Principles of Green Chemistry
Paul Anastas and John C. Warner defined green chemistry as the utilization of a set of principles that reduces or eliminates the use or generation of hazardous substances in the design, manufacture, and applications of chemical products.1
The 12 principles of green chemistry are:
- It is better to prevent waste than to treat or clean up waste after it 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 preserve efficacy of function while reducing toxicity.
- The use of auxiliary substances (e.g. solvents and separation agents) should be made unnecessary wherever possible and innocuous when used.
- Energy requirements should be recognized for their environmental and economic impacts and should be minimized. Synthetic methods should be conducted at ambient temperature and pressure.
- A raw material or feedstock should be renewable rather than depleting wherever technically and economically practicable.
- Unnecessary derivatization (blocking group, protection and deprotection, temporary modification of physical or chemical processes) 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 innocuous degradation products.
- Analytical methodologies need to be further developed to allow for real-time, in-process monitoring and control prior to the formation of hazardous substances.
- Substances and the form of a substance used in a chemical process should be chosen to minimize potential for chemical accidents, including releases, explosions, and fires.
These 12 principles fall into 4 broad groups:
- reduce energy use
- reduce waste
(see also Atom Economy)
- reduce hazards
- reduce resource use and utilize renewable resources
In practice, making a chemical process comply with the principles of green chemistry may mean:
- redesigning production methods to use different starting materials
- using different reaction conditions (eg, different solvents or catalysts)
- using production methods with fewer steps