane could explain this peculiar behavior. Some phenols derivatives could thus modify the EACN of the oil, by lowering its value, not penetrate the interfacial layer but order it, in the vicinity of the interface. Such a behavior has been ascribed to the so-called lipophilic-linker effect . On the other hand, the presence of an oxygen atom in the 2-phenoxyethanol 20 reduces by a factor 2 the decrease of the slope in comparison to phenethyl alcohol 17. The depression of the PIT induced by phenethyl alcohol 17 is more pronounced than that observed by Tchakalova et al. on equilibrated C10E5/n-decane/water system using 1% . Here again, as stressed by these authors, phenethyl alcohol interacts with the polar head groups of the surfactant layer, promoting its dehydration. Indeed, phenol is able to complex with aqueous solutions of polyethyleneglycol (PEG) , so interactions between the ethylene oxide units of the CiEj and phenolic compounds could explain the observed results. Our data show that the effect on dPIT/d(%A) of phenethyl alcohol (−15.9 °C/wt.%) is as large as that of heptanol (−16 °C/wt.%). On the other hand, we demonstrate that inserting a second carbon atom between the hydroxyl group and the aromatic ring has a dramatic effect on f(A) since the value for phenol (−49.1 °C/wt.%) is much larger than that for benzyl alcohol (−14.6 °C/wt.%). A third carbon has practically no effect and values of phenethyl alcohol 17 and benzyl alcohol 16 are quite similar.