Determination of configurational isomers in cyclic polysulfides by Raman spectroscopy

Cyclic polysulfides such as trithiolanes, tetrathianes and their derivatives are found in natural sources like archaea, mushrooms and vegetables. They gained interest for research and industrial applications because of their pronounced flavors and biological activity. This study compares Raman spectra of reference compounds and cyclic polysulfides which were synthesized in-house and separated by preparative gas chromatography. The data show that the positions of the Raman bands due to SS stretching vibrations in the wavenumber region from 550 to 450 cm−1 can determine the relative stereochemistry of 2,5-dialkyl trithiolanes and 4,6-dialkyl tetrathianes. Configurational cis isomers were distinguished from their corresponding trans isomers. In addition, 4,6-dialkyl-1,2,4,5-tetrathiane with disulfide bonds were distinguished from the constitutive isomer 3,6-dialkyl-1,2,3,5-tetrathiane with trisulfide bonds.