Sodium Salts Dissolution in an Aprotic Solvent by Coordination of Poly(ethylene glycol) for Effective Anodic Reactions of Organic Compounds

Abstract

The electrochemical oxidation of various organic compounds using inorganic salts like sodium halides and sodium tetrafluoroborate has been accomplished under mild conditions. The long-standing problem of solubility of inorganic salts in aprotic organic solvents in electroorganic synthesis has been overcome by the addition of poly(ethylene glycol) to the electrolytic solutions through cyclic voltammetry analysis and macro-scale electrolysis. By using this method, anodic halogenation, anodic deprotection, and anodic coupling reaction of organic compounds were successfully carried out to provide desired products efficiently.

Synthetic Organic Electrochemical Methods Since 2000: On the Verge of a Renaissance

“…As most (pseudo)­halides have relatively low oxidation potentials, their selective oxidation in the presence of an electron-neutral arene is possible. Electrochemical arene chlorination, − bromination, , iodination ( vide infra ), and thiocyanation − have been reported within the time frame of this review. Applications of electrochemical arene bromination using aqueous NaBr have been surveyed on complex late-stage intermediates and drug molecules …”

Electrochemical strategies for C–H functionalization and C–N bond formation

“…However, this can to some extent be circumvented using poly-(ethylene glycol) as an additive, which enhances the solubility of the inorganic salts in aprotic organic solvents. 372 By employing a biphasic system, bromination of various arenes 373 (Scheme 31) as well as benzylic mono-374 (Scheme 32) and dibromination 375 (Scheme 33) of alkyl aromatics has been achieved. In addition to these examples, electrochemical chlorination of 1,3-dicarbonyl compounds using Cu catalysis, 376 azulene derivatives, 377,378 olefins, 379-384 phenols 385 and pyrazolecarboxylic acids, 386 as well as bromination of heterocycles 387 and olefins [388][389][390][391] have been reported.…”

Electrochemical C–H Mono-/Multi-Bromination Regulation of N-Sulfonylanilines on a Cost-Effective Carbon Fiber Electrode and Its Prospective Electroactive Molecule Screening

“…17−19 The past decade has witnessed that the electrochemical organic synthesis has become one of the fascinating fields owing to its redox ability without using chemical oxidants. 20−30 Recently, we noted that the direct electrochemical C−H bromination of anilines could be accomplished under oxidant-free conditions from simple and available bromine sources, such as the bromine anions (NaBr, 31 NH 4 Br, 32 and n-Bu 4 NBr 33 ) and brominated alkanes (CH 2 Br 2 , 34 3-bromopropyne, 35 and 2-bromoethan-1-ol 36 ) (Figure 1b). Despite these significant advances, there are some limitations: (1) the relatively expensive electrodes were required, such as Pt or RVC, and (2) the substrate scope was limited to the unique 8-aminoquinolines, 32,34 N,N-dialkylanilines, 31,33,35 N-acylated anilines, 36 and free anilines.…”