Atom utilisation, E factors and the catalytic solution

It is widely acknowledged that there is a pressing need for more environmen tally acceptable processes in the chemical industry. This trend towards wha t has become known as Green Chemistry necessitates a paradigm shift from tr aditional concepts of process efficiency, that focus exclusively on chemica l 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 c ure. The key to the development of environmentally acceptable processes is the widespread substitution of antiquated technologies with cleaner catalyt ic alternatives. Two useful measures of the potential environmental accepta bility 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 we ights of all substances produced in the stoichiometric equation.