S. V. Basenko

Efficient method for the synthesis of symmetrical α,ω-dichloro-1,1,3,3-tetraorganyldisiloxanes

203 α,ω Dichloroorganyldisiloxanes (DCSs) are used as precursors in preparing linear and cyclic siloxanes and polysiloxanes showing biological activity; adhe sive, hydrophobic, dielectric and properties; durability and ability to operate under extreme conditions (tem perature, humidity, etc.). They find a wide application in aerospace, automotive, and chemical industry; electrical engineering, pharmacy, food processing industry, cosmetics, and medicine [1–3].

MASS SPECTRA OF LINEAR AND BRANCHED METHYL(VINYL)SILOXANES

The mass spectra of some linear and branched methyl(vinyl)siloxanes Me3SiOSi(Me)(R)(OSiMeVin)nY (R=Vin, OSiMe3; Y=OSiMe3, Cl;n=0–2) were studied. The regularities of their fragmentation and an anomalously high probability of elimination of the ethylene molecule to form the stable 1,3-dioxa-2,4,6-trisilacyclohexane skeleton were revealed.

Reaction of Organylchlorosilanes with Dimethyl Sulfoxide in the Presence of Octamethyltrisiloxane

Dichloro(methyl)(vinyl)silane reacts with DMSO in the presence of octamethyltrisiloxane to form cyclooligomethyl(vinyl)siloxanes(MeViSiO)n (n = 3-6). The reaction involves disproportionation of octamethyltrisiloxane into hexamethyldisiloxane and decamethyltetrasiloxane. Along with the latter two products, insertion products of methyl vinyl silanone into both permethyloligosiloxanes were identified. Alkyltrichlorosilanes RSiCl3 (R = Me, Et) react with DMSO in the presence of octamethyltrisiloxane to form cyclic oligoalkyltrichlorosiloxanes (RClSiO)m (m = 3-6).

Phenyl(acyloxy)fluorosilanes C6H5Si(OCOR)nF3−n (n = 1, 2) and phenyl(acyloxy)fluorochlorosilanes C6H5Si(OCOR)FCl

The method of synthesis of the hitherto unknown class of organosilicon compounds, phenyl(acyloxy)fluorosilanes C6H5Si(OCOR)nF3−n (n = 1, 2) and phenyl(acyloxy)fluorochlorosilanes C6H5Si(OCOR) FCl in up to 91% yield has been developed based on the reaction of phenyl(fluoro)chlorosilanes C6H5SiClnF3−n (n = 1, 2) with trimethylsilyl esters of carboxylic acids Me3SiOC(O)R [R = H, CH3, CF3, CCl3, ClCH2, BrCH2, CH2=CHCH3, CH2=CHPh, CH(CH3)=CH2, Ph].

Phenyl(fluoro)chlorodisiloxanes

Cohydrolysis of phenyltrichlorosilane with phenyl(fluoro)dichloro- and phenyl(difluoro)-chlorosilanes and thermolysis of the formed siloxanes leading to the formation of phenyl(difluoro)chlorosilane are studied. The scheme of thermal decomposition of disiloxanes possessing fluorine atoms in the 1,3 positions is suggested. The scheme is based on the intermediate formation of an active four-membered cyclic complex closed by the fluorine bridge between the silicon atoms. In agreement with the scheme, no thermolysis of 1,3-diphenyl-1-fluoro-1,3,3-trichlorodisiloxane is observed under the studied conditions.

Generation and capture of alkylchlorosilanones

Alkyltrichlorosilanes react with DMSO (molar ratio 1 : 1 0 °C) to give cyclic oligoalkylchlorosiloxanes of the general formula [R(Cl)SiO]n (where R=Me or Et;n=3–6). With an excess of alkyltrichlorosilane (2: 1), linear oligoalkylchlorosiloxanes Cl[R(Cl)SiO]mSiCl2R (where R=Me or Et;m=1–5) are also formed. In the presence of hexamethyldisiloxane (molar ratio Cl3SiR : DMSO: (Me3Si)2O=1:1:2, 20 °C), the reaction products are both cyclic and linear oligoalkyl(trimethylsilyloxy)siloxanes [R(Me3SiO)SiO]n (n=3–5) and Me3Si[OSi(OSiMe3)R]mOSiMe3 (m=1–3), respectively. The reaction of DMSO with trichloro(vinyl)silane and hexamethyldisiloxane occurs in a similar manner. A plausible scheme of formation of the final products via intermediate alkylchlorosilanones RClSi=O and alkyl(trimethylsilyloxy)silanones is discussed.

Generation and capture of methyl(vinyl)silanone

Methyl(vinyl)dichlorosilane reacts with DMSO in the presence of hexamethyldisiloxane to give the corresponding linear oligosiloxanes of the general formula Me3Si(OSiMeVin)nOSiMe3 (n=1–6) as well as MeSi(OSiMe3)3 and Me3Si(MeOSiVin)mOSi(OSiMe3)(Me)OSiMe3 (m=1–2). The same reaction in the presence of chlorotrimethylsilane results in oligomers of the general formula Me3Si(OSiMeVin)nCl (n=1–3). A possible scheme of their formation is discussed.

Phenyl(fluoro)dichlorosilane: A new synthon for the preparation of compounds containing chiral silicon atom

219 Compounds containing asymmetric silicon atom have long attracted the attention of researchers [1–4]. The known methods of synthesis of chiral silicon com pounds containing simultaneously two different halo gen atoms are based either on the treatment of hydro carbylfluorosilanes with aluminum chloride [5] and their analogs containing Si–H bonds with copper chloride [6], or irradiation of reaction mixtures of hexafluoro and pentafluorochlorobenzene [7] or 1,4 dichlorotetrafluorobenzene [8] with trichloro and methyldichlorosilanes by accelerated electrons. We have found a simplest and convenient method for the synthesis of compounds of such a type. It is based on the displacement of one of the chlorine atoms in phenyl(fluoro)dichlorosilane (I) by OR, OC(O)R, OSiMe3, NHSiMe3, OSiMe2OSiMe3, and other groups. All compounds resulting from this reac tion were previously unknown.

Unusual transformations of difluorosilanone F2Si=O

The structure and properties of fluorosilicon polymer (fluorosil) formed by the reaction of phenyltrifluorosilane with aliphatic alcohols have been studied by the methods of IR, 19F, 29Si NMR spectroscopy, high temperature mass-spectrometry, derivatography and atom emission analysis. Due to its high reactivity, this polymer readily reacts with glass of the reaction vessel extracting the ions of all metals entering into its composition. Fluorosil formed in a quartz, teflon or polypropylene reactors is characterized by low stability and is slowly decomposed to SiF4 and SiO2. Apparently, fluorosil is the product of incorporation of SiF4 into the SiO2 matrix.

Phenyl(trimethylsiloxy)fluorosiloxanes PhSi(OSiMe3)nF3−n

The siloxane bond splitting reaction in hexamethyldisiloxanes PhSiClnF3−n was studied.