Adipic acid green synthesis

Industry, in fact, has a major interest in these diesters as building blocks for nylon 6,6 and nylon 7,7 in the production of polyesters and polyamides. However, their present synthesis raises an environmental concern. For instance, the oxidation of cyclohexanone by nitric acid (for the preparation of adipic acid), accounts for more than 10% of the total yearly release of N2O, which is among the main gases responsible for the greenhouse effect. The reaction of Scheme 4.14 represents an eco-friendly alternative synthesis of a,(i)-diesters which uses green reagents and, relevantly, has a 100% atom economy. The overall process is mechanistically described as a retro-Claisen condensation. 

Reed, S. M. Hutchison, J. E. Green Chemistry in the Organic Teaching Laboratory An Environmentally Benign Synthesis of Adipic Acid , J. Chem. Educ. 2000, 77, 1627-1629. 

Reed SM, Hutchison JE. Green chemistry in the organic teaching laboratory an environmentally benign synthesis of adipic acid. J Chem Ed 2000 77 1627-9. 

CHEMICAL CONNECTIONS 12A A Green Synthesis of Adipic Acid... 

Genetically engineered microbes have been used by Draths and Frost (1998a, b) to synthesize common but important chemicals such as adipic acid and catechol (see Fig. 3.23). The noteworthy aspect of this work is that the starting materials were renewable feedstock. The principles of green chemistry state that "a raw material of feedstock should be renewable rather than depleting wherever technically and economically practicable" (Anastas and Warner, 1998). This reaction addresses this principle and more, as it can be seen. Classical catechol synthesis beginning with benzene (obtained from petroleum, a nonrenewable feedstock) involves a multistep process (see Fig. 3.22). 

An environmentally benign (or green) synthesis of adipic acid, catechol and BHT (a potential replacement for BHT) has been developed by John W. Frost and Karen M. Draths starting with glucose and using a biocatalyst (genetically altered E. coli bacteria) (Scheme 5). 

Scheme 5. Green synthesis of catechol and adipic acid...

The new synthetic route to ibuprofen is an important example of how ideas of green chemistry can influence for the better the industrial synthetic methods used, not only from the point of view of economic efficiency, but also by introducing more effective methods of science and technology. Improved methods of synthesis for hexan-l,6-dioic acid (adipic aid) and cis-butenediol acid (maleic anhydride) - important for the industrial synthesis of nylon and polyesters respectively - are two other examples of the impact of a greener synthetic approach to industrial chemistry. 

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