Dynamics of theory change in chemistry: Part 1. The benzene problem 1865–1945

Strong Chemical Bonds

“…With these two seemingly different treatments of benzene, the chemical community faced two alternative descriptions of one of its molecular icons, which began the VB-MO rivalry [44,46] that seems to accompany chemistry to the twenty-first century [21].…”

Quantum Chemistry and Chemometrics Applied to Conformational Analysis

“…(Drayer, 1993;Cintas, 2007) In 1865, August Kekulé proposed his theory of the benzene molecular structure and proposed that the carbon atom has valence 4. (Brush, 1999) His principal idea was that the carbon atom is tetravalent and can form valence bonds with other carbon atoms yielding to chains. These carbon chains can sometimes have closed arrangements, forming rings.…”

Was Kekule's Mind Brainbound? The Historiography of Chemistry and the Philosophy of Extended Cognition."

“…By 1864 Alexander Crum Brown had worked out the notation still used today (see Figure 4, page 169). 4 Kekulé's second visual contribution, associated with the fireside dream, was the idea of a hexagonal benzene ring (Rocke 19;Brush 1999). In Kekulé's 1866 paper "On the Constitution of Aromatic Substances," he proposed that aromatics, of which benzene (or "benzol") is the simplest, were formed of a nucleus of six carbon atoms in a closed chain with alternating double and single bonds (see Figure 5, page 171).…”