Family of reactions

The second family of reactions are those in which the aryl group acts as a sub stituent and affects the reactivity of a functional unit to which it is attached... 

The main disadvantage seems to be the lack of a standard, universally applicable method for fitting multidimensional non-quadratic surfaces. Each family of reactions is a special case. 

In this section indirect methods will be explored. One was given in Section 3.6. There, data were presented for two members of a large family of reactions of the phenyl radical with organic halides. Pairs of halides were used, and the ratio of two competing products was determined. Expanding the general scheme of Eq. (5-1) further, to use a pair of competing traps, we have... 

The route from kinetic data to reaction mechanism entails several steps. The first step is to convert the concentration-time measurements to a differential rate equation that gives the rate as a function of one or more concentrations. Chapters 2 through 4 have dealt with this aspect of the problem. Once the concentration dependences are defined, one interprets the rate law to reveal the family of reactions that constitute the reaction scheme. This is the subject of this chapter. Finally, one seeks a chemical interpretation of the steps in the scheme, to understand each contributing step in as much detail as possible. The effects of the solvent and other constituents (Chapter 9) the effects of substituents, isotopic substitution, and others (Chapter 10) and the effects of pressure and temperature (Chapter 7) all aid in the resolution. 

We shall now derive a result first obtained24 by more complicated mathematics than the alternative25 given here. The 1992 Nobel Prize in Chemistry was awarded to R. A. Marcus for developing this work. We construct a family of reaction profiles (see Fig. 10-8) for different members of the series. The horizontal axis is now used to show the relative locations of the transition states. The larger AG is, the closer to product the transition states lies, and the larger AG is. By assuming that the sensitivity coefficient... 

The Marcus treatment applies to both inorganic and organic reactions, and has been particularly useful for ET reactions between metal complexes that adopt the outer-sphere mechanism. Because the coordination spheres of both participants remain intact in the transition state and products, the assumptions of the model are most often satisfied. To illustrate the treatment we shall consider a family of reactions involving partners with known EE rate constants. 

The initial four families of reactions were chosen to test the above linear relationship for several reasons. All four decompose... 

Hydrolysis is one of a family of reactions which leads to the transformation of pollutants. Under environmental conditions, hydrolysis occurs mainly with organic compounds. Hydrolysis is a chemical transformation process in which an organic RX reacts with water, forming a new molecule. This process normally involves the formation of a new carbon-oxygen bond and the clearing of the carbon-X bond in the original molecule ... 

P32 (Fill-the-gap statement in fourth paragraph) Thus encouraged, we envision a special style of organic synthesis, one based on an entire family of reactions for which water is the best solvent. ... 

Benzoylation constitutes the first step of the Reissert and Reissert-Henze reactions of quinoline and quinoline 1-oxides respectively, but as the benzoyl intermediates are rarely isolated this topic will be dealt with in Section 2.05.4.7. Pyridine and quinoline N-oxides react easily with p-toluenesulfonyl chloride in pyridine solution to give a variety of products which closely resemble those from the last two reactions discussed (equations 22 and 23). These belong to a family of reactions that have considerable synthetic potential and much mechanistic interest (B-67MI20501) which will be discussed collectively in Section 2.05.4.5. 

The hydrogenation reaction mechanisms may be classified according to the role played by the substrate in the coordination sphere of the metal catalyst. Thus, those mechanisms proceeding with coordination of the substrate to the metal center can be labeled as inner-sphere mechanisms, whereas those with no direct coordination of the substrate to the metal center can be labeled as outer-sphere reaction mechanism (see Scheme 4). Hydrogenation reactions belonging to the so-called hydrogen transfer reactions (where the hydrogen source is usually an alcohol) can be also classified within these two families of reaction... 

Salvage pathway. A family of reactions that permits nucleosides or purine and pyrimidine bases resulting from the partial breakdown of nucleic acids, to be reutilized in nucleic acid synthesis. 

In short, photochemical reactions should be classified as photoisomerization, photodissociation, photosubstitution, etc. Definite efforts should be made to use the terms already developed by inorganic and organic chemists to describe transformations involving the particular stoichiometric changes. There already exists enough descriptive names to classify reactions and it would be a pity to allow photochemistry to spawn another, independent family of reaction names. ... 

The reaction dimensions that have so far been found necessary (though this list will doubtless increase as more families of reaction are analyzed by NBT) are bond formation/breaking, proton transfer, geometry change, and proton transfer (between electronegative atoms). The use of proton transfer between... 

Once the [3+2] mechanism was accepted as the operative one, to investigate the transition states associated with the formation of the osmate ester in a chiral system, one must take into account all of the different ways that an olefin can approach the catalyst. These different paths were classified according to the criteria shown in Fig. 12. The olefin binds to an axial and to an equatorial oxygen, providing three different families of reaction paths labeled as regions A, B and C. When the olefin has one substituent, it can be placed in four different orientations , which are labeled as I, II, III, IV. The... 

In summary, catalytic C-H transformations in small unfunctionalized alkanes is a technically very important family of reactions and processes leading to small olefins or to aromatic compounds. The prototypical catalysts are chromia on alumina or vanadium oxides on basic oxide supports and platinum on alumina. Reaction conditions are harsh with a typical minimum temperature of 673 K at atmospheric pressure and often the presence of excess steam. A consistent view of the reaction pathway in the literature is the assumption that the first C-H abstraction should be the most difficult reaction step. It is noted that other than intuitive plausibility there is little direct evidence in heterogeneous reactions that this assumption is correct. From the fact that many of these reactions are highly selective toward aromatic compounds or olefins it must be concluded that later events in the sequence of elementary steps are possibly more likely candidates for the rate-determining step that controls the overall selectivity. A detailed description of the individual reactions of C2-C4 alkanes can be found in a comprehensive review [59]. 

The next step in the reaction kinetics analysis is to choose for each family of reactions (i.e., adsorption/desorption, oligomerization//-) -scission, isomerization, and hydride transfer) whether to parameterize the kinetic model in terms of either the forward or the reverse rate constant (kj,for or khrey) since the ratio of the forward and the reverse rate constants must equal the known value of Kit q ... 

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