A simple hydroxypyridine ionic liquids for conversion of CO2 into quinazoline-2,4(1H,3H)-diones under atmospheric conditions

The transformation of CO 2 into high value-added product is a promising pathway for utilizing CO 2 . However, the process tends to require harsh reaction conditions owing to CO 2 chemical inertness. Designing a high efficiency catalytic system with environmentally benign characteristic are important determinants. In this work, protic ionic liquids [TMG][2-OPy] were prepared via one-step neutralization between 1,1,3,3-tetramethylguanidine and 2-hydroxypyridine, applying to the domain of synthesizing quinzoline-2,4(1H , 3H) - diones from CO 2 and 2-aminobenzontiles without any solvent or metal, achieving the yield of 97% at 90 °C for 8 h under atmospheric. A series of substrates with good to acceptable yield were detected, revealing the generality and universality of the catalyst. Furthermore, the system could be facilely reused for at least six runs, retaining the yield of 94%. A preliminary kinetic equation is calculated with the activation energy of 68 kJ·mol −1 , and a plausible reaction mechanism was put forward. This study highlights that the [TMG][2-OPy] enables to activate CO 2 carboxylation efficiently.