Kissner R, Nauser T, Bugnon P, Lye P G, Koppenol W H
Laboratorium für Anorganische Chemie, Eidgenössische Technische Hochschule Zürich, Switzerland.
Chem Res Toxicol. 1997 Nov;10(11):1285-92. doi: 10.1021/tx970160x.
Flash photolysis of alkaline peroxynitrite solutions results in the formation of nitrogen monoxide and superoxide. From the rate of recombination it is concluded that the rate constant of the reaction of nitrogen monoxide with superoxide is (1.9 +/- 0.2) x 10(10) M-1 s-1. The pKa of hydrogen oxoperoxonitrate is dependent on the medium. With the stopped-flow technique a value of 6.5 is found at millimolar phosphate concentrations, while at 0.5 M phosphate the value is 7.5. The kinetics of decay do not follow first-order kinetics when the pH is larger than the pKa, combined with a total peroxynitrite and peroxynitrous acid concentration that exceeds 0.1 mM. An adduct between ONOO- and ONOOH is formed with a stability constant of (1.0 +/- 0.1) x 10(4) M. The kinetics of the decay of hydrogen oxoperoxonitrate are not very pressure-dependent: from stopped-flow experiments up to 152 MPa, an activation volume of 1.7 +/- 1.0 cm3 mol-1 was calculated. This small value is not compatible with homolysis of the O-O bond to yield free nitrogen dioxide and the hydroxyl radical. Pulse radiolysis of alkaline peroxynitrite solutions indicates that the hydroxyl radical reacts with ONOO- to form [(HO)ONOO].- with a rate constant of 5.8 x 10(9) M-1 s-1. This radical absorbs with a maximum at 420 nm (epsilon = 1.8 x 10(3) M-1 cm-1) and decays by second-order kinetics, k = 3.4 x 10(6) M-1 s-1. Improvements to the biomimetic synthesis of peroxynitrite with solid potassium superoxide and gaseous nitrogen monoxide result in higher peroxynitrite to nitrite yields than in most other syntheses.
碱性过氧亚硝酸盐溶液的闪光光解会生成一氧化氮和超氧化物。根据复合速率得出，一氧化氮与超氧化物反应的速率常数为(1.9±0.2)×10¹⁰ M⁻¹ s⁻¹。氢过氧亚硝酸的pKa取决于介质。采用停流技术，在毫摩尔浓度的磷酸盐中测得的值为6.5，而在0.5 M磷酸盐中该值为7.5。当pH大于pKa且过氧亚硝酸盐和过氧亚硝酸的总浓度超过0.1 mM时，衰变动力学不遵循一级动力学。ONOO⁻和ONOOH之间形成加合物，其稳定常数为(1.0±0.1)×10⁴ M。氢过氧亚硝酸的衰变动力学对压力的依赖性不强：从高达152 MPa的停流实验中，计算出活化体积为1.7±1.0 cm³ mol⁻¹。这个小值与O - O键均裂生成游离二氧化氮和羟基自由基不相符。碱性过氧亚硝酸盐溶液的脉冲辐解表明，羟基自由基与ONOO⁻反应形成[(HO)ONOO]⁻，速率常数为5.8×10⁹ M⁻¹ s⁻¹。该自由基在420 nm处有最大吸收(ε = 1.8×10³ M⁻¹ cm⁻¹)，并通过二级动力学衰变，k = 3.4×10⁶ M⁻¹ s⁻¹。用固体超氧化钾和气态一氧化氮进行过氧亚硝酸盐的仿生合成改进后，与大多数其他合成方法相比，过氧亚硝酸盐与亚硝酸盐的产率更高。
