Cationic chemicals

TIricooRlinate caibocations are fiequendy called carbonium ions. The terms methyl cation, butyl cation, etc., are used to describe the c >rTesixiiulir.ji tricoordinate cations. Chemical Abstracts uses as specific names methylium, ethyUum, propylium. We will use carbocation as a generic term for trivalent carbon cations. 

The electrons might be free or else may be associated with variable valence cations, chemically transforming M2+ ions (Mm) to M+ ions (MV) ... 

The purpose of this chapter is not to cover the entire chemistry of the high Tc oxides but instead is to focus on one specific point the study of these materials through cationic chemical substitutions in order to illustrate how this type of chemistry can aid in the understanding of some of the crystal-chemical aspects of these new high Tc... 

Cationic photoinitiators are frequently found in classes of compounds such as the triaryl sulfonium, tetraaryl phosphonium, and diaryliodonium salts of large protected anions (hexafluorophosphates or antimonates). These compounds are soluble in most epoxy resins, do not activate epoxy cure until exposed to uv light, are insensitive to room lighting, and have long storage life at room temperature. Cationic photoinitiators form an acid catalyst when exposed to uv light and consequently start the cationic chemical reaction. 

Furthermore, the radical cation (37 ), produced by electrolysis and/or by the use of one-electron-oxidizing agents, appears totally inert vs triplet molecular oxygen, envisaging, also in this case, an inefficient Barton-type reaction. The whole of these complex results, of course, induce an easy question what factors control whether radical cations, chemically and/or photochemically generated, react with oxygen species or not ... 

This describes the situation where oxygen is lost from the crystal, and the surplus electrons, two per lost oxygen, reside on separate metal atoms in the crystal. In formal ionic terms, two M + cations are transformed to M+ cations. In semiconductor terms, two electrons are trapped on separate M + cations. Chemically this process may be considered as equivalent to doping of MO with M2O. The law of mass action, applied in its simplest form with concentrations instead of activities, in view of the supposed noninteraction of the defects, then gives an expression for the equilibrium constant, (9) ... 

Cations Cation Chemical Shift / ppm Solvation Number... 

Insoluble catalysts offer an important advantage of simple catalyst removal by filtration or centrifugation after the completion of a PTC reaction. Regen [82] demonstrated that quaternary onium cations chemically bound to insoluble resins could act as PTC catalysts and suggested the term triphase catalysis to describe the related PTC reactions. Insoluble PTC catalysts can be grouped into three categories, namely, the resin bound, the inorganic solid bound, and the third-liquid-phase catalysts as described in Section... 

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Cation Chemical spot or crystal Flame color... 

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