C18‐DABCO‐AA: A Novel Brønsted Acidic Gemini Surfactant for the Environmental Benign Synthesis of 2,3‑Dihydroquinazolin‑4(1H)‑ones in Water at Ambient Temperature

We have successfully synthesized a new acidic surfactant named C18‐DABCO‐AA, which contains octadecyl and acetic acid substituent on DABCO (1,4‐diazabicyclo [2.2.2] octane) unit, with an excellent yield. The synthesized surfactant was analyzed using FT‐IR, 1H NMR, and 13C NMR spectroscopic techniques. Its thermal behavior was analyzed by using the TGA–DTA technique. Our analysis indicates that the synthesized surfactant has excellent surfactant properties. Its critical micelle concentration (CMC) is 0.80 mM as determined by the conductivity method and UV–vis absorption measurement at 298.15 K. Surfactant also showed strong acidic properties with a pKa of 3.3. It is the best catalyst for the synthesis of 2,3‑dihydroquinazolin‑4(1H)‐ones (DHQs) in water at 40 °C. The synthesis is achieved via two‐component reactions of various aromatic aldehydes and anthranilamide in water at a CMC concentration of C18‐DABCO‐AA. The method was also extended for synthesizing DHQs via two‐component reactions of different ketones and anthranilamide under similar reaction conditions. The products were achieved in with yields ranging from good to excellent within 60–90 min. Additionally, the aqueous solution with C18‐DABCO‐AA was reused up to five times with a minor decrease in product yield. The present protocol is fast, energy‐efficient, and can be used on a large scale for synthetic purposes. Additionally, it boasts impressive environmentally friendly credentials. We synthesized an acidic surfactant called C18‐DABCO‐AA, which demonstrated excellent surfactant properties, with a CMC of 0.80 mM and a pKa of 3.3. This surfactant effectively facilitates the synthesis of 2,3‐dihydroquinazolin‐4(1H)‐ones in water at 40 °C via the reaction of aromatic aldehydes or ketones with anthranilamide at its CMC. Additionally, the surfactant solution can be reused up to five times.