Alkaline cleavage of silicon-hydrogen bonds in pentamethyl- and tetramethyldisiloxane

Tondeur, J. J.; Vandendunghen, G.; Xhigne, M.

doi:10.1007/bf02062464

Cited by 1 publication

(3 citation statements)

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“…). The alkaline cleavage of the silicon–hydrogen bond in TMDS results in silanol formation and hydrogen release, as previously reported . According to Tondeur et al , formation of silanediols takes place only for siloxanes containing more than three silicon atoms (Fig.…”

Section: Resultssupporting

confidence: 60%

“…Reaction rates of the TMDS transformations in the presence of 6.25 and 1.25 mmol NaOH were calculated. Plotting logarithm of the TMDS transformation rate as a function of the logarithm of sodium hydroxide concentration the reaction order in sodium hydroxide was obtained, giving a negative value (–0.42), whereas according to the literature the reaction is first order in hydroxide. To explain the observed negative apparent reaction order further mechanistic studies are required.…”

Section: Resultsmentioning

confidence: 99%

“…The alkaline cleavage of the silicon-hydrogen bond in TMDS results in silanol formation and hydrogen release, as previously reported. 13,14 According to Tondeur et al, 14 formation of silanediols takes place only for siloxanes containing more than three silicon atoms ( Fig. 2), since the first silicon atom bonded to the hydroxyl group, makes the other silicon through the siloxane link less available for nucleophilic attack.…”

Section: Base-catalyzed Tmds Transformation Pathwaysmentioning

confidence: 99%

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Transformation of tetramethyldisiloxane in used oil alkali treatment conditions: mechanism and kinetic modeling

Kupareva

Wärnå

Grénman

et al. 2015

J of Chemical Tech & Biotech

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BACKGROUND The behavior of silicon species in the recycling processes of waste lube oils is of great interest because of the negative effect of silicon compounds on the performance of hydrotreating catalysts and the formation of undesired solid deposits at various locations in the re‐refining units. To operate alkali treatment of silicon‐containing used oils efficiently in the recycling industry prediction of silicon species behavior is required. To this end kinetic modeling of the base catalyzed transformation of a model siloxane compound was done. RESULTS A kinetic model was developed for tetramethyldisiloxane (TMDS) transformation reactions under industrially relevant alkali treatment conditions in dodecane with sodium hydroxide as alkali agent. A reaction scheme describing the main pathways of TMDS transformation was proposed considering experimental and literature data. The studied model compound underwent hydrolysis, condensation and disproportionation reactions with formation of different molecular weight linear siloxanes. The latter were transformed to cyclic siloxanes through sodium silanolates generation. The data obtained experimentally were validated with the advanced kinetic model. CONCLUSIONS The proposed model fitted experimental data adequately, indicating that it can be used in the design and control of the caustic treatment of used oil containing silicon species. © 2015 Society of Chemical Industry

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Section: Resultssupporting

confidence: 60%

Section: Resultsmentioning

confidence: 99%