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Green Chemistry – R. Vijaya Anand

The range of chemical products in available to today’s society is colossal and these chemicals make a precious contribution to the quality of our lives. The design and manufacture of pharmaceutical products has facilitated us in curing diseases that have ravaged humankind throughout history. Chemicals which are associated with crop protection and growth enhancement have enabled us to increase our food yields considerably. However, the successful development of the chemical industries has almost had an inverse affiliation with public perception due to environmental pollution caused by chemical wastes from the industries.
Chemistry is having a difficult time! While the society perseveres to demand larger quantities of sophisticated chemical products, it also regards the industries that manufacture these products with increasing degrees of distrust and dread. There is an unprecedented social, economic and environmental pressure on chemical industries to ‘clean up its act’ and make chemical processes and products more sustainable and environmentally compatible. A growing environmental awareness and increasingly stringent environmental legislation have focused the attention of chemical manufacturers on what has become known as ‘Sustainable Development’. In a world with a continuously increasing population and limited resources, the idea of sustainable development is of major significance for the future. Essentially, the discussion of sustainability began when the 1987 UN Commission on Environment and Development (usually referred as the Bruntland Commission) noted that economic development might lead to deterioration, not an improvement, in the quality of people’s lives. This led to the now commonly accepted definition of ‘Sustainable Development’ as being: Development which meets the needs of the present without compromising the ability of future generations to meet their own needs. The definition is intentionally broad, covering all aspects of the society. However, sustainable development has a particular relevance for chemistry-based industries because it is concerned with evasion of pollution and inattentive use of natural resources.

The role of chemistry is essential in ensuring that our next generation of chemicals, materials and energy is more sustainable than the current generation. One of the most attractive concepts in chemistry for sustainability is ‘Green Chemistry’. The Green Chemistry Movement was started in the early 1990s by the US Environmental Protection Agency (EPA) as a means of encouraging industry and academia to use chemistry for pollution prevention. The Green Chemistry mission was: ‘To promote innovative chemical technologies that reduce or eliminate the use or generation of hazardous substances in the design, manufacture and use of chemical products’. In conjunction with the American Chemical Society, the EPA has developed a set of twelve principles, which are commonly accepted as green chemistry principles.
The Twelve Principles of Green Chemistry:

Pollution prevention: It is better to prevent waste than to treat or clean up waste after it is formed.
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 synthesis: Whenever practicable, synthetic methodologies 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 preserve efficacy of the function while reducing the toxicity.
Safer solvents and auxiliaries: The use of auxiliary substances (solvents, separation agents etc) should be made unnecessary whenever possible and, when used, innocuous.
Design for energy efficiency: Energy requirements should be recognized for their environmental and economic impacts and should be minimized. Synthetic methods should be conducted at ambient temperature and pressure.
Use of renewable feedstocks: A raw material or feedstock should be renewable rather than depleting whenever technically and economically practical.
Reduce derivatives: Unnecessary derivatization (blocking group, protection/ deprotection) should be avoided whenever possible.
Catalysis: Catalytic reagents are superior to stoichiometric reagents).
Design for degradation: Chemical products should be designed so that at the end of their function they do not persist in the environment and instead break down into harmful degradation products.
Real time analysis for pollution prevention: Analytical methods needs 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:Substance and the form of substance used in a chemical process should be chosen so as to minimize the potential for chemical accidents including explosions and fires.

It is evident from these principles that green chemistry encompasses much more of the concepts of sustainability than simply preventing pollution; two important aspects are the design for energy efficiency and the use of renewable feed stocks.

Green chemistry can be considered as a series of reductions, which lead to the goal of triple bottom-line benefits of economic, environmental and social improvements (Fig. 1).

Costs are saved by reducing waste (which is becoming increasingly expensive to dispose of, especially when hazardous) and energy use (larger proportion of process costs in the future) as well as making processes more efficient by reducing materials consumption. These reductions also led to environmental benefit in terms of both feedstock consumption and end-of-life disposal. The reduction in hazardous incidents and the handling of dangerous substances provides additional social benefit – not only to plant operators but also the local communities.

Our responsibility! Intervention to minimize and remediate environmental pollution effects should be given the first priority. In places where the environment is broken, we must intervene immediately to fix it.

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