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以S(-I)化合物二硫甲脒作为研究对象,利用高效液相色谱(HPLC)和质谱(MS)为快速分析手段,对酸性溶液中二硫甲脒水解和氧化动力学进行了研究.通过控制慢反应速度和选择合适的流动相,HPLC在物种追踪和动力学机理研究方面比其他方法(UV-vis和化学分离分析)显示出独特的优越性.二硫甲脒在酸性条件下可缓慢分解成多种硫化合物,通过HPLC可确定硫脲和二氧化硫脲两种产物,同时使用HPLC-MS联用还可以检测出两个未知产物,即MS测定表明该分子量为92.28和116.36的物种分别为甲脒次磺酸和联硫氰.为了确定水解过程中二氧化硫脲的产生途径,我们设计了一组对比实验,使水解分别在有氧和无氧环境中进行,发现结果并无明显差异,且硫脲生成量与二硫甲脒消耗量之比都保持在1.25～1.30之间,故推断二氧化硫脲是由甲脒次磺酸歧化得到.在过氧化氢氧化二硫甲脒反应中,除了硫脲、甲脒亚磺酸、甲脒次磺酸、联硫氰和尿素之外,甲脒磺酸和硫酸根也被检测出,该氧化反应对于二硫甲脒和过氧化氢均为一级反应,在pH1.5～3.0测定了二硫甲脒水解和氧化的速率常数,表明都随pH的增加而增大.我们提出的过氧化氢氧化二硫甲脒反应机理包括二硫甲脒水解平衡和甲脒次磺酸不可逆水解的两步连续反应、二硫甲脒及氧化中间物的氧化反应和甲脒磺酸的水解反应,该机理能够有效模拟氧化反应过程中不同物种的动力学实验曲线.
Using dithiamidine as the target compound, the hydrolysis and oxidation kinetics of dithiolactam in acidic solution were investigated by high performance liquid chromatography (HPLC) and mass spectrometry (MS). By controlling the slow reaction rate and choosing the appropriate mobile phase, HPLC shows unique advantages over other methods (UV-vis and chemical separation) in species tracing and kinetic mechanisms studies. Slow decomposition into a variety of sulfur compounds, thiourea and thiourea dioxide can be identified by HPLC two products, while using HPLC-MS combined can also detect two unknown products, namely, MS determination showed that the molecular weight of 92.28 and 116.36 respectively species For formamidine sulfenic acid and dithiocarbamate.To determine the production of thiourea dioxide hydrolysis process, we have designed a comparative experiment, the hydrolysis was carried out in aerobic and anaerobic environments, found no significant difference in the results, And the ratio of the amount of thiourea produced and the consumption of dithiocarbamidine remained between 1.25 and 1.30, it was inferred that thiourea dioxide was disproportionated from formamidine sulfenic acid. In the reaction of dichoethane amidine peroxide with hydrogen peroxide, Thiourea Formamidine sulfenic acid, formamidine sulfenic acid, dithiocarbamate and urea, formamidine sulfonic acid and sulfate were also detected. The oxidation reaction was a first-order reaction for both dithiocarboxamidine and hydrogen peroxide, The rate constants for the hydrolysis and oxidation of dithiolaminamidate were determined at pH 1.5-3.0, both of which show an increase with increasing pH. The reaction mechanism of the dichoethanidimidine hydroperoxide oxidized by us includes the hydrolysis equilibrium of dithiocarboxamidine and The two-step continuous reaction of formamidine sulfenic acid with irreversible hydrolysis, the oxidation reaction of dithiocarbamidine and oxidation intermediate and the hydrolysis reaction of formamidine sulfonic acid can effectively simulate the kinetic curves of different species during the oxidation reaction.