Ogunwale Mumiye A, Knipp Ralph J, Evrard Clint N, Thompson Lee M, Nantz Michael H, Fu Xiao-An
Department of Chemistry, University of Louisville, Louisville, KY 40208, USA.
Department of Chemical Engineering, University of Louisville, Louisville, KY 40208, USA.
Chemphyschem. 2019 Mar 18;20(6):815-822. doi: 10.1002/cphc.201801143. Epub 2019 Mar 5.
The click-chemistry capture of volatile aldehydes and ketones by ammonium aminooxy compounds has proven to be an efficient means of analyzing the carbonyl subset in complex mixtures, such as exhaled breath or environmental air. In this work, we examine the carbonyl condensation reaction kinetics of three aminooxy compounds with varying β-ammonium ion substitution using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). We determined the activation energies for the reactions of the aminooxy compounds ATM, ADMH and AMAH with a panel of ketones and aldehydes that included acrolein and crotonaldehyde. The measurements indicate that the activation energies for the oximation reactions are quite low, less than 75 kJ mol . ADMH is observed to react the fastest with the carbonyls studied. We postulate this result may be attributed to the ADMH ammonium proton effecting a Brønsted-Lowry acid-catalyzed elimination of water during the rate-determining step of oxime ether formation. A theoretical study of oxime ether formation is presented to explain the enhanced reactivity of ADMH relative to the tetraalkylammonium analog ATM.
通过铵基氨氧基化合物对挥发性醛和酮进行点击化学捕获，已被证明是分析复杂混合物（如呼出气体或环境空气）中羰基子集的有效方法。在这项工作中，我们使用傅里叶变换离子回旋共振质谱（FT-ICR-MS）研究了三种具有不同β-铵离子取代的氨氧基化合物的羰基缩合反应动力学。我们确定了氨氧基化合物ATM、ADMH和AMAH与一组包括丙烯醛和巴豆醛在内的酮和醛反应的活化能。测量结果表明，肟化反应的活化能相当低，小于75 kJ mol 。观察到ADMH与所研究的羰基反应最快。我们推测这一结果可能归因于ADMH铵质子在肟醚形成的速率决定步骤中引发了布朗斯特-劳里酸催化的水消除反应。本文提出了肟醚形成的理论研究，以解释ADMH相对于四烷基铵类似物ATM的增强反应性。
