Base-catalyzed transformations of tetramethyldisiloxane

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    The behavior of the simplest linear siloxane under base-catalyzed conditions was investigated in the temperature range of 60-110 degrees C for different concentrations of linear siloxane (0.05-0.5 wt %) in dodecane as the solvent with an aqueous solution of sodium hydroxide added as the alkali agent. Samples were taken regularly and analyzed by GC-MS. The activation energy for the studied conditions was found to be equal to 68 kJ/mol. The reaction rate decreased with increasing sodium hydroxide concentration as a result of the formation of dibasic siloxanolates, which are less reactive than single siloxanolates. The proposed reaction mechanism includes stages of polycondensation and siloxane cyclization. The composition of the final reaction mixture (i.e., the ratio between the solid and liquid products) was found to depend strongly on the reaction parameters. Analysis of the solid products by scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDXA), and Fourier transform infrared (FTIR) spectroscopy confirmed the formation of sodium siloxanolates. Thermogravimetric analysis (TGA) and temperature-programmed oxidation-mass spectrometry (TPO-MS) results demonstrated that the water content in the solid products decreased with increasing relative concentration of alkali agent in the reaction mixture.
    OriginalspråkOdefinierat/okänt
    Sidor (från-till)10080–10088
    Antal sidor9
    TidskriftIndustrial & Engineering Chemistry Research
    Volym52
    Utgåva30
    DOI
    StatusPublicerad - 2013
    MoE-publikationstypA1 Tidskriftsartikel-refererad

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