Electrolytic Reduction of Organic Compounds.

Popp, Frank D.; Schultz, Harry P.

doi:10.1021/cr60215a002

Cited by 128 publications

(65 citation statements)

References 68 publications

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“…Formation of a radical anion is the first step, then, a neutral radical and chloride ion upon dissociation. Later, the fate of the radical depends largely on the availability of protons [41][42][43]. If they are available from, for example, amphiprotic methanol or traces of water, a second electron transfer is possible, and a neutral product joins the chloride ion as released products in an overall two electron per molecule process.…”

Section: Electrochemistry Of Solvents and Dissolved Speciesmentioning

confidence: 99%

“…For much of this work, details of electrochemical mechanisms are not essential, nonetheless it should not be ignored that electrochemical reduction or oxidation [41][42][43] can lead to a wide variety of released ions, which in turn, enter secondary chemical reactions, and also secondary electrochemical reactions. It is more common than not, that exotic secondary reaction pathways become possible.…”

Section: Electrochemistry Of Solvents and Dissolved Speciesmentioning

confidence: 99%

“…It is more common than not, that exotic secondary reaction pathways become possible. There are examples of reactions [41][42][43] which, from one substrate, produce dozens of different products. Of course, one also has to be cautious in transferring details of the reactions from one solvent to another, as well as from polarographic data acquired at a dropping mercury surface to other metals such as platinum, used here.…”

Section: Electrochemistry Of Solvents and Dissolved Speciesmentioning

confidence: 99%

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Negative ion mode evolution of potential buildup and mapping of potential gradients within the electrospray emitter

Pozniak

Cole

2004

J. Am. Soc. Mass Spectrom.

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Differential electrospray emitter potential (DEEP) maps, displaying variations in potential in the electrospray (ES) capillary and in the Taylor cone, have been generated in the negative ion mode of ES operation. In all examples, measured potential was found to be the highest at the points furthest into the Taylor cone, and values descended to zero at distances beyond approximately 15 mm within the ES capillary. In agreement with results obtained previously in the positive ion mode, negative mode data show a strong influence of electrolyte concentration on measured potentials. Weakly conductive solutions exhibited the highest values, and the steepest gradients, at points furthest into the Taylor cone. However, these same low conductivity solutions did not yield nonzero measured potentials to as deep a distance into the ES capillary as was possible from their higher conductivity counterparts. Addition of a readily reducible compound lowered measured potentials at all points near the ES capillary exit, in accordance with the description of the ES device as a controlled-current electrolytic cell. The development of potential inside the ES capillary upon the onset of ES was also studied, and initial results are presented. Potential waves are observed that can require 15 min or longer, to stabilize. The slow drift to steady potentials is evidence of upstream movement of electrochemically-produced species and follow-up reaction products; low conductivity solutions require longer intervals to reach a steady state. Potentials measured along the central ES axis reflect those at the ES capillary surface, although equipotential lines can be considered to be more compressed at the latter surface. (J Am Soc Mass Spectrom 2004, 15, 1737-1747

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Section: Electrochemistry Of Solvents and Dissolved Speciesmentioning

confidence: 99%

Section: Electrochemistry Of Solvents and Dissolved Speciesmentioning

confidence: 99%

Section: Electrochemistry Of Solvents and Dissolved Speciesmentioning

confidence: 99%

See 1 more Smart Citation

Negative ion mode evolution of potential buildup and mapping of potential gradients within the electrospray emitter

Pozniak

Cole

2004

J. Am. Soc. Mass Spectrom.

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“…In negative-mode operation as in Figure°8a,°the°predominant°electrode°reaction°is°ca-thodic. The solution used consists of 1,4-benzoquinone, an°easily°reducible°species° [36].°At°2°mM°concentration, the reduction of benzoquinone is likely to provide most of the cathodic current. At 0.0 V difference between the wire probe and the ES capillary, the former contributes only a small fraction of the total current.…”

