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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Kinetic study of the hexacyanoferrate (III) oxidation of dihydroxyfumaric acid in acid
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Kinetic study of the hexacyanoferrate (III) oxidation of dihydroxyfumaric acid in acid

机译：酸中二羟基富马酸六氰合铁酸酯（III）氧化的动力学研究

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The kinetics of the hexacyanoferrate (III) oxidation of dihydroxyfumaric acid to hexacyanoferrate (11) and diketosuccinic acid was looked into within the 0.04 to 5.3 M HCl acidity range under different temperatures, ionic strengths, and solvent permittivity conditions. The kinetic effect of alkali metal ions, transition metal impurities, and substrate concentrations have also been analyzed. The observed inhibition effect brought about by addition of the reaction product, hexacyanoferrate (II), is a sign of a complex mechanism. The rate constants remained essentially unchanged up to 1 M HCl, diminished between 1.0 and 3.0 M HCl, and rose above 3.0 M HCl. Depending on the medium acidity, three mechanisms can be put forward, which involve different kinetically active forms. At low acidity, the rate-determining step involves a radical cation and both the neutral and the anion substrate forms are equally reactive (k(1) = k(2) = 2.18 +/- 0.05 M-1 s(-1), k(-1) = 0.2 +/- 0.03). When the medium acidity is boosted, the rate-determining step involves the neutral dihydroxyfumaric acid and two hexacyanoferrate (111) forms. In the intermediate region the rate constant diminished with rising [H+] (k(1)' = 0.141 +/- 0.01 and k(2)' = 6.80 +/- 0.05). Specific catalytic effect by binding of alkali metal ions to oxidant has not been observed. In all instances it was assessed that the substrate decomposition is slow compared to the redox reaction.
机译：研究了在不同温度，离子强度和溶剂介电常数条件下，在0.04至5.3 M HCl酸性范围内，二羟基富马酸六氰合铁酸酯（III）氧化为六氰合铁酸酯（11）和二酮丁二酸的动力学。还分析了碱金属离子，过渡金属杂质和底物浓度的动力学影响。通过添加反应产物六氰合铁酸盐（II）所观察到的抑制作用是复杂机理的标志。速率常数在1 M HCl以下基本保持不变，在1.0到3.0 M HCl之间减小，在3.0 M HCl以上上升。根据介质的酸度，可以提出三种机理，涉及不同的动力学活性形式。在低酸度下，速率确定步骤涉及自由基阳离子，中性和阴离子底物形式均具有同等反应性（k（1）= k（2）= 2.18 +/- 0.05 M-1 s（-1）， k（-1）= 0.2 +/- 0.03）。当提高中等酸度时，确定速率的步骤涉及中性二羟基富马酸和两种六氰基高铁酸盐（111）形式。在中间区域，速率常数随[H +]的增加而减小（k（1）'= 0.141 +/- 0.01，k（2）'= 6.80 +/- 0.05）。尚未观察到碱金属离子与氧化剂结合产生的特定催化作用。在所有情况下，均评估了与氧化还原反应相比，底物分解较慢。

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