Partial oxidation without allylic carbon-hydrogen bond activation: the conversion of propene to acetone on rhodium(111)-p(2.times.1)-O
Partial oxidation without allylic carbon-hydrogen bond activation: the conversion of propene to acetone on rhodium(111)-p(2.times.1)-O
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无烯丙基碳氢键活化的部分氧化：在铑(111)-p(2×1)-O上丙烯转化为丙酮
DOI：
10.1021/ja00018a010
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发表时间：
1991
影响因子：
15
通讯作者：
C. Friend
中科院分区：
文献类型：
--
作者：
Xueping Xu;C. Friend
Conclusions The use of isotopic (1 2H,, 3C) double labeling in neutral product studies of gas-phase ion chemistry has here been demonstrated for the first time. Analysis of fluorine-containingproducts by 19F NMR reveals the position and extent of isotopic label in the reaction mixture, since the breadth of the fluorine chemical shift scale permits resolution of every isotopomeric product. Theformal equivalent of CH3CDFCH2+ rearranges by deuteride shift, methyl shift, or fluorine shift in the proportions 1.9: 1: 0.45. In ion-neutral complexes, the ions formed by the latter two shifts (deuterated analogues of 3 and 4) interconvert, signaling that these ions are of comparable stability (as predicted by SCF calculations at 6-31G**). As free ions, these cations rearrange extensively to the more stable 2-propyl cations on the millisecond timescale. In ion-neutral complexes, however, the lifetimes are so brief that no rearrangement to this global minimum (deuterated 1, which is also the ion formed by initial deuteride shift) can bedetected. From the proportions of recovered neutral products, we can extract approximate values of conformational equilibrium constants, branching ratios, and isotope effects. The scope and range of isotopic double labeling are thus exemplified.Acknowledgment. Ab initio computations were performed on the Cray X-MP/48 and Y-MP 8/864 at the San Diego Supercomputing Center. Calculations on F-protonated vinyl fluoride and 14 were performed by Lohri Grishow Phelan. This work was supported by NSF Grant CHE8802086.
