Metal‐Free SF 6 Activation: A New SF 5 ‐Based Reagent Enables Deoxyfluorination and Pentafluorosulfanylation Reactions

Tetrafluoro(aryl)sulfanylated Bicyclopentane Crystals That Self-Destruct upon Cooling

Whereas single crystals of organic compounds that respond to heat or light have been reported and studied in detail, studies on crystalline organic compounds that elicit an extreme mechanical response upon cooling to very low temperatures are relatively rare in the chemical literature. A tetrafluoro(aryl)sulfanylated bicyclopentane synthesized in our laboratory was discovered to exhibit such behavior; i.e., the crystals jumped and forcefully disintegrated upon cooling below ∼193 K. Accordingly, the origin of this low-temperature thermosalient effect was investigated through NMR, SC-XRD, PXRD, microscopy, DSC, Raman, and Brillouin experiments. To our surprise, NMR, SC-XRD, PXRD, and DSC experiments suggest the phenomenon can neither be attributed solely to a chemical transformation nor a phase transition of the entire material. Rather, XRD, Raman, and Brillouin experiments provide evidence that built-up strain released from the crystal upon self-destruction may be associated with crystal microstructure or a phase transition that occurs in another material (i.e., an impurity) in the crystal. This study demonstrates that molecular structural changes in organic material microstructure or impurity phases (which may not necessarily be visible by X-ray diffraction) can have a significant impact on the behavior of the bulk crystalline material. Thus, the role of microstructure may be considered more heavily in future mechanistic studies on mechanically responsive crystals.

Recent progresses, challenges and proposals on SF6 emission reduction approaches

The increasing utilization and emission of sulfur hexafluoride (SF6) pose severe threats to the climate and the environment, owing to its potent greenhouse gas properties. In this paper, we comprehensively review the recent progresses of SF6 emission reduction approaches. Currently, the use and emission of SF6 are still on the rise, and mainly concentrated in the power industry. Restrictive use and emission reduction policies are fundamental step in guiding SF6 emission, but they are poor promoted in developing economies. More specific policies and regulations are needed in conjunction with timely and accurate assessments of SF6 atmospheric properties and emissions. SF6 recovery is the direct emission reduction approach, but defects in recovery methods and equipment limit its applications. The development of SF6 purification technologies and optimizations in recovery devices and processes are needed for its treatment of different regions and SF6 volumes. SF6 degradation is the final step of waste gas treatment, and its development needs to better balance the degradation rate and product selectivity, as well as to improve their multi-scenario responsiveness. SF6 substitution is a necessity for future large-scale SF6 emission reduction. Improvements in SF6-free applications and its long-term stability are critical via new gas design, gas mixture optimization and equipment updates. Finally, all the emission reduction approaches are closely related, and promoting their synergistic development and complementarity is the ultimate way to realize SF6 lifecycle management.

Oxidative Fluorination of Heteroatoms Enabled by Trichloroisocyanuric Acid and Potassium Fluoride

In synthetic method development, the most rewarding path is seldom a straight line. While our initial entry into pentafluorosulfanyl (SF5 ) chemistry did not go according to plan (due to inaccessibility of reagents such as SF5 Cl at the time), a "detour" led us to establish mild and inexpensive oxidative fluorination conditions that made aryl-SF5 compound synthesis more accessible. The method involved the use of potassium fluoride and trichloroisocyanuric acid (TCICA)-a common swimming pool disinfectant-as opposed to previously employed reagents such as F2 , XeF2 , HF, and Cl2 . Thereafter, curiosity led us to explore applications of TCICA/KF as a more general approach to the synthesis of fluorinated Group 15, 16, and 17 heteroatoms in organic scaffolds; this, in turn, prompted SC-XRD, VT-NMR, computational, and physical organic studies. Ultimately, it was discovered that TCICA/KF can be used to synthesize SF5 Cl, enabling SF5 chemistry in an unexpected way.