| | 1 | Author
| L. Xie, W. H. Saunders | Requires cookie* | | | Title
| Is  | | | | Abstract
| o to p e E ffe c ts in K in e tic E n o la te F o r m a tio n fro m 2 -P e n ta n o n e a n d 2 -P e n t a n o n e -l , l , l -d 3 This paper is dedicated to Professor Jacob Bigeleisen on the occasion of his 70th birthday 2-Pentanone and 2-pentanone-l,l,l-d3 were treated with three-fold excesses of lithium diiso-propylamide (LDA) or lithium hexamethyldisilazide (LHMDS) in tetrahydrofuran (THF) with and without hexamethylphosphoric triamide (HMPA, 3 mol per mol of base) at temperatures ranging from 24 to — 70 °C. The deuterium kinetic isotope effects calculated from the product ratios (mea sured by GLC as trimethylsilyl enol ethers) showed a range of temperature dependences: none (LDA in THF), attenuated with A^jA^ = 2.53 (LHMDS in THF), and normal with /1H//1D~0.6 indicating moderate tunneling (LDA and LHMDS in THF-HMPA). The variation in temperature dependence is attributed to reaction via multiple base species in which HMPA affects the equilibria between the base species. | | | |
Reference
| Z. Naturforsch. 44a, 413 (1989); received January 13 1989 | | | |
Published
| 1989 | | | |
Keywords
| Isotope Effects, Kinetic Enolates, Temperature Dependence, Lithium Dialkylamide Bases | | | |
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| default:Reihe_A/44/ZNA-1989-44a-0413.pdf | | | | Identifier
| ZNA-1989-44a-0413 | | | | Volume
| 44 | |
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