7065-59-0Relevant academic research and scientific papers
(Me3N)Mo(CO)5-catalyzed reduction of DMF by disiloxane and disilane moieties: Fate of the silicon-containing fragments
Sharma, Hemant K.,Arias-Ugarte, Renzo,Tomlinson, David,Gappa, Rie,Metta-Magana, Alejandro J.,Ito, Haruhiko,Pannell, Keith H.
, p. 3788 - 3794 (2013/08/23)
The use of HSiMe2OSiMe2H (1) and various hydrodisilanes, R3SiSiMe2H (2; R = alkyl, aryl), as reductants for N,N-dimethylformamide (DMF) in the presence of (Me 3N)Mo(CO)5 as a catalyst led to the formation of a series of novel and structurally interesting siloxanes as well as trimethylamine. In the case of 1 the cyclic poly(dimethylsiloxanes) D4 and D6 are obtained, and for 2 the products are bis(disilyl) ethers, (R 3SiSiMe2)2O. Siloxymethylamine intermediates resulting from an initial hydrosilylation of DMF, (Me2NCH 2OSiMe2)2O (3) and R3SiSiMe 2OCH2NMe2 (4; R = Me, Ph), from the reactions of 1 and 2, respectively, can be observed and, in the case of 3, isolated and purified. In the presence of the respective starting silanes and the catalyst the intermediates readily react to form the appropriate siloxane materials and trimethylamine. Compound 3 was functionalized by reaction with R3ECl (E = Si, Ge, R = Me, Ph) to provide group 14 containing products (R 3EOSiMe2)2O (R = Me, E = Si (5a), Ge (6a); R = Ph, E = Si (5b), Ge (6b)). Reactions of Me3SiSiMe2OCH 2NMe2 (4a) with R3ECl produced Me 3SiSiMe2OER3 (R = Me, E = Si (7), R = Ph, E = Ge, 8). The crystal structure of (Ph3SiSiMe2)2O (9c) is reported and exhibits an Si-O-Si angle of 165 and the longest Si-Si bond length (2.376(2) A) for such bis(disilyl) ethers. The new (Ph 3EOSiMe2)2O derivatives 5b and 6b have been structurally characterized and exhibit distinct conformations about the central SiOSi fragment. In the case of the Ph3Si compound 5b the dihedral angle between the two end groups is 180 with completely staggered SiMe groups on the central Si atoms, whereas for the Ge congener it is 55.7 and the structure exhibits eclipsed SiMe groups. The distinction seems to be due to both intra- and intermolecular phenyl group π stacking in 6b stabilizing this formally higher energy conformation.
DEHYDROCONDENSATION OF ORGANIC HYDROSILANES WITH SILANOLS. PART II. EFFECT OF SILOXANE CHAIN LENGTH ON THE REACTIVITY OF SI-H END-GROUPS. THE SUBSTITUTION EFFECT
Chrusciel, Jerzy,Lasocki, Zygmunt
, p. 121 - 128 (2007/10/02)
It has been found that the reactivity of Si-H end-groups in the homologous series of α,-dihydropolidimethylsiloxanes H(Me2SiO)nSiMe2H in their reaction with diphenylsilanediol in DMF and in presence of ZnCl2 decreases for n changing from 1 to 3 and is stabilized for larger n.The substitution effect of a single Si-H group in 1,1,3,3-tetramethyldisiloxane by triphenylsilanol was determined from rate measurements of the reaction of the primary product of condensation: 1,1,3,3-tetramethyl-5,5,5-triphenyltrisiloxane, which was prepared independently.A kinetic model of non-equilibrium polycondensation proceeding with a single reactivity change of a functional group was devised and numerically checked.
