An Essay on Green Chemistry and its Applications

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The term green chemistry was first used in 1991 by Poul T. Anastas in a special program launched by the US Environmental Protection Agency (EPA) to implement sustainable development in chemistry and chemical technology by industry, academia and government

Green chemistry, also called sustainable chemistry, is an area of chemistry and chemical engineering focused on the design of products and processes that minimize the use and generation of hazardous substances. Whereas environmental chemistry focuses on the effects of polluting chemicals on nature, green chemistry focuses on technological approaches to preventing pollution and reducing consumption of nonrenewable resources.

Green chemistry overlaps with all sub disciplines of chemistry but with a particular focus on chemical synthesis, process chemistry, and chemical engineering, in industrial applications. To a lesser extent, the principles of green chemistry also affect laboratory practices. The overarching goals of green chemistry—namely, more resource-efficient and inherently safer design of molecules, materials, products, and processes—can be pursued in a wide range of contexts.

In the United States, the Environmental Protection Agency played a significant early role in fostering green chemistry through its pollution prevention programs, funding, and professional coordination. At the same time in the United Kingdom, researchers at the University of York contributed to the establishment of the Green Chemistry Network within the Royal Society of Chemistry, and the launch of the journal Green Chemistry.[

The development of green chemistry in Europe and the United States was linked to a shift in environmental problem-solving strategies: a movement from command-and-control regulation and mandated reduction of industrial emissions at the "end of the pipe," toward the active prevention of pollution through the innovative design of production technologies themselves.

The Twelve Principles of Green Chemistry:

·         Prevention
It is better to prevent waste than to treat or clean up waste after it has been created.

·         Atom Economy
Synthetic methods should be designed to maximize the incorporation of all materials used in the process into the final product.

·         Less Hazardous Chemical Syntheses
wherever practicable, synthetic methods should be designed to use and generate substances that possess little or no toxicity to human health and the environment.

·         Designing Safer Chemicals
Chemical products should be designed to effect their desired function while minimizing their toxicity.

·         Safer Solvents and Auxiliaries
The use of auxiliary substances (e.g., solvents, separation agents, etc.) should be made unnecessary wherever possible and innocuous when used.

·         Design for Energy Efficiency
Energy requirements of chemical processes should be recognized for their environmental and economic impacts and should be minimized. If possible, synthetic methods should be conducted at ambient temperature and pressure.

·         Use of Renewable Feedstock’s
A raw material or feedstock should be renewable rather than depleting whenever technically and economically practicable.

·         Reduce Derivatives
Unnecessary derivatization (use of blocking groups, protection/ deportation, temporary modification of physical/chemical processes) should be minimized or avoided if possible, because such steps require additional reagents and can generate waste.

·         Catalysis
Catalytic reagents (as selective as possible) are superior to stoichiometric reagents.

·         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.

·         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.

·         Inherently Safer Chemistry for Accident Prevention
Substances and the form of a substance used in a chemical process should be chosen to minimize the potential for chemical accidents, including releases, explosions, and fires.

Benefits of Green Chemistry:

Human health:

·         Cleaner air: Less release of hazardous chemicals to air leading to less damage to lungs

·         Cleaner water: less release of hazardous chemical wastes to water leading to cleaner drinking and recreational water

·         Increased safety for workers in the chemical industry; less use of toxic materials; less personal protective equipment required; less potential for accidents (e.g., fires or explosions)

·         Safer consumer products of all types: new, safer products will become available for purchase; some products (e.g., drugs) will be made with less waste; some products (i.e., pesticides, cleaning products) will be replacements for less safe products

·         Safer food: elimination of persistent toxic chemicals that can enter the food chain; safer pesticides that are toxic only to specific pests and degrade rapidly after use

·         Less exposure to such toxic chemicals as endocrine disruptors

Environment:

·         Many chemicals end up in the environment by intentional release during use (e.g., pesticides), by unintended releases (including emissions during manufacturing), or by disposal. Green chemicals either degrade to innocuous products or are recovered for further use

·         Plants and animals suffer less harm from toxic chemicals in the environment

·         Lower potential for global warming, ozone depletion, and smog formation

·         Less chemical disruption of ecosystems

·         Less use of landfills, especially hazardous waste landfills

Economy and business:

·         Higher yields for chemical reactions, consuming smaller amounts of feedstock to obtain the same amount of product

·         Fewer synthetic steps, often allowing faster manufacturing of products, increasing plant capacity, and saving energy and water

·         Reduced waste, eliminating costly remediation, hazardous waste disposal, and end-of-the-pipe treatments

·         Allow replacement of a purchased feedstock by a waste product

·         Better performance so that less product is needed to achieve the same function

·         Reduced use of petroleum products, slowing their depletion and avoiding their hazards and price fluctuations

·         Reduced manufacturing plant size or footprint through increased throughput

·         Increased consumer sales by earning and displaying a safer-product label (e.g., Safer Choice labeling)

·         Improved competitiveness of chemical manufacturers and their customers

CONCLUSION:

Green Chemistry is new philosophical approach that through application and extension of the principles of green chemistry can contribute to sustainable development. Presently it is easy to find in the literature many interesting examples of the use of green chemistry rules. Great efforts are still undertaken to design an ideal process that start from nonpolluting materials. It is clear that the challenge for the future chemical industry is based on safer products and processes designed by utilizing new ideas in fundamental research.

Furthermore, the success of green chemistry depends on the training and education of a new generation of chemists. Students at all levels have to be introduced to the philosophy and practice of green chemistry.

Reference:

1.      Wikipedia

2.       Anastas, P. T.; Warner, J. C. Green Chemistry: Theory and Practice, Oxford University Press: New York, 1998,

3.      http://edugreen.teri.res.in/explore/laws.htm

4.      Green Chemistry by msnarayana

5.      A good introduction to Green Chemistry by Sheldon, Arends and Hanefeld

6.       (Green Chemistry and Catalysis, Wiley-VCH Weinheim, 2007,