Green chemistry is chemistry, the scientific discipline of arranging molecules to create new materials and products; it places emphasis on the intentional integration of source and hazard reduction into the design of matter. Green chemistry is the knowledge and technology to design and manufacture of chemical products, which is targeted to reduce or eliminate the use or generation of hazardous substances to the greatest extent. Green chemistry can be applied across the life cycle of a chemical product, including its design, manufacture, use, and ultimate disposal, to reach our ultimate objective of safe, clean and efficient production of various chemicals. Green chemistry is also known as sustainable chemistry. Below are the 12 principles of Green chemistry:

1, Prevent waste: Rational designed synthetic route to prevent waste, leave no or least waste to post-processing or clean-up
2, Maximize atom economy: Designed syntheses so that the final product contains the maximum proportion of the starting materials, waste few or no atoms from starting material

3, Design less hazardous chemical syntheses: Design syntheses to use and generate substances with little or no toxicity to either humans being or the environment
4, Design safer chemicals and products: Design chemical products that are fully effective and well function yet have little or no toxicity
5, Use safer solvents and reaction conditions: Avoid using hazardous and hazardous solvents, separation agents, or other auxiliary chemicals. If they are must, use safer ones and minimum amounts
6, Increase energy efficiency: Run chemical reactions at room temperature and atmospheric pressure whenever possible
7, Use renewable feed-stocks: Use starting materials that are renewable rather than depletable, the source of renewable feed-stocks is often agricultural products or the wastes of other processes, the source of depletable feed-stocks is often fossil fuels (petroleum, natural gas, or coal) or mining products
8, Avoid chemical derivatives: Avoid using blocking or protecting groups or any temporary modifications if possible, derivative reactions use additional reagents and generate more wastes 
9, Use catalysts, avoid stoichiometric reagents: Minimize waste by using catalytic reactions, catalysts are effective in small amounts and can carry out a single reaction many times, preferable to avoid stoichiometric reagents, which are used in excess and carry out a reaction only once
10, 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 
11, Analyze in real time to prevent pollution: Include in-process, real-time monitoring and control during syntheses or manufacture, to minimize or eliminate the formation of by-products
12, Minimize and prevent the potential for accidents: Design chemicals and their physical forms (solid, liquid, or gas) to minimize the potential for chemical accidents including explosions, fires, and their releases to the environment