Ceric Sulfate as a Volumetric Oxidizing Agent. Xi. The Oxidation of Organic Acids

Willard, H. H.; Young, Philena

doi:10.1021/ja01364a021

Cited by 50 publications

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“…• is so short-lived that it reaches EPRdetectable concentrations only within the dead time of our EPR flow-experiment; (2) concentrations are below the detection limit during the whole course of the reaction, implying that although GOAO 2 • is formed, it undergoes a fast conversion to a nonradical species; (3) the formation of a peroxy radical is just not favored or is, at least, not a major pathway here. Notice, of course, that the explanations 1 and 2 explicitly require a reaction between the primary radical GOA • and molecular oxygen, i.e., assume that the reaction follows the standard autooxidation pathway.…”

Section: Reaction Kinetics Of Ce(iv)mentioning

confidence: 91%

“…1 However, most reaction mechanisms are highly complex and thus not yet fully understood, possibly because of the lack of direct experimental data on the involvement of radical species. A striking example is the Ce(IV) oxidation of malonic acid (CH 2 (COOH) 2 ) which was first investigated at least as early as 1930. 2 It was generally considered that in this reaction the first step was the abstraction of a hydrogen atom by Ce(IV) to form the malonyl radical, which then decayed by disproportionation.…”

Section: Introductionmentioning

confidence: 99%

“…A striking example is the Ce(IV) oxidation of malonic acid (CH 2 (COOH) 2 ) which was first investigated at least as early as 1930. 2 It was generally considered that in this reaction the first step was the abstraction of a hydrogen atom by Ce(IV) to form the malonyl radical, which then decayed by disproportionation. 3 In 1994, however, Gao et al 4 demonstrated that the first stable product was ethanetetracarbonic acid, formed by dimerization of the primary (malonyl) radical.…”

Section: Introductionmentioning

confidence: 99%

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Oxidation of Glyoxylic Acid by Cerium(IV): Oxygen-Induced Enhancement of the Primary Radical Concentration

et al. 1996

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In order to help understand the role of oxygen in Ce(IV)-induced oxidation of small carbonic acids, we investigated the reaction of glyoxylic acid (HCOCOOH) and Ce(IV) in 1 M sulfuric acid. Spectrophotometric data showed that in excess of glyoxylic acid the consumption of Ce(IV) obeys pseudo-first-order kinetics, with a rate constant of 8.8 L mol -1 s -1 at 25°C and an activation energy of 80 kJ mol -1 . Rapid-flow EPR measurements revealed an approximately 1:2:1 triplet with a g value of 2.0071 ( 0.0005 and a hyperfine splitting of 7.1 ( 0.2 G, assignable to the primary radical formed by abstraction of a hydrogen atom from hydrated glyoxylic acid. The rate constant for the anaerobic self-decay of the radical was measured as approximately 3.7 × 10 9 L mol -1 s -1 . Surprisingly, oxygen had no effect on the Ce(IV) kinetics, while the radical decay was significantly inhibited under aerobic conditions (ratio of experimental rate constants ≈6.3). Amperometric measurements revealed accompanying oxygen consumption. Analyses based on numerical simulations show that the observed oxygen-induced increase in radical concentration cannot be explained in the framework of standard autooxidation mechanisms. An alternative reaction scheme is suggested which reproduces the observed aerobic radical kinetics and which thus could be relevant to similar oxidation reactions.

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Section: Reaction Kinetics Of Ce(iv)mentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Oxidation of Glyoxylic Acid by Cerium(IV): Oxygen-Induced Enhancement of the Primary Radical Concentration

et al. 1996

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“…An important application is the potentiometric determination of acids in oils ( 1 ) . Various dibasic and hydroxy acids may be oxidized with cerate, and the excess cerate determined potentiometrically with a reducing agent (54).…”

Section: Functional Groups Determinable By Electrometric Methodsmentioning

confidence: 99%

Determination of Organic Functionality by Electrical Measurements

Lykken

1950

Anal. Chem.

