Reactions of Type

Types of antigen antibody reactions that are of analytical importance are the precipitin reaction and those at a solid-liquid interface. 

If the antigen or antibody of interest is bound to a soEd phase, such as a cell membrane, or to a synthetic particle (polystyrene or ceEulose), the protein wEl exist in a microenvironment that is dffferent from that of a protein in free solution. The water surrounding the protein is more highly ordered near the surface of the solid phase, and a condition results that is more favorable for van der Waals-London dipole-dipole interaction and coulombic bonding. This situation favors the formation of low- and high-avidity antigen antibody complexes and, hence, can provide lower detection limits for analytical applications. Some studies 

Soluble complexes Schematic diagram for precipitin reaction. 

Antibody excess All antigenic sites are covered with antibody, and lattice formation is inhibited. 

State occurs when 2 to 3 antibody molecules are present for each antigen molecule produces maximum lattice formation and therefore maximum precipitate. 

There are thousands of different chemical reactions. However these can largely be classified into one of three different categories on the basis of how the valency electrons are involved during reactions. 

Here the generalized or Lewis definition of an acid and a base is applied. Thus an add is a substance that can accept a pair of electrons and a base is a substance that donates a pair of electrons. It follows then that a metal ion, like hydrogen ion, is an acid and a ligand with its pair of electrons is a base. The formation of metal complexes and the replacement of one ligand by another or one metal by another in these systems then are examples of acid-base reactions. 

Oxidation-reduction reactions differ from acid-base reactions in that electron interchange occurs instead of electron sharing. Since metals generally 

Many reactions are known to proceed by a free radical process. This type of reaction may be considered as something between types (1) and (2). For metal complexes such reactions are often classified as oxidation-reduction reactions. For example, in the last equation above, Br is reduced to Br while Co (II) is oxidized to Co (III). 

The various types of heterogeneous reactions are shown in Table 3.3. They are broadly grouped as solid-gas, solid-liquid, solid-solid, liquid-gas, and liquid-liquid reactions. The different types included in each group are also shown in the compilation. Some representative processes have been indicated as examples. It may be pointed out that in the group of solid-liquid reactions a specific mention of what is known as autocatalytic reactions has not been made. The autocatalytic processes occur when the liquid product reacts further with the solid undergoing reaction. The dissolution of copper in dilute sulfuric acid (or aqueous ammonia) in the presence of oxygen may be cited as an example  

The cupric ions formed react further with metallic copper to form cuprous ions  

Therefore, the amount of copper dissolved will increase as the process continues. 

LEARNING GOAL Write a balanced chemical equation from the formulas of the reactants and products for a reaction determine the number of atoms in the reactants and products. 

Determine whether each of the following chemical equations is balanced or not balanced  

A great number of reactions occur in nature, in biological systems, and in the laboratory. However, there are some general patterns that help us classify most reactions into five general types. 

In a combination reaction, two or more elements or compounds bond to form one product. For example, sulfur and oxygen combine to form the product sulfur dioxide. 

Several general types of chemical reactions can occur based upon the identity of the reactants and products and/or which bonds are broken and made. The more common reactions are combination, decomposition, single displacement, double displacement, combustion, and reduction-oxidation (redox) reactions. 1 describe them all here. 

In combination reactions, two or more reactants form one product. The reaction of sodium and chlorine to form sodium chloride, 

There are four basic types of multiple reactions series, parallel, complex, and independent. These types of multiple reactions can occur by themselves, in pairs, or all together. V en there is a combination of parallel and series reactions. they are often referred to as complex reactions. 

Parallel reactions (also called competing reactions) are reactions where the reactant is consumed by two different reaction pathw-ays to form different products  

Complex reactions coupled simultaneous series and parallel 

An example of an industrially significant parallel reaction is the oxidation of ethylene to ethylene oxide while avoiding complete combustion to carbon dioxide and water. 

