Introduction of Halogen Atoms into Organic Compounds Under Solvent- Free Reaction Conditions

Abstract

Avoiding volatile and toxic organic solvents during each particular phase of synthetic protocols should become important goal of chemical synthesis designers in academia and particularly in the industrial research community. Solvent-free reaction conditions (SFRC) are becoming a widely used experimental technique for the selective and efficient introduction of halogen atoms into organic compounds. The different approaches to the preparation of halosubstituted organic molecules using equimolar amount of the substrate and reagent under SFRC are reviewed and evaluated. Fluorination of various types of organic compounds under SFRC using fluorine gas, N-F reagents, and hydrogen or metal fluorides is compiled. Chloro-, bromo-or iodofunctionalisation under SFRC using molecular halogens, N-halosuccinimides, hydrogen or others halides is reviewed. Oxidative halogenations of comprehensive types of organic compounds under SFRC are evaluated.

Solvent‐Free Fluorination of Electron‐Rich Aromatic Compounds with F‐TEDA‐BF4: Toward “Dry” Processes

“…However, the most significant decrease of the environmental footprint of most industrial processes would be the complete elimination of the solvent. The avoidance of the use of solvents is a crucial point for the sustainability of organic synthesis …”

Selective Bromination of Dehydroacetic Acid withN-Bromosuccinimide

“…In view of the encouraging recent reports [21] on the advantages of using solvent-free reaction conditions (SFRC) in bromination, we attempted the bromination of DHA under SFRC using conventional heating and microwave irradiation (Scheme 2).…”

Facile and eco-friendly synthesis of bis(tetrahydrobenzofuran-2-yl)alkane derivatives catalyzed by H2S04.SiO2 under solvent-free conditions

“…21,22 As a silica-supported reagent, H 2 SO 4 •SiO 2 has attracted much attention for its ease of preparation, low cost, high efficiency and environmental benignness. 23 H 2 SO 4 •SiO 2 has already been used in cylcoadditions, 24 Beckmann rearrangements, 25 glycosylations, 26 condensations 27 and esterifications.…”