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GREEN CHEMISTRY by RASHID.pptx

8. Aug 2022
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GREEN CHEMISTRY by RASHID.pptx

  1. Department of pharmaceutical sciences Dr. Harisingh Gour central University, sagar, [M.P.] GREEN CHEMISTRY SUBMITTED TO: DR. ADARSH SAHU Presented by: MOHD RASHID M.Pharma 2nd sem Y21254018
  2. CONTENTS • DEFINITION • NEED OF GREEN CHEMISTRY • PRINCIPLES OF GREEN CHEMISTRY • USES OF GREEN CHEMISTRY • MICROWAVE CHEMISTRY • ULTRA-SOUND MEDIATED REACTIONS • REFERENCES. 2
  3. GREEN CHEMISTRY • Green Chemistry is the utilization of a set of principles that reduces or eliminates the use or generation of hazardous substances in the design, manufacture and application of chemical products . • Green Chemistry is a recent approach to design of energy efficient processes and the best form of waste disposal. • The awareness among the organic chemists to practice green chemical routes for organic transformations is significantly increasing in the place of mineral acids, mild solid acids or clays are used. The reactions are carried out in organized media or in green solvents. 3
  4. Green Chemistry Is About 4 Cost Waste Hazard Risk Energy
  5. GREEN CHEMISTRY IS ABOUT • Waste Minimization at Source • Use of Catalysts in place of Reagents • Using Non-Toxic Reagents • Use of Renewable Resources • Improved Atom Efficiency • Use of Solvent Free or Recyclable Environmentally Benign Solvent systems 5
  6. Why do we need Green Chemistry ? • Chemistry 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. -A famous example is the pesticide DDT. • Hundreds of tons of hazardous waste are released to the air, water and land by industry every hour of every day. The chemical industry is the biggest source of such waste. • In recent years, pollution control board regulated to reduce harmful emissions , effluents and workers safety. 6
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  8. The 12 Principles of Green Chemistry 1. Prevention – It is better to prevent waste than to treat or clean up waste after it has been created. 2. Atom Economy – Synthetic methods should be designed to maximise the incorporation of all materials used in the process into the final product. 3. Less Hazardous Chemical Synthesis – Wherever practicable, synthetic methods should be designed to use and generate substances that possess little or no toxicity to people or the environment. 4. Designing Safer Chemicals – Chemical products should be designed to effect their desired function while minimising their toxicity. 8
  9. The 12 Principles of Green Chemistry 5. Safer Solvents and Auxiliaries – The use of auxiliary substances (e.g., solvents or separation agents) should be made unnecessary whenever possible and innocuous when used. 6. Design for Energy Efficiency – Energy 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 pressure. 7. Use of Renewable Feedstocks – A raw material or feedstock should be renewable rather than depleting whenever technically and economically practicable. 8. Reduce Derivatives – Unnecessary 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 waste. 9
  10. The 12 Principles of Green Chemistry 9. Catalysis – Catalytic reagents (as selective as possible) are superior to stoichiometric reagents. 10. Design for Degradation – 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 environment. 11. Real-time Analysis for Pollution Prevention – Analytical methodologies need to be further developed to allow for real-time, in-process monitoring and control prior to the formation of hazardous substances. 12. Inherently Safer Chemistry for Accident Prevention – 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 fires. 10
  11. Production of allyl alcohol • Traditional route: Alkaline hydrolysis of allyl chloride, which generates the product and hydrochloric acid as a by-product • Greener route, to avoid chlorine: Two-step using propylene (CH2=CHCH3), acetic acid (CH3COOH) and oxygen (O2) • Added benefit: The acetic acid produced in the 2nd reaction can be recovered and used again for the 1st reaction, leaving no unwanted by-product. 11 C H 2 = C H C H 2 O C O C H 3 + H 2 O C H 2 = C H C H 2 O H + C H 3 C O O H C H 2 = C H C H 3 + C H 3 C O O H + 1 / 2 O 2 C H 2 = C H C H 2 O C O C H 3 + H 2 O C H 2 = C H C H 2 C l + H 2 O C H 2 = C H C H 2 O H + H C l p r o b l e m p r o d u c t
  12. Production of styrene • Traditional route: Two-step method starting with benzene, (which is carcinogenic) and ethylene to form ethylbenzene, followed by dehydrogenation to obtain styrene 1ST STEP 2ND STEP • Greener route: To avoid benzene, start with xylene (cheapest source of aromatics and environmentally safer than benzene). • Another option, still under development, is to start with toluene (benzene ring with CH3 tail). 12 + H 2 C = C H 2 c a ta y st C H 2 C H 3 e th y lb e n z e n e c a t a y s t C H = C H 2 C H 2 - C H 3 e t h y l b e n z e n e s t y r e n e