Series reactions (also called consecutive reactions) are reactions where the retictant forms an intermediate product, which reacts further to form another product  

An example of a series reaction is the reaction of ethylene oxide (EO) with ammonia to form mono-, di-, and triethanolamine  

We first present further examples of the types of reactions involved in two main classifications, and then a preliminary discussion of various types of reactors used. Following an examination of some factors affecting the choice of reactor, we develop design equations for some reactor types, and illustrate their use with examples. The chapter concludes with a brief introduction to trickle-bed reactors for three-phase gas-liquid-solid (catalyst) reactions. 

As indicated in Section 9.2, a fluid-fluid reaction may be considered from one of two points of view depending on its involvement in a separation process or in a reaction 

Hydrogen fluoride is very versatile in its ability to catalyze the reactions of organic chemical compounds. In what follows, reactions which have been published are listed under a number of headings. As 

As alkylation was the first reaction reported which demonstrated the truly catalytic power of hydrogen fluoride and it is the one now being used on the largest scale in industry, it is appropriate to begin the discussion of specific reactions with alkylation. 

Elsewhere the author has published examples of the use of hydrogen fluoride to catalyze the alkylation of benzene using a variety of alkylating agents (Simons, 22, 23, 24). The breadth and scope of the catalytic power of hydrogen fluoride can be better obtained by a more complete examination of the alkylations now published using this catalyst. For reasons of organization, the subject is divided into aromatic and aliphatic reactions. 

The first reactions concerned (Simons and Archer, 27) alkylation of benzene with propylene to form isopropylbenzene, with isobutene to form f-butylbenzene and di-f-butylbenzene, and trimethylethylene to form amylbenzene. Later on (Simons and Archer, 28) studied these and other reactions in more detail and showed that high yields could be obtained and that the product was not contaminated with tars or other obnoxious impurities. It was shown that the products obtained with trimethylethylene were mono- and di-f-amylbenzene, that phenyl-pentane resulted from the use of pentene-2, and that cyclohexene produced cyclohexylbenzene. Cinnamic acid reacted with benzene (Simons and Archer, 29) to form /3-phenylpropionic acid and allyl benzene reacted with benzene to form 1,2-diphenylpropane. It is interesting to note that although allyl alcohol reacted with benzene to form 1,2-diphenylpropane, the intermediate in the reaction, allylbenzene, was isolated and identified. This shows that in this case the hydroxyl reacted at a more rapid rate than the double bond. Both di- and triisobutylene reacted with phenol (Simons and Archer, 30) at 0°, when using hydrogen fluoride containing only relatively small quantities of water, to form f-butyl-benzene, but diisobutylene with 70% hydrogen fluoride produced p-f-octylphenol. Cyclohexene reacted with toluene to form cyclohexyl-toluene and octene-1 rapidly reacted with toluene to form 2-octyltoluene (Simons and Basler, 31). 

The Jackson laboratory of the du Pont Company soon became interested in the catalytic power of hydrogen fluoride. The results of its work are recorded in three excellent papers. Using acrolein as the alkylating agent and hydrogen fluoride as the catalyst, peri syntheses have been performed (Calcott et al, 32), both those that are catalyzed by sulfuric acid and others that are not. By appropriate condensation, dehydration, and reduction, perylene was obtained from phenanthrene 

13 Write a balanced equation using the correct formulas and include conditions (x, /, g, or aq) for each of the following chemical reactions  

In other examples of combination reactions, elements or compounds combine to form a single product. 

The reactions of hydrogen and oxygen to form water and carbon and oxygen to yield carbon dioxide are examples of combination reactions. A combination or synthesis reaction results when two or more substances unite to form a compound. Many other types of reactions exist. Three other common types of reactions are decomposition, single replacement, and double replacement. 

Decomposition is the opposite of combination. Decomposition takes place when a compound breaks down into two or more simpler substances. An electric current can be used to decompose water into hydrogen and oxygen  

Decomposition reactions are used to obtain pure metals from their ore. 

In a single replacement reaction, one element replaces another element in a compound. An example of a single replacement is when sodium is added to water. The reaction of sodium and water is represented by the following chemical equation  

Sodium displaces the hydrogen in the water molecule. The displaced hydrogen is liberated from the water resulting in the formation of hydrogen gas and sodium hydroxide. 

