Answer the following questions. 1. What are the benefits of green chemistry? 2. How can non-beneficial chemical reactions be minimized and stopped? 3. Discuss how chemical engineering applies the concept of limiting reagent and excess reagent in a reaction.

Chemistry: The Molecular Science
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ISBN:9781285199047
Author:John W. Moore, Conrad L. Stanitski
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Green Chemistry and Atom Economy


The purposeful design of chemical products and processes that minimize the use of environmentally hazardous substances and the generation of waste is known as green chemistry. Green chemistry is a philosophical approach that is being applied to many areas of science and technology, and its practice is summarized by guidelines known as the “Twelve Principles of Green Chemistry” (see details at this website (http://openstaxcollege.org/l/16greenchem) ). One of the 12 principles is aimed specifically at maximizing the efficiency of processes for synthesizing chemical products. The atom economy of a process is a measure
of this efficiency, defined as the percentage by mass of the final product of a synthesis relative to the masses of all the reactants used: atom economy = mass of product/mass of reactants × 100%
Though the definition of atom economy at first glance appears very similar to that for percent yield, be aware that this property represents a difference in the theoretical efficiencies of different chemical processes. The percent yield of a given chemical process, on the other hand, evaluates the efficiency of a process by comparing the yield of product actually obtained to the maximum yield predicted by stoichiometry. The synthesis of the common nonprescription pain medication, ibuprofen, nicely illustrates the success of a green chemistry approach (Figure 4.14). First marketed in the early 1960s, ibuprofen was produced using a six-step synthesis that required 514 g of reactants to generate each mole (206 g) of ibuprofen, an atom economy of 40%. In the 1990s, an alternative process was developed by the BHC Company (now BASF Corporation) that requires only three steps and has an atom economy of ~80%, nearly twice that of the original
process. The BHC process generates significantly less chemical waste; uses less hazardous and recyclable materials; and provides significant cost savings to the manufacturer (and, subsequently, the consumer). In
recognition of the positive environmental impact of the BHC process, the company received the Environmental Protection Agency’s Greener Synthetic Pathways Award in 1997.

Answer the following questions.

1. What are the benefits of green chemistry?
2. How can non-beneficial chemical reactions be minimized and stopped?
3. Discuss how chemical engineering applies the concept of limiting reagent and excess reagent in a reaction.

How Sciences Interconnect
Green Chemistry and Atom Economy
The purposeful design of chemical products and processes that minimize the use of environmentally
hazardous substances and the generation of waste is known as green chemistry. Green chemistry is a
philosophical approach that is being applied to many areas of science and technology, and its practice is
summarized by guidelines known as the "Twelve Principles of Green Chemistry" (see details at this website
(http://openstaxcollege.org//16greenchem) ). One of the 12 principles is aimed specifically at maximizing
the efficiency of processes for synthesizing chemical products. The atom economy of a process is a measure
of this efficiency, defined as the percentage by mass of the final product of a synthesis relative to the masses
of all the reactants used:
mass of product
x 100%
atom economy
mass of reactants
Though the definition of atom economy at first glance appears very similar to that for percent yield, be
aware that this property represents a difference in the theoretical efficiencies of different chemical processes.
The percent yield of a given chemical process, on the other hand, evaluates the efficiency of a process by
comparing the yield of product actually obtained to the maximum yield predicted by stoichiometry.
The synthesis of the common nonprescription pain medication, ibuprofen, nicely illustrates the success of a
green chemistry approach (Figure 4.14). First marketed in the early 1960s, ibuprofen was produced using
a six-step synthesis that required 514 g of reactants to generate each mole (206 g) of ibuprofen, an atom
economy of 40%. In the 1990s, an alternative process was developed by the BHC Company (now BASF
Corporation) that requires only three steps and has an atom economy of -80%, nearly twice that of the original
process. The BHC process generates significantly less chemical waste; uses less-hazardous and recyclable
materials; and provides significant cost-savings to the manufacturer (and, subsequently, the consumer). In
recognition of the positive environmental impact of the BHC process, the company received the Environmental
Protection Agency's Greener Synthetic Pathways Award in 1997.
Transcribed Image Text:How Sciences Interconnect Green Chemistry and Atom Economy The purposeful design of chemical products and processes that minimize the use of environmentally hazardous substances and the generation of waste is known as green chemistry. Green chemistry is a philosophical approach that is being applied to many areas of science and technology, and its practice is summarized by guidelines known as the "Twelve Principles of Green Chemistry" (see details at this website (http://openstaxcollege.org//16greenchem) ). One of the 12 principles is aimed specifically at maximizing the efficiency of processes for synthesizing chemical products. The atom economy of a process is a measure of this efficiency, defined as the percentage by mass of the final product of a synthesis relative to the masses of all the reactants used: mass of product x 100% atom economy mass of reactants Though the definition of atom economy at first glance appears very similar to that for percent yield, be aware that this property represents a difference in the theoretical efficiencies of different chemical processes. The percent yield of a given chemical process, on the other hand, evaluates the efficiency of a process by comparing the yield of product actually obtained to the maximum yield predicted by stoichiometry. The synthesis of the common nonprescription pain medication, ibuprofen, nicely illustrates the success of a green chemistry approach (Figure 4.14). First marketed in the early 1960s, ibuprofen was produced using a six-step synthesis that required 514 g of reactants to generate each mole (206 g) of ibuprofen, an atom economy of 40%. In the 1990s, an alternative process was developed by the BHC Company (now BASF Corporation) that requires only three steps and has an atom economy of -80%, nearly twice that of the original process. The BHC process generates significantly less chemical waste; uses less-hazardous and recyclable materials; and provides significant cost-savings to the manufacturer (and, subsequently, the consumer). In recognition of the positive environmental impact of the BHC process, the company received the Environmental Protection Agency's Greener Synthetic Pathways Award in 1997.
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