Formal Homogeneous Catalytic Reactions

It wiU be stressed that agreement of the macrokinetic law with the expression obtained from the formal scheme of a homogeneous catalytic reaction is yet no proof that the reaction mechanism satisfying this scheme is correct. 

In many homogeneous catalytic reactions, old bonds are broken by OA, and new bonds are formed by insertion and RE. A few representative examples that are of relevance in catalysis are shown by reactions 2.3.2.1-2.3.2.4. As mentioned earlier, curly arrow formalism is used for ease of understanding. Reaction 2.3.2.1 is of course an OA reaction. 

The homogeneous catalytic decomposition of hydrogen peroxide (H2O2) (with Fe ions as catalyst) in a batch reactor can be formally described by a first-order reaction ... 

In this chapter we consider some problems of the formal kinetics of homogeneous catalytic and enzymatic reactions. Since many public editions are devoted to the kinetics of chemical and enzymatic reactions, here we revise briefly only general problems. A great attention is given to sections directly associated with the specific problems of catalysis. The theory of elementary acts of chemical and enzymatic processes is presented in Giapters 4 and 6. 

Almost all homogeneous catalytic processes involve a relatively small set of typical reactions. Here we discuss some of the more important ones. In many cases we follow the curly arrow formalism of organic chemistry, as it helps to see where the new bonds are formed and where the old bonds are broken. However, it must be remembered that this formalism need not necessarily represent the actual mechanism. 

The hydrosilylation reaction is one of those catalytic reactions where the formal dividing line between homogeneous and heterogeneous catalysis can sometimes be blurred. In some hydrosilylation... 

As mentioned, complexity can also arise by a combination of homogeneous and catalytic steps in a single reaction. The approach to such a reaction need not follow the formal procedure outlined for complex reactions in general. It tends to be system specific, and we illustrate in Example 5.S an approach that can be modified as required to suit individual systems. 

The maintenance of a supported liquid layer in gas-phase reactions is also important in other heterogeneous catalytic applications, such as the Bayer/Hoechst process for vinyl acetate manufacture. However, in these systems, the catalytic metal is reduced to the metallic state, leading to significant mechanistic differences from the formally related homogeneous Wacker-type alkene oxidation/acetoxylation processes (section 11.7.7.3). 

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