关键词: 钛硅分子筛, 氧化溴化, 无有机溶剂, H2O2/HBr, 多溴离子

Abstract: Hollow titanium silicalite (HTS) zeolite catalyzed toluene oxidative bromination in aqueous medium without the need for organic solvent under mild conditions by employing H2O2 and HBr was investigated. A high toluene conversion (90.7%) and high selectivity of mono-bromotoluene (99.0%) was achieved under optimal reaction conditions. UV-Raman spectroscopy was applied for the mechanism study and the result reveals that HTS is efficient for catalyzing the HBr and H2O2 oxidation reaction and producing abundant active bromine species, which further facilitate the toluene electrophilic bromination reaction. A two-step toluene bromination reaction mechanism involving HTS catalyzed active bromine species “generation-storage-utilization” process is proposed based on the Raman results.

Key words: titanium silicalite, oxidative bromination, organic solvent free, H2O2/HBr, polybromine ion