While H2O2 is a powerful oxidant, decomposing into environmentally benign H2O and O2, a catalyst is often required for reactions with H2O2 to proceed at synthetically useful rates. Organotellurium and organoselenium compounds catalyze the oxidation of halide salts to hypohalous acids using H2O2. When sequestered into xerogel monoliths, the xerogel-chalcogenide combinations have demonstrated increased catalytic activity relative to the organochalcogen compound alone in solution for the oxidation of halide salts to hypohalous acids with H2O2. Diorganotellurides, diorganoselenides, and diorganodiselenides bearing triethoxysilane functionalities were sequestered into xerogel monoliths and their catalytic activity and longevity were investigated. The longevity of the catalyst-xerogel combinations was examined by isolating and recycling the catalyst-xerogel combination. It was found tellurium-containing catalyst 3 and selenium-containing catalyst 8 maintained their catalytic activity through three recycling trials and adding electron-donating substituents to catalyst 3 also increased the catalytic rate. The presence of organotellurium and organoselenium groups in the +4 oxidation state was determined by X-ray photoelectron spectroscopy.
A computational experiment investigating common organic chemistry mechanisms has been developed and implemented in a junior/senior-level physical chemistry laboratory course at two institutions. Students investigated various reactions that proceed via S N 1, S N 2, E1, and E2 mechanisms using hybrid Density Functional Theory (DFT). Our pre/post-assessments indicate that students at both institutions were able to better visualize and interpret the 3D representation of transition states, stepwise reaction mechanisms, and reaction coordinate diagrams of the aforementioned reactions.
Synthetic pathways leading to tellurium‐ and selenium‐containing heterocycles are summarized for the period 1995 to the present. In addition, the utility of various tellurium‐ and selenium‐containing heterocycles are summarized. Primarily, the synthesis of tellurium‐ and selenium‐containing heterocycles of five‐ and six‐membered rings are described with various degrees of unsaturation, as well as their benzo‐fused analogues. In particular, the syntheses of selenophenes , tellurophenes and their mono‐ and dibenzo‐fused analogues are described. Similarly, syntheses of tellurazoles, selenazoles, telluradiazoles, selenadiazoles and their benzo‐fused analogues are described. Among the six‐membered rings, synthetic routes to telluropyrans and selenopyrans and their benzo analogues are described. Further degrees of unsaturation provide the telluropyrylium and selenopyrylium compounds and their benzo‐ and dibenzo‐fused analogues. Synthetic routes to chalcogenopyrylium compounds, chalcogenorosamine compounds and chalcogenorhodamine compounds are described and some of the uses of these materials are also provided. A review of synthetic routes to the core‐modified porphyrins—21‐chalcogenoporphyrins and 21,23‐dichalcogenoporphyrins—is also provided. Porphyrin‐like molecules with an expanded structure of five or six‐membered rings in the porphyrin core are also reviewed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.