Chemistry has become very important in our everyday life during last few centuries. Although chemistry is helping enormously to the quality of life, negative effect of some chemicals are not exactly known to the human health and environment, even though they have been in use for several decades. One of the biggest problems of today’s world is facing environmental pollution. Environmental pollution is the major causes of nature thrown chemicals, toxic gases drained from factory chimneys, water, mixed organic solvents. Displays on the rapidly growing environmental pollution by the most responsible as chemicals, chemists and chemical engineers began looking at alternative solutions. The most significant of alternative ways to reach a sustainable improvement in a world with a continually growing population and restricted resources is green chemistry. The term green chemistry1 was first used in 1991 by Prof. Paul T. Anastas to implement sustainable development2, 3, 4, 5 in chemistry and chemical technology by industry, academia and government. Green chemistry embodies two main components. First, it addresses the problem of efficient utilisation of raw materials and the concomitant elimination of waste. Second, it deals with the health, safety and environmental issues associated with the manufacture, use and disposal or reuse of chemicals. Green chemistry incorporates a new approach5, 6, 7 to the synthesis, processing and application of chemical substances in such a manner as to reduce threats to health and the environment. Green chemistry is commonly presented as a set of twelve principles proposed by Anastas and Warner. These principles are:
It is better to prevent waste than treat or clean up waste after 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 reduce toxicity
The use of solvents should be made unnecessary wherever possible.
Energy requirements should be minimized. Synthetic methods should be conducted at low temperature and pressure.
Raw material or feedstock should be renewable.
Unnecessary derivatization (blocking group, protection/deprotection should be avoided whenever possible
Catalytic reagents (as selective as possible are superior to stoichiometric reagents.
Chemical products should be designed so that at the end of their function they do not persist in the environment and break down into degradation products.
Analytical methodologies need to be further developed to control the formation of hazardous substances.
Substances and the form of a substance used in a chemical process should be chosen so as to minimize the potential for chemical accidents, including releases, explosions, and fires.
Benefits of Green Chemistry
Green Chemistry provides less waste formation. In fact Green Chemistry is a new approach to ensure preservation of human health and the environment. Energy conservation and consumption has long been known to produce a major environmental effect. Microwave irradiation in the solid state8 is a technique that is being utilized to affect chemical transformations rapidly, in contrast to those that have classically been conducted in liquid solutions. Solvent-free microwave assisted reactions9, 10, 11 provide an opportunity to work with open vessels and thus, avoiding the risk of high pressure and increasing the potential for scale up of such reactions. The practical feasibility of microwave assisted solvent free synthesis has been demonstrated in various useful transformations and in the synthesis of heterocyclic systems.8, 9, 10, 11
Significance of Green Chemistry
Green chemistry is multidisciplinary research area which involves knowledge from various disciplines like chemistry, chemical technology, biotechnology, molecular biology, ecology, toxicology. The inputs from the various disciplines can help while developing new and innovative technologies and green synthetic routes for chemical production. The greenness of a chemical synthesis can be evaluated quantitatively and qualitatively. As we are all aware that, Perchloroethylene (PERC), Cl2C=CCl2 is commonly being used as a solvent for dry cleaning. It is now known that PERC contaminates groundwater and is a suspected carcinogen. A technology, Known as Micell Technology developed by Joseph De Simons, Timothy Romark, and James McClain made use of liquid CO2 and a surfactant for dry cleaning clothes, thereby replacing PERC. Dry cleaning machines have now been developed using this technique. Micell Technology has also evolved a metal cleaning system that uses CO2 and a surfactant, thereby eliminating the need of halogenated solvents.
Green chemistry aims to develop new practice of chemistry with rules which provides resolutions to problems that human is facing today such as climate changes. Green Chemistry is a science that aims to emphasize the development of chemical methods and substances to protect the environment. It is significant to understand the principles of green chemistry for future generations. Most importantly we need the relevant scientific, engineering, educational and other communities to work together for sustainable future through Green Chemistry. Many inorganic and organic materials cause harmfull effects to human, ecosystem and environment. But Green chemistry plays a key role in sustainable development through green synthesis and energy efficient process of production, recyclable and reusable materials. Various international organizations working on principles of green chemistry i.e. prevention of wastage, incorporation all material used in the process, designing less hazardous synthetic methods, safer chemicals, biodegradable materials, using of renewable feed stock, more energy efficient process, catalytic process, use of green solvents etc.