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Decomposition of 1,1‐dimethyl‐1‐silacyclobutane on a tungsten filament—evidence of both ring CC and ring SiC bond cleavages
Author(s) -
Tong L.,
Shi Y. J.
Publication year - 2010
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.1712
Subject(s) - chemistry , diradical , bond cleavage , propene , cyclopropane , photochemistry , allene , ring (chemistry) , cleavage (geology) , catalysis , organic chemistry , singlet state , physics , geotechnical engineering , fracture (geology) , nuclear physics , engineering , excited state
The decomposition of 1,1‐dimethyl‐1‐silacyclobutane (DMSCB) on a heated tungsten filament has been studied using vacuum ultraviolet laser single photon ionization time‐of‐flight mass spectrometry. It is found that the decomposition of DMSCB on the W filament to form ethene and 1,1‐dimethylsilene is a catalytic process. In addition, two other decomposition channels exist to produce methyl radicals via the SiCH 3 bond cleavage and to form propene (or cyclopropane)/dimethylsilylene. It has been demonstrated that both the formation of ethene and that of propene are stepwise processes initiated by the cleavage of a ring CC bond and a ring SiC bond, respectively, to form diradical intermediates, followed by the breaking of the remaining central bonds in the diradicals. The formation of ethene via an initial cleavage of a ring CC bond is dominant over that of propene via an initial cleavage of a ring SiC bond. When the collision‐free condition is voided, secondary reactions in the gas‐phase produce various methyl‐substituted 1,3‐disilacyclobutane molecules. The dominant of all is found to be 1,1,3,3‐tetramethyl‐1,3‐disilacyclobutane originated from the dimerization of 1,1‐dimethylsilene. Copyright © 2010 John Wiley & Sons, Ltd.