green chemistry is very important to mitigate the environmental footprint of chemical processes on air, water and soil.
Redesigning a chemical synthesis process can eliminate a large amount of waste products and pollution and reduce the amount of resources used in the process.
examine the important concept of efficient atomic (EA). This concept was developed by Barry Trost of Stanford University and was awarded the Presidential Green Chemistry Challenge Award in 1998 (prize established by the U.S. EPA in 1996 to reward outstanding examples of green chemistry). This concept invokes the principle 2 of green chemistry, wondering how many of the atoms in the molecules of the reagents are incorporated into the desired end product and those who are lost. In fact, in the process of synthesis of a product, not all atoms in the molecules of the reactants in the end product desired. Many of these atoms may end up in unwanted molecules product (products) that are often considered as waste. These waste products can be toxic and cause considerable environmental damage if not disposed of properly (with additional energy costs). In the past, these waste products and other chemical processes have not been disposed of properly and they have produced environmental disasters.
The following is an example of how to calculate the parameter EA, using the production of the desired compound, l '1- bromobutano , from 1-butanol:
1-butanol + sodium bromide + sulfuric acid = 1 - bromobutano + water + sodium hydrogen
If we look at this reaction, we see that with ' 1-bromobutano not only form the desired product but also unwanted by-products of hydrogen sodium and water. The reaction is colored red all the atoms of the reagents that are incorporated into the desired product, while the atoms that become part of the waste products are represented in black . Adding the atomic mass of all atoms in red left arrow reaction (reagents) we get: 4C + 9H 1BR + = 137 amu (the mass of the desired product). The sum of the atomic masses of all atoms of the reactant molecules (red and black) instead is: 4C + 12H + + 5O 1BR + 1NO + 1S = 275 uma. If we divide the mass of the atoms used to generate the desired product to that of all the atoms of the reactant molecules, we obtain the atomic efficiency parameter (multiplied by 100 to obtain the result expressed as a percentage) that, in this case is 50%.
EA% = 137: 275 x 100 = 50%
So, for this reaction, half the mass of all atoms in the reagents is lost and only half is actually incorporated into the desired product. This is a way to determine the efficiency of a reaction. With this information you can groped to explore other methods of synthesis of 1-bromobutano to ensure a higher percentage of atomic efficiency.
Now an exercise for you on the synthesis of ibuprofen, a drug that there is no doubt that you have used in some unpleasant moments of your life.
Redesigning a chemical synthesis process can eliminate a large amount of waste products and pollution and reduce the amount of resources used in the process.
examine the important concept of efficient atomic (EA). This concept was developed by Barry Trost of Stanford University and was awarded the Presidential Green Chemistry Challenge Award in 1998 (prize established by the U.S. EPA in 1996 to reward outstanding examples of green chemistry). This concept invokes the principle 2 of green chemistry, wondering how many of the atoms in the molecules of the reagents are incorporated into the desired end product and those who are lost. In fact, in the process of synthesis of a product, not all atoms in the molecules of the reactants in the end product desired. Many of these atoms may end up in unwanted molecules product (products) that are often considered as waste. These waste products can be toxic and cause considerable environmental damage if not disposed of properly (with additional energy costs). In the past, these waste products and other chemical processes have not been disposed of properly and they have produced environmental disasters.
The following is an example of how to calculate the parameter EA, using the production of the desired compound, l '1- bromobutano , from 1-butanol:
1-butanol + sodium bromide + sulfuric acid = 1 - bromobutano + water + sodium hydrogen
CH 3 CH 2 CH 2 CH 2 OH + Na + Br H 2 SO 4 = CH 3 CH 2 CH 2 CH 2 Br + NaHSO 4 + H 2 O
If we look at this reaction, we see that with ' 1-bromobutano not only form the desired product but also unwanted by-products of hydrogen sodium and water. The reaction is colored red all the atoms of the reagents that are incorporated into the desired product, while the atoms that become part of the waste products are represented in black . Adding the atomic mass of all atoms in red left arrow reaction (reagents) we get: 4C + 9H 1BR + = 137 amu (the mass of the desired product). The sum of the atomic masses of all atoms of the reactant molecules (red and black) instead is: 4C + 12H + + 5O 1BR + 1NO + 1S = 275 uma. If we divide the mass of the atoms used to generate the desired product to that of all the atoms of the reactant molecules, we obtain the atomic efficiency parameter (multiplied by 100 to obtain the result expressed as a percentage) that, in this case is 50%.
EA% = 137: 275 x 100 = 50%
So, for this reaction, half the mass of all atoms in the reagents is lost and only half is actually incorporated into the desired product. This is a way to determine the efficiency of a reaction. With this information you can groped to explore other methods of synthesis of 1-bromobutano to ensure a higher percentage of atomic efficiency.
Now an exercise for you on the synthesis of ibuprofen, a drug that there is no doubt that you have used in some unpleasant moments of your life.
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