Action of Organoaluminum Reagents on Esters: Alkene Production and the Degradation of Synthetic Lubricants
Reactions of methylaluminum reagents with ester-based lubricating oils are mimicked through the reaction of trimethylaluminum (TMA) with tetraesters C(CH2OC(O)R)4 (R = C5H11 4 Pent, Bn 4 Bn). Using a 2:1 stoichiometry gave adduct 4 Pent(TMA)4. NMR spectroscopy on 1:1–12:1 TMA/4 Pent systems sugge...
Saved in:
Published in | Organometallics Vol. 38; no. 2; pp. 395 - 408 |
---|---|
Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
WASHINGTON
American Chemical Society
28.01.2019
Amer Chemical Soc |
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | Reactions of methylaluminum reagents with ester-based lubricating oils are mimicked through the reaction of trimethylaluminum (TMA) with tetraesters C(CH2OC(O)R)4 (R = C5H11 4 Pent, Bn 4 Bn). Using a 2:1 stoichiometry gave adduct 4 Pent(TMA)4. NMR spectroscopy on 1:1–12:1 TMA/4 Pent systems suggested 4 Pent gave dimethylated adduct C5H11CMe2OAlMe2(TMA), 2 Pent(TMA). Similar combination of TMA with 4 Bn at raised temperatures transformed 4 Bn into C(CH2OAlMe2)4(2 Bn)4 5(2 Bn)4 by sequential reaction of each ester group. Doubly reacted {BnC(O)OCH2}2C(CH2OAlMe2)2(2 Bn)2 7 Bn(2 Bn)2 was isolated and characterized. A Mitsubishi molecule could also be isolated, its formation rationalized by the elimination of 2 Bn and TMA from 5(2 Bn)4. The action of Me n AlCl3–n (n = 1, 1.5, 2) was studied initially on monoester BnC(O)OMe 1 Bn. Combining excess Me2AlCl with 1 Bn gave adduct 1 Bn(Me2AlCl) and small amounts of dimethylated BnCMe2OAlMe2(Me2AlCl), 2 Bn(Me2AlCl), and MeOAlCl2 10. 2 Bn(Me2AlCl) was fully characterized and, in the presence of 10, acted as a source of 2 Bn(MeAlCl2). From this species, a mixture of alkenes could be generated by formal elimination of Me3Al2(OH)Cl2 13, the decomposition of which was presumed to also explain MeH observation. Replacing Me2AlCl with aluminum sesquichloride or MeAlCl2 led to progressively more sluggish but similar reactions. Using Me n AlCl3–n (n = 1, 1.5, 2) with tetraesters suggested similar reactivity to monoesters. |
---|---|
Bibliography: | UKRI |
ISSN: | 0276-7333 1520-6041 |
DOI: | 10.1021/acs.organomet.8b00763 |