Theoretical investigations on the conversions of cyclic polysulfides to acyclic polysulfide diradicals and subsequent reactions of biological interest

Molecular Simulation to Explore the Dissolution Behavior of Sulfur in Carbon Disulfide

Soluble sulfur (S₈) and insoluble sulfur (IS) have different application fields, and molecular dynamics simulation can reveal their differences in solubility in solvents. It is found that in the simulated carbon disulfide (CS₂) solvent, soluble sulfur in the form of clusters mainly promotes the dissolution of clusters through van der Waals interaction between solvent molecules (CS₂) and S₈, and the solubility gradually increases with the increase in temperature. However, the strong interaction between polymer chains of insoluble sulfur in the form of polymer hinders the diffusion of IS into CS₂ solvent, which is not conducive to high-temperature dissolution. The simulated solubility parameter shows that the solubility parameter of soluble sulfur is closer to that of the solvent, which is consistent with the above explanation that soluble sulfur is easy to dissolve.

Power Law Distribution Concerning Absolute Free Energies of Linear Sulfur Chains, Polythiazyls, Polyisoprenes, Linear trans-Polyenes, and Polyynes

After quantum calculations of absolute free energies of polyatomic sulfur derivatives or hydrocarbon oligomer compounds, we have studied the variations of G _n as a function of the number of repeating units n (sulfur atoms or hydrocarbon units, n = 2 to about 60), and observed that these values can be correlated by (a) a nearly perfect linear relationship, G _n = An + B (A and B, constants), with a high accuracy which enables an extrapolation for higher values of n, and (b) a power law:, δ G = G _n/ n - G_{( n-1)} /( n - 1) = C/ n ^d ( C and d, constants). From comparison of variations of the C-C bond lengths, we show that the conjugation of trans-polyenes (up to C₆₀H₆₂) is more important than for polyynes (up to C₆₀H₂).