Harnessing applied potential to oxidation in water

Abstract

Oxidation is one of the most important types of transformation in chemistry, and practical mild oxidation without added reagents or solvents has been a long-standing challenge. We have developed a highly practical solvent-free (biphasic) electrochemically driven oxidation system for the selective conversion of sulfides to the corresponding sulfoxides, and alkenes to the corresponding epoxides, in a very simple reactor system. Excellent yields are obtained for a variety of substrates, and neither over-oxidation to sulfone nor formation of diol by-products from alkene oxidation is observed. This simple system has excellent potential for scale-up, requires no storing or transport of stoichiometric oxidants, no heavy metals, and can be carried out with just water, sodium carbonate, hydrochloric acid, and an applied potential in a single cell. The electrolyte solution can be recycled and reused with no loss in activity

On‐Demand Electrochemical Epoxidation in Nano‐Electrospray Ionization Mass Spectrometry to Locate Carbon–Carbon Double Bonds

“…The lipid double bonds can be electro‐epoxidized in the presence of hydrochloric acid and an acetonitrile/water solvent system in a nanoESI emitter with a large orifice (Figure ; the effect of orifice size will be discussed below) which serves as an electrochemical cell. We reasoned that the addition of chloride in an acidic environment might introduce a superior oxidative pathway by in situ formation of hypochlorite and conversion of double bonds into the corresponding epoxides (see Section S3 in the Supporting Information for electro‐epoxidation reagent study and optimization of HCl concentration). The voltage applied to the nanoESI working electrode plays two roles: 1) it initiates electrospray; and 2) it initiates/terminates electro‐epoxidation of lipid double bonds.…”

“…In this work, we present anovel electrochemical strategy for characterizing double-bond positions in unsaturated lipids.T he lipid double bonds can be electro-epoxidized in the presence of hydrochloric acid and an acetonitrile/water solvent system in an anoESI emitter with al arge orifice ( Figure 1; the effect of orifice size will be discussed below) which serves as an electrochemical cell. We reasoned that the addition of chloride in an acidic environment might introduce as uperior oxidative pathway by in situ formation of hypochlorite and conversion of double bonds into the corresponding epoxides [23] (see Section S3 in the Supporting Information for electro-epoxidation reagent study and optimization of HCl concentration). Thev oltage applied to the nanoESI working electrode plays two roles:1 )iti nitiates electrospray;a nd 2) it initiates/terminates electro-epoxidation of lipid double bonds.I nterestingly,t he epoxidation of lipid double bonds can be well-controlled by tuning the applied voltage while maintaining the electrospray plume.As aresult, the lipid epoxidation can be switched off by applying av oltage of 2.5 kV,a nd counter-intuitively switched on by reducing the voltage to 1.8 kV ( Figure 1).…”

Selective Formation of Trimethylene Carbonate (TMC): Atmospheric Pressure Carbon Dioxide Utilization

“…We have recently shown that electrosynthesis can be a powerful tool for a range of important reactions[ 16 ] and can be employed in the catalyst-free synthesis of five-membered ring cyclic carbonates under atmospheric pressure carbon dioxide and mild temperatures. [ 17 ] The importance of six-membered ring cyclic carbonates and their inherent thermodynamic instability prompted us to investigate this important carbon dioxide insertion reaction.…”

Asymmetric Oxidation of Enol Derivatives to α-Alkoxy Carbonyls Using Iminium Salt Catalysts: A Synthetic and Computational Study

“…32 The asymmetric epoxidation processes utilizing iminium salt catalysts 1 and 2 have been used in syntheses of levcromakalim, 33 (−)-lomatin and (+)-trans-khellactone, 34 scuteflorin, 35 and mollugin,. 36 Alternative oxidants, such as hydrogen peroxide or sodium hypochlorite, 37 and electrochemically generated oxidants 38 may also be used in these iminium salt-catalyzed epoxidation reactions.…”

“…Alternative oxidants such as hydrogen peroxide or sodium hypochlorite, 37 and electrochemicallygenerated oxidants, 38 may also be used in these iminium salt-catalysed epoxidation reactions.…”