Green chemistry substitution principle

SAFERCHEMICALS WITHIN REACH Using the Substitution Principle to drive Green Chemistry... 

The Draths-Frost method for making adipic acid illustrates a common goal in much green chemistry research, the ability to include more than one green chemistry principle at a time in new processes. Not only did Draths and Frost find a way of substituting a safer feedstock in their reaction, but they also found a safer catalyst, the simple bacterium Escherichia coli. The use of the bacterium eliminated the necessity of using hazardous metals as catalysts in the traditional reaction. 

Industrial research and development increasingly incorporates the principles of green chemistry and development of safer substitutes, but safer has usually meant less toxic. However, persistence should also be considered in product design. Chemicals that persist remain potentially available to biota to exert toxic effects, not all of which may be known or predictable at the outset Persistent chemicals that are bioaccumu-lative are of even greater concern because levels may be achieved in organisms that... 

Safer Chemicals Within Reach Using the Substitution Principle to Drive Green Chemistry, REACH Report prepared for the Greenpeace Environmental Trust by Clean Production Action, Clean Production Action, 2004. www. cleanproduction. org/library/SafeChem.pdf. 

Clean Production Action. 2003. Safer chemicals within REACH. Using the substitution principle to drive green chemistry. Report prepared for Green Peace Environmental Trust. 

However, the minimization of the risk, both in terms of environment and process safety, could be equally reached by adopting an on-demand synthesis of phosgene and MIC [46]. This is the approach preferred industrially and evidences that the same goal could be reached by a different philosophy, other than the substitution of chemicals indicated by green chemistry principles. 

This new process illustrates two of the principles of green chemistry listed above. First of all, DMC is manufactured without using the hazardous phosgene feed. In fact, the phosgene is not even produced in the new pathway. Second, the DMC can be a raw material substitution for phosgene in the manufacture of pesticides and urethanes. Furthermore, the first principle of waste management hierarchy is demonstrated in that the by-product HCl is not produced (although, if market conditions were appropriate, the HCl produced could be purified and sold as a commodity). 

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