Electron-transfer catalyzed cycloaddition reactions of unactivated cyclic olefins in weakly coordinating anion electrolyte

Stewart, Michael; Lam, Kevin; Chong, Daesung; Geiger, William E.

doi:10.1016/j.jelechem.2015.02.001

Cited by 8 publications

(5 citation statements)

References 46 publications

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“…This large difference in potentials likely indicates the electron transfer to PIDA from the trans -anethole is endergonic. This result is in agreement with previous work which has highlighted how for SET initiated cycloadditions the oxidant should be sufficiently weak so as to ensure only low concentrations of the radical cation are produced in situ avoiding dimerization and associated formation of the dication . Second, the difference between the voltammetric oxidation and reduction peak potentials is almost 1 V less in HFIP as compared to ACN!…”

Section: Resultssupporting

confidence: 92%

Hydrogen Bonding to Hexafluoroisopropanol Controls the Oxidative Strength of Hypervalent Iodine Reagents

et al. 2016

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Hexafluoroisopropan-2-ol (HFIP) has been found to be an unusually beneficial solvent for undertaking hypervalent iodine-initiated [2+2] cycloaddition of styrenes. For the initiator phenyliodine(III) diacetate (PIDA), voltammetric data demonstrate that the enhanced reactivity in HFIP is due to its greater oxidizing abilities in this fluorinated solvent such that in HFIP the reactivity of PIDA is comparable if not superior to its fluorinated analog phenyliodine(III) bis(trifluoroacetate). These results contrast with the often reported view that the role of the fluoroalcohol is to stabilize a radical cation formed by single electron transfer. Moreover, combined NMR and HRMS results reveal the formation of a strong H-bonded adduct between the solvent and oxidizing reagent which is the physical origin of the observed altered synthetic reactivity.

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Section: Resultssupporting

confidence: 92%

Hydrogen Bonding to Hexafluoroisopropanol Controls the Oxidative Strength of Hypervalent Iodine Reagents

et al. 2016

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“…488 Additionally, electrochemical [2 + 2] cycloaddition of cyclooctene and [2 + 2+2] reaction of cyclopentene have been achieved by Geiger and co-workers using rhenium-based or triaryl amine-based mediators. 489,490 2.12.3. Oxidation of other electron-rich olefins.…”

Section: Chemical Reviewsmentioning

confidence: 99%

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

2017

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“…The graphite rods were placed in the emulsion solution, and a bias of −0.7 V vs Cp 2 Fe 0/+ was applied. − Because the electrode was large (∼3 mm in radius), individual droplet collisions could not be resolved against the background. However, scanning electron microscopy (SEM) was used to visualize the NPs, and energy-dispersive X-ray spectroscopy (EDS) as well as X-ray photoelectron spectroscopy (XPS) were used for elemental analysis to confirm the presence of Pt 0 postdeposition.…”

Section: Introductionmentioning

confidence: 99%

A Universal Platform for the Electrodeposition of Ligand-Free Metal Nanoparticles from a Water-in-Oil Emulsion System

Glasscott

Pendergast

Dick

2018

ACS Appl. Nano Mater.

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Prodigious resources are currently being devoted to control the size and morphology of metal nanoparticles (NPs). Several homogeneous chemical and photochemical techniques exist for the synthesis of metal NPs; however, these synthetic methods generally leave a distribution of NP shapes and sizes and require a stabilizing ligand to prevent aggregation. Electrodeposition of metal NPs onto conductive surfaces is a versatile technique. However, spatial control on the conductive surface is difficult to attain, even on well-behaved materials like highly oriented pyrolytic graphite. Here, we achieve spatial control of Pt NPs on amorphous graphite by confining a precursor metal salt, such as hexachloroplatinic acid (HCPA), to a water droplet suspended in oil, such as dichloroethane. When a graphite electrode was placed in solution and biased at a mild potential (−0.7 V vs the ferrocene/ferrocenium couple, Cp 2 Fe 0/+ ), droplet-mediated electrodeposition produced NPs characterized by the electrochemical collision method and scanning electron microscopy (SEM). The flux of droplets to the graphite surface followed the familiar Cottrell relationship for semiinfinite linear diffusion. Pt NP size selectivity can be directly modulated by tuning the initial concentration of HCPA in the droplet. Interestingly, the size, morphology, roughness, and coverage are shown to be influenced by the surfactant used to stabilize the water droplets, the concentration of HCPA, and the deposition potential. For instance, no surfactant, sodium dodecyl sulfate (SDS), and Span-20 generated NPs with relative roughness values of 46, 50, and 54%, respectively. Importantly, the incorporation of Span-20, a neutral emulsifier, facilitated homogeneously distributed Pt NP surface coverage on amorphous graphite, indicating the technique is apathetic to basal planes and edges of the graphite surface. The addition of SDS to droplets with large concentrations of HCPA resulted in conical and pillar-like NP morphologies, furthur enhancing surface area. The effect of deposition potential was also explored, which indicated that the roughness of the NPs can be increased by ∼10% depending on the potential. We also demonstrate that the method can be extended to the deposition of several other metal NPs, including silver, gold, copper, tin, iron, and cerium onto various substrates such as gold, silicon, boron-doped diamond (BDD), and highly oriented pyrolytic graphite (HOPG). The advantage of this technique is that size-selective electrodeposition of ligand-free, uniformly distributed NPs can be achieved.

show abstract

Electron-transfer catalyzed cycloaddition reactions of unactivated cyclic olefins in weakly coordinating anion electrolyte

Cited by 8 publications

References 46 publications

Hydrogen Bonding to Hexafluoroisopropanol Controls the Oxidative Strength of Hypervalent Iodine Reagents

Hydrogen Bonding to Hexafluoroisopropanol Controls the Oxidative Strength of Hypervalent Iodine Reagents

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

A Universal Platform for the Electrodeposition of Ligand-Free Metal Nanoparticles from a Water-in-Oil Emulsion System

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