Efficient Synthesis of Quinazoline-2,4(1H,3H)‑dione via Simultaneous Activated CO₂ and 2‑Aminobenzonitrile by 1‑Methylhydantoin Anion-Functionalized Ionic Liquid through the Multiple-Site Cooperative Interactions

A novel basic anion-functionalized ionic liquid with a 1-methylhydantoin anion ([1-MHy]⁻) and [P₄₄₄₂]⁺ cation was synthesized for efficient CO₂ capture and catalytic conversion of CO₂ to quinazoline-2,4­(1H,3H)-dione, and CO₂ absorption and conversion mechanisms were investigated by NMR, FT-IR, and DFT calculations. CO₂ absorption results show that the capture capacity of [P₄₄₄₂]­[1-MHy] at 303.15 K and 0.1 MPa is up to 1.58 mol_CO2/mol_IL, which is attributed to the multiple-site cooperative interactions between CO₂ with N^– and CO of [1-MHy]⁻ originated from the electron conjugation effect, resulting in a decrease in the CO₂ absorption enthalpy (−51.4 kJ/mol) and an increase in the activation of CO₂. Moreover, the high yield of quinazoline-2,4­(1H,3H)-dione obtained by using [P₄₄₄₂]­[1-MHy] to catalyze 2-aminobenzonitrile with atmospheric-pressure CO₂ was 97% and is solvent- and metal-free. The reaction mechanism indicates that [1-MHy]⁻ with the multiple-site cooperative interactions can not only activate CO₂ but also can activate 2-aminobenzonitrile by forming two types of hydrogen bonds with −NH₂ (N–H···N^– and N–H···OC), thus ensuring the excellent catalytic performance of [P₄₄₄₂]­[1-MHy]. Furthermore, due to the similar basicity of [1-MHy]⁻ to the quinazolide anion ([Quinazolide]⁻), it can effectively prevent the deprotonation of the acidic quinazoline-2,4-dione into [Quinazolide]⁻, thereby improving its yield. In addition, [P₄₄₄₂]­[1-MHy] has good recycling performance during CO₂ capture and conversion. The physicochemical properties of [P₄₄₄₂]­[1-MHy] are also reported. The obtained results may provide a new strategy for converting CO₂ into value-added chemicals under green conditions.