Organic chemistry anion

Chapter 2 covers kinetics, which provides useful information about reaction mechanisms, and allows us to distinguish between possible mechanisms in many cases. Elementary reactions do not involve intermediates, but go through a transition state. Although this transition state cannot be isolated, it can be studied in various ways which provide insights into the reaction mechanism, and this forms the subject matter of Chapter 3. This is followed by three chapters on the most important intermediates in organic chemistry anions, radicals and cations. A final chapter on molecular reactions concerns thermal and photochemical processes. The concepts of frontier orbitals and the aromatic transition state allow us to predict which reactions are allowed and which are forbidden , and provide insights into why most reactions of practical interest involve multi-step processes. 

Protonated Anions. Ions such as HSOy are recommended to be named hydrogensulfate with the two words written as one following the usual practice for polyatomic anions. However, in the Nomenclature of Organic Chemistry, 1979 edition, hydrogen is used as a separate word this practice is followed in this Handbook. 

The most common oxidation state of niobium is +5, although many anhydrous compounds have been made with lower oxidation states, notably +4 and +3, and Nb can be reduced in aqueous solution to Nb by zinc. The aqueous chemistry primarily involves halo- and organic acid anionic complexes. Virtually no cationic chemistry exists because of the irreversible hydrolysis of the cation in dilute solutions. Metal—metal bonding is common. Extensive polymeric anions form. Niobium resembles tantalum and titanium in its chemistry, and separation from these elements is difficult. In the soHd state, niobium has the same atomic radius as tantalum and essentially the same ionic radius as well, ie, Nb Ta = 68 pm. This is the same size as Ti ... 

An expanding development is the use of peroxodisulfates as oxidants in organic chemistry (80,81). These reactions are initiated by heat, light, gamma rays, or transition-metal ions. The primary oxidising species is usually the sulfate ion radical, P hskip -3pt peroxodisulfate anion... 

The organic chemistry of thiocyanates is notably that of nucleophilic displacement of alkyl haHdes by thiocyanate anion to form alkyl thiocyanates ... 

Anionic Surfactants Organic Chemistry, edited by Helmut W. Stache... 

Anions of (3-keto esters are said to be synthetically equivalent to the enolates of ketones. The anion of ethyl acetoacetate is synthetically equivalent to the enolate of acetone, for example. The use of synthetically equivalent groups is a common tactic in synthetic organic chemistry. One of the skills that characterize the most creative practitioners of organic synthesis is an ability to recognize situations in which otherwise difficult transfonnations can be achieved through the use of synthetically equivalent reagents. 

Although many carbonyl derivatives act as acyl cation equivalents, R(C=0)" in synthetic chemistry, the inherent polarity of the carbonyl group makes it much more difficult to find compounds that will act as equivalents of acyl anions, R(C=0) . Since the 1960s, major progress has been made in this area, and there are now a wide variety of compound types that can react in this way. As in so many areas of organic chemistry, heterocyclic compounds take pride of place and form the basis of many of the most useful methods. In recent years there has been particular interest in developing chiral acyl anion equivalents that will show high... 

A carboxylic acid can be represented as R — CO2 H. Many different carboxylic acids participate in organic chemistry and biochemishy. Although carboxylic acids react in many different ways, breaking the C—OH bond is the only reaction that is important in polymer formation. A carboxylic acid is highly polar and can give up H to form a carboxylate anion, R — CO2. The carboxyl group (— CO2 H) also forms hydrogen bonds readily. These properties enhance the solubility of carboxylic acids in water, a particularly important property for biochemical macromolecules. 

Uson, R., Laguna, A. and Arrese, M.L. (1984) A new approach to the synthesis of cationic, neutral or anionic diarylgold(III) complexes. Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry, 14 (4), 557-567. 

In the last decade, a new aspect of nickel-catalyzed reactions has been disclosed, where nickel serves to selectively activate dienes as either an al-lyl anion species or a homoallyl anion species (Scheme 1). These anionic species are very important reactive intermediates for the construction of desired molecules. Traditionally they have been prepared in a stoichiometric manner from the corresponding halides and typical metals, e.g., Li, Mg. In this context, the catalytic generation method of allyl anions and homoallyl anions disclosed here might greatly contribute to synthetic organic chemistry and organotransition metal chemistry. 

H W Stache, Anionic surfactants organic chemistry (New York Marcel Dekker 1995). 

The combination of an anionic and a pericyclic process has found broad application in synthetic organic chemistry. In these transformations, a primary addition is frequently followed by an elimination to give a reactive intermediate, which is then... 

The discussion and classification of reagents is masterful in identifying Ingold s new nomenclature and principles with more widely known oxidation-reduction and acid-base theory. The 1953 lectures at Cornell University, published as Structure and Mechanism in Organic Chemistry, follow this same strategy, showing how old classification schemes overlap with each other and how apparent inconsistencies disappear as old schemes are incorporated into the new one. Nineteenth-century Berzelian electrochemical dualism, revived by Lapworth and Robinson in the cationic/anionic schema, disappears into the electrophilic/nucleophilic language. 

The base-catalysed addition of thiols to Jt-electron-deficient alkenes is an important aspect of synthetic organic chemistry. Particular use of Triton-B, in place of inorganic bases, has been made in the reaction of both aryl and alkyl thiols with 1-acyloxy-l-cyanoethene, which behaves as a formyl anion equivalent in the reaction [1], Tetra-n-butylammonium and benzyltriethylammonium fluoride also catalyse the Michael-type addition of thiols to a,P-unsaturated carbonyl compounds [2], The reaction is usually conducted under homogeneous conditions in telrahydrofuran, 1,2-dimethoxyethane, acetone, or acetonitrile, to produce the thioethers in almost quantitative yields (Table 4.22). Use has also been made of polymer-supported qua-... 

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