Reference

Enolization of 3-pentanone-2,2-d2: deuterium kinetic isotope effects and stereoselectivity

Enolization of 3-pentanone-2,2-d2: deuterium kinetic isotope effects and stereoselectivity. Held, Gary; Xie, Linfeng (Dep. Chem., Univ. Wisconsin, Oshkosh, WI 54901, USA). Microchemical Journal, 55(2), 261-269 (English) 1997 Academic. CODEN: MICJAN. ISSN: 0026-265X. DOCUMENT TYPE: Journal CA Section: 22 (Physical Organic Chemistry) 3-Pentanone-2,2-d2 was subjected to enolization by lithium diisopropylamide (LDA), lithium N-isopropyl(trimethylsilyl)amide (LITA), and lithium hexamethyldisilazide (LHMDS). Internal deuterium kinetic isotope effects were measured by 1H-NMR anal. of the corresponding trimethylsilyl enol ethers after quenching the enolates with chlorotrimethylsilane. The kH/kD values range from 2.3 (LDA) to 5.2 (LITA) to 6.6 (LHMDS), suggesting that the proton transfer is involved in the rate-detg. step of kinetic enolization with the transition state changing from reactant-like for LDA to more sym. for LHMDS. An improved E/Z ratio of 85%:15% at 0°C was obsd. 112896-23-8 is just another one chemical used in this study. for the deprotonation of 3-pentanone by LITA, compared to 71%:29% by LDA and 44%:66% by LHMDS. .

Formation of the 3-pentanone ion from ionized propyl propanoate through ion-neutral complexes

Formation of the 3-pentanone ion from ionized propyl propanoate through ion-neutral complexes. Traeger, John C.; Hudson, Charles E.; McAdoo, David J. (Chem. Dep., LaTrobe Univ., Bundoora, Australia). J. Am. Soc. Mass Spectrom., 3(3), 183-7 (English) 1992. CODEN: JAMSEF. ISSN: 1044-0305. DOCUMENT TYPE: Journal CA Section: 22 (Physical Organic Chemistry) Formation of the 3-pentanone ion (3) from ionized Pr propanoate through the complex [C2H5CO+ ·OC3H7] is proposed based on data obtained by photoionization. The threshold and energy dependence for forming 3 relative to those for related processes support this proposal. The threshold for forming 3 coincides with that predicted for forming [CH3CH2CO+ ·CH2CH3], suggesting that that complex is also an intermediate in the path to 3. 3-Pentanone ion formation is important much further above threshold than is alkane elimination through [RCO+ ·R] complexes. This adds to evidence that reactions between the partners in ion-dipole complexes take place over a wider energy range than do such reactions in complexes contg. nonpolar neutral partners.