When chemists talk about intuition, they’re referring to the knowledge and practical knowhow they’ve accumulated over years that helps them make the right call. It’s a condensed set of rules of thumb that enables ‘good enough’ decisions to be made without having to resort to lengthy explorations of the underlying physics. In recent years, however, chemists have started to make these qualitative hand‑waving descriptions much more rigorous. Two studies we’ve written about recently illustrate that shift. One revisits the long-debated anomeric effect; the other offers a new way to quantify steric repulsion. Together, they point towards a more disciplined way of reasoning about cause and effect in molecules.
For decades, the anomeric effect has often been explained in terms of hyperconjugation: a ring substituent adopts an equatorial position to receive a stabilising lone pair donation from its neighbour. In January, we covered a study that used computational modelling and statistical analysis to quantify all of the factors at play – stereoelectronic, electrostatic, steric, hybridisation and dispersion – in a series of tetrahydropyrans. Its conclusion was not that one explanation wins, but that none of them works alone.
Not long after, we reported on a steric repulsion tool that focuses on making just make one of those factors more tractable. It replaces the vague notion of ‘bulk’ that often appears in mechanistic arguments with a detailed map showing where steric clashes occur, how strong they are and which atoms are responsible. Built on kinetic energy associated with Pauli repulsion, the approach connects quantum-mechanical descriptors to the practical choices chemists need to make.
Neither study aims to replace intuition; both, in fact, refine it. The anomeric analysis shows why single-cause explanations can break down under scrutiny: chemistry is complex with several factors often in play and changes in solvent, substituent or stereochemistry can reshuffle their relative importance. By contrast, tools that quantify steric repulsion allow us to isolate one of those factors and examine it in enough detail to design around it deliberately. Better understanding and clearer visualisations don’t drain chemistry of its intuitive character, they make that intuition more dependable. When our instincts are informed by numbers, it becomes easier to see which rules still apply, which ones fail and how to make decisions with greater confidence.
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