Alfrets Daniel Tikoalu

Sulfur-sulfur bonds are ubiquitous across broad classes of natural products, peptides and proteins, drug molecules, and synthetic polymers and materials. The ability to make and break these bonds in a controlled manner is critical for their many scientific and technological applications. In this study, we report the discovery of a new and unusual S-S metathesis reaction of linear organic trisulfides. When exposed to certain polar aprotic solvents, trisulfides were found to undergo spontaneous metathesis, with equilibrium established in seconds in some cases. No exogenous reagents, heat, light, or other stimuli were required to provoke this reaction. Understanding the scope and mechanism of this reaction enabled diverse applications of this chemistry in dynamic combinatorial library synthesis, covalent modification of complex natural products, and S-S metathesis polymerization and depolymerization as a platform for chemically recyclable plastics.

The synthesis of a sulfated silica catalyst and its modification with Ni and/or Mo metal, along with its application for the hydrocracking of fresh and waste frying oil into biogasoline, were conducted. Synthesis of the catalysts was initiated with the sulfation of silica (SiO₂) material by H₂SO₄ using the sol-gel method. Ni and/or Mo metal were impregnated into the SO₄/SiO₂ matrix with concentration variations of 1, 2, and 3 wt%. The sulfation process and promotion by Molybdenum (Mo) metal in the modified catalyst successfully increased the catalytic activity and selectivity. Among the catalysts investigated, Ni-SS2 exhibited the best performance for the hydrocracking reaction with waste frying oil. This catalyst was able to achieve a conversion of the liquid product of 71.47% and a selectivity of 58.73% for the gasoline fraction (C₅-C₁₂). NiMo-SS3 showed the highest percentage of activity and selectivity in the hydrocracking of fresh frying oil at 51.50 and 43.22 wt%, respectively.