The significance of fluorine atoms: The cover artwork symbolizes the importance of fluorine atoms on drug molecules, just as the red flower blossoms bring beauty and brilliance to an old tree. Although fluorine atoms greatly enhance the biological properties of pharmaceuticals and agrochemicals, fluorination reactions present persistent challenges due to their hazardous nature and limited selectivity and scalability. This review explores recently developed continuous flow techniques that addressed the challenges of fluorination reactions. The design and application of continuous flow systems specifically for fluorination reactions are discussed. More information can be found in the Review by Tsz Chun Lee, Yi Tong, and Wai Chung Fu.

Photoinduced organic synthesis, recognized for its eco-friendliness, represents a green energy alternative. The catalyst-free photoinduced approach has gained prominence in contemporary times, especially in synthesis. This review endeavors to collect relevant literature pertaining to photo-induced borylation reactions without photocatalysts and transition metals.

Abstract

The increasing global warming concerns have propelled a surge in the demand for sustainable energy sources within the domain of synthetic organic chemistry. A particularly prominent area of research has been the development of mild synthetic strategies for generating heterocyclic compounds. Heterocyclic compounds containing boron have notably risen to prominence as pivotal reagents in a myriad of organic transformations, showcasing their wide-ranging applicability. This comprehensive review is aimed at collecting the literature pertaining to borylation reactions induced by light, specifically focusing on photocatalyst-free and transition metal-free methodologies. The central emphasis is on delving into selective mechanistic investigations. The amalgamation and analysis of these research insights elucidate the substantial potential inherent in eco-friendly approaches for synthesizing heterocyclic compounds, thus propelling the landscape of sustainable organic chemistry.

The reaction between [2-(MeOCH₂)C₆H₄]MgBr and SnCl₄ yielded the highly crowded stannanes [2-(MeOCH₂)C₆H₄)]₃SnBr (1), [2-(MeOCH₂)C₆H₄)]₂SnX₂ (2, X₂=Br₂ (a) and BrCl (b)), together with trace amounts of the distannane [{2-(MeOCH₂)C₆H₄}₃Sn]₂ (3), and a distannoxane [2-{(MeOCH₂)C₆H₄)}₂SnBr]₂O (4). The new compounds 1–4 were characterized by single crystal X-ray crystallography showing that 1, 2a and 4 exhibit significant Sn…O secondary bonding interactions that persist in solution for 1.

Abstract

The reaction between the Grignard reagent formed from Mg and 2-bromobenzylmethyl ether and SnCl₄ produced four products: [2-(MeOCH₂)C₆H₄]₃SnBr (1), [2-(MeOCH₂)C₆H₄]₂SnX₂ (2, X₂=Br₂ (a) and BrCl (b)), [{2-(MeOCH₂)C₆H₄}₃Sn]₂ (3), and [{2-(MeOCH₂)C₆H₄}₂SnBr]₂O (4). In the case of 1, two of the three dangling arm O atoms coordinate to the central tin atom with O−Sn internuclear distances of 2.53 (O1) and 2.91 (O2) Å, the shorter interaction being trans to the Br atom, the other trans to a phenyl carbon atom. In the case of 2a the resulting hexacoordinate structure exhibits two very short O−Sn interactions of 2.42 and 2.50 Å, well below the sum of the VdW radii of O and Sn, 3.69 Å. The sterically crowded ditin compound 3 was obtained in trace amounts and the structure demonstrates no dangling O−Sn interactions. General changes in structure compared to other distannane systems are reflective of the great steric crowding. Distannoxane 4, has a Sn−O−Sn bond angle of 148.1(2)° which is larger compared to other distannoxane structures. The intermolecular interactions between Sn−O 2.470(3) and 2.521(3)Å and 2.665(3) and 2.629(3)Å for Sn1 and Sn2 respectively are responsible for a distorted octahedral geometry around the two tin atoms. The various ¹¹⁹Sn_, ¹³C and ¹H NMR spectra are in accord with their structural analysis for 1 and 2, and in the solid state ¹³C NMR spectrum of 1 the dangling methylene group is observable whereas is solution there is a rapid dynamic equilibrium resulting in a single resonance for all methylene groups.

A CISC@S/CNTs graded composite electrode with C−O, C−N, and C−S bonds stabilization and CNTs coating protection was prepared using the organic waste chestnut inner shell. It can effectively suppress the shuttling effect of sulfur and polysulfide ions, enhance the charge and electrolyte transfer kinetics, and provide an effective way to commercialize lithium-sulfur batteries.

Abstract

The shuttle effect of lithium-sulfur (Li−S) batteries and the poor conductivity of sulfur (S) and lithium polysulfide severely limit their practical applications. Currently, compounding carbon materials with S is one of the effective ways to solve this problem. Therefore, green, low-cost chestnut inner shell biochar (CISC) with graded porous structure was used as the S carrier in this experiment, and carbon nanotubes (CNTs) coating was employed as the S protective layer to improve the electrical conductivity and inhibit the shuttle effect. The results showed that the CISC prepared in this experiment had a relatively high specific surface area (1135.11 m² g⁻¹), and the S loading rate was as high as 65.72 %. The graded porous structure and high specific surface area of CISC can increase the loading rate of S and thus increase the battery capacity. Meanwhile, the naturally contained O and N elements can improve the chemisorption of S. The initial discharge capacity of the CISC@S/CNTs battery at 0.1 C is 967.3 mAh g⁻¹, and the capacity retention rate is 74.3 % after 500 cycles. The unique composite structure improves the battery‘s electrical conductivity, reduces the dissolution of polysulfides, and enhances the battery cycle stability.