Abstract

The kinetics of Os(VIII)-accelerated L-tryptophan (Trp) oxidation by hexacyanoferrate(III) in CTAB micellar medium were investigated by measuring the decline in absorbance at 420 nm, which corresponds to [Fe(CN)₆]^3–. By adjusting one variable at a time, the progression of the reaction has been inspected as a function of [OH^–], ionic strength, [CTAB], [Os(VIII)], [Trp], [Fe(CN) \(_{6}^{{3 - }}\) ], and temperature using the pseudo-first-order condition. The results show that [CTAB], [Trp], and [OH^–] are the critical parameters with a discernible influence on reaction rate. The reaction rate is independent of the [Fe(CN) \(_{6}^{{3 - }}\) ]; hexacyanoferrate(III) is merely used up to regenerate the Os(VIII) during the reaction. In the investigated concentration range of Os(VIII), as well as at lower [OH^–] and [Trp], the reaction displays first-order kinetics with respect to [Os(VIII)], [OH^–], and [Trp] but follows less than unit order at larger Trp and alkali concentrations. The linear increase in reaction rate with added electrolyte is indicative of a positive salt effect. CTAB significantly catalyzes the process, and once at a maximum, the rate remains almost constant as [CTAB] increases. The observed decrease in CTAB CMC could be attributed to reduced repulsion between the positive charge heads of surfactant molecules caused by the negatively charged [Fe(CN)₆]^3–, OH^–, and [OsO₅(OH)]^3–.

中文翻译：

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CTAB 胶束介质中六氰基铁酸盐 (III) 催化 Os(VIII) 催化 L-色氨酸氧化的动力学和机理研究

摘要

通过测量 420 nm 处吸光度的下降（​​对应于 [Fe(CN)），研究了 CTAB 胶束介质中六氰基铁酸盐 (III) 促进 Os(VIII) 加速 L-色氨酸 (Trp) 氧化的动力学。 ₆]^3–。通过一次调整一个变量，反应进程被检查为 [OH^–]、离子强度、[CTAB]、 [Os(VIII)]、[色氨酸]、[Fe(CN)\(_{6}^{{3 - }}\)]和温度使用伪一阶条件。结果表明，[CTAB]、[Trp]和[OH^–]是对反应速率有明显影响的关键参数。反应速率与[Fe(CN)\(_{6}^{{3 - }}\)]无关；六氰基铁酸盐(III)仅用于在反应过程中再生Os(VIII)。在所研究的 Os(VIII) 浓度范围内，以及较低的 [OH^–] 和 [Trp] 下，反应表现出一级动力学相对于 [Os(VIII)]、[OH^–] 和 [Trp]，但在较大的色氨酸和碱浓度下遵循小于单位顺序。添加电解质后反应速率的线性增加表明了正盐效应。 CTAB 显着催化该过程，一旦达到最大值，随着 [CTAB] 的增加，速率几乎保持恒定。观察到的 CTAB CMC 下降可能是由于带负电荷的 [Fe(CN)₆] 导致表面活性剂分子的正电荷头之间的排斥力降低。 ^3–、俄亥俄州^–和[OsO< a i=23>5(OH)]^3–。