Percentage atom economy

One of the fundamental and most important principles of Green Chemistry is that of atom economy. This essentially is a measure of how many atoms of reactants end up in the final product and how many end up in byproducts or waste. The percentage atom economy can be calculated as 100 times the relative molecular mass (RMM) of all atoms used to make wanted product divided by the RMM of all reactants. Box 1.2. The real benefit of atom economy is that it can be calculated at the reaction planning stage from a balanced reaction equation. Taking the following theoretical reaction ... 

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 ... 

It is often difficult to know the structures of all the by-products therefore, the percentage atom economy may be determined by dividing the molecular formula weight (MFW) of the desired product by the sum of the MFWs of all the reactants and multiplying by 100. 

The percentage atom economy of this reaction is 44.14. This means that 44.14% of the mass of the reactants ends up in the desired product. 

The percentage yield or percentage atom economy is a widely reported quantitative metric for evaluating a microfluidic synthesis route and comparing it with conventional-scale synthesis. In the case of parallel reactions, the evaluation criterion with respect to obtaining the desired product is the percentage selectivity. The figures of merit are defined below ... 

The elimination reaction is not very atom-economical. The percentage atom economy is 35.30%. In fact this is least atom-economical of all the above reactions. 

The percentage yield or percentage atom economy is a widely reported quantitative metric for evaluating... 

L9.96 Waste reduction is an important goal of the green chemistry movement. In many chemical syntheses in industry, not all the atoms required for the reaction appear in the product. Some end up in by-products and are wasted. Atom economy is the use of as few atoms as possible to reach an end product and is calculated as a percentage, using atom economy = (mass of desired product obtained)/(nrass of all reactants consumed) X 100%. 

Another method for determining the efficiency of a chemical reaction is atom economy. Atom economy is a method of determining the efficiency with which raw materials (reactants or feedstocks) are used regardless of the percentage yield obtained in the reaction. 

An even more precise measure of the atom economy of the reaction is the mass percentage of reactants used in the final product. By dividing that number by the total mass of reactants, a numerical measure of atom economy can be obtained. That is ... 

Barry Trost of Stanford University published the first formal green metric in 1991 in Science. Trost s idea, atom economy, measures the percentage ratio of the total mass of the products to starting materials (Equation 13.2).26... 

It is instructive to compare the atom economies of the two pathways. Atom economy is a measure of the efficiency of a chemical process, defined in percentage terms as x (formula wt. of atoms utilized)/(formula wt. of all reactants). For the old six-step ibuprofen synthesis the atom economy was only 40% (with MeC02H, EtOH, NaCl, Et0C02H, 2H2O and NH3 as waste). This is dramatically improved to 77% for the new three-step route with only MeC02H as a by-product from the first step. Recovery and use of this increases the atom economy to 99%. Additionally, the catalytic amounts of HF and Pd complex used in the BHC process are recovered and reused, whereas stoichiometric quantities of AICI3 hydrate were produced as waste by the old route. 

The atom economy (AE, as percentage) was calculated considering the mass-balance of a process related to its stoichiometric equation, that is, the percentage of atoms of the reagent that end up in the product ... 

Atom efficiency the percentage yield (molar flow of the desired product divided by the molar flow of the limiting reactant, taking into account the stoichiometry of the reaction) multiplied by the atom economy. It could be used to replace yield and A E. Eor example, AE could be 100% and yield 5%, making this a not very green reaction. 

Reaction mass efficiency (RME) the percentage of the mass of the reactants that remains in the product. It takes into account the atom economy, yield and reactant stoichiometry. 

Reaction mass efficiency (RME) is a metric that was first introduced by Curzons et al. [4] as a means of including the concept of atom economy (AE), while adding yield and the reactant stoichiometry. RME is defined as the percentage of the mass of the reactants that remain in the product. There are two ways to calculate RME. 

The new process is an example of atom economy, a phrase that means that a high percentage of the atoms from the starting materials end up in the product. 

Industrial processes are being designed that are based on the concept of atom economy. Atom economy means that close attention is paid to the design of chemical reactions so that all or most of the atoms that are starting materials in the process are converted into molecules of the desired product rather than into wasted by-products. Atom economy in the industrial world is the equivalent of ensuring that a chemical reaction proceeds with a high percentage yield in a classroom laboratory experiment. 

Green chemistry consists of chemicals and chemical processes designed to reduce or eliminate impacts on the environment. The use and production of these chemicals may involve reduced waste products, non-toxic chemicals, and improved efficiency. Industrial chemists evaluate chemical pathways and their economic and environmental costs by calculating the relative efficiency of the chemical reactions involved. Percentage yield provides a means of comparison of the theoretical and actual quantity of product, and used to be the main way of evaluating reaction efficiency. However, calculation of atom economy has become a more important means... 

Finding the eoneentration of an aeid solution Manufaeturing halogens and their eompounds Hydrochloric acid -an industrial success Concentration of solutions (titrations) Percentage of yield and atom economy (atom economy)... 

Nueleophilic substitution reaetion mechanism How do halogenoalkanes differ in reactivity Making of halogenalkane Treasures of the sea Halogenalkanes Percentage yield and atom economy (percentage yield)... 

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