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1、Chapter 2: Atom Economy - Avoiding Waste,0403809 Green Chemistry Chapter 2: Atom Economy Z. Weng,100 % atom economy,0403809 Green Chemistry Chapter 2: Atom Economy Z. Weng,Outline,2.1 Environmental Factor: E 2.2 Where Does Chemical Waste Come From 2.3 Atom Economy 2.4 Examples of Atom Economy 2.5 De
2、sign Atom-Economic Reactions,2.1 Environmental Factor: E,Roger A.Sheldon in 1992,It is used to quantify the effects of production process to the environment Idea: All other compounds formed other than the target product are considered to be WASTE.,0403809 Green Chemistry Chapter 2: Atom Economy Z. W
3、eng,Environmental Factor:,If the atom Utilization = 100% E = 0,The more waste formed, the higher of E and the more serious of the pollution,0403809 Green Chemistry Chapter 2: Atom Economy Z. Weng,The Environmental Factor,0403809 Green Chemistry Chapter 2: Atom Economy Z. Weng,Sheldon, R. A. Green Ch
4、em., 2007, 9, 1273.,Is the actual amount of waste formed in the process, including solvent losses, acids and bases used in work-up, process aids, and, in principle, waste from energy production. Can be derived from amount of raw materials purchased /amount of product sold, i.e., from the mass balanc
5、e: E= raw materials-product/product. A good way to quickly show the enormity of the waste problem.,The Environmental Factor,0403809 Green Chemistry Chapter 2: Atom Economy Z. Weng,2.2 Where does chemical waste come from?,Stoichiometric Bronsted acid and bases - Aromatic nitrations with H2SO4 / HNO3
6、- Acid promoted rearrangements, e.g. Beckmann (H2SO4) - Base promoted condensations, e.g. Aldol (NaOH, NaOMe) 2. Stoichiometric Lewis acids - Friedel-Crafts acylation (AlCl3, ZnCl2, BF3) 3. Stoichiometric oxidants and reductants - Na2Cr2O7, KMnO4, MnO2; - LiAlH4, NaBH4, Zn, Fe/HCl 4. Halogenation an
7、d halogen replacement - Nucleophilic substitutions 5. Solvent losses - Air emissions & aqueous effluent,0403809 Green Chemistry Chapter 2: Atom Economy Z. Weng,Barry Trost, Professor of Stanford University,Commodity chemical producers typically practice good atom economy,0403809 Green Chemistry Chap
8、ter 2: Atom Economy Z. Weng,2.3 Atom Economy,Fine chemical and pharmaceutical producers typically do not practice good atom economy Relatively low percentage of starting material atoms end up in final product Many atoms are wasted (form waste stream) Unconverted or unused raw material is paid for tw
9、ice,0403809 Green Chemistry Chapter 2: Atom Economy Z. Weng,The two main characteristics of chemical reaction with 100% atom utilization: The reactants could be fully utilized, and the resource could be most possibly used economically The waste could be minimized,0403809 Green Chemistry Chapter 2: A
10、tom Economy Z. Weng,0403809 Green Chemistry Chapter 2: Atom Economy Z. Weng,0403809 Green Chemistry Chapter 2: Atom Economy Z. Weng,0403809 Green Chemistry Chapter 2: Atom Economy Z. Weng,Example 1: Methyl Methacrylate,For the manufacture of polymethyl methacrylate acrylic plastics (PMMA) and PVC.,C
11、alculate the atom economy of the following ACH process:,0403809 Green Chemistry Chapter 2: Atom Economy Z. Weng,2.4 Examples of Atom Economy,0403809 Green Chemistry Chapter 2: Atom Economy Z. Weng,Example 2: Ibuprofen 布洛芬,0403809 Green Chemistry Chapter 2: Atom Economy Z. Weng,The Original Boots Syn
12、thesis of Ibuprofen,0403809 Green Chemistry Chapter 2: Atom Economy Z. Weng,Summe: -7 C, 24 H, N, 8 O, Cl, Na,Atom Economy of the Boots synthesis of ibuprofen,0403809 Green Chemistry Chapter 2: Atom Economy Z. Weng,% Atom Economy = (206 / 514.5) 100% = 40%,An improved synthesis by BASF won the Presi
13、dential Green Chemistry Challenge Greener Synthetic Pathways Award in 1997,0403809 Green Chemistry Chapter 2: Atom Economy Z. Weng,Atom Economy of the BASF Improved Synthesis of Ibuprofen,0403809 Green Chemistry Chapter 2: Atom Economy Z. Weng,% Atom Economy = (206 / 266) 100% = 77%,2.5 Design Atom-Economic Reactions,0403809 Green Chemistry Chapter 2: At
