Lee Cronin

The Metaphysics of Chemical Reactivity

Discovery in chemistry falls mainly into one of four types of areas with the discovery of new molecules, new reactions, new reactivity, and finally new physical properties of the resulting compounds or materials. Establishing new reactivity leads to new reactions which also leads to new molecules. This is therefore the order of impact for discoveries in terms of the amount of chemical knowledge that they contribute. Such findings must, by definition, belong outside the known or predictable; and they are outliers and as such can oppose conventions, assumptions and biases.  By developing the meta-physics of chemistry and chemical reactivity we should be able to establish a new set of ontologies in chemistry that relate back to the practical core operations, but also can be translated into molecular structures and the discovery of function. The truth of chemistry lies with finding the intrinsic reactivity of the input chemicals, and then encouraging or enabling reactivity by process control. Whilst the new discovery and reaction should be translatable to chemical bonding theory, chemists need to grapple with the fact that the application of the current rules will not allow discovery, instead they will act to restrict it to the known rules.  So chemical discovery requires that the current rules are updated, broken, or new ones are made where before there were none. The discovery of Diels-Alder or cross-coupling reactions are excellent examples of new rules that were just discovered without any prior warning.  Without a deeper development of a meta-physics of chemistry the use of big data and artificial intelligence will just tell us what we already know we know, and maybe predictable extensions, rather than enabling discovery. The challenge for the chemist