Green Chemistry

One of the major cause of environmental pollution is the rapid industrilization particularly the development of those industries which either produce or use toxic chemicals. One way to protect our environment from chemical effluents and wastes is to use Green Chemistry. By green chemistry , we mean producing the chemicals of our daily needs using such reactions and chemical processes which neither use toxic chemicals nor emit such chemicals into the atmosphere. Although it is a challenging task but some initial efforts have already been made to acheive this goal.

Techniques Used :- Green Chemistry does not employ toxic reagent or solvents and severe conditiin but use mild and environmental friendly reagent such as sunlight , microwaves , sound waves , and enzymes. Each of these is briefly described below :-

1. Use of sun light and microwaves :- The use of sunlight and ultraviolet light have given birth to photochemistry. During the past forty years, a number of photochemical reactions have been studied and their condition standardized. One major advantage of these reaction is that sometimes the prroduct of photochemical reactions are such that they cannot obtained by usual chemical method. Recently, many known reaction have also been carried out using microwave ovens. In these reaction , no toxic solvent are used but only the reactant in proper ratio are mixed on a solid support such a alumina and exposed to microwaves. The reaction is complete with in minutes and yields are not only comparable but in some cases, they are even higher than those obtained under serve conditions using toxic solvents. Thus the uses of microwave have not only reduced the time of reaction but have also increased the yields. Efforts are , however, needed to develop the solid support and optimization the dose of microwave radiation to realise the desired results.

2. Use of Sound Waves :- Instead of microwaves , sound wave have also been used to carry out certain known chemical reaction with encouraging results. This branch of chemistry is called sonochemistry. Here again efforts are needed to developed conditions to achieve the desired goals.

3. Use Of Enzymes :- One of the most throughly investigated environmental friendly reagents are enzymes. These work in aqueous solution and at ambient temperature. Using these enzymes many biochemical method have been developed to prepare precursors and intermediates of certain medicine and antibiotics.

Green Chemistry in Day-to-Day Life :- A few examples are of the chemical used/produced and the techniques employed in green chemistry are given below :-

1. Dry cleaning of clothes and laoundary :- Earlier tetrachloroethene was used as solvent for dry cleaning. This compound is suspected to be carcinogenic and contaminated the ground water. It's use has been replaced by liquefied carbon dioxide along with a suitable detergent which is less harmful. Similarly, for bleaching of clothes in the laundary, hydrogen peroxide is beings used which gives better results and is not harmful. Moreover, it saves as a lot of water.

2. Bleaching of paper :- Earlier , chlorine gas was used for bleaching paper which is highly toxic chemical. It's use has been replaced by hydrogen peroxide along with a suitable catalyst.

3. In synthesis of chemicals :- For examples ,  ethanal is now-a-days being prepared on a commercial scale using environment - friendly chemical and conditions. The yields is about 90% .

From the above discussion , it is evident that if concerted efforts are made to develop green chemical products, it will certainly help us to keep our environment pollution free.