Mechanistic Investigations into the Catalytic Levulinic Acid Hydrogenation, Insight in H/D Exchange Pathways, and a Synthetic Route to d<sub>8</sub>-γ-Valerolactone
作者:Qingqing Yuan、Henk H. van de Bovenkamp、Zhenlei Zhang、Anna S. Piskun、Selim Sami、Remco W.A. Havenith、Hero J. Heeres、Peter J. Deuss
DOI:10.1021/acscatal.1c02662
日期:2021.8.20
α-angelica lactone (α-AL). The insight provided by these studies revealed an as of yet unexploited sequential deuteration route to synthesize fully deuterated LA and GVL. The route starts by the conversion of LA to α-AL followed by a selectivedeuteration of the acidic protons of α-AL by H/D exchange with D2O. Subsequent ring-opening in D2O (d2-AL to d3-LA) and exchange of the remaining protons of d3-LA
γ-戊内酯 (GVL) 很容易通过碳水化合物衍生的乙酰丙酸 (LA) 的催化氢化获得,并且是一种有吸引力的生物基化学品,在化学品(例如,作为生物质衍生的溶剂)和运输燃料中都有广泛的应用部门。在这项研究中,我们使用同位素标记实验深入了解了在不同反应条件下将 LA 转化为 GVL 所涉及的催化氢化途径,使用水作为环境无害溶剂和 Ru/C 作为容易获得的催化剂。2结合量子化学计算的 H NMR 实验表明,氘原子可以在不同的位置结合,以及不同的中间体 4-羟基戊酸和 α-当归内酯 (α-AL) 的参与。这些研究提供的见解揭示了一种尚未开发的连续氘化途径来合成完全氘化的 LA 和 GVL。该路线首先将 LA 转化为 α-AL,然后通过与 D 2 O的 H/D 交换选择性氘化 α-AL 的酸质子。随后在 D 2 O 中开环(d 2 -AL 至 d 3 -LA) 和通过在 D 2 中加热通过酮-烯醇互变异构交换
Deuterated analogues of the free radical trap DEPMPO: synthesis and EPR studies
Three analogues of 5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide (DEPMPO, 1) labelled with two (1-d2), five (1-d5) or seven (1-d7)
2H were synthesized and used to trap the tert-butylperoxyl radical. The EPR spectra of 1-d2-OOBut and 1-d7-OOBut spin adducts exhibited more straightforward patterns and better signal to noise ratio than those obtained with 1 or 1-d5. The use of the easily available 1-d2 as spin trap could help significantly the analysis of the EPR signals when the signal of either superoxide or alkylperoxyl spin adduct is superimposed with the signals of other spin adducts.