107-52-8Relevant articles and documents
Polycondensation and disproportionation of an oligosiloxanol in the presence of a superbase
Grzelka, Agnieszka,Chojnowski, Julian,Cypryk, Marek,Fortuniak, Witold,Hupfield, Peter C.,Taylor, Richard G.
, p. 14 - 26 (2002)
Kinetics of reactions of model oligosiloxanols, 1,1,3,3,3-pentamethyldisiloxane-1-ol (MDH) and 1,1,3,3,5,5,5-heptamethyltrisiloxane-1-ol (MD2H), which occur in the presence of phosphazenium superbase, hexapyrrolidine-diphosphazenium hydroxide, in an acid-base inert solvent, toluene, was studied using sampling and gas chromatographic analysis method. In addition, kinetics of reactions of MDH and MD2H with trimethylsilanol (MH) was studied. In the MDH and MD2H systems the oligosiloxanol condensation competes with the oligosiloxanol disproportionation, the latter being the dominating process. The disproportionation products, i.e. MDn+1H and MDn-1H, n=1, 2, ? undergo analogous consecutive disproportionation and condensation reactions. The kinetic law was derived and rate parameters determined from initial rates and by computer simulation to the best agreement with experimental data. Both competing reactions, the disproportionation and the condensation, conform to the same general kinetic law being first internal order in substrate and first order in catalyst. Activation parameters of these reactions were determined. The results were interpreted in terms of a bimolecular mechanism in which nucleophilic attack of the silanolate anion directed to silicon of the silanol group causes the cleavage of one of its geminal bonds to oxygen, either the one to hydroxyl leading to condensation or the one to siloxane which leads to disproportionation. The latter is faster as the silanolate is a better leaving group compared with OH-. Moreover, in the pentacoordinate silicon transition state (or intermediate) the siloxane substituent preferentially enters the apical position, thus driving the OH substituent into the unreactive equatorial position.
Kinetics and mechanism of the reaction between oligosiloxanes and P-trichloro-N-dichlorophosphoryl monophosphazene (Cl3P=N-POCl2)
Meliani, Abdeslam,Vaugeois, Yann,Bali, Hamza,Mazzah, Ahmed,De Jaeger, Roger,Habimana, Jean
, p. 283 - 301 (2000)
31P NMR investigation has been made of the action of Cl3P=N-POCl2 (I) first on hexamethyldisiloxane (Me3Si)2O and then on oligosiloxanes Me3Si-(OSiMe2)n-OSiMe3 n = 2 and n=3. The reactions were carried out in bulk or in solution with molar ratios siloxane/(I) varying from 1 to 5. It was demonstrated that only the monosubstitution of a chlorine atom by the -(OSiMe2)n-OSiMe3 species n = 0, 2, 3 with elimination of trimethylchlorosilane occurred leading to the derivatives Cl2OP-N=PCl2O-(SiMe2-O)nSiMe 3 (II). For n=2, 3 the siloxane redistribution reactions were observed by 29Si NMR analysis. A two steps mechanism is proposed, consisting in a nucleophilic substitution, involving a tricoordinate phosphazenium intermediate, followed by the formation of an active ionic centre probably an oxonium ion, arising from the solvatation by the siloxane of this phosphazenium ion and /or of (II) leading to the redistribution reactions. The influences of the solvent, of trimethylchlorosilane, of the temperature, and of the addition of a protonated species (MDH) were investigated.
One-Step Synthesis of Siloxanes from the Direct Process Disilane Residue
Neumeyer, Felix,Auner, Norbert
supporting information, p. 17165 - 17168 (2016/11/23)
The well-established Müller–Rochow Direct Process for the chloromethylsilane synthesis produces a disilane residue (DPR) consisting of compounds MenSi2Cl6?n(n=1–6) in thousands of tons annually. Technologically, much effort is made to retransfer the disilanes into monosilanes suitable for introduction into the siloxane production chain for increase in economic value. Here, we report on a single step reaction to directly form cyclic, linear, and cage-like siloxanes upon treatment of the DPR with a 5 m HCl in Et2O solution at about 120 °C for 60 h. For simplification of the Si?Si bond cleavage and aiming on product selectivity the grade of methylation at the silicon backbone is increased to n≥4. Moreover, the HCl/Et2O reagent is also suitable to produce siloxanes from the corresponding monosilanes under comparable conditions.
Cosmetic composition comprising a volatile fatty phase
-
, (2008/06/13)
The invention relates to a composition comprising, in a physiologically acceptable medium, a volatile silicone fatty phase comprising at least one non-cyclic volatile silicone oil, wherein the volatile silicone fatty phase has an evaporation profile such that the mass of the at least one volatile silicone oil evaporated after 30 minutes is from 2 mg/cm2 to 9 mg/cm2. The invention also relates to making up and caring for human keratin materials using the inventive compositions.
FEATURES OF INFLUENCE OF HCl ON HYDROLYTIC COPOLYCONDENSATION OF BIFUNCTIONAL ORGANOCHLOROSILANES WITH TRIMETHYLCHLOROSILANE
Kopylov, V. M.,Agashkov, S. P.,Sunkovich, G. V.,Prikhod'ko, P. L.
, p. 1257 - 1261 (2007/10/02)
The hydrogen chloride that is formed in the hydrolytic copolycondensation of R'RSiCl2 with Me3SiCl affects the composition of the reaction products only at cocentrations above 30-35percent, where it is responsible for splitting out the terminal trimethylsiloxy group.The stability of the terminal groups increases with increasing size of the substituents on the silicon atom in the R'RSiCl2.The total yield of Me3SiO(R'RSiO)mSiMe3 with m = 1-4 also increases with increasing size of the substituents on the silicon atom in the R'RSiCl2.The total yield of p with p = 3-5 increases with decreasing tendency of the R'RSiCl2 to form rings by hydrolytic polycondensation, and with increasing sensitivity of the terminal trimethylsiloxy group in the cocondensation products to the action of HCl and its activity with respect to the siloxane bond.
Cleavage of poly(diorganosiloxanes) by trimethyialuminum
Apblett, Allen W.,Barron, Andrew R.
, p. 2137 - 2141 (2008/10/08)
The interaction of AlMe3 at elevated temperatures with poly(diorganosiloxanes), (RMeSiO)x (R = Me, n-C18H37, -CH2CH2CF3, Ph), leads to rupture of the silicon-oxygen framework and yields the dimeric aluminum siloxides [Me2Al(OSiMe2R)]2. The molecular structure of [Me2Al(OSiMe2Ph)]2 has been confirmed by X-ray crystallography. The compound [Me2Al(OSiMe2Ph)]2 crystallizes in the monoclinic space group P21/n with unit cell dimensions a = 7.970 (3) ?, b = 24.563 (10) ?, c = 13.322 (4) ?, β= 105 05 (3)° Z = 4, 2754 observed data, R = 0.0478, and Rw = 0.0639. At ambient temperatures the cyclic trisiloxane (Me2SiO)3 forms a highly fluxional 1:1 Lewis acid-base adduct with AlMe3.
