The siliconoxygen double-bonded intermediates

Tomadze, A. V.; Yablokova, N. V.; Yablokov, V. A.; Razuvaev, G. A.

doi:10.1016/s0022-328x(00)85524-2

Cited by 12 publications

(4 citation statements)

References 6 publications

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“…The intermediacy of free silanones has been proposed for many reactions which primarily involve gas-phase, high-temperature conditions − but has been questioned in some of these processes . Much of the evidence for silanone formation is inferred from the presence of small silicone cyclics in reaction mixtures, − as in the reaction between DMSO and R 2 SiCl 2 . , …”

Section: Resultsmentioning

confidence: 99%

Using “Anhydrous” Hydrolysis To Favor Formation of Hexamethylcyclotrisiloxane from Dimethyldichlorosilane

et al. 1998

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The reaction between dimethyl sulfoxide and Me 2 SiCl 2 leads to the formation of cyclic siloxanes, principally the more highly strained six-membered ring hexamethylcyclotrisiloxane (D 3 ), via linear R,ω-dichlorosiloxanes. At short reaction times (∼15 min), the reaction was shown not to be undergoing equilibration reactions (ligand metathesis) to a significant degree. A mechanism for the formation of D 3 and D 4 (octamethylcyclotetrasiloxane) is proposed that invokes conversion of a chlorosilane group into a sulfonium ion intermediate 12. The preferential formation of D 3 over D 4 is attributed to the greater steric encumbrance of the activated chain termini (SiOS + Me 2 ) than in the corresponding hydrolysis reaction (SiOH). Both the chain extension reactions 12 f 3 and cyclization reactions 12 f D 3 are retarded, resulting in a higher selectivity (with DMSO as the oxygen source) for the intramolecular reaction producing D 3 than in the case of hydrolysis. The experimental results are inconsistent with silanone formation.

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Section: Resultsmentioning

confidence: 99%

Using “Anhydrous” Hydrolysis To Favor Formation of Hexamethylcyclotrisiloxane from Dimethyldichlorosilane

et al. 1998

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“…Much of the evidence for silanone formation is inferred from the presence of small silicone cyclics in reaction mixtures. Thus, hexamethylcyclotrisiloxane @, ) and octamethylcyclotetrasiloxane (D,) have been observed in the thermosylates of silylketenes (Scheme lA, 11) and silylperoxides (Scheme lB, 12), in the thermal decomposition of siloxetanes (Scheme lC, 13), as products of retroene reactions (14), and in other reactions (Scheme ID, 15,16). Some of the clearest evidence for silanone formation results from the thermal decomposition of D,; Me#-formation is inferred from the initial first-order kinetics for the formation of D, (17,18).…”

Section: Introductionmentioning

confidence: 99%

The thermolysis of ε-halodisilanes: a preference for 1,2-Si Si → O rearrangement or Si—O cleavage over Si=O bond formation

Roos¹,

McGibbon²,

Brook³

1996

Can. J. Chem.

