Novel synthesis of cyclic methylvinylsiloxanes by the reaction of methylvinyl diethoxysilane with phosphorous pentachloride

Abstract

We report a novel synthesis of the cyclic oligomers [(H2C = CH)(CH3)SiO]n obtained by the reaction between phosphorous pentachloride and methylvinyl diethoxysilane. According to gas chromatography/mass spectrometry data, the reaction product consisted of a mixture of cyclic oligomers in which the most important fractions were composed of cycles with n = 5, 6, or 7. The reaction product was also characterized by Fourier transform infrared and 1H and 13C NMR spectroscopy. Experimental results suggested a new kind of reaction between the phosphorous pentachloride and terminal olefins directly bonded to silicon, which was probably associated with sterical effects favoring C - O - Si bond cleavage of ethoxy groups instead of the conventional addition of phosphorous pentachloride to olefinic linkages. © 2002 Wiley Periodicals, Inc. J. Polym. Sci. Part A: Polym. Chem.