green chemistry & its principles
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Presented By: Ayesha IshfaqRoll # 357GREEN CHEMISTRY & ITS PRINCIPLESGREEN CHEMISTRY23Paul Anastas : Father of Green Chemistry
3WasteMaterialsHazardsRisksEnergyCost4Green Chemistry is about reducing4Chemistry is undeniably a very prominent part of our daily lives.Chemical developments also bring new environmental problems and harmful unexpected side effects, which result in the need for greener chemical products.5Why do we need Green Chemistry5To reduce adverse environmental impact, try appropriate and innovative choice of material & their chemical transformation.To develop processes based on renewable rather than non-renewable raw materials.To develop processes that are less prone to obnoxious chemical release, fires & explosion.To minimize by-products in chemical transformation by redesign of reactions & reaction sequences.To develop products that are less toxic.6Goals of Green Chemistry6To develop products that degrade more rapidly in the environment than the current products.To reduce the requirements for hazardous persistent solvents & extractants in chemical processes.To improve energy efficiency by developing low temperature & low pressure processes using new catalysts.To develop efficient & reliable methods to monitor the processes for better & improved controls.7Goals of Green Chemistry7PRINCIPLES OF GREEN CHEMISTRYWe designed this template so that each member of the project team has a set of slides with its own theme. Members, heres how you add a new slide to just your set:
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It is better to prevent waste than to treat or clean up waste after it is formed
10Prevention of Waste or by-products
1011Environmental Load FactorSynthetic methods should be designed to maximize incorporation of all materials used in the process into the final productAtom economy(atom efficiency) describes the conversion efficiency of a chemical process in terms of all atoms involved (desired products produced).
122. Maximize Atom Economy1213Example
Simply put, even if our percent yield is 100%, only half the mass of the reactants atoms are incorporated in the desired product while the other half is wasted in unwanted by-products. Imagine telling your mom you baked a cake and threw away half the ingredients! Thus chemists must not only strive to achieve maximum percent yield, but also design syntheses that maximize the incorporation of the atoms of the reactants into the desired product.
14ContWherever practicable, synthetic methods should be designed to use and generate substances that possess little or no toxicity to people or the environment
wherever practicable. Saying those two words implies that it may not be practical or possible to avoid using substances that are toxic, and thats why most chemists use to try to avoid applying this principle to their work.153. Minimization of hazardous products15Chemical products should be designed to effect their desired function while minimising their toxicity164. Designing Safer Chemicals
16Achieving this goal requires an understanding of not only chemistry but also of the principles of toxicology and environmental science. Highly reactive chemicals are often used by chemists to manufacture products because they are quite valuable at affecting molecular transformations. However, they are also more likely to react with unintended biological targets, human and ecological, resulting in unwanted adverse effects. 174. Designing Safer ChemicalsThe use of auxiliary substances (e.g. solvents, separation agents, etc.) should be made unnecessary wherever possible, and innocuous when used185. Safer Solvents & Auxiliaries
18Choose solvents that make sense chemically, reduce the energy requirements, have the least toxicity, have the fewest life cycle environmental impacts and don't have major safety impacts.195. Safer Solvents & AuxiliariesEnergy requirements of chemical processes should be recognised for their environmental and economic impacts and should be minimised. If possible, synthetic methods should be conducted at ambient temperature and pressure206. Design for Energy Efficiency20Developing the alternatives for energy generation (photovoltaic, hydrogen, fuel cells, bio based fuels, etc.) as well as Continue the path toward energy efficiency with catalysis and product design at the forefront.216. Design for Energy Efficiency21A raw material or feedstock should be renewable rather than depleting whenever technically and economically practicable227. Use of Renewable Feedstock
22In the past 10 years, significant advances have been made in the development of fuels, chemicals and materials from renewable feed stocks from thin air with minimal impact on human health and the environment.These for example, have included biodiesel from plant oils and algae, bioethanol and butanol from sugars and lignocellulose, plastics, foams and thermosets from lignin and plant oils, and even electronic materials from chicken feathers. 237. Use of Renewable FeedstockUnnecessary derivatization (use of blocking groups, protection/de-protection, and temporary modification of physical/chemical processes) should be minimised or avoided if possible, because such steps require additional reagents and can generate waste248. Reduce Derivatives24One of the best ways of doing this is the use of enzymes. Enzymes are so specific that they can often react with one site of the molecule and leave the rest of the molecule alone and hence protecting groups are often not required.A great example of the use of enzymes to avoid protecting groups and clean up processes is the industrial synthesis of semi-synthetic antibiotics such as ampicillin and amoxicillin25ExampleCatalytic reagents (as selective as possible) are superior to stoichiometric reagents A catalyst is defined as a substance that changes the velocity of a reaction without itself being changed in the process. It lowers the activation energy of the reaction but in so doing it is not consumed. This means that, in principle at least, it can be used in small amounts and be recycled indefinitely, that is it doesnt generate any waste. 269. Catalysis26The reduction of a ketone to the corresponding secondary alcohol using sodium borohydride or molecular hydrogen as the reductant. Reduction with the former has an atom economy of 81% while reduction with the latter are 100% atom economic, that is everything ends up in the product and, in principle, there is no waste.
Chemical products should be designed so that at the end of their function they break down into innocuous degradation products and do not persist in the environment2810. Designing of degradable products
28Green chemistry principles 3, 4, 5, and 12 guide designers to reduce the hazards of chemicals. Principle 10, however, guides the design of products that degrade after their commercial function in order to reduce risk or the probability of harm occurring. 2910. Designing of degradable productsAnalytical methodologies need to be further developed to allow for real-time, in-process monitoring and control prior to the formation of hazardous substances.3011. New Analytical Methods
30Most chemists are familiar with laboratory analysis from their undergraduate training. But analysis can also be performed in-line, on-line, or at-line in a chemical plant, a sub-discipline known as process analytical chemistry. Such analysis can detect changes in process temperature or pH prior to a reaction going out of control, poisoning of catalysts can be determined, and other deleterious events can be detected before a major incident occurs.3111. New Analytical MethodsAnalytical Substances and the form of a substance used in a chemical process should be chosen to minimise the potential for chemical accidents, including releases, explosions, and fires3212. Safer Chemicals For Accident Prevention
32Green Chemistry Principle # 12 is known as the Safety Principle. It may be the most overlooked of the twelve principles, yet it is the logical outcome of many of the other principles. In fact it is practically impossible to achieve the goals of Principle 12 without the implementation of at least one of the others.3312. Safer Chemicals For Accident PreventionEnergyGlobal ChangeResource Depletion Food SupplyToxics in the EnvironmentComputer ChipsMedicineBiodegradable PlasticsPaint
The major uses of GREEN CHEMISTRY34Green chemistry offers a different approach to conventional chemistry and engineering through the thoughtful application of principles that aid the design of sustainable chemical products and processes by focusing individuals on the development of innovative solutions, opportunities, and challenges. Applying these principles collectively will result in products and processes that protect and benefit the economy, people, and the planet and help us make significant strides toward a more sustainable future.35Conclusionhttp://www.slideshare.net/hecrod/green-chemistry3985228?related=1http://www.slideshare.net/Santachem/green-chemistry-15990119http://www.acs.org/content/acs/en/greenchemistry/what-is-green- chemistry/principles.htmlhttp://www.acs.org/content/acs/en/greenchemistry/what-is-green-chemistry/principles/12-principles-of-green-chemistry.htmlhttp://www.epa.gov/sciencematters/june2011/principles.htm
36ReferencesTHANKS A LOT!!!