Figure.1 Green chemistry

GOAL OF GREEN CHEMISTRY:

The goal of Green Chemistry in personal care product development is to create products that are effective and healthy, that protect the skin, hair, and body as much as the environment. The strategy is to minimize the presence of toxicity and pollution at the material source and prevent these issues later in the product life cycle. This is achieved by minimizing energy consumption and waste generation and promoting the use of non–toxic, renewable, and biodegradable raw materials².

(1) Energy:

The vast majority of the energy generated in the world today is from non-renewable sources that damage the environment. Green Chemistry will be essential in developing the alternatives for energy generation (photovoltaic, hydrogen, fuel cells, biobased fuels, etc.) as well as continue the path toward energy efficiency with catalysis and product design at the forefront.

Figure.2 Prevent pollution by green chemistry

(2) Global Change:

Figure.3 Global change by green chemistry

Concerns for climate change, oceanic temperature, stratospheric chemistry and global distillation can be addressed through the development and implementation of green chemistry technologies³.

(3) Resourse depletion:

Due to the over utilization of non-renewable resources, natural resources are being depleted at an unsustainable rate. Fossil fuels are a central issue. Renewable resources can be made increasingly viable technologically and economically through green chemistry.

(4)Toxics in the Environment:

Substances that are toxic to humans, the biosphere and all that sustains it, are currently still being released at a cost of life, health and sustainability. One of green chemistry’s greatest strengths is the ability to design for reduced hazard⁴.

Figure.4 Environmental pollution

GREEN CHEMISTRY IN PRODUCTIVITY:

As a chemical philosophy, green chemistry derives from organic chemistry, inorganic chemistry, biochemistry, analytical chemistry, and even physical chemistry. However, the philosophy of green chemistry tends to focus on industrial applications. Click chemistry is often cited as a style of chemical synthesis that is consistent with the goals of green chemistry. The focus is on minimizing the hazard and maximizing the efficiency of any chemical choice.

Figure.5 Green chemistry in production

It is distinct from environmental chemistry which focuses on chemical phenomena in the environment. There are three key developments in green chemistry: use of supercritical carbon dioxide as green solvent, aqueous hydrogen peroxide for clean oxidations and the use of hydrogen in asymmetric synthesis. Examples of applied green chemistry are supercritical water oxidation, on water reactions and dry media reactions. Bioengineering is also seen as a promising technique for achieving green chemistry goals^5-6.

PRINCIPLES OF GREEN CHEMISTRY^7-8:

Twelve Principles of Green Chemistry

· Prevent waste: Design chemical syntheses to prevent waste, leaving no waste to treat or clean up.

· Design safer chemicals and products: Design chemical products to be fully effective, yet have little or no toxicity.

· Design less hazardous chemical syntheses: Design syntheses to use and generate substances with little or no toxicity to humans and the environment.

Figure.6 Green world with green chemistry

· Use renewable feedstocks: Use raw materials and feedstocks that are renewable rather than depleting. Renewable feedstocks are often made from agricultural products or are the wastes of other processes; depleting feedstocks are made from fossil fuels (petroleum, natural gas, or coal) or are mined.

· Use catalysts, not stoichiometric reagents: Minimize waste by using catalytic reactions. Catalysts are used in small amounts and can carry out a single reaction many times. They are preferable to stoichiometric reagents, which are used in excess and work only once.

· Avoid chemical derivatives: Avoid using blocking or protecting groups or any temporary modifications if possible. Derivatives use additional reagents and generate waste.

· Maximize atom economy: Design syntheses so that the final product contains the maximum proportion of the starting materials. There should be few, if any, wasted atoms.

· Use safer solvents and reaction conditions: Avoid using solvents, separation agents, or other auxiliary chemicals. If these chemicals are necessary, use innocuous chemicals.

· Increase energy efficiency: Run chemical reactions at ambient temperature and pressure whenever possible.

· Design chemicals and products to degrade after use: Design chemical products to break down to innocuous substances after use so that they do not accumulate in the environment.

· Analyze in real time to prevent pollution: Include in-process real-time monitoring and control during syntheses to minimize or eliminate the formation of byproducts.

· Minimize the potential for accidents: Design chemicals and their forms (solid, liquid, or gas) to minimize the potential for chemical accidents including explosions, fires, and releases to the environment.

GREN SOLVENT:

Green solvents is engaged in researching and developing cleaner, greener and safer chemicals for global industrial use.Green solvents can be easily recycled though simple filtering or distillation for repeated reuse, and the low evaporation rate and high solvency formula can significantly reduce overall solvent usage. Chemical solvents contain no water and are completely reactive, unlike other green solvents which may contain up to 50% water. Use of supercritical carbon dioxide as green solvent, aqueous hydrogen peroxide for clean oxidations and the use of hydrogen in asymmetric synthesis^9-10.

Figure.7 Green solvents in chemical reaction

GREEN SOLVENTS FEATURES:

· Not a flammable liquid.

· Excellent resin and adhesive cleaner.

· Cleans polyester, vinyl ester, and epoxy resins from tools and guns.

· Effective against polyurethanes, varnishes, enamels, and UV curable coatings.

· One cleaner does it all. Multiple solvents not required.

· Suitable for paint preparation and wipe down. Leaves no residue after drying.

· High solvency. Can effectively replace and outperform all petroleum based solvents.