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Tris(trimethylsily1)-2,2,2-trifluoroethoxysilane 6, tris(trimethylsily1)-2-fluoroethoxysilane 7, and tris(trimethylsily1)-2-chloroethoxysilane 8 were synthesized and characterized by 'H, "C and '9Si NMR, IR spectroscopy, and EI and CI mass spectrometry. Thermodynamic considerations would suggest that, as a result of the driving force provided by the formation of a Si-F or Si-Cl bond, the thermolyses of these compounds would lead to the formation of bis(trimethylsily1)silanone 4. To examine this question, gas chromatography -mass spectrometry was as used a detection technique for products resulting from the high-pressure thermolyses of 6-8. The elimination of (Me,Si),SiCl appears to be the major thermolytic pathway of decomposition for 8 at ambient or higher pressures, although it is accompanied by the formation of other products, some of which could have arisen from the addition of various halosilanes to a silanone. Neither 6 nor 7 thermolyzed cleanly; the former compound was essentially unreactive under the thermolysis temperatures used (850°C). Of the products produced in the thermolysis of 7, no evidence for the formation of the silanone was obtained. Independently, mass spectrometry was used to study unimolecular reactions of molecular ions derived from 6-8. The major route to solitary ions appears to involve a 1,2-trimethylsilyl migration from Si to 0 (9+10) prior to decomposition, for example, of the mlz 346 parent ion in the decomposition of 6. The preparation of the ionized silanone may be a minor pathway. Some of the other fragmentation pathways for 6-8 are discussed. Key words: gas phase thermolysis, ion rearrangements, silyl group migration, silanone, halosilane.RCsume : On a synthCtisC le tris(trimtthylsily1)-2,2,2-trifluorosilane 6, le tris(trimCthylsily1)-2-fluoroCthoxysilane 7, et les tris(trimCthylsily1)-2-chloroCthoxysilane, 8, et on les a caractCrists par la RMN du 'H, du ',c et du 2 9~i , par la spectoscopie IR et par spectromCtrie de masse sous IC et IE. Les considtrations thermodynamiques portent h penser que la thermolyse de ces composCs pourrait conduire i la formation de bis(trimCthylsilyl)silanone, 4, en raison de la force directrice crCC par la formation des liaisons Si-F ou Si-Cl. Pour vCrifier cette hypothese, on a utilisC comme technique de dktection, la spectromCtrie de masse couplCe h la chromatographie en phase gazeuse, pour les produits rksultant des thermolyses h haute pression des composCs 6 8 . L'Climination du (Me3Si),SiC1 semble &tre le processus thermolytique principal de dCcomposition du composC 8 h tempkrature ambiante ou h de plus hautes pressions, bien qu'il se forme d'autres produits dont quelques uns proviennent de l'addition de divers halosilanes sur la silanone. Ni le composC 6 ni le composC 7 ne subissent nettement la thermolyse; le premier composC ne rCagit pas du tout aux tempkratures de thermolyse utilisCes (850°C). On n'a pas pu mettre en Cvidence la prisence de silanone parmi les produits rCsultants de la thermolyse du composC 7. D'une f a~o n indepe...

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“…Several experimental studies have suggested that silanones are formed as intermediates in the thermal reactions of low‐molecular organosilicon compounds such as silylperoxides and hydrosilylperoxides, siloxetanes, silenes, hydridosilylketenes, allyloxysilanes, alkoxyvinylsilanes, and polysilylated diazomethanes . Linear and cyclic PDMS were reported to generate dimethylsilanone .…”

Section: Introductionmentioning

confidence: 99%

“…[32,33] Several experimental studies have suggested that silanones are formed as intermediates in the thermalr eactions of lowmolecular organosilicon compounds such as silylperoxides and hydrosilylperoxides, siloxetanes, silenes,h ydridosilylketenes, allyloxysilanes, alkoxyvinylsilanes, and polysilylated diazomethanes. [16,[34][35][36][37][38][39] Linear and cyclic PDMS were reported to generate dimethylsilanone. [15][16][17][18][19][20][21] These claims of dimethylsilanone formationw ere usually based on kinetic dataa nd chemical trapping experiments.…”

Section: Introductionmentioning

confidence: 99%

Dimethylsilanone Generation from Pyrolysis of Polysiloxanes Filled with Nanosized Silica and Ceria/Silica

et al. 2016

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Temperature‐programmed desorption mass spectrometry (TPD MS) was used to study the pyrolysis of PDMS and its composites with nanosized silica and ceria/silica. The results suggest that the elusive organosilicon compound, dimethylsilanone, is generated from PDMS over a broad temperature range (in some cases starting at 70 °C). The presence of nano‐oxides catalyzes this process. Ions characteristic of the fragmentation of dimethylsilanone under electron ionization are assigned with the aid of DFT structure calculations. Possible reaction mechanisms for dimethylsilanone generation are discussed in the context of the calculated kinetic parameters. Observed accompanying products of PDMS pyrolysis, such as tetramethylcyclodisiloxane and hexamethylcyclotrisiloxane, indicate that multiple channels are involved in the dimethylsilanone release.

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The siliconoxygen double-bonded intermediates

Cited by 12 publications

References 6 publications

Using “Anhydrous” Hydrolysis To Favor Formation of Hexamethylcyclotrisiloxane from Dimethyldichlorosilane

Using “Anhydrous” Hydrolysis To Favor Formation of Hexamethylcyclotrisiloxane from Dimethyldichlorosilane

The thermolysis of ε-halodisilanes: a preference for 1,2-Si Si → O rearrangement or Si—O cleavage over Si=O bond formation

Dimethylsilanone Generation from Pyrolysis of Polysiloxanes Filled with Nanosized Silica and Ceria/Silica

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