Green chemistry also referred as sustainable chemistry. It is the branch of chemistry as well as engineering which focusing on making products and processes which produce less hazardous substances that pollute nature and have dangerous environmental impact affecting humans, animals, and plants. Main objectives of green chemistry are to reduce consumption of non-renewable resources and to make molecules, materials, products, and processes in a sustainable way by reducing waste, energy and decreases chemical toxicity.
In 1962, Silent spring book was launched by Rachel Carson, which was regarding the effects of chemicals on ecosystems, which caught the attention of public and scientists. Because of this in 1969, National environmental policy act (NEPA) was passed by Congress. In 1970, U.S environmental policy agency (EPA) was established by President Richard Nixon. In the 1980’s organization for economic co-operation and development (OECD) hold meeting with countries addressing environmental issues. EPA staff members later coined the term “Green chemistry”. In 1995, the annual presidential green chemistry challenge award was created. In 1997, University of Massachusetts started a Ph.D. program in green chemistry. In 1998, Paul Anastas and John C. Warner launched the book “Green chemistry: theory and practice” that consists of 12 principles of green chemistry which guided green chemistry movement.
Principles include prevention i.e. to prevent waste production rather than managing the produced waste. The weight of waste is measured as E-factor i.e. weight of waste produced along with the desired product. Eg. pharmaceutical companies producing when manufacturing drugs about 100 kilos of waste for 1 kilo of Active pharmaceutical ingredient (API) but with the application of green chemistry principles waste can be reduced to ten-times. Atom economy is also called atom efficiency, which is used to measure the greenness of synthesis or process. Atom economy is the molecular weight of the desired product over the molecular weight of all reactants multiply by 100%. Eg. If products are enantiomer highly stereoselective has atom economy of 100%.
Methods which produce less impact on the environment and toxicity should be used for less hazardous synthesis. Designing safe chemicals products which reduce toxicity to enhance the efficacy of function. Use of safe chemicals which are derived from renewable resources. Catalytic reagents should be used in small quantities. Analytical methodologies to be developed for real-time analysis for pollution prevention. The substances used in the process could be chosen wisely that reduce the risks like explosions, fires, and accidental releases.