Atom economy concept

Using benzene typical selectivities of around 65% are obtained commercially whilst for butene it is approximately 55%. If we multiply the theoretical atom economies by these figures we obtain practical atom economies of 28.7% for the benzene route and 35.6% for butene. This is a useful illustration of how the atom economy concept is a valuable additional tool in measuring overall reaction efficiency, and how good atom economy can compensate for poorer yields or selectivities. 

The atom utilization [13-18], atom efficiency or atom economy concept, first introduced by Trost [21, 22], is an extremely useful tool for rapid evaluation of the amounts of waste that will be generated by alternative processes. It is calculated by dividing the molecular weight of the product by the sum total of the molecular weights of all substances formed in the stoichiometric equation for the reaction involved. For example, the atom efficiencies of stoichiometric (Cr03) vs. catalytic (02) oxidation of a secondary alcohol to the corresponding ketone are compared in Fig. 1.1. 

I m teaching more the inorganic section and materials, nonetheless I had to revise on some mechanisms, such as polymerization mechanisms. The need to balance chemical equations for the purposes of teaching the atom economy concept forced me to relearn and strengthen my understanding of the fundamentals, particularly for reduction and oxidation-type reactions, where by-products are not often declared in the literature and in textbooks. 

This is a very low atom efficiency, reflecting the large mass of undesired product that is formed, and the strong desire for carbon capture as an opportunity to minimize air pollution. In addition, the atom economy concept does not take into account the use of energy, auxiliaries, or catalysts and the toxicity of the waste, and in this case, the reaction is impacted by the high temperature required. 

In Chapter 1 the concept of atom economy was discussed as a design tool. Similarly in Chapter 2 the term E-factor was introduced as a measure of the amount of by-products formed per unit weight of product. Unlike atom economy the E-factor is determined from an actual process or can be extrapolated from laboratory work. As a valuable extension to the E-factor concept Sheldon has proposed an Environmental Quotient which is the product of the E-factor and a by-product unfriendliness ... 

Trost articulated the concept of atom economy, which characterizes the greenness of a synthetic process by calculating the number of atoms from aU of the reactants that make it into the final product. Even though this concept is an important part of the overall green chemistry approach it does not address the hazard associated with the final product. 

One of the major themes in the Brundtland Report was a concept now known in green chemistry as atom economy (also sometimes known as atom utilization), the notion that chemical manufacturing should attempt to conserve as much of the raw materials (and, hence, atoms) with which it begins as possible and to prevent losing materials (and, hence, atoms) to the environment during manufacturing processes. 

As noted above, a knowledge of the stoichiometric equation allows one to predict the theoretical minimum amount of waste that can be expected. This led to the concept of atom economy [8] or atom utilization [9] to quickly assess the environmental acceptabihty of alternatives to a particular product before any experiment is performed. It is a theoretical number, that is, it assumes a chemical yield of 100% and exactly stoichiometric amounts and disregards substances which do not appear in the stoichiometric equation. 

While the concept of atom economy is simple, unlike the E factor it does not take into account the actual yield or stoichiometry (actual masses or molar excesses)... 

This chapter outlines the principles of green chemistry, and explains the connection between catalysis and sustainable development. It covers the concepts of environmental impact, atom economy, and life-cycle analysis, with hands-on examples. Then it introduces the reader to heterogeneous catalysis, homogeneous catalysis, and biocatalysis, explaining what catalysis is and why it is important. The last two sections give an overview of the tools used in catalysis research, and a list of recommended books on specialized subjects in catalysis. 

The concept of atom economy, introduced by Barry Trost in 1991, is similar to that of the. E-factor [12]. Here one considers how many and which atoms of the reactants are incorporated into the products. With these two concepts, we can evaluate chemical reactions to get a quantitative result. 

Examine the list of the 12 principles of green chemistry shown at the beginning of this chapter. Which of these principles relate to the concepts of atom economy, the E-factor, and the environmental quotient Q ... 

The move toward catalytic reactions is reflected in the increase in the number of chapters in this book on the topic compared to the first edition. The trend has been observed by noted chemists in the previous decade. Professor Seebach, for example, in 1990 stated the primary center of attention for all synthetic methods will continue to shift toward catalytic and enantioselective variants indeed, it will not be long before such modifications will be available for every standard reaction. 6 Professor Trost in 1995 was a little more specific with catalysis by transition metal complexes has a major role to play in addressing the issue of atom economy—both from the point of view of improving existing processes, and, most importantly, from discovering new ones. 7 However, the concept can be extended to biological and organic catalysts and to those based on transition metals. 

Many ruthenium-catalyzed nonmetathesis C-C bond formation reactions in aqueous media are of high efficiency and exemplify the concept of atom-economy [30]. The vast majority of the reactions are on alkynes. 

Over the last twenty years, the tandem process involving transition metal-promoted cyclization reactions initiated or determined by a Michael addition has attracted an increasing interest in organic chemistry. The diversity of examples discussed in this work demonstrates the high potential of these tandem reactions for the efficient one-pot synthesis of complex structures with limiting catalysts and remarkable atom economy. It is expected that the development of further useful new sequences founded on this concept will be developed in the near future. 

This discrepancy therefore necessitates the introduction of the concept of atom economy. Atom economy is an assessment in which one looks at all the reactants to measure the degree of their incorporation in the product. Thus, if all the reactants are completely incorporated into the product, the synthetic pathway is said to be 100% atom economical because it will not generate waste. The atom economy is calculated with the following equation (seeTrost, 1991) ... 

The concept of atom economy was developed by B. M. Trost which deals with chemical reactions that do not waste atoms. Atom economy describes the conversion efficiency of a chemical process in terms of all atoms involved. It is widely used to focus on the need to improve the efficiency of chemical reactions. 

A logical extension of B. M. Trost s concept of atom economy is to calculate the percentage atom economy. This can be done by taking the ratio of the mass of the utilized atoms to the total mass of the atoms of all the reactants and multiplying by 100. 

R. A. Sheldon has developed a similar concept called percentage atom utilization. For instance, the percentage atom economy and percentage atom utilization calculation for the oxidation reaction of benzene to maleic anhydride is given below ... 

Chapter 1 is devoted to exploring strategies involved in organic synthesis. It seeks to explain concepts like retrosynthetic analysis, atom economy, umpolung approach, click chemistry and asymmetric synthesis. On the basis of interesting and relevant examples, protection and deprotection of different functional groups are explained and the most probable mechanism is also mentioned for important reactions. 

The Invention and Commercialization of a New Family of Insecticides Design and Application of Surfactants for Carbon Dioxide The Concept of Atom Economy... 

Green chemistry does not have to be complicated, but it does need to be intentional. Faculty members should look for opportunities to introduce green chemistry concepts and examples into the classroom and the laboratory. A simple example is atom economy, which is a natural fit when discussing the basic types of organic reactions. Addition and rearrangement reactions inherently have a higher atom economy than elimination and substitution reactions. The same concept of atom economy can be introduced into general chemistry in discussions of mass balance. 

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