Chemists Unlock New Synthetic Pathways with High-Temperature Capillary Reactions

Chemists in Russia have pioneered a method to conduct solution-phase organic reactions at temperatures up to 500°C using sealed glass capillaries. This breakthrough, achieved at the Zelinsky Institute of Organic Chemistry, overcomes previous limitations imposed by the thermal degradation of solvents and substrates at high temperatures. Traditionally, solution-phase synthesis has been limited to temperatures below 250°C, restricting the activation energy that could be overcome. The new method involves confining a small volume of solvent and reactant within glass pipettes, sealing them, and then heating them using induction heating, microwaves, or a muffle furnace. Aromatic or saturated hydrocarbons, particularly p-xylene, proved to be the most compatible solvents for these high-temperature reactions. The team successfully tested their method on the isomerization of N-substituted pyrazoles, completing reactions in just five minutes that typically require multiple steps. Researchers hope to scale up the method to discover new reactions and make previously inaccessible transformations possible, significantly simplifying the preparation of complex molecules.