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Before we can proceed with the choice of reactor and operating conditions, some general classifications must be made regarding the types of reaction systems likely to be encountered. We can classify reaction systems into five broad types ... 

Enzymes are classified in terms of the reactions which they catalyse and were formerly named by adding the suffix ase to the substrate or to the process of the reaction. In order to clarify the confusing nomenclature a system has been developed by the International Union of Biochemistry and the International Union of Pure and Applied Chemistry (see Enzyme Nomenclature , Elsevier, 1973). The enzymes are classified into divisions based on the type of reaction catalysed and the particular substrate. The suffix ase is retained and recommended trivial names and systematic names for classification are usually given when quoting a particular enzyme. Any one particular enzyme has a specific code number based upon the new classification. 

Another type of reaction that has been studied is that of the oxidation of a double bond. In the case of triolein, Mittelmann and Palmer [309] found that, on a dilute permanganate substrate, the area at constant him pressure hrst increased and then decreased. The increase was attributed to the reaction... 

Still another type of adsorption system is that in which either a proton transfer occurs between the adsorbent site and the adsorbate or a Lewis acid-base type of reaction occurs. An important group of solids having acid sites is that of the various silica-aluminas, widely used as cracking catalysts. The sites center on surface aluminum ions but could be either proton donor (Brpnsted acid) or Lewis acid in type. The type of site can be distinguished by infrared spectroscopy, since an adsorbed base, such as ammonia or pyridine, should be either in the ammonium or pyridinium ion form or in coordinated form. The type of data obtainable is illustrated in Fig. XVIII-20, which shows a portion of the infrared spectrum of pyridine adsorbed on a Mo(IV)-Al203 catalyst. In the presence of some surface water both Lewis and Brpnsted types of adsorbed pyridine are seen, as marked in the figure. Thus the features at 1450 and 1620 cm are attributed to pyridine bound to Lewis acid sites, while those at 1540... 

All tliree types of reactions begin with adsorption of species onto a surface from the gas phase. 

There are significant differences between tliese two types of reactions as far as how they are treated experimentally and theoretically. Photodissociation typically involves excitation to an excited electronic state, whereas bimolecular reactions often occur on the ground-state potential energy surface for a reaction. In addition, the initial conditions are very different. In bimolecular collisions one has no control over the reactant orbital angular momentum (impact parameter), whereas m photodissociation one can start with cold molecules with total angular momentum 0. Nonetheless, many theoretical constructs and experimental methods can be applied to both types of reactions, and from the point of view of this chapter their similarities are more important than their differences. 

Consequently, the reaction yield F in figure B2.5.15 is shown as a fiinction of the fluence, F. At the end of a laser-pulse sequence with a typical fluence F 3 J cm, practically 100% of the CF I is photolysed. As described in section B2.5.4.3. the product-level distribution of the iodine atoms fonned in this type of reaction can be detemiined... 

Discuss (a) the acidity and (b) the substitution reactions of metal hexa-aquo cations. [MfH O) ]" (where n = 2 or 3), giving two examples of each type of reaction. Discuss the effect upon the stabilities of the -t- 2 and -f- 3 oxidation states of... 

This reaction classification allows users to browse through hits of reaction searches, thus enabling them to focus on the types of reaction in which they are interested. 

First, a quei y must be drawn using the MOL" ISIS/Draw program. By using this reaction query, a eurrent reaction search " can be performed. This type of reaction retrieval compares the starting material and the product of the reaction query with all the reactions in the CIRX database. Both query structures must match exactly, including the implicit hydrogen atoms not shown in the reaction query. In this case, one hit is found in the CIRX databases. 

Figure 10.3-4. Trained networks of 626 pyrazole building reactions, a) The trained network after classifying all 626 reactions, Light gray neurons that have received known reactions black neurons that have received reactions considered to have a low yield dark gray conflict neurons obtaining both types of reactions white empty neurons that have not received a reaction at all b) Each conflict neuron is assigned to the most populated class within it, and each empty neuron to the most populated class in its neighborhood.

