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 degrees 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.