Front Propagation in the Autocatalytic Fmoc–Piperidine Deprotection Reaction Visualized by Bromothymol Blue

Spatiotemporal phenomena that develop in autocatalytic reaction networks are essential for the operation of nonequilibrium chemical and biochemical systems. Designing complex chemical systems with appropriate kinetic and transport properties is a challenging task. The discovery of small organic molecule‐based autocatalytic networks opens a unique way due to the structural diversity of carbon‐containing compounds. Here, we study the front propagation in the autocatalytic 9‐fluorenylmethoxycarbonyl (Fmoc)‐piperidine reaction in the presence of p ‐nitrophenyl acetate inhibitor and bromothymol blue indicator. We demonstrate that the color change of the indicator is driven not only by piperidine but also by the product of the inhibitory reaction, p ‐nitrophenol. Numerical simulations support the experimental observations. Front propagation was observed at 50, 60, and 70 ℃ in thin solution layers. In the latter case, a convective instability is coupled to the reaction–diffusion phenomena. We anticipate that our results pave the way for discovering more complex spatiotemporal phenomena in networks of small organic molecules.