Section: Different Potentials On Wire Electrodementioning

confidence: 99%

Current measurements within the electrospray emitter

Pozniak

Cole

2007

J. Am. Soc. Mass Spectrom.

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A movable disc-like wire probe electrode placed inside the electrospray (ES) capillary was used to measure currents flowing within the ES device for the first time. Currents were measured between the wire probe and the ES capillary. Current maps revealing measured current versus wire probe position were generated for a variety of solution conditions in the positive and negative ion modes and are compared to potential maps. The electrospray device was found to subsist on highly stable total currents; this current regulator aspect of the ES device showed remarkable resiliency regardless of the proportion of current produced at the wire probe electrode versus the ES capillary. However, kinks observed in the current and potential maps are attributed to adsorbed air participating in electrochemical reactions, and turbulence in solution flow in the region of the Taylor cone. From differential electrospray emitter potential (DEEP) maps, current maps, and cyclic voltammetry experiments performed at different wire probe locations, evidence is provided for separate regimes of current flow in the bulk solution and in the thin "skin" of highly conductive electrolyte constituting the outer surface (air interface) of the Taylor cone. Current maps reveal that current is drawn more evenly along the length of the ES capillary when solutions are highly conductive, in agreement with previous results for DEEP maps. In less conductive solutions, the area close to the capillary exit contributes more heavily to current production. Evidence that contaminant participation in electrochemical processes occurring within the electrospray device can be largely responsible for production of the excess charge in ES droplets is also provided. These investigations complement previous DEEP mapping studies to further elucidate the details of the electrochemical processes occurring within the electrospray device. 1-3] is a convenient tool to deliver ions from the liquid phase to the gas phase, so that they may subsequently be analyzed by mass spectrometry (MS). The inherent electrochemical nature of the ES device was first expounded by Paul Kebarle and coworkers [4,5], but in many cases, as discussed in an excellent presentation of arguments by de la Mora, Van Berkel, Enke, and Fenn [6], experimentalists are often unaware of the electrochemical processes taking place during the operation of electrospray. In order to use electrospray prudently and efficiently, and to be able to remove chance elements, and extend its reach into new applications, a good grasp of the fundamental electrochemistry that underlies electrospray becomes necessary. Alongside the pursuit of practical applications of this atypical electrochemical cell comes an interest in explaining fundamentals of the electrochemical nature of electrospray [7].The electrospray device-typically consisting of a capillary filled with liquid and a counter-electrode placed at some distance in front of it with a kilovolt potential difference between the two-was discovered to behave in a manner anal...

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“…There are many methods used in the preparation of PAP from p-nitrophenol (PNP) such as metal/acid reduction (11), catalytic hydrogenation (12), electrolytic reduction (13), homogeneous catalytic transfer hydrogenation (14), and heterogeneous catalytic transfer hydrogenation. Although all of these methods are still used today, each method has its shortcoming.…”

Section: Introductionmentioning

confidence: 99%

The use of nano supported nickel catalyst in reduction ofp-nitrophenol using hydrazine as hydrogen donor

Maksod

Saleh

2010

Green Chemistry Letters and Reviews

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p-Aminophenol was prepared by hydrogenation of p-nitro phenol over nano-sized nickel catalysts supported on two different supports, SiO 2 and Al 2 O 3 . Hydrazine hydrate was used as hydrogen source in this reaction. Several loadings of nano-sized Ni were used, thus 20, 5, and 2.5 wt% were prepared. X-ray diffraction (XRD) and electron spin resonance (ESR) were employed to investigate the prepared catalysts. The Ni/Al 2 O 3 was found to be more effective and give high durability. The catalytic activity of the reaction was found to be influenced by both the crystallinity of the nickel and the strain among nano-sized nickel particles. The prepared catalysts showed higher catalytic activity, especially at lower loading. During the reaction, a detectable change of the color was observed from yellow to green and finally to colorless, which enable us to suppose a mechanism of this reaction.

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Electrolytic Reduction of Organic Compounds.

Cited by 128 publications

References 68 publications

Negative ion mode evolution of potential buildup and mapping of potential gradients within the electrospray emitter

Negative ion mode evolution of potential buildup and mapping of potential gradients within the electrospray emitter

Current measurements within the electrospray emitter

The use of nano supported nickel catalyst in reduction ofp-nitrophenol using hydrazine as hydrogen donor

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