Anodic oxidation under pulse conditions

Fleischmann, M.; Goodridge, F.

doi:10.1039/df9684500254

Cited by 27 publications

(13 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The vast majority of electrocatalyzed reactions are enabled by direct current, where the polarity of the electrodes remains constant over time and the flow of electrons in the reaction media is unidirectional. While alternating current (AC) was used to realize decarboxylation, nitro reduction, and electrolysis of propylene in the early 20th century, − it was rarely explored in mainstream organic synthesis. In 2021, Baran studied the use of AC for a controlled reduction of phthalimides (Scheme ).…”

Section: Elsf Of Functional Groupsmentioning

confidence: 99%

Electrochemical Late-Stage Functionalization

Wang,

Dana,

Long

et al. 2023

Chem. Rev.

View full text Add to dashboard Cite

Late-stage functionalization (LSF) constitutes a powerful strategy for the assembly or diversification of novel molecular entities with improved physicochemical or biological activities. LSF can thus greatly accelerate the development of medicinally relevant compounds, crop protecting agents, and functional materials. Electrochemical molecular synthesis has emerged as an environmentally friendly platform for the transformation of organic compounds. Over the past decade, electrochemical late-stage functionalization (eLSF) has gained major momentum, which is summarized herein up to February 2023.

show abstract

Section: Elsf Of Functional Groupsmentioning

confidence: 99%

Electrochemical Late-Stage Functionalization

Wang,

Dana,

Long

et al. 2023

Chem. Rev.

View full text Add to dashboard Cite

show abstract

“…+ iRn + Voc [9] where i is the current density, 0r is the cathodic overpotential, ~a is the anodic overpotential, iRa is the ohmic loss, and Voc is the open-circuit potential. To determine the limiting current for the reduction of 5.48 mM NB used in these experiments, the background current from hydrogen evolution must be subtracted at the same cathodic overpotential; however, this cannot be done directly since cell voltage rather than overpotential was controlled.…”

Section: Integral-conversion Experimentsmentioning

confidence: 99%

“…To determine the limiting current for the reduction of 5.48 mM NB used in these experiments, the background current from hydrogen evolution must be subtracted at the same cathodic overpotential; however, this cannot be done directly since cell voltage rather than overpotential was controlled. [9] to eliminate ~a and rearranging produces -~1r + Voc = Vceu ----iRa [11] Box In ~ From the measured voltage-current relationship and the known ohmic and kinetic parameters, the left side of Eq. An estimate of the cathodic overpotential at a given cell voltage may be obtained by using a macroscopic potential balance.…”

Section: Integral-conversion Experimentsmentioning

confidence: 99%

Reduction of Nitrobenzene in a Parallel‐Plate Reactor: II . Integral Conversion Using Periodic Cell‐Voltage Control

Smeltzer

Fedkiw

1992

J. Electrochem. Soc.

View full text Add to dashboard Cite

The reduction of nitrobenzene (NB) to p-aminophenol (PAP) in an electrolyte recirculated from a holding tank to a parallel-plate reactor was investigated both theoretically and experimentally to determine the effects of periodic, step cellvoltage control on the selectivity for the production of PAP. An integral-conversion model was developed to predict the species concentration in the catholyte vessel during the course of the batch reaction. The calculational procedure utilizes the differential-conversion model of Part I to calculate the cycle-averaged reaction rates at the stationary state for a given set of reactant bulk concentrations. The best periodic control strategy examined was predicted to produce a PAP selectivity which was 200% of the steady cell-voltage result for equal PAP concentration. Under periodic control, PAP production was predicted to increase with duty cycle, while PAP selectivity was predicted to increase with frequency and decreasing duty cycle. The results from experiments performed in a laboratory parallel-plate reactor qualitatively matched the model predictions although quantitative differences were observed. Under step cell-voltage control, PAP production increased with duty cycle, but the trends of PAP selectivity with duty cycle and frequency were obscured by scatter in the data. The PAP selectivity under periodic control was, as predicted, always above the steady-control selectivity for the same average PAP production rate. Excellent quantitative agreement was found between the theoretical and experimental PAP and phenylhydroxylamine (PHA) concentration at the end of the batch run under both steady and step cell-voltage control, but the amount of AN produced was consistently underpredicted. This work has shown both theoretically and experimentally that periodic control may enhance the selectivity for the desired product of a branched chemical-electrochemical reaction sequence in the industrially significant, parallel-plate reactor system.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.217.227.3 Downloaded on 2014-07-10 to IP

