DFT Evaluation of H2S Scavengers Based on Aryl Ethers Functionalized with Ionic Liquid Cations

The mitigation of toxic and corrosive hydrogen sulfide (H₂S) is a critical challenge in the oil and gas industry, driving the search for non-triazine-based scavengers (NTBS). This study proposes a novel NTBS strategy by strategically coupling aryl-ether reactive probes with functionalized ionic liquid cations. Using Density Functional Theory (DFT) calculations, the mechanism was investigated, revealing a two-step pathway involving a Meisenheimer complex (MC) intermediate. The neutral aryl ether proved kinetically unfavorable due to a high activation barrier (ΔG^‡≈ 42.3 kcal mol^-1). Conversely, the ionic liquid species, which combine the pyridinium charge with NO₂ substitutions, enhanced the electrophilicity of the system and successfully lowered the energy barrier to 32.5 kcal mol^-1. While providing the first kinetic evidence of these functionalized ethers as viable NTBS, the pathways faced a thermodynamic bottleneck (endergonic product formation), guiding future molecular optimization.