Facile and Efficient Production of Biomass-Derived Isosorbide Dioxides via Epoxidation Using In situ-generated DMDO under Ultrasonication.

Herein, we present a facile synthetic process for producing biomass-derived isosorbide (ISB) dioxides using dimethyl dioxirane (DMDO) as an efficient oxidizing agent, which was generated in situ from acetone and KHSO5 . To achieve high conversion and product yield, the KHSO5 concentration, KHSO5 flow rate, and reaction temperature were optimized. Under the optimal conditions, rapid and efficient epoxidation using the in situ-generated DMDO was observed under ultrasonication, yielding the desired product within 35 min at 0 °C. This study offers a convenient and efficient method for generating biomass-derived ISB building blocks, which have significant potential for the fabrication of bioplastics.

Redox- and light-switchable N-heterocyclic carbenes: a "soup-to-nuts" course on contemporary structure-activity relationships.

Switchable catalysts respond to various types of stimuli in a manner that results in distinct structural or electronic changes. When each state exhibits a different activity, selectivity, or solubility, the corresponding catalyst may be used to control chemical reactions in a temporally- or spatially-resolved fashion. N-Heterocyclic carbenes (NHCs) are versatile scaffolds for building switchable catalysts and many examples that respond to changes in electrochemical potential or light have been introduced. Such types of switchable NHCs will be described in this Feature Article. The accompanying discussions include design considerations, characterization methodology, quantification of the underlying switching phenomena, and utility in catalytic applications. Challenges for the field as well as perspectives on potential opportunities for future development are also provided.