Oxidation-reduction reactions

The third remarkable aspect of enzyme catalysis is the versatility of these species. They catalyze an extremely wide variety of reactions— oxidation, reduction, polymerization, dehydration, dehydrogenation, etc. Their versatility is a reflection of the range and complexity of the chemical reactions necessary to sustain life in plants and animals. 

Equilibrium considerations other than those of binding are those of oxidation/reduction potentials to which we drew attention in Section 1.14 considering the elements in the sea. Inside cells certain oxidation/reductions also equilibrate rapidly, especially those of transition metal ions with thiols and -S-S- bonds, while most non-metal oxidation/reduction changes between C/H/N/O compounds are slow and kinetically controlled (see Chapter 2). In the case of fast redox reactions oxidation/reduction potentials are fixed constants. 

Subsequent ion exchange of the metal cation with the quaternary ammonium ion catalyst provides a lipophilic ion pair (step 2), which either reacts with the requisite alkyl electrophile at the interface (step 3) or is partitioned into the electrophile-containing organic phase, whereupon alkylation occurs and the catalyst is reconstituted. Enantioselective PTC has found apphcation in a vast number of chemical transformations, including alkylations, conjugate additions, aldol reactions, oxidations, reductions, and C-X bond formations." ... 

ELECTRON TRANSFER REACTIONS Oxidation-Reduction Theory... 

The goal of this chapter is to give you a stronger handle on the basics of chemical reactions, which were introduced in Chapter 2. Then in the following chapters we ll look at specific classes of chemical reactions, such as acid-base reactions, oxidation-reduction reactions, and reactions involving organic chemicals. 

As will become evident in this section, in the net transformation from reactant —s-product transformations many of the synthetically useful reactions involving >C=C<"+ are analogous to those involving neutral, un-ionized carbon-carbon double bonds (e.g. the Diels-Alder reaction, oxidation/reduction reactions, nucleophilic addition etc.). However, many of the reactions involving a neutral >C=C< often require the presence of an activating substituent in order to make the alkene more electron-deficient. In a sense, one-electron oxidation of an alkene to its radical cation provides a simple and unique mechanism for increasing the electrophilic (and, of course, radical) properties of... 

Any time electrons are transferred between reactants in a chemical reaction, the reaction is called an oxidation-reduction reaction. Oxidation-reduction reactions are also called redox reactions. 

Green Chemistry and Catalysis, R. A. Sheldon, I. W. C. E. Arends, and U. Hanefeld, Wiley-VCH 2007, 433 pp., ISBN 3-527-30715-9. An up-to-date advanced reference book, containing a collection of chapters on green chemistry applications in academia and industry. The subjects are ordered by reaction (oxidations, reductions, etc.) and are well presented. 

Classification of Solvents. Solvent classification helps to identify properties useful in solvent selection for individual applications for example, the study of acid-base reactions, oxidation-reduction reactions, inorganic coordination chemistry, organic nucleophilic displacement reactions, and electrochemistry. 

Chemical reactions—oxidation, reduction, dehydration, hydrolysis, acid rain... 

There is another common way to classify chemical reactions acid-base reactions, oxidation-reduction reactions, and reactions of more complicated types (beyond the scope of this book). Acid-base reactions are considered to involve the reactions of hydrogen ions with hydroxide ions. The reactions of acids and bases will be taken up in this section, and a more sophisticated view of these reactions is presented in Chapter 19. Oxidation-reduction reactions involve the transfer of electrons from one substance to another. Many combination reactions, many decomposition reactions, all single substitution reactions, and all combustion reactions are of this type, but more complex examples are presented in Chapters 16 and 17. 

Precipitation reactions Acid-base reactions Oxidation-reduction reactions... 

Typically reported topics are solvolytic reactions, oxidations, reductions, and C-C coupling reactions. The saponification of activated esters in aqueous micelles is a typical model for an enzyme mimetic reaction. The influence of the micellar medium on the reaction rate has been investigated, as well as the alteration of the stereoselectivity. Models of metalloenzymes were developed with the ligands 1-3 [8]. 

It is thus obvious that for all the cases described above the oxide reacted with the element to form a volatile oxide. A chemical reaction (oxidation-reduction reaction... 

A battery is a complex device that delivers electrical energy by transforming chemical energy. The electrical energy is provided by electrochemical reactions (oxidation-reduction reactions) that take place at the anode and the cathode of the battery. While the term battery is often used, the basic electrochemical unit being referred to is the cell [1]. A battery is composed of several cell units that are connected in series or in parallel... 

Standard substances in clinical chemistry include primary standards, which can be obtained sufficiently pure to be used for the preparation of solutions by weighing or by reference to other definable physical characteristics (e.g., constant-boiling hydrochloric acid). Primary standard chemicals are available for acid-base reactions, precipitation reactions, oxidation-reduction reactions, etc. (V3), and are used in these various categories of analytical determination to validate the preparation of solutions of other chemical substances which cannot be obtained in a form suitable to meet the criteria demanded for a primary standard. Following their calibration in terms of a primary standard, these other chemieals can act as secondary standards. 

Anion alkylation. O-alkylation with bcn/.ylic halides (Williamson reaction), oxidation, reduction. 

Are these reactions oxidation-reduction reactions Are electrons transferred Simply reading a chemical equation does not always tell us whether oxidation and reduction have occurred, so chemists have developed a numerical system to help identify a reaction as redox. For redox reactions, this system also shows us which element is oxidized, which is reduced, what the oxidizing agent is, and what the reducing agent is. 

Whereas acid-base reactions can be characterized as proton-transfer processes, the class of reactions called oxidation-reduction, or redox, reactions are considered electron-transfer reactions. Oxidation-reduction reactions are very much a part of the world around ns. They range from the burning of fossil fuels to the action of household bleach. Additionally, most metallic and nomnetaUic elements are obtained from their ores by the process of oxidation or reduction. 

The solution came, in part, by the application of biotransformations. These can be defined as biological processes that modify organic compounds via simple chemical reactions (oxidations, reductions) by means of enzymes contained in microbial, plant, or even animal cells. The aim is usually a one-step reaction to a recoverable product in a sequence of steps in which the majority of conversions are chemical steps (i.e., synthesis). In fermentation processes the whole sequence of reactions is carried out by microorganisms, be it a carbohydrate breakdown to alcohol (or other solvents), the production of antibiotics, or even enzymes. 

Precipitation Reactions Reactions with Oxygen Acid-Base Reactions Oxidation-Reduction Reactions... 

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