Atom utilisation, E factors and the catalytic solution

It is widely acknowledged that there is a pressing need for more environmentally acceptable processes in the chemical industry. This trend towards what has become known as Green Chemistry necessitates a paradigm shift from traditional concepts of process efficiency, that focus exclusively on chemical yield. to one that assigns economic value to eliminating waste at source and avoiding the use of toxic and!or hazardous substances. Green chemistry eliminates waste at source, i.e. it is primary pollution prevention rather than waste remediation (end-of-pipe solutions). Prevention is better than cure. The key to the development of environmentally acceptable processes is the widespread substitution of antiquated technologies with cleaner catalytic alternatives. Two useful measures of the potential environmental acceptability of chemical processes are the E factor, defined as the mass ratio of waste to desired product, and the atom utilisation, calculated by dividing the molecular weight of the desired product by the sum of the molecular weights of all substances produced in the stoichiometric equation.