Department of Chemistry, Virginia Tech, 1040 Drillfield Drive, Blacksburg, VA-24060, USA.
Chempluschem. 2022 Nov;87(11):e202200213. doi: 10.1002/cplu.202200213. Epub 2022 Aug 25.
Rate constants for the reaction of nitrate radical (NO ⋅) with several carboxylic acids (RCO H) were measured in acetonitrile using laser flash photolysis, and found to be on the order of 10 -10 M s . No observable H/D kinetic isotope effect was observed at the carboxyl O-H group, α-C-H bond and (possibly) in the case of formic acid, the formylic C-H bond. This suggests that NO ⋅ does not abstract hydrogen from any of these positions despite the fact that all these processes are thermodynamically favorable. Reactivity increases with increased length and/or branching of the alkyl side chain (R), and approaches, but does not quite reach, that of an alkane towards NO ⋅. The relative inertness of carboxylic acids towards NO ⋅ can be explained by the polar effect.
用激光闪光光解法在乙腈中测量了硝酸根自由基（NO ⋅）与几种羧酸（RCOH）的反应速率常数，发现其数量级为 10 -10 M s 。在羧基 O-H 键、α-C-H 键（以及可能在甲酸的情况下，甲酰基 C-H 键）处未观察到可观察到的 H/D 动力学同位素效应。这表明，尽管所有这些过程在热力学上都是有利的，但 NO ⋅ 并没有从这些位置中提取氢。反应性随烷基侧链（R）的长度和/或支化程度的增加而增加，并接近，但不完全达到与 NO ⋅ 反应的烷烃的反应性。羧酸对 NO ⋅ 的相对惰性可以用极性效应来解释。