A di awback is that the evaluation scheme for modeling the course of chemical reactions, as set up by the initial developer, is difficult to change as any alteration might have unexpected consequences for other types of reactions. Thus, it is a beautiful edifice that has basically not been changed since the early Nineties. 

Transition state theory calculations present slightly fewer technical difficulties. However, the accuracy of these calculations varies with the type of reaction. With the addition of an empirically determined correction factor, these calculations can be the most readily obtained for a given class of reactions. 

Strike couldn t find any decent nitroethane synths except for a couple of Chemical Abstract articles. One suggestion is to treat 1.5 moles of Na2C02 with 1 mole of sodium ethylsulfite and 0.0645 moles of K2CO3 at 125-130°C. Another route would be to use silver nitrate and ethyl iodide [8 p119]. This type of reaction has been used to nitrate other paraffins and would probably work. 

Alcohols can be synthesized by the addition of carbanions to carbonyl compounds (W.C. Still, 1976) or epoxides. Both types of reactions often produce chiral centres, and stereoselectivity is an important aspect of these reactions. 

When the substituent on the nitrogen atom is -CH-C-R, R = H, Me, Rj = Ph. Me. two types of reactions can occur, according to the nature of the medium in which the base is allowed to react ... 

A quote from a biochemistry text IS instructive here This IS not an easy reaction in or game chemistry It is how ever a very important type of reaction in metabolic chemistry and is an integral step in the oxidation of car bohydrates fats and several ammo acids G L Zubay Biochemistry 4th ed William C Brown Publishers 1996 p 333... 

Several types of reactions are commonly used in analytical procedures, either in preparing samples for analysis or during the analysis itself. The most important of these are precipitation reactions, acid-base reactions, complexation reactions, and oxidation-reduction reactions. In this section we review these reactions and their equilibrium constant expressions. 

The most important types of reactions are precipitation reactions, acid-base reactions, metal-ligand complexation reactions, and redox reactions. In a precipitation reaction two or more soluble species combine to produce an insoluble product called a precipitate. The equilibrium properties of a precipitation reaction are described by a solubility product. 

Other types of reactions can be used to chemically separate an analyte and interferent, including precipitation, electrodeposition, and ion exchange. Two important examples of the application of precipitation are the... 

The following experiments may he used to illustrate the application of titrimetry to quantitative, qtmlitative, or characterization problems. Experiments are grouped into four categories based on the type of reaction (acid-base, complexation, redox, and precipitation). A brief description is included with each experiment providing details such as the type of sample analyzed, the method for locating end points, or the analysis of data. Additional experiments emphasizing potentiometric electrodes are found in Chapter 11. 

Type of Reaction Mediator Electrochemically Generated Reagent G en erato r-E1 ectrod e Reaction Representative Reaction ... 

Balancing a redox reaction is often more challenging than balancing other types of reactions, because we must balance both electrons and elements. Perhaps the simplest way to balance a redox reaction is by the half-reaction method, which consists of the following steps. 

Acid chlorides are generally more reactive than the parent acids, so polyester formation via reaction 5 in Table 5.3 can be carried out in solution and at lower temperatures, in contrast with the bulk reactions of the melt as described above. Again, the by-product molecules must be eliminated either by distillation or precipitation. The method of interfacial condensation, described in the next section, can be applied to this type of reaction. 

Step-growth polymerizations can be schematically represented by one of the individual reaction steps VA + B V —> Vab V with the realization that the species so connected can be any molecules containing A and B groups. Chain-growth polymerization, by contrast, requires at least three distinctly different kinds of reactions to describe the mechanism. These three types of reactions will be discussed in the following sections in considerable detail. For now our purpose is to introduce some vocabulary rather than develop any of these beyond mere definitions. The principal steps in the chain growth mechanism are the following ... 

Uses. Boron triduoride is an excellent Lewis acid catalyst for numerous types of organic reactions. Its advantages are ease of handling as a gas and the absence of undesirable tarry by-products. As an electrophilic molecule, it is an excellent catalyst for Friedel-Crafts and many other types of reactions (63-65) (see Friedel-craftsreactions). 

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