Microreactor processing for the aqueous Kolbe-Schmitt synthesis of hydroquinone and phloroglucinol

Hydroquinone and phloroglucinol were used as substrates for the aqueous Kolbe-Schmitt synthesis, using a novel processing methodology, termed high-p,T processing, recently demonstrated for the carboxylation of resorcinol. By the high-p,T approach, the temperature limitations of classical batch synthesis, e.g., set by reflux conditions (solvent boiling point), can be overcome by simple technical expenditure, e.g., the use of a few microstructured components, a capillary, and a needle valve at very low internal holdup. In this way, favorable speed-up of chemical reaction is achieved at temperatures normally outside the useful range for organic synthesis. While the hydroquinone synthesis gave …