Green Chemistry
Uploaded by msnarayana on May 07, 2013
Green chemistry, also called sustainable chemistry, is a philosophy of chemical research and engineering that encourages the design of products and processes that minimize the use and generation of hazardous substances.[1] Whereas environmental chemistry is the chemistry of the natural environment, and of pollutant chemicals in nature, green chemistry seeks to reduce and prevent pollution at its source.
As a chemical philosophy, green chemistry applies to organic chemistry, inorganic chemistry, biochemistry, analytical chemistry, and even physical chemistry. While green chemistry seems to focus on industrial applications, it does apply to any chemistry choice. 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. It is distinct from environmental chemistry which focuses on chemical phenomena in the environment.
In 2005 Ryōji Noyori identified 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.[2] 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. A number of important process chemicals can be synthesized in engineered organisms, such as shikimate, a Tamiflu precursor which is fermented by Roche in bacteria.
The term green chemistry was coined by Paul Anastas in 1991.[3]
Principles [edit]
Paul Anastas, then of the United States Environmental Protection Agency, and John C. Warner developed 12 principles of green chemistry,[4] which help to explain what the definition means in practice. The principles cover such concepts as:
the design of processes to maximize the amount of raw material that ends up in the product;
the use of safe, environment-benign substances, including solvents, whenever possible;
the design of energy efficient processes;
the best form of waste disposal: not to create it in the first place.
The 12 principles are:
It is better to prevent waste than to treat or clean up waste after it is formed.
Synthetic methods should be designed to maximize the incorporation of all materials used in the process into the final product.
Wherever practicable, synthetic methodologies should be designed to use and generate substances that possess little or no toxicity to human health and the environment.
Chemical products should be designed to preserve efficacy of function while reducing toxicity.
The use of auxiliary substances (e.g. solvents, separation agents, etc.) should be made...