Green Chemistry

What is Green Chemistry?   Introduction The Pollution Prevention Act of 1990 established a national policy to prevent or reduce pollution at its source whenever feasible. Green chemistry is the use of chemistry for pollution prevention. More specifically, green chemistry is the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances. Green chemistry is a highly effective approach to pollution prevention because it applies innovative scientific solutions to real-world environmental situations. The 12 principles of green chemistry originally developed by Paul Anastas and John Warner in Green Chemistry: Theory and Practice, provide a road map for chemists to implement green chemistry.   12 Principles of Green Chemistry   Prevent waste: Design chemical syntheses to prevent waste, leaving no waste to treat or clean up. Design safer chemicals and products: Design chemical products to be fully effective, yet have little or no toxicity. Design less hazardous chemical syntheses: Design syntheses to use and generate substances with little or no toxicity to humans and the environment. Use renewable feedstocks: Use raw materials and feedstocks that are renewable rather than depleting. Renewable feedstocks are often made from agricultural products or are the wastes of other processes; depleting feedstocks are made from fossil fuels (petroleum, natural gas, or coal) or are mined. Use catalysts, not stoichiometric reagents: Minimize waste by using catalytic reactions. Catalysts are used in small amounts and can carry out a single reaction many times. They are preferable to stoichiometric reagents, which are used in excess and work only once. Avoid chemical derivatives: Avoid using blocking or protecting groups or any temporary modifications if possible. Derivatives use additional reagents and generate waste. Maximize atom economy: Design syntheses so that the final product contains the maximum proportion of the starting materials. There should be few, if any, wasted atoms. Use safer solvents and reaction conditions: Avoid using solvents, separation agents, or other auxiliary chemicals. If these chemicals are necessary, use innocuous chemicals. Increase energy efficiency: Run chemical reactions at ambient temperature and pressure whenever possible. Design chemicals and products to degrade after use: Design chemical products to break down to innocuous substances after use so that they do not accumulate in the environment. Analyze in real time to prevent pollution: Include in-process real-time monitoring and control during syntheses to minimize or eliminate the formation of byproducts. Minimize the potential for accidents: Design chemicals and their forms (solid, liquid, or gas) to minimize the potential for chemical accidents including explosions, fires, and releases to the environment.     History   Shortly after the passage of the Pollution Prevention Act of 1990, the Office of Pollution Prevention and Toxics (OPPT) explored the idea of developing new or improving existing chemical products and processes to make them less hazardous to human health and the environment. In 1991, OPPT launched a model research grants program called "Alternative Synthetic Pathways for Pollution Prevention". This program provided unprecedented grants for research projects that include pollution prevention in the design and synthesis of chemicals. Since then, the Green Chemistry Program has built many collaborations with academia, industry, other government agencies, and non-government organizations to promote the use of chemistry for pollution prevention through completely voluntary, non-regulatory partnerships.