Monday, October 14, 2013

What is Green Chemistry?

  • Green chemistry can be defined as the practice of chemical science and manufacturing in a manner that is sustainable, safe, and non-polluting and that consumes minimum amounts of materials and energy while producing little or no waste material. 
  • The practice of green chemistry begins with recognition that the production, processing, use, and eventual disposal of chemical products may cause harm when performed incorrectly. 
  • In accomplishing its objectives, green chemistry and green chemical engineering may modify or totally redesign chemical products and processes with the objective of minimizing wastes and the use or generation of particularly dangerous materials. 
  • Those who practice green chemistry recognize that they are responsible for any effects on the world that their chemicals or chemical processes may have. 
  • Far from being economically regressive and a drag on profits, green chemistry is about increasing profits and promoting innovation while protecting human health and the environment.

Green chemistry, as first defined by Paul Anastas and John Warner in their book Green Chemistry: Theory and Practice, 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.

Twelve Principles of Green Chemistry

1. Prevent waste: Design chemical syntheses to prevent waste, leaving no waste to treat or clean up.
2. Design safer chemicals and products: Design chemical products to be fully effective, yet have little or no toxicity.
3. Design less hazardous chemical syntheses: Design syntheses to use and generate substances with little or no toxicity to humans and the environment.
4.  Use renewable feedstock: Use raw materials and feedstock that are renewable rather than depleting. Renewable feedstock are often made from agricultural products or are the wastes of other processes; depleting feedstock are made from fossil fuels (petroleum, natural gas, or coal) or are mined.
5.  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.
6.  Avoid chemical derivatives: Avoid using blocking or protecting groups or any temporary modifications if possible. Derivatives use additional reagents and generate waste.
7.  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.
8.  Use safer solvents and reaction conditions: Avoid using solvents, separation agents, or other auxiliary chemicals. If these chemicals are necessary, use innocuous chemicals. If a solvent is necessary, water is a good medium as well as certain eco-friendly solvents that do not contribute to smog formation or destroy the ozone.
9.  Increase energy efficiency: Run chemical reactions at ambient temperature and pressure whenever possible.
10.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.
11.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.
12. 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.

Green Chemistry and India 
In a country like India, there hasn’t been much emphasis laid on development or practicing of green chemistry. The laidback approach doesn’t really see the benefits that green chemistry can bring. With the increasing levels of pollution in all forms due to rapid industrialization, there is a need to understand the need of green chemistry. 
Though there has been some research done by some groups like development of solid support reagents and catalysts useful for organic transformations at IICT, Hyderabad or the initiation of a program to develop green synthetic methods by designing reaction protocols without involving organic solvents by IACS, Kolkata.
Green chemistry has major contributions to make to the quality of life, human welfare, and sustainable development. However, before green chemistry can contribute fully to these areas, it must be integrated into the discipline of chemistry itself. This requirement presents a number of major challenges to the chemical profession:
  • Chemists will need to integrate into pure chemistry the questions of why or why not, on environmental protection grounds.
  • It is vital that green chemistry not become a fad, in which chemistry that is not really “green” gets paraded as such before the scientific community and the world.
  • Certain of the largest sustainability issues, where chemists have so much to offer, will require new approaches that can only be built with long-term commitment.
In order to allow for the full potential of green chemistry to explore the scientific and economic advances the scientific community needs to provide educational opportunities to train chemists of the future. Since green chemistry requires the same skills and abilities of traditional chemistry, students of all ages can learn the fundamental concepts in ways that are more environmentally benign. 
Practicing of green chemistry in India is a necessity rather than an option. The future of green India is in the hands of young researchers and students, as the practice of green chemistry is a moral responsibility for them. Government agencies should enforce the laws strictly to practice green chemistry. Industries should also understand their moral responsibility toward the fragile environment.

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