Hydrogen sulfide, H₂S, stand as one of the major issues in petroleum industry. Aqueous solutions of triazines are the most utilized non-regenerative H₂S scavenger. Although they present a theoretical capture capacity of 3 mol of H₂S per mole of triazine, it effectively scavenges only 2 mol. Herein, we employed Density Functional Theory at CAM-B3LYP/6–311++G(2d,2p) level of calculation to rationalize the full mechanism for capture of H₂S by hexahydro-1,3,5-triazines, in particular the reason why the reaction stops at the second equivalent of H₂S. For the capture of the first equivalent of H₂S, we found an unprecedented S_N1 pathway to be less energetic than S_N2, the most commonly accepted in literature. For capture of a second H₂S molecule, however, both mechanisms are energetically similar. High barriers were found for the capture of the third molecule of H₂S, related to the lower electrophilicity of the carbon atom bonded to nitrogen and sulfur atoms.

硫化氢，H ₂ S，是石油工业的主要问题之一。三嗪的水溶液是最常用的非再生H ₂ S清除剂。尽管它们的理论捕获容量为每摩尔三嗪3摩尔H ₂ S，但它仅能有效清除2摩尔。在本文中，我们在CAM-B3LYP / 6–311 ++ G（2d，2p）的计算水平上采用了密度泛函理论，以合理化六氢-1,3,5-三嗪捕获H ₂ S的完整机理，特别是反应在第二当量H ₂ S处停止的原因。为了捕获第一当量H ₂ S，我们发现前所未有的S _N 1途径比S 2的能量更低_N 2，在文学中最普遍接受的。但是，为了捕获第二个H ₂ S分子，两种机理在能量上相似。发现捕获H ₂ S的第三分子的障碍很高，这与键合到氮和硫原子上的碳原子的较低亲电性有关。