Raman study of pressure and temperature effects on the conformational equilibrium of diethyl disulfide in solutions

The effects of pressure and temperature on the conformational equilibrium of diethyl disulfide in various organic solvents were studied by Raman spectroscopy. From the pressure and temperature dependences of the intensities of S-S and C-S stretching bands, the volume and enthalpy differences between the trans-gauche-gauche and gauche-gauche-gauche conformers in organic solvents were determined. The volume differences of - 1.1 - 1.3 cm(3) /mol are close to the values reported previously for liquid alkanes, which are explained by the packing effect of liquid. The solvent effect on the enthalpy difference also shows that the repulsive intermolecular interaction is a crucial factor in the conformational equilibrium of diethyl disulfide in the solutions. Based on the present results, the conformational change of the disulfide bridge in protein is discussed from the viewpoint of solution chemistry.