15261-06-0Relevant articles and documents
NOVEL 2,4-DISILATHIETANE RING SYSTEM FROM CYCLOADDITION OF 1,1-DIMETHYL-1-SILAETHYLENE, Me2Si=CH2, TO DIMETHYLSILANTHIONE, Me2Si=S. PERTURBATION MOLECULAR ORBITAL (PMO) STUDY ON REACTIVITY OF INTERMEDIATES WITH A DOUBLE-BONDED SILICON ATOM
Gusel'Nikov, L. E.,Volkova, V. V.,Avakyan, V. G.,Volnina, E. A.,Zaikin, V. G.,et al.
, p. 191 - 206 (1984)
Copyrolysis of 1,1-dimethyl-1-silacyclobutane (I) with both hexamethylcyclotrisilthiane (II) and tetramethylcyclodisilthiane (III) at 500 deg C involves 1,1-dimethyl-1-silaethylene, Me2Si=CH2 (IV), and dimethylsilanthione, Me2Si=S (V), intermediates and yields the following cycloaddition products: the new 2,2,4,4-tetramethyl-2,4-disilathietane (VI), 1,1,3,3-tetramethyl-1,3-disilacyclobutane (VII), and III.Six-membered cyclocarbosilthianes, 1,1,3,3,5,5-hexamethyl-2-thia-1,3,5-trisilacyclohexane (VIII) and 1,1,3,3,5,5-hexamethyl-2,4-dithia-1,3,5-trisilacyclohexane (IX) have also been derived by inserting IV and V into the Si-S bond of VI.Copyrolysis of I with thiethane (X) also results in four- and six-membered cyclocarbosilthianes, the major product being VI.This is discussed in terms of dimethylsilanthione formation via cycloaddition of IV to thioformaldehyde (XI) followed by 2 + 2>cyclodecomposition of the 2-silathiethane intermediate.A perturbation molecular orbital study of cycloaddition involving intermediates IV, V, and XI has shown that IV reacts more readily with V and XI than it cyclodimerizes.Dimerization of V is the most prominent reaction.
A PROCESS FOR THE PRODUCTION OF POLYSILALKYLENESILOXANES
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Page/Page column 12-13, (2011/06/11)
The present invention relates to a process for the production of an intermediate siloxane monomer and use of said monomer to produce high molecular weight linear polysilalkylenesiloxanes. The siloxane monomer is prepared by ring opening polymerization of a cyclic monomer of the structure in the presence of an acidic or basic ring opening polymerisation catalyst; to form a mixture of siloxane monomers and linear oligomers. The linear oligomers are then extracted and discarded before a further step of ring opening polymerization using the aforementioned intermediate siloxane monomer mixture as the starting material. The second polymerisation step is undertaken at a temperature within the melting point range of said siloxane monomer mixture. The intermediate, final product and methods of their manufacture are described.
