Green synthesis

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1. Environmental chemistry MSc 3rd

2. TOPIC GREEN SYNTHESIS PRESENTED TO MAM SARAH HASSAN PRESENTETED BY AROOJ ANWAAR CLASS MSC 3 RD SUBJECT ENVIROEMENTAL CHEMSITR

3. TABLE OF CONTENT DEFINATION OBJECTIVE TECHNIQUES OF GREEN SYNTHENSIS ADVANTAGES CONCLUSION

4. DEFINITION Green synthesis looks at pollution prevention on the molecular scale and is an extremely important area of Chemistry due to the importance of Chemistry in our world today and the implications it can show on our environment.

5. OBJECTIVE 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

6. GREEN SYNTHESIS TECHNIQUES PHYSICAL AND CHEMICAL METHODS Ball milling Magnetic field-assisted synthesis Supercritical green solvents Microwave assited method Ultrasound reaction 2.  BIOLOGICAL METHODS Nano particles synthesis

7. PHYSICAL AND CHEMICALS METHOD BALL MILLING The use of ball milling allows us to increase energy efficiency and, at the same time, avoid toxic reagents and solvents. These reactions, as well as MW-assisted processes, take place without the use of solvents and at room temperature. Being simple and environmentally friendly, the ball milling is also considered as a green tool for chemistry, but it is not used in a widespread manner by chemists, despite its big potential.

8. Among other reactions, carried out by ball milling, are those with the use of solid oxidants and reductants for oxidation and reduction purposes, respectively, dehydrogenate coupling, synthesis of polymers, amino acids and peptides, coordination compounds, composites ‘cellulose-plastic’, asymmetric organic reactions using catalysts.

9. MICROWAVE ASSISTED SYNTHESIS Microwave assisted organic synthesis is defined as the preparation of desired organic compound from available starting material via some procedure involving microwave irradiation . Microwave Synthesis opens up new opportunities to the synthetic chemist in the form of new reaction that are not possible by conventional heating.  It is an enabling technology for accelerating drug discovery and development processes.

10. MICROWAVE A Microwave is a form of electromagnetic energy that falls at lower frequency at the end of electromagnetic spectrum(300 to 300000MHz ). It is present between infrared radiation and radio waves. Microwave uses EMR that passes through material and causes oscillation of molecules which produces heat.

11. MICROWAVE Increase in reaction rate Specific material is heated Specific temperature Less solvent Efficient internal heating Heat flow: inside to out side CONVENTIONAL Decrease in reaction rate Compounds in the mixture heated equally No specific temperature More solvent Efficient external heating Heat flow: outside to inside

12. ULTRASOUND MEDIATED REACTION Two of the most important advantages in the use of sonochemistry in organic synthesis . 1. Increase of reaction rates 2. Increase of product yields So this methodology is more convenient when compared with the traditional method, and it can be easily controlled . For Heterocycles are one of the most popular and important organic compounds because they are involved in many fields of science.

13. MAGNETIC FIELD-ASSISTED SYNTHESIS Magnetic field-assisted synthesis is currently studied as an alternative to traditional methods B ecause some of the traditional methods require the use of toxic solvents or additional steps that need more energy and can generate unwanted residues The synthesis assisted by magnetic fields allows obtaining morphologies different from those prepared by traditional methods

14. SUPERCRITICAL GREEN SOLVENTS Among other greener solvents, non-flammable, non-toxic and environmentally friendly SC CO 2  is known from long ago as a good alternative solvent for the synthesis of polymers. The SCF technologies have been used in materials synthesis processes such as extraction, cleaning, fractionation, drying, polymerization, hydrothermal reactions, plating, biomass conversion, dyeing, among others, providing solvent-free media, simplicity and recyclability, high yields, absence of wastewater and secondary pollution, etc .

15. BIOLOGY-BASED GREEN CHEMISTRY METHODS Biology-based green chemistry methods consist of the use of  bacteria, viruses, yeasts, plant extracts, fungi  and  algae , among which we consider plant extracts as most frequent and popular green routes. t will be shown below especially for the synthesis of nanoparticles, not only those of noble metals, but also carbon dots, metal sulfides, oxides, etc.

16. EXAMPLE (NANO PARTICALES) The methods for making nanoparticles can generally involve either a “top down” approach or a “bottom up” approach. 1.BOTTOM UP TECHNIQUE In bottom up synthesis, the nanoparticles are built from smaller entities, for example by joining atoms, molecules and smaller particles . In bottom up synthesis, the nanostructured building blocks of the nanoparticles are formed first and then assembled to produce the final particle.

17. 2. TOP-DOWN SYNTHESIS In top-down synthesis, nanoparticles are produced by size reduction from a suitable starting material. Size reduction is achieved by various physical and chemical treatments. Top down production methods introduce imperfections in the surface structure of the product and this is a major limitation because the surface chemistry and the other physical properties of nanoparticles are highly dependent on the surface structure.

18. USE OF PLANT EXTRACT IN NANO PARTICLE SYNTHESIS In producing nanoparticles using plant extracts, the extract is simply mixed with a solution of the metal salt at room temperature. The reaction is complete within minutes. Nanoparticles of silver, gold and many other metals have been produced this way. The nature of the plant extract, its concentration, the concentration of the metal salt, the pH, temperature and contact time are known to affect the rate of production of the nanoparticles, their quantity and other characteristics.

19. BLOCK DIAGRAM

20. CHARACTERIZATION OF NANOPARTICLES Nanoparticles are generally characterized by their size, shape, surface area, and dispersity A homogeneity of these properties is important in many applications. The common techniques of characterizing nanoparticles are as follows : UV–visible spectrophotometry, dynamic light scattering (DLS), scanning electron microscopy (SEM),

21. ADVANTAGES prevention of unnecessary wastes; the avoiding of unnecessary waste in organic synthesis can be reached by recyclability of most solvents, catalysts and reagents economy of matter (atoms): minimization of loss of precursors and intermediate compounds during synthesis of final material lower-hazard chemical reactions using little-toxic and safe chemical substances.

22. use of most selective catalysts, allowing higher yields of reaction products; degradable reaction products, non-persisting in the environment; contamination prevention via permanent (real-time) analysis of reaction intermediates when possible;

23. CONCLUSION the green chemistry methods include several non-contaminating physical methods as microwave heating, ultrasound-assisted and hydrothermal processes or ball milling, frequently in combination with the use of natural precursors, which are of major importance in the greener synthesis, as well as solvent-less and biosynthesis techniques.

24. Biological methods (the use of bacteria, viruses, yeasts, plant extracts, fungi and algae) perfectly fit to the green chemistry, in particular to Nano chemistry, resulting in biologically produced nanoparticles, which are non-toxic, stable, environmentally friendly and cost effective