Other Ways to Classify Reactions

OBJECTIVE To consider additional classes of chemical reactions. 

So far in this chapter we have classified chemical reactions in several ways. The most commonly used of these classifications are 

However, there are still other ways to classify reactions that you may encounter in your future studies of chemistry. We will consider several of these in this section. 

Many chemical reactions that involve oxygen produce energy (heat) so rapidly that a flame results. Such reactions are called combustion reactions. We have considered some of these reactions previously. For example, the methane in natural gas reacts with oxygen according to the following balanced equation  

There are many combustion reactions, most of which are used to provide heat or electricity for homes or businesses or energy for transportation. Some examples are  

A chemical reaction involving oxygen as one of the reactants that produces enough heat so that a flame results 

Classes of reactions. Combustion reactions are a special type of oxidation-reduction reaction. 

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Other Ways to Classify Reactions 189 Chapter Review 193... 

What are three other ways to classify oxidation-reduction reactions ... 

One way to classify EGBs is according to the atom to which proton transfer takes place, typically nitrogen, oxygen or carbon. As in other proton transfer reactions, proton transfer to/from heteroatoms (N or O) is generally much faster than to/from carbon when comparing reactions... 

Copper is the third most abundant metallic element in the human body, following iron and zinc. It also occurs in all other forms of life and it plays a role in the action of a multitude of enzymes that catalyze a great variety of reactions. There are two cross-cutting ways to classify the copper-containing enzymes (1) According to the structural and spectroscopic characteristics of the copper complex at the active site. (2) According to the function of the enzyme. We shall base discussion on the first of these, with allusions to function as we go along. 

The measurement and identification of the hydrated-electron spectrum led to a major increase in activity. It was now possible to directly measure the rate of hydrated-electron reactions with a large variety of inorganic and organic species. With these data, it was then possible to classify reactions in ways that had not been possible previously. It was possible to show that some reactions were diffusion controlled and to suggest that there were some reactions that were even faster than diffusion controlled (at least if one assumed normal reaction radii). Conductivity measurements could directly measure the mobility of ions and could provide information that was unavailable in other ways. ... 

And, while there are many redox reactions that do not involve free elements, we ll focus here on the many others that do. One way to classify these is by comparing the numbers of reactants and products. By that approach, we have three types ... 

In many redox reactions, such as those in Sample Problem 4.9, atoms occur as an element on one side of an equation and as part of a compound on the other. While there are many redox reactions that do not involve free elements, we ll focus here on the many others that do. One way to classify these is by comparing the numbers of reactants and products. With that approach, we have three types—combination, decomposition, and displacement one other type involving elements is combustion. In this section, we survey each type with several examples. 

There are several ways to classify chemical reactions, and none are entirely satisfactory. The classification scheme described in this section provides an introduction to five basic types of reactions synthesis, decomposition, singledisplacement, double-displacement, and combustion reactions. In later chapters, you will be introduced to categories that are useful in classifying other types of chemical reactions,... 

For example, when the network shown in Figure 3 was first created, the direction of the links to the variable class were reversed. This network was created to classify reactions on the basis of attribute values, i.e., the value of class should be determined by the attribute values, and not the other way around. The solution is manually to reverse the causal links. 

There are many ways to categorize the oxidation of double bonds as they undergo a myriad of oxidative transformations leading to many product types including epoxides, ketones, diols, endoperoxides, ozonides, allylic alcohols and many others. Rather than review the oxidation of dienes by substrate type or product obtained, we have chosen to classify the oxidation reactions of dienes and polyenes by the oxidation reagent or system used, since each have a common reactivity profile. Thus, similar reactions with each specific oxidant can be carried out on a variety of substrates and can be easily compared. 

There are, however, other ways in which excited-state decay can be accelerated by other species, which cannot be classified as reversible chemical reactions. Such processes can be represented generally by (1.12), where a star denotes electronic excitation. The excited state of A is said to be quenched by B. If B is converted into an electronically excited state (B ) during the process, an overall transfer of electronic energy takes place between the excited and unexcited partners of the interaction. 

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