Tri(tert-butyl)methylenphosphoran : Konsequenzen sterischer Hinderung für innermolekulare Beweglichkeit und thermischen Zerfallsmechanismus / Tri(tert-butyl)methylenephosphorane : Consequences of Sterical Hindrance for Intramolecular Motions and Thermal Decomposition Mechanism
Open Access
- 1 July 1977
- journal article
- Published by Walter de Gruyter GmbH in Zeitschrift für Naturforschung B
- Vol. 32 (7) , 757-761
- https://doi.org/10.1515/znb-1977-0707
Abstract
Dimethyl(tert-butyl)-, di(tert-butyl)methyl- and tri(tert-butyl)methylenephosphorane (CH3)n[(CH3)3C]3-nP=CH2, 3a-c, (n = 2,1, 0) have been synthesized from the corresponding phosphonium bromides, using standard methods, but under mild conditions. 3 c was found to be thermally unstable, undergoing reductive elimination of isobutene already at room temperature, with di(tert-butyl)methylphosphine as a by-product. 3 b is decomposed similarly above 80 °C. A mechanism for this unusual mode of ylide decomposition is proposed, based on the extreme steric crowding of the molecules. Restricted P–C bond rotation has been detected by 1H and 13C NMR spectroscopy for 3 c in toluene solution. Traces of protic species cause a rapid intermolecular H2C(P) hydrogen exchange.Keywords
This publication has 0 references indexed in Scilit: