KINETICS OF THE REACTION OF NITRIC-OXIDE WITH OXYGEN IN AQUEOUS-SOLUTIONS
KINETICS OF THE REACTION OF NITRIC-OXIDE WITH OXYGEN IN AQUEOUS-SOLUTIONS
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DOI：
10.1021/tx00040a013
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发表时间：
1994-07-01
影响因子：
4.1
通讯作者：
DEEN, WM
中科院分区：
文献类型：
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作者：
LEWIS, RS;DEEN, WM
在评估NO在体内的各种作用时，需要了解水溶液中一氧化氮（NO）与氧的反应速率。开发了一种新的方法来研究该反应的动力学，它允许同时和连续测量NO和主要产物亚硝酸盐（NO2-）的浓度。使用化学发光检测器测量一氧化氮，通过将NO扩散通过安装在小型搅拌反应器底部的膜来实现连续采样。不同初始NO和O-2浓度的结果证实了反应速率在NO中为二级，在O-2中为一级。NO的反应速率由表达式4K（1）[NO]（2）[O-2]描述，其中K-1在23 ℃时为（2.1 +/- 0.4）x 10（6）M（-2）s（-1），在37 ℃时为（2.4 +/- 0.3）x 10（6）M（-2）s（-1）。在pH 4.9和7.4时，k（1）值相同。NO2-的形成速率等于NO的反应速率（在几个百分点的实验不确定性内），并且没有可检测到的硝酸盐（NO3-）的形成。这证实了NO和NO2-是唯一的NOx物种存在的显着量，并支持伪稳态假设的有效性NO2和N2 O3，这是在NO的转化为NO2-的中间体。一个动力学模型被开发来预测NO，O-2，NO2-，NO2，和N2 O3的浓度在所研究的系统中的时间变化，这部分是由于跨气-液界面和跨膜在反应器的基础上传输。该分析强调了在开放系统中研究反应速率时定量相间传质的重要性，这一点在以前的一氧化氮研究中并不总是被认识到。
An understanding of the rate of reaction of nitric oxide (NO) with oxygen in aqueous solutions is needed in assessing the various actions of NO in the body. A novel approach was developed for studying the kinetics of this reaction, which permitted simultaneous and continuous measurements of the concentrations of NO and the principal product, nitrite (NO2-). Nitric oxide was measured using a chemiluminescence detector, with continuous sampling achieved by diffusion of NO through a membrane fitted into the base of a small, stirred reactor. The results with various initial NO and O-2 concentrations confirmed that the rate of reaction is second-order in NO and first-order in O-2. The rate of reaction of NO was described by the expression 4K(1) [NO](2)[O-2], where K-1 was (2.1 +/- 0.4) x 10(6) M(-2) s(-1) at 23 degrees C and (2.4 +/- 0.3) x 10(6) M(-2) s(-1) at 37 degrees C. The value of k(1) was the same at pH 4.9 and 7.4. The rate of formation of NO2- equaled the rate of reaction of NO (within experimental uncertainty of a few percent), and there was no detectable formation of nitrate (NO3-). This confirmed that NO and NO2- were the only NOx species present in significant amounts and supported the validity of pseudo-steady-state assumptions for NO2 and N2O3, which are intermediates in the conversion of NO to NO2-. A kinetic model was developed to predict temporal variations in the concentrations of NO, O-2, NO2-, NO2, and N2O3 in the system studied, which were due in part to transport across the gas-liquid interface and across the membrane at the base of the reactor. The analysis emphasizes the importance of quantifying interphase mass transfer when studying reaction rates in open systems, a point which has not always been recognized in previous studies with nitric oxide.