General types of reaction

Alcohol amination reactions are described by a network of two general types of reaction. 

The Subject Index of over 20 000 entries has been compiled from keywords, names and formulae in the text and tables. It covers general classes of compound, specific compounds, general types of reaction, specific and named reactions, spectral and other properties, and other topics in heterocyclic chemistry. More details are again given at the beginning of the index in Volume 8. 

We have now made use of the principles of equilibrium in two general types of reactions. In Chapter 10 we considered reactions involving a solid and a solution dissolving and precipitation. In Chapter 11 we turned to reactions occur-... 

There are essentially four general types of reaction which organic compounds can undergo ... 

The reactivity of heterocyclic compounds composed of three fused ring systems (6 6 6) has been classified below according to general types of reactions. 

Additional Transformation Reactions. Other reactions that can be catalyzed by mineral surfaces are substitution, elimination, and addition reactions of organic molecules. Substitution and elimination are two general types of reactions that occur at saturated carbon atoms of organic molecules. Both types are initiated by nucleophilic attack however, in elimination reactions it is the basicity of the nucleophile that determine its reactivity rather than its nucleophilicity. Since mineral surfaces are expected to have both nucleophilic and basic properties, these types of reactions should also occur at mineral-water interfaces (see Chapter 22). It remains to be shown whether or not these reactions are catalyzed under environmental conditions. 

There are two important general types of reaction by which six-membered heterocycles containing two or more heteroatoms can be transformed into other six-membered heterocyclic systems, namely reactions which involve an ANRORC mechanism, and reactions which proceed by a Diels-Alder/retro-Diels-Alder type of mechanism. Transformation of 1,3-oxazinones and -thiazinones into pyrimidones (equations 193 and 194) has been extensively used, especially in the conversion of isatoic anhydride into quinazolinones (e.g. equation 195). 2,4-Diaryl-l,2,3,5-oxathiadiazines, which are readily accessible by reaction of sulfur trioxide with aryl isocyanates, are useful precursors to pyrimidines and 1,3,5-triazines (equation 196). 

The formation of blue cations like 73 is a very general type of reaction. It can be used as a characteristic reaction with all 2.4.6-aryl-substituted X -phospha-cyclohexadiene compounds with an OH or OR group at position 2 or 4. An analogous reaction is well known from experiments with 2.4.6-triphenyl-4-hydroxy-(or alkoxy) cyclohexadiene(2,5)-one 76 which also gives a deep blue cation 77 with strong acids. With water or alcohols it can be reconverted to the hydroxy or alkoxy compounds 76... 

Alkanes such as ethane are relatively unreactive and reactions involving alkanes require high-energy atoms or free radicals. Three general types of reactions involving alkanes are combustion, halogenation, and pyrolysis. The most common reactions of alkanes involve combustion. Combustion of alkanes has been the primary source of heat for human civilizations throughout... 

Scheme 1. Schematic illustration of the general types of reactions undergone by Ce (and higher fullerenes).

Photosynthetic bacteria have relatively simple phototransduction machinery, with one of two general types of reaction center. One type (found in purple bacteria) passes electrons through pheophytin (chlorophyll lacking the central Mg2+ ion) to a quinone. The other (in green sulfur bacteria) passes electrons through a quinone to an iron-sulfur center. Cyanobacteria and plants have two photosystems (PSI, PSII), one of each type, acting in tandem. Biochemical and biophysical... 

Although the intramolecular alkoxide displacement of a halide ion discussed above is by far the most common example of that general type of reaction, another oyolization of considerable synthetic import once involves monoalkyl- or monoeryisulfonate esters of J, 2-djols, shown in the following general case in Eq. (232). 

However, benzene and its derivatives can be reduced to cyclohexa-dienes by solutions of metals such as Li, Na, K, Zn, and Hg in a weakly acidic solvent, such as liquid ammonia, amines, or ether-alcohol mixtures. This general type of reaction is known as the Birch reduction after the Australian chemist, A. J. Birch. With benzene, reduction with metals leads to 1,4-cyclo-hexadiene ... 

A great variety of aza macrocycle complexes have been formed by condensation reactions in the presence of a metal ion, often termed template reactions . The majority of such reactions have inline formation as the ring-closing step. Fourteen- and, to a lesser extent, sixteen-membered tetraaza macrocycles predominate, and nickel(II) and copper(II) are the most widely active metal ions. Only a selection of the more general types of reaction can be described here, and some closely related, but non metal-ion-promoted, reactions will be included for convenience. The reactions are classified according to the nature of the carbonyl and amine reactants. 

In the following sections a number of general types of reactions recur constantly. These are summarized here. The first three most commonly involve activation of the hydrogen molecule. 

Heating of a mixture of 2-phenyl-1,4-naphthoquinone (1 eq.) with dimethyl malonate (4 eq.) and manganese(III) acetate (6 eq.) in acetic acid at 80°C for 16 hours gives 1 in 76% yield, and this has been shown to be a general type of reaction for a variety of 2-aryl-l,4-naphthoquinones. 

A further example of this general type of reaction is provided by the synthesis of cyclooctene sulphide (6).4 Here an alkene is converted into an adduct with succinimide-A-sulphenyl chloride (reaction formulated in full in Expt 8.3), which is reduced with lithium aluminium hydride at — 78 °C to form the product. 

Hydrogen radical ( H) accounts for approximately 10% of the total free radical concentration in irradiated water. H undergoes two general types of reactions with organic compounds ... 

Steady-state isothermal heat-flow balance of a general type of reaction calorimeter... 

The limitations of the oxidative addition method in the preparation of trifluoromethyl derivatives appear to be those inherent in this general type of reaction. The most productive substrates have been low valent, electron-rich, coordinatively unsaturated species, preferably... 

Examination of the methods that have been used in preparing the mixed-metal clusters listed in Table I reveals that the majority have been synthesized via four general types of reaction (1) pyrolysis, (2) addition... 

After chains have been initiated, there are three general types of reaction that can occur propagation, chain transfer, and chain termination. If represents the active site, A represents the initiator, and M is a monomer unit, then the four reaction types are ... 

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