(中南大學(xué) 化學(xué)化工學(xué)院，長沙 410083)
摘 要: 在B3LYP/6-31+G(d, p)水平，對2-巰基苯并噻唑(MBT)、2-巰基苯并惡唑(MBO)和2-巰基苯并咪唑(MBI)的真空結(jié)構(gòu)進行優(yōu)化，然后采用積分連續(xù)介質(zhì)模型(IEF-PCM)進一步優(yōu)化它們及其相應(yīng)離子在水溶液(介電常數(shù)為78.39)中的結(jié)構(gòu)；通過反應(yīng)中心原子電荷以及前線分子軌道能量和組成分析O、N、S雜原子對MBO、MBI、MBT反應(yīng)性的影響規(guī)律。理論研究結(jié)果表明：在真空中和溶液中，MBO、MBI、MBT的硫酮形式均比其硫醇形式穩(wěn)定，且反應(yīng)活性更高，但在溶液中MBO、MBI、MBT存在硫酮−硫醇−離子3種互變形式，其中離子形式反應(yīng)性最高；作為硫化礦捕收劑，3種苯并雜環(huán)巰基捕收劑的捕收能力從大到小的順序為MBT，MBI，MBO；其選擇性從大到小的順序為MBT，MBI，MBO。
關(guān)鍵字: 2-巰基苯并噻唑；2-巰基苯并咪唑；2-巰基苯并惡唑；密度泛函理論；化學(xué)反應(yīng)性
（School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China）
Abstract:The molecular structures of 2-mercaptobenzothiazole (MBT), 2-mercaptobenzoxazole (MBO), 2-mercaptobenzimidazole (MBI) were fully optimized at the B3LYP/6-31+G(d, p) level in the vacuum phase. The integral equation formalism for the polarizable continuum model (IEF-PCM) was employed to optimize the structures of the three agents and their ions in water with dielectric constant of 78.39. The effects of the O, N and S atoms on the chemical reactivities of MBO, MBI and MBT molecules were inferred by the energies of frontier molecular orbital and the atomic charges which were related to the reactive behavior of them. The results of the calculation indicate that their thione forms of MBO, MBI and MBT are more stable and have stronger reactivities than their thiol forms, both in the vacuum and aqueous phases. But in aqueous phase, there are three forms of thione−thiol−ion tautomerizations for MBO, MBI and MBT, and the ion forms have the strongest reactivities. As collectors for the flotation of sulfide minerals, the following collecting ability order form high to low is theoretically obtained as MBT, MBI, MBO, and their selectivity against pyrite is followed as the order from low to high as MBT, MBI, MBO.
Key words: 2-mercaptobenzothiazole; 2-mercaptobenzoxazole; 2-mercaptobenzimidazole; density functional theory; chemical reactivity
