General consideration of the mechanism

R Catalyst system % trans Ref R Catalyst system % trans Ref  

As the metathesis reaction proceeds it is necessary to take account of the secondary reactions of the products in order to understand the evolution of the composition of the reaction mixture with time. There will then be another eight reactions involving fra i-pent-2-ene, and four each for cis- and lrans-but-2-ene and cis- and frans-hex-3-ene, making 32 propagation reactions in all. By assuming that the concentrations of [Mt]=CHMe and [Mt]=CHEt are the same, and by equating various ratios of rate constants, it is possible to show that a linear relationship of the type shown in Fig. 6.2 is to be expected (Leconte 1979b). 

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The oxidation of methane has already been discussed from the viewpoint of forming valuable oxygenated products, and a general consideration of the mechanism involved need not be repeated. However, a consideration of some of the experimental results which are particularly relevant and of the thermodynamics involved in the production of hydrogen according to the equation ... 

General considerations on the mechanism of C3Hg reaction over HZSM-5 and Ga- HZSH-5. The products obtained from the reaction of C2 C5 alkanes over H-ZSM-5 zeolites were nicely interpreted (3-6) according to the classical carbenlum ion theory and the non-classical theory developed for reactions occurring in superacid media where an alkane is protonated to form the carbocation species. The general scheme proposed for propane reaction over H-ZSM-5 is ... 

In section C we summarize the recent contributions under subsections. The general considerations on the mechanism of the B-Z reaction are in four subsections. Following these general considerations, we have sections C.2. Mathematical models and techniques, C.3. Experiments with different substrates, C.4. Experiments with different catalysts, and C.5. Horatian oscillations in bromate oxidations. The name horatian has recently been proposed for replacing the term chaotic. Here we simply state that throughout this article instead of chaotic oscillations, the term horatian oscillations will be used. 

Consideration of the mechanism of electroinitiated polymerization of heterocycles and related monomers is essential in order to understand why morphology should vary with the method of preparation. Let us consider the polymerization of pyrrole as being the most typical of the polyheterocycles. In the generally accepted mech-... 

In general, however, the population about any point in the domain may be well mixed only in a local neighborhood whose extent should be of interest to us. The size of this neighborhood may be estimated from physical considerations of the mechanism of relative motion between particles over a time scale small compared with the time scale in which noticeable change in the population takes place by aggregation. If the volume of mixing is very small, allowing only a very small population, then one is faced with the... 

The ultimate source of chirality in all asymmetric synthesis is nature. In this chapter we survey the most important naturally occurring chiral compounds and the ways in which they can be used. This is followed by a classification of the known methods of asymmetric synthesis and a general consideration of their mechanisms. 

In view of the multi-component nature of the Petasis reaction, a general consideration of the MCR concept is briefly presented in the next section, in order to complete the picture of the mechanism and synthetic scope of these reactions. 

Among the second- and third-row transition metal halide complexes, those of platinum have received considerable study. Both the octahedral platinum(IV) complex PtCli and the square planar platinum(II) complex PtCl have been investigated. Both complexes are substitution inert under thermal conditions, and kinetic studies of their substitution chemistry have been important in the development of a general understanding of the mechanisms of substitution reactions in transition metal chemistry. The photochemistry of PtCli" was one of the earliest such studies to be made, and the early discoveries of the photosensitive nature of platinum halides led to these salts being used in photographic processes. The subsequent decision to use a silver-based process was based more on economical rather than on technical reasons. 

There are two general theories of the stabUity of lyophobic coUoids, or, more precisely, two general mechanisms controlling the dispersion and flocculation of these coUoids. Both theories regard adsorption of dissolved species as a key process in stabilization. However, one theory is based on a consideration of ionic forces near the interface, whereas the other is based on steric forces. The two theories complement each other and are in no sense contradictory. In some systems, one mechanism may be predominant, and in others both mechanisms may operate simultaneously. The fundamental kinetic considerations common to both theories are based on Smoluchowski s classical theory of the coagulation of coUoids. 

Heat Transfer In general, the fluid mechanics of the film on the mixer side of the heat transfer surface is a function of what happens at that surface rather than the fluid mechanics going on around the impeller zone. The impeller largely provides flow across and adjacent to the heat-transfer surface and that is the major consideration of the heat-transfer result obtained. Many of the correlations are in terms of traditional dimensionless groups in heat transfer, while the impeller performance is often expressed as the impeller Reynolds number. 

The more general question of whether chemistry is reducible to quantum mechanics is more subtle and requires a consideration of the nature of ab initio calculations. According to some authors, the question even depends on the problems in the foundations of quantum mechanics 44). 

The physical interpretation of the quantum mechanics and its generalization to include aperiodic phenomena have been the subject of papers by Dirac, Jordan, Heisenberg, and other authors. For our purpose, the calculation of the properties of molecules in stationary states and particularly in the normal state, the consideration of the Schrodinger wave equation alone suffices, and it will not be necessary to discuss the extended theory. 

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