Investigations of methyl lactate in the presence of reverse micelles by vibrational spectroscopy and circular dichroism

The FT-IR and vibrational circular dichroism (VCD) spectra of (S)- and -(R)-methyl lactate have been recorded for neat samples and at various concentrations in CCl4 and DMSO solutions. These spectra are used to analyse the FT-IR and VCD spectra of methyl lactates in presence of sodium bis(2-ethylhexyl)sulfosuccinate (AOT) in CCl4, where the surfactant molecules are known to form reverse micelles. Some tendency of methyl lactate to interact with AOT micellar aggregates is observed, but not as well defined as previously observed for dimethyl tartrate in analogous circumstances. Besides, near infrared (NIR) absorption and VCD data have been obtained for most of the above systems, allowing to monitor the first overtone of the OH-stretching vibration of methyl lactates, especially in the spectroscopic region where the OH bond is not involved in hydrogen bond with other molecules. The NIR absorption and NIR VCD data for dilute solutions are reproduced and interpreted by anharmonic DFT calculations. Further understanding of the behavior of aggregated methyl lactate systems has been gained on this basis.