title: Heterogeneous oxidation of pyrimidine and alkyl thioethers in ionic liquids over mesoporous Ti or Ti/Ge catalysts.
abstract: Heterogeneous catalytic oxidation of a series of thioethers (2-thiomethylpyrimidine, 2-thiomethyl-4,6-dimethyl-pyrimidine, 2-thiobenzylpyrimidine, 2-thiobenzyl-4,6-dimethylpyrimidine, thioanisole, and n-heptyl methyl sulfide) was performed in ionic liquids by using MCM-41 and UVM-type mesoporous catalysts containing Ti, or Ti and Ge. A range of triflate, tetrafluoroborate, trifluoroacetate, lactate and bis(trifluoromethanesulfonyl)imide-based ionic liquids were used. The oxidations were carried out by using anhydrous hydrogen peroxide or the urea-hydrogen peroxide adduct and showed that ionic liquids are very effective solvents, achieving greater reactivity and selectivity than reactions performed in dioxane. The effects of halide and acid impurities on the reactions were also investigated. Recycling experiments on catalysts were carried out in order to evaluate Ti leaching and its effect on activity and selectivity.
authors.affiliation: Institute of Organic Chemistry, Romanian Academy, Bucharest 060023, Romania.
authors.forename: Valentin
authors.initials: V
authors.lastname: Cimpeanu
authors.forename: Vasile I
authors.initials: VI
authors.lastname: Parvulescu
authors.forename: Pedro
authors.initials: P
authors.lastname: Amorós
authors.forename: Daniel
authors.initials: D
authors.lastname: Beltrán
authors.forename: Jillian M
authors.initials: JM
authors.lastname: Thompson
authors.forename: Christopher
authors.initials: C
authors.lastname: Hardacre
mesh_terms: D002384:Catalysis; D005857:Germanium / Q000737:chemistry*; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010316:Particle Size; D016062:Porosity; D011743:Pyrimidines / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013440:Sulfides / Q000138:chemical synthesis / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*
chemical_list: D011743:Pyrimidines; D012997:Solvents; D013440:Sulfides; D005857:Germanium; D012822:Silicon Dioxide; D014025:Titanium; C030986:pyrimidine