Catalysis, one of the overarching principles of green chemistry, is capable of producing substantial material and energy savings as well as economic benefits. When comparing catalytic methods to traditional stoichiometric syntheses, catalysis offers undisputable economy in reagent use. Stoichiometric reactions would require at least one mole of reagent per mole of starting material, whereas a catalyst, subject to turnover number (TON), can carry out a transformation multiple times per mole of catalyst. Catalytic reagents can be used to improve product selectivity, by enabling diastereomeric control and site specific transformations in multi-functionalised molecules. Catalysts also allow reactions to proceed under milder reaction conditions and catalytic methods can circumvent the need for pre-functionalisation of the starting materials with activating or directing groups, which would later need to be removed from the final molecule. Thus the use of catalytic rather than stoichiometric methods can dramatically enhance the atom economy of a synthesis, save time and energy, as well as decreasing the amount of raw materials consumed and waste generated. The development and application of catalytic methods can significantly improve both the economic and environmental profile when designing synthetic routes within process research and development (R&D). [1].
There are several factors to consider when selecting a catalyst in terms of its green credentials, including:
As catalysts play a crucial role in synthetic chemistry, they are covered in more detail in the Synthetic Toolbox topic, whilst methods for objectively measuring greenness are covered in the Metrics module.
A. Hunt, Sustainable Catalysis : With Non-endangered Metals, Parts 1 and 2, Royal Society of Chemistry, 2015.
C. P. R. Anastas, Handbook of Green Chemistry – Green Catalysis, (ed. P. Anastas) Wiley, 2009.
R. Arthur Sheldon, I. W. C. E. Arends and U. Hanefeld, Green Chemistry and Catalysis, Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
Science Aid: Catalysis and Catalysts (Last accessed: August 16, 2022).
J. Clark, Understanding Chemistry – Catalysis Menu (Last accessed: August 16, 2022).
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