· Low vapor pressure and evaporation rate. Lasts five times longer than traditional solvents.

· Easily recycled and reused. Saves money. Less downstream waste.

GREENING ACROSS THE PHARMACEUTICAL CHEMISTRY:

Global pharmaceutical corporations took a program of pharmaceutical roundtable to encourage the integration of green chemistry and green engineering into the pharmaceutical industry and developed a list in three categories of research to discover novel methodologies of proven greener alternatives to current reaction processes followed frequently in synthesis of pharmaceuticals: (i) Reactions that pharmaceutical industries frequently use but strongly prefer greener and better reagents and processes (ii) More aspirational reactions that companies would like to use, if they are available and potentially greener and cleaner alternatives (iii) Ideas concerning with solvent use. we need to develop new, more environmentally friendly, chemical products and processes. Catalysis, which has played such a vital role in the success of the industry in this millennium, will also play a very important role in the new greener industry of the new century.

Figure.8 Pharmaceutical chemistry with green solvents

Reactions that pharmaceutical industries frequently use but strongly prefer greener and better reagents for amide formation by avoiding poor atom economy reagents, hydroxyl group activation for nucleophilic substitution, reduction of amides without hydride reagents, oxidation/epoxidation methods without the use of chlorinated solvents that are safe and environmentally friendly Mitsunobu reactions, Friedel-Craft reactions on inactivated systems in nitration. C-H activation of aromatics (cross couplings avoiding the preparation of halo-aromatics), aldehyde or ketone + NH + 'X' to give chiral amine asymmetric hydrogenation of unfunctionalised olefins/enamines/ imines by green fluorination methods under mild conditions. N-Centred chemistry avoiding azides, hydrazine asymmetric hydro-amination. In solvent theme category, pharmaceutical companies would like to prefer to develop the ideas for better alternatives to polar aprotic solvents, NMP, DMAc, DMF etc, healthier substitute to chlorinated solvents, and the solvent less reactor cleaning. More aspirational reactions can be done by designing of synthesis involving less number of reaction steps eliminating the waste formation in multistep syntheses by (i) Designing newer synthetic strategy of reduced steps (ii) Developing new methodologies activating directly C-H bonds, that do not need extra steps for generating functional groups (iii) Use of Molecular Chain Reactions, one pot, and catalytic cascade processes. Bio-catalytic cascade conversion over chemo-catalytic cascade process has distinct advantages that the subsequent reactions can take place at or close to ambient temperature and pressure. In emulation of natural processes, where several different ensures can co-exit in the cell, it can be advantageous to immobilize these various enzymes as Cross-Linked Enzyme Aggregates (CLEAs) in such one pot catalytic cascade process. The use of a combi-CLEA containing two enzymes has been reported for one-pot conversion of benzaldehyde to S-mandelic acid with high yield and enantioselectivity^11-12.

ADVANTAGE OF GREEN CHEMISTRY:

· Green chemistry mainly reduces the waste, material, hazard, Environmental Impact, risk, energy, cost.

· Making chemical products that do not harm either our health or the environment

· Minimize the potential for accidents

· Design chemicals and products to degrade after use

CONCLUSION:

Green Chemistry program supports the invention of more environmentally friendly chemical processes which reduce or even eliminate the generation of hazardous substances. Green chemistry mainly reduces the waste, material, hazard, risk, energy, and cost so it is not a solution to all environmental problems but the most fundamental approach to preventing pollution.

REFERENCES:

1. R. A. Sheldon. Chemistry and Industry 1, 12 (1997); J. H. Clark. Green Chem. 1, 1 (1999).

2. B. M. Trost. Angew. Chem. Int. Ed. Eng. 34, 259 (1995); R. A. Sheldon. Green Chemtech 38 (1994).

3. P. M. Price, J. H. Clark, D. J. Macquarrie. J. Chem. Soc., Dalton 101 (2000).

4. D. J. Macquarrie. Phil. Trans. R. Soc. Lond., A 358, 419 (2000).

5. K. Wilson and J. H. Clark. Pure Appl. Chem. 72, 1313 (2000).

6. Sen, D.J. and Patel, D.A.; Biofertilizers: A correlation approach with chemical fertilizers towards economy, ecosystem and health: Journal of Advances in Biological Sciences, (2004), Vol-3 (1and 2), p: 55-57.

8. Anastas, Paul T., and Warner, John C. Green Chemistry Theory and Practice, Oxford University Press, New York, (1998).

9. H. L. Chum, V. R. Koch, L. L. Miller, R. A. Osteryoung. J. Am. Chem. Soc. 97, 3264–3267 (1975).

10. J. S. Wilkes, J. A. Levisky, R. A. Wilson, C. L. Hussey. Inorg. Chem. 21, 1236–1264 (1982).

11. K. R. Seddon. In Molten Salt Forum: Proceedings of 5th International Conference on Molten Salt Chemistry and Technology, Vol. 5–6, H. Wendt (Ed.), pp. 53–62 (1998).

12. C. L. Hussey, T. B. Scheffler, J. S. Wilkes, A. A. Fannin, Jr. J. Electrochem. Soc. 133, 1389–1391(1986).

Received on 22.10.2010

Accepted on 12.11.2010

Research J. Science and Tech. 3(1): Jan.-Feb. 2011: 12-16