The Raman and resonance Raman spectra of some substituted dialkyl dithioesters and their rotational isomers
The Raman spectra of ethyl dithioacetate, methyl dithiopropionate, and ethyl thionoacetate are presented for the liquid phase at 25 °C and for the solid phase at approximately −130 °C. Certain spectral features disappear upon going from the liquid to the solid phase allowing the assignment of these bands to rotational isomers which are present in the liquid state only. The consequences of placing a tert-butyl group proximal to the CSS moiety in dithioesters are explored by considering the absorption, Raman, and resonance Raman spectra of ethyl dithiotrimethylacetate and tert-butyl dithioacetate. The resonance Raman spectra of the ionized and unionized forms of dithioacetic acid are also presented. The vibrational spectra of ethyl thiolacetate, and ethyl and methyl thionoacetate are compared to the spectra of the corresponding dithioesters.
Resonance Raman spectra of the pyridoxal coenzyme in aspartate aminotransferase. Evidence for pyridine protonation and a novel photochemical H/D exchange at the imine carbon atom.