THE PRACTICE OF 'GREEN CHEMISTRY'
In a world where the need for manufactured products is increasing exponentially, the search for more efficient, high-yield industrial processes are becoming inevitable. This inevitability caused the increase of the research in several fields mainly in chemistry. Chemical processes are inherent in any and every industry known to man. While those processes show several, the main drawback is the pollution they can cause whether, from the raw material, the unwanted by-products or simply from the energy a process necessitates in order to initiate or propagate.
The pollution is quite harmful on several levels to the ecosystems, from the health issues on an individual level to the extinction of species and the perturbation of the natural equilibrium on an ecosystem level. Because of that a new and silent revolution is taking place in order to remediate to this problem, the people are turning to natural or “green” products thus requiring the industry to turn to safer and environmentally conscious processes. This revolution led to the birth of a new discipline in chemistry titled “Green Chemistry”. This discipline showed that an industrial process should be evaluated by more parameters than its yield, a process should also be evaluated by the quality of waste it generates, its energy requirements, the renewability of the raw material, and many more parameters.
In 1991, under the EPA’s Green Chemistry Program Fact Sheet, the goal of the discipline was identified as “the design of chemical products and processes that reduce or eliminate the use or generation of hazardous substances” . In order to achieve this goal, twelve principles were agreed upon and considered to be the fundamental metrics for any process to be considered “Green” .
THE TWELVE PRINCIPLES
1. Prevention of waste: The first and most important principle states that waste prevention is better than waste treatment.
2. Atom economy: Chemists are encouraged to design synthetic methods which maximise the incorporation of starting materials into the final product.
3. Safer synthesis: It is important, wherever practicable, to design chemical methods which require and generate substances with little or no toxicity to people and the environment.
4. Safer Chemicals: Chemical products should be designed to achieve the desired function with minimal toxicity.
5. Safer Solvents and auxiliaries: Auxiliary substances such as solvents and separation agents should be eliminated whenever possible and made innocuous when used.
6. Energy efficiency: It is important to identify and minimise the environmental and economic impacts associated with energy use in chemical synthesis. Methods conducted at ambient temperature and pressure should be adopted whenever possible.
7. Renewable feedstocks: Starting materials originating from renewable feedstocks should be used whenever technically and economically practicable.
8. Fewer derivatives: The use of blocking groups, protection/deprotection, and temporary modification of physical/chemical processes should be minimised or excluded for waste reduction purposes.
9. Catalysis: When compared to stoichiometric reagents, catalytic reagents that are engineered for selectivity are more efficient and generally produce less waste.
10. Design for degradation: It is important to design chemical products which break down into innocuous degradation materials at the end of their function and which do not persist in the environment.
11. Real-time analysis: It is important to develop and adopt analytical methods that provide real-time, in-process monitoring and control prior to the formation of hazardous substances.
12. Safer chemistry for accident prevention: The potential for chemical accidents such as releases, explosions, and fires should be minimised by choosing inherently safer substances.
These principles ensure that the chemical process from which the industrial process derives has no, to little, environmental footprint. They are considered the best compromise between the industry requirements and the safety standards for the environment.
While this discipline is still young many achievements have been done such as the BHC’s Ibuprofen Synthesis, the Merck’s Synthesis of Januvia and Pfizer’s Sertraline Process .
Finally, this effort even though it is still in its beginnings, is a huge step for humanity in the direction of living in harmony with nature and in preserving this planet for our children and children’s children. It is a new practice for the preservation of an old world.