  13. The major uses of GREEN CHEMISTRY • Energy • Global Change • Resource Depletion • Food Supply • Toxics in the Environment 13
  14. MICROWAVE CHEMISTRY • Microwave chemistry is the science of applying microwave radiation to chemical reactions. • Microwaves act as high frequency electric fields and will generally heat any material containing mobile electric charges, such as polar molecules in a solvent or conducting ions in a solid. • Polar solvents are heated as their component molecules are forced to rotate with the field and lose energy in collisions. • Semiconducting and conducting samples heat when ions or electrons within them forman electric current and energy is 14
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  16. • Microwave heating in the laboratory began to gain wide acceptance following papers in 1986, although the use of microwave heating in chemical modification can be traced back to the 1950s. • Although occasionally known by such acronyms as MADS (Microwave Assisted Organic Synthesis), MEC(Microwave- Enhanced Chemistry) or MORE synthesis (Microwave-organic Reaction Enhancement), these acronyms have had little acceptance outside a small number of groups. 16
  17. Microwave Assisted Synthesis • The development of the technology for organic Chemistry has been rather slow compared to inorganic, computational and combinatorial chemistry • This slow uptake of the technology has been principally attributed to its lack of controllability and reproducibility, safety aspects and a generally low degree of understanding of the basics of microwave dielectric heating 17
  18. Why Microwave assisted synthesis? • Short reaction times • Easy work-up procedure • Reaction may be carried out in the presence of solvent • Solvent free technique is facilitated • Ease of synthesis of libraries of compounds • The availability of commercial microwave equipment intended for organic chemistry 18
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  23. Ultrasound mediated reaction • This is very popular technique for promoting various chemical reactions since the decade 1990-1999. • The application of ultrasound has been useful in accelerating dissolution, enhancing the reaction rates, and renewing the surface of a solid reactant or catalyst in a variety of reaction systems. • In recent years, the effect of ultrasonic energies in organic synthesis (homogeneous and heterogeneous reactions) has widely increased The use of ultrasound in chemical reactions in solution provides specific activation based on a physical phenomenon. 23
  24. • Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is different from 'normal' (audible sound in its physical properties except in that humans cannot hear it. • This limit varies from person to person and is approximately 20 kilohertz (20,000 hertz) in healthy, young adults. Ultrasound devices operate with frequency from 20 kHz up to several gigahertz. 24
  25. Ultrasonics/Sonochemistry Synthesis Applications in Organic Synthesis 1. Homogeneous Sonochemistry - Aqueous medium -Non-aqueous media 2. Heterogeneous Sonochemitsry -Phase Transfer Catalysis -Reactions with metals - Heterogeneous Catalysis 3. Enzyme reactions 25
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  28. Conclusion 28 Green chemistry Not a solution to all environmental problems But the most fundamental approach to preventing pollution. “If the facts don’t fit the theory , change the facts “ – Albert Einstein
  29. REFERENCES • "The 12 principles of green chemistry" United states environmrental protection agency. Retrieved 2006-07-31. • http://en.wikipedia.org/wiki/Green_chemistryDoi:10.1021/ed100892p • http://www.greeningschools.org/docs/twelveprinciplesofgreenchemistry.pdf • http://www.towson.edu/saacs/green.htm • http://web.njit.edu/~mitra/green chemistry/Green chemiatry • http://www2.gvsu.edu/gilliamj/Chemistry.htm • http://profmaster.blogspot.com/2007/06/green-chemistry-12-rules.html • http://greenchemistry.yale.edu/javascript/tinymce/plugins/filemanager/files/principles- of-green-chemistry.pdf • http://academic.scranton.edu/faculty/cannm1/intro.html • Robert thornton Morrison, Robert Neilson boyd and Saibal Kanti Bhattacharjee. "organic chemistry" seventh edition pg. no. 1419- 1427. • http://www.organic-chemistry.org/topics/green-chemistry.shtm • http://pubs.rsc.org/en/journals/journalissues/ge • G.-y. Bai, K. Xu, G.-f. Chen, Y.-h. Yang, T.-y. Li, Synthesis, 2011, 1599-1603.22) M. C. Wilkinson, Org. Lett., 2011, 13, 2232-2235 29
  30. 30 “Learn from yesterday ,live for today, hope for tomorrow. The important thing is to not stop questioning “ - Albert Einstein
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