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The various electrical analytical methods are reviewed with respect to their general applicabilit? , advantages, and limitations when applied to the determination of organic functional groups. The functional groups are considered separately and the electrical methods applicable to each are discussed. The greatest utility is found in the determination of acids and bases (amines), carbonyl compounds, halides, cyclic compounds, nitro compounds, olefinic and polynuclear aromatic hydrocarbons, phenols, peroxides, and sulfur compounds. Electrical methods are frequently of great value, particularly in special cases where other methods are not suitable or adequate. However, these methods cannot be taken as the ultimate solution to organic analysis in general because of the many varied types of interferences and complications C R I S G recent years, steadily incrcasing emphasis has been D placed on the development and use of instrumental methods of analysis, including those based on the measurement of electrical current or potential. Although much of the work has been confined to aqueous solutions and to inorganic materials, the problem of determining functional groups in organic substances has been aided by successful use of certain electre metric methods. In general, such methods have been of most value when other methods were not applicable or when speed was a critical factor. Polarographic methods have been most useful because they are often selective. Successful use has also been made of potentiometric, conductometric, amperometric, highfrequency, and polarized electrode (dead-stop) titrations, especially when an indicator could not he used or when high sensitivity or precision was desired.In many cases, the scope of the electrical methods overlaps that of the conventional chemical methods or the recent photometric approaches. Experience has made it apparent (1) that all the electrical methods availablc are not always the best or ultimate means of determining functional groups in certain organic materials, because of interferences and other complications, and (2) that they sometimes only augment other analytical measurenicnts. This creates a problem in the practical task of deciding which is the most suitable approach for the particular problem a t hand and which, if any, of the electiictll methods secmfi promising. I t is this question which the present paper deals with b y rwiewing, in a very general way, the various electrical methods available and briefly discussing their utility and limitations when applied to the determination of organic functional groups Thus, no attempt is made to present a thorough review of tlir literature, but many references are given to procedures that serve to illustrate the particular usefulness of each type of electrical method considered.The literature already contains a number of excellent surveys and publications dealing with specific electrical methods. Thus, Furman (11) has reviewed the applications of potentiometric titrations to both organic and inorganic analysis. A bibliograp...

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“…This originates mainly from various washing operations during the crushing and pressing of grapes, as well as rinsing of fermentation tanks, barrels and other equipment or surfaces [10]. This organic substrate has been studied using different methods of degradation [11][12][13][14][15][16][17], such as KMnO 4 , H 2 O 2 , Ce(SO 4 ) 2 , vanadium(V) in acidic media, and EO.…”

Section: Introductionmentioning

confidence: 99%

Anodic Oxidation of Tartaric Acid at Different Electrode Materials

Silva¹,

Ferreira²,

Brito³

et al. 2012

COC

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Aim of the present communication is to show experimental results, and related conclusions, on the electrochemical oxidation (EO) of tartaric acid (TA), which has been oxidized at Ti/PbO2, Ti/Pt, Pt and HBDD electrodes at different current densities in acidic media. TA complete mineralization has been achieved only at HBDD and Ti/PbO2, being higher the faradaic efficiency at the latter electrode. At Pt electrode, the electroxidation was found to be extremely slow, in acidic conditions. The experimental evidence has shown that the main factor is the interaction of the organic substrate and hydroxyl radicals with the electrode surface, during TA oxidation. In the case of the EO of oxalic acid (OA) in acidic media that was previously studied, better results were obtained at the Pt electrode, supporting the idea that the interaction of organic substrate with the electrode surface, was the main determining parameter and based on the results here reported, this idea was confirmed for TA, more complex compound than OA.

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Ceric Sulfate as a Volumetric Oxidizing Agent. Xi. The Oxidation of Organic Acids

Cited by 50 publications

References 0 publications

Oxidation of Glyoxylic Acid by Cerium(IV): Oxygen-Induced Enhancement of the Primary Radical Concentration

Oxidation of Glyoxylic Acid by Cerium(IV): Oxygen-Induced Enhancement of the Primary Radical Concentration

Determination of Organic Functionality by Electrical Measurements

Anodic Oxidation of Tartaric Acid at Different Electrode Materials

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