show abstract

“…As a means to improve reaction selectivity, Fedkiw and Scott (1) demonstrated theoretically under kineticcontrol conditions that periodic electrode-potential control could be used to increase the selectivity of certain branched chemical-electrochemical reaction sequences. Other examples of periodic voltage or current control of electroorganic reactions may be found in the literature [e.g., (3)(4)(5)(6)(7)(8)(9)]. Other examples of periodic voltage or current control of electroorganic reactions may be found in the literature [e.g., (3)(4)(5)(6)(7)(8)(9)].…”

mentioning

confidence: 99%

Reduction of Nitrobenzene in a Parallel‐Plate Reactor: I . Differential Conversion Using Periodic Cell‐Voltage Control

Smeltzer

Fedkiw

1992

J. Electrochem. Soc.

View full text Add to dashboard Cite

The effect of steady and periodic, step cell-voltage control on the selectivity of the reduction of nitrobenzene in a parallel-plate reactor was theoretically investigated. Under step cell-voltage control, the potential is continuously oscillated from a constant high to a constant low value. Nitrobenzene (NB) is electroreduced to the intermediate phenylhydroxylamine (PHA) which may undergo further electrochemical reduction to aniline (AN) or may rearrange chemically to form the desired product, p-aminophenol (PAP). A reactor model was developed which assumes a well-mixed core, masstransfer boundary layers for NB and PHA at the cathode, concurrent hydrogen evolution, oxygen evolution at the anode, and negligible migration transport. An analytic, stationary-state solution to the transient-diffusion equation within the boundary layers was coupled through the reaction kinetics to an analytic solution of the one-dimensional Laplace equation for electrolyte potential. Differential-conversion simulations were performed in which the homogeneous reaction (PHA --* PAP) need not be considered because its characteristic reaction time is large compared to both those of the other reactions and to the cycle time of the control. The best periodic cell-voltage control strategy employed in the simulations was found to produce a PHA selectivity 250% of that under steady control at the same cycle-averaged PHA production rate. Under periodic control, PHA selectivity was shown to increase asymptotically with decreasing cycle time; high-frequency operation lowered the depletion of NB and overabundance of PHA in the boundary layer which otherwise would occur during the high-polarization portion of the cycle. Decreasing the duty cycle (fraction of cycle time spent at high polarization) increased the PHA selectivity since smaller duty cycles resulted in a higher NB concentration and a lower PHA concentration at the cathode surface, but simultaneously the PHA production rate decreased. Increasing the voltage of the high-polarization portion of the cycle kinetically favors the production of PHA over AN. An increase in the mass-transfer rate causes a like effect on the PHA selectivity and to a much smaller extent on the PHA production rate for any set of steady or periodic-control parameters. The differential-conversion results provide a basis for the control strategies used in integral-conversion simulations and experiments presented in Part II of this work.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 129.130.252.222 Downloaded on 2014-07-10 to IP

show abstract

Anodic oxidation under pulse conditions

Cited by 27 publications

References 0 publications

Electrochemical Late-Stage Functionalization

Electrochemical Late-Stage Functionalization

Reduction of Nitrobenzene in a Parallel‐Plate Reactor: II . Integral Conversion Using Periodic Cell‐Voltage Control

Reduction of Nitrobenzene in a Parallel‐Plate Reactor: I . Differential Conversion Using Periodic Cell‐Voltage Control

Contact Info

Product

Resources

About