Synthesis and Characterization of Silicone Resin Precursors and Intermediates

Synthesis and Characterization of Silicone Resin Precursors and Intermediates
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제2회 한국실리콘학회
This presentation relates the synthesis and characterization of cyclopentylsilanepolyol derivatives such as cyclopentylsilanetriol (1), 1,3-bis(cyclopentyl)-1,1,3,3-disiloxanetetraol (2), and silicone resin. Cyclopentylsilanepolyol derivatives having cyclopentyl and more than two silanol groups were synthesized by hydrolysis of cyclopentyltrimethoxysilane (3)1 in the presence of acid catalyst, and characterized by 1H, 13C NMR data. 1 and 2 were synthesized in 71% and 64% yields by hydrolysis of 3 under acidic conditions, respectively. Cyclopentylsilanepolyol was reacted with R3SiCl (R = Me, Vi) to give completely silylated cyclopentylsiloxane derivatives as colorless and stable liquids. 1 and 2 were reacted with R3SiCl (R = Me, Vi) and triethylamine which acts as a base catalyst, respectively. The use of a catalyst was able to shorten the reaction time and to get a better yield. In order to separate the unreacted silanol compounds, the completely silylated compounds were separated through a column chromatography with a hexane eluent. 1,3,5,7-Tetrahydroxy-1,3,5,7-tetracyclopentylcyclotetrasiloxane (4), a precursor of silsesquioxane, was synthesized in 39% yield by hydrolysis of cyclopentyltrichlorosilane (5), and analyzed by 1H NMR. As the reaction proceeding, the number of Si‒OH peaks was increased. 4 was obtained as a mixture of isomers which was confirmed by multiple silanol peaks in 1H NMR.2-3 To prevent the rapid molecular weight growing, silicone resins [(C5H9SiO3/2)x(RMe2SiO1/2)y, / R = Me, Ph, Vi] were synthesized by the hydrolysis and co-condensation of 5 with monochlorosilanes, thus we could obtained organic solvent soluble silicone resins. By increasing the molar ratio of the monochlorosilane to 5, viscosity was decreased, however, there was little change in the molecular weight. For addition curable functionality, vinyl terminated silicone resin was prepared with vinlydimethylchlorosilane.
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