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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Direct Observation of Acyl Nitroso Compounds in Aqueous Solution and the Kinetics of Their Reactions with Amines, Thiols, and Hydroxamic Acids
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Direct Observation of Acyl Nitroso Compounds in Aqueous Solution and the Kinetics of Their Reactions with Amines, Thiols, and Hydroxamic Acids

机译：用胺，硫醇和羟肟酸直接观察水溶液中的酰基亚硝基化合物和其反应的动力学

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摘要

Acyl nitroso compounds or nitrosocarhonyls (RC(O)N=O) are reactive short-lived electrophiles, and their hydrolysis and reactions with nucleophiles produce HNO. Previously, direct detection of acyl nitroso species in nonaqueous media has been provided by time-resolved infrared spectroscopy demonstrating that its half-life is about 1 ms. In the present study hydroxamic acids (RC(O)NHOH) are oxidized electrochemically in buffered aqueous solutions (pH 5.9-10.2) yielding transient species characterized by their maximal absorption at 314-330 nm. These transient species decompose via a first-order reaction yielding mainly HNO and the respective carboxylic acid and therefore are ascribed to RC(O)N=O. The sufficiently long half-life of RC(O)N=O in aqueous solution allows for the first time the study of the kinetics of its reactions with various nucleophiles demonstrating that the nucleophilic reactivity follows the order thiolate hydroxamate amine. Metal chelates of CH3C(O)NHOH catalyze the hydrolysis of CH3C(O)N=O at the efficacy order of Cu-II Zn-II Ni-II Co-II where only Cu-II catalyzes the hydrolysis also in the absence of the hydroxamate. Finally, oxidation of hydroxamic acids generates HNO, and the rate of this process is determined by the half-life of the respective acyl nitroso compound.
机译：酰基亚硝基化合物或亚硝基烃（RC（O）n = O）是反应性的短寿命的电子手理，它们的水解和与亲核试剂产生HNO的反应。以前，通过时间分辨的红外光谱法显示了非水介质中酰基亚硝基物质的直接检测，证明其半衰期为约1毫秒。在本研究中，羟肟酸（RC（O）NHOH）在缓冲水溶液（pH 5.9-10.2）中被电化学氧化（pH5.9-10.2），得到瞬态物种，其特征在于314-330nm的最大吸收。这些瞬时物种通过主要是HNO和各自的羧酸产生的一阶反应分解，因此归因于RC（O）N = O.水溶液中RC（O）N = O的足够长的半衰期允许首次研究其反应的动力学与各种亲核试验，证明亲核反应性遵循硫醇酸酯＆羟胺＆胺。 CH3C（O）NHOH的金属螯合物催化CH3C（O）n = O以Cu-II＆GT的疗效顺序的水解。 Zn-II＆GT; NI-II＆GT; CO-II在没有羟肟酸盐的情况下，只有Cu-II催化水解。最后，羟肟酸的氧化产生HNO，并且该方法的速率由各种酰基亚硝基化合物的半衰期确定。

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