ausblenden:
Schlagwörter:
carbon dioxide;
solvent effects;
solvolysis;
supercritical fluids;
sustainable chemistry
Zusammenfassung:
A series of SN1-type reactions has been studied under various conditions to clarify the role of supercritical carbon dioxide (scCO2) as reaction medium for this kind of transformations. The application of scCO2 did not result in higher yields in any of the experiments in comparison to those under neat conditions or in the presence of other inert compressed gases. High-pressure UV/Vis spectroscopic measurements were carried out to quantify the degree of carbocation formation of a highly SN1-active alkyl halide as a function of the applied solvent. No measureable concentration of carbocations could be detected in scCO2, just like in other low polarity solvents. Taken together, these results do not support the previously claimed activating effect via enhanced SN1 ionization due to the quadrupolar moment of the supercritical fluid.
