Interconversion and Selective Reactivity of Sulfur Dioxide Reduction Intermediates Inserted on Graphene Oxide

Graphene oxide, MPGO, was obtained by oxidation of graphite microparticles by a H2SO4/KMnO4/H2O2 mixture followed by thermal exfoliation. Non‐thermal plasma treatment of MPGO under SO2 atmosphere resulted in the insertion of the oxidized intermediates only. Refluxing this material in CS2 (46 °C) showed sulfur elimination and interconversion of the oxidized into non‐oxidized intermediates with an energetic barrier of ΔG‡ = 25.81 kcal mol−1 without decarboxylation. The episulfide content in modified MPGO increases with respect to the oxidized intermediates when increasing temperature. Modification of MPGO with SO2 at 630 °C presented exclusively the non‐oxidized intermediate. These results support the hypothesis that there are two major reactions with different energetic demand in the SO2 reduction on carbons: desulfurization and decarboxylation. The selectivity of thiolysis and aminolysis towards the intermediates inserted in the MPGO matrix allowed the amino‐thiolysis of a sample containing both intermediates with the insertion of the amino group on the episulfide site followed by an intramolecular thiolysis with double functionalization of the matrix. Copyright © 2016 John Wiley & Sons, Ltd.