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Unexpected Selectivity in Cyclotetrasiloxane Formation by the Hydrolytic Condensation Reaction of Trichloro(phenyl)silane
Author(s) -
Yagihashi Fujio,
Igarashi Masayasu,
Nakajima Yumiko,
Sato Kazuhiko,
Yumoto Yoshiyuki,
Matsui Chinami,
Shimada Shigeru
Publication year - 2016
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201600454
Subject(s) - diastereomer , chemistry , yield (engineering) , selectivity , hydrolysis , aqueous solution , cis–trans isomerism , condensation reaction , silane , condensation , medicinal chemistry , stereochemistry , organic chemistry , catalysis , materials science , physics , metallurgy , thermodynamics
The hydrolytic condensation reaction of PhSiCl 3 in aqueous solution forming cyclotetrasiloxane [C 6 H 5 SiO(OH)] 4 was studied in detail. The reaction, originally reported by J. F. Brown, was believed to provide only one cyclotetrasiloxane diastereomer, cis , cis , cis ‐isomer 1 . However, our detailed study clearly showed not only the formation of 1 (55.5 % yield) but also the formation of two other diastereomers, the cis , cis , trans isomer (11.9 % yield) and the cis , trans , cis isomer (4.3 % yield), without the formation of the last conceivable trans , trans , trans isomer (<0.1 % yield). A possible mechanism for the selective formation of the three diastereomers was proposed, in which it was assumed that the cyclotetrasiloxanes were formed by cyclization exclusively through the meso diastereomer of the linear tetrasiloxanes but not through the dl diastereomer. This selective cyclization was reasonably explained by considering the stable conformations of the linear tetrasiloxanes in a highly polar aqueous medium.