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A mechanistic study of the low pressure pyrolysis of linear siloxanes

Almond, Matthew J.; Becerra, Rosa; Bowes, Sarah J.; Cannady, John P.; Ogden, J. Steven; Young, Nigel A.; Walsh, Robin


Matthew J. Almond

Rosa Becerra

Sarah J. Bowes

John P. Cannady

J. Steven Ogden

Dr Nigel Young
Senior Lecturer/ Director of Studies/ Deputy Head of Chemistry and Biochemistry/ Industrial Placements Coordinator

Robin Walsh


Matrix isolation IR spectroscopy has been used to study the vacuum pyrolysis of 1,1,3,3-tetramethyldisiloxane (L1), 1,1,3,3,5,5-hexamethyltrisiloxane (L2) and 3H,5H-octamethyltetrasiloxane (L3) at ca. 1000 K in a flow reactor at low pressures. The hydrocarbons CH3, CH4, C2H2, C2H4, and C2H6 were observed as prominent pyrolysis products in all three systems, and amongst the weaker features are bands arising from the methylsilanes Me2SiH2 (for L1 and L2) and Me3SiH (for L3). The fundamental of SiO was also observed very weakly. By use of quantum chemical calculations combined with earlier kinetic models, mechanisms have been proposed involving the intermediacy of silanones Me2Si = O and MeSiH = O. Model calculations on the decomposition pathways of H3SiOSiH3 and H3SiOSiH2OSiH3 show that silanone elimination is favoured over silylene extrusion.

Journal Article Type Article
Publication Date Oct 21, 2009
Print ISSN 1463-9076
Electronic ISSN 1463-9084
Publisher Royal Society of Chemistry
Peer Reviewed Peer Reviewed
Volume 11
Issue 40
Pages 9259-9267
APA6 Citation Almond, M. J., Becerra, R., Bowes, S. J., Cannady, J. P., Ogden, J. S., Young, N. A., & Walsh, R. (2009). A mechanistic study of the low pressure pyrolysis of linear siloxanes. Physical chemistry chemical physics : PCCP, 11(40), 9259-9267. doi:10.1039/b910549b
Keywords Physical and Theoretical Chemistry; General Physics and Astronomy