Synthesis of novel organic oligomers containing SiH bonds

Abstract

Several organic oligomers (Mw = 103–104 order) containing SiH bonds of the general formula 1 have been successfully synthesized by platinum‐catalyzed partial hydrosilylation reaction of an allyloxy (or an allyl carbonate) end‐blocked linear organic oligomer 2 with 2,4,6,8‐tetramethylcyclotetrasiloxane, [CH3(H)SiO]4 (3) (hereafter called hydrocyclotetrasiloxane). 1H‐NMR spectroscopy confirmed the introduction of hydrocyclotetrasiloxane moiety into the oligomers through SiC linkage by hydrosilylation reaction. 13C‐NMR analysis revealed that the cyclic structure of the starting hydrocyclotetrasiloxane 3 was retained intact in product 1. As the precursor for 1, allyloxy (or allyl carbonate) end‐blocked oligomers 2 could be prepared from hydroxyl‐terminated oligomers 4. The storage stability of product 1 was significantly influenced by the platinum catalyst still remaining in it. The poor stability was improved by decreasing the amount of the platinum catalyst and/or by adding coordinating compounds. As a result, an excellent stability of product 1 was obtained. © 1993 John Wiley & Sons, Inc.

Catalysis of hydrosilylation: Part XXXI. Functionalization of poly(methylhydro)siloxanes via hydrosilylation of allyl derivatives

“…The products isolated from reactions of siloxane A with particular allyl derivatives and 1-octene were characterized mainly by 1 H NMR, FT IR and GPC methods. Figure 1 presents 1 H NMR spectra of unmodified poly(methylhydro)siloxane A (1), and of A hydrosilylated with allyl phenyl ether (2), allyl glycidyl ether (3) or with 1-octene (4).…”

“…Synthesis of hybrid materials of such a kind is usually performed directly by adding unsaturated derivatives of bulky molecules to a siloxane network (e.g. allyloxy end-blocked linear organic oligomers 4 to achieve a polymeric system miscible with organic polymers) as well as by adding macromolecules, e.g., carbohydrates, to poly(methylhydro)siloxanes to introduce hydrophilicity and chirality to the polysiloxane, 5 or by other methods directed to photo-crosslinkable and optically active side-chain liquid-crystalline copolymers. 6 These reactions frequently involve steric hindrances and, therefore, proceed only to a slight degree and lead to incomplete conversion of the Si-H groups.…”

“…The reaction has usually been reported to be catalysed by platinum complexes (mostly based on H 2 PtCl 6 precursors). 4,6,7,10,11,13,14 Acidic Speier's catalyst could not be used for all the hydrosilylations since it causes isomerizations of the allylic bond, followed by acidic cleavage of the functional group 5 and, in some cases, gelation of the reaction mixture, 4 even during the process of addition. In such a case neutral Pt(0) and Pt(II) precursors are used; for example Pt/C, 10 Pt 2 [(CH 2 = CH)SiMe 2 OSiMe 2 (CH = CH 2 )] 3 , 9,15 PtCl 2 (cod) 2 (cod = cyclo-octadiene) 8 and PtCl 2 (C 5 H 5 ) 2 .…”

Synthesis and characterization of polysiloxanes with pendant bicyclic fragments

“…The difference between V 2 and V 1 gives the volume of eliminated hydrogen gas ( V , mL). The SiH content of an oligomer is given by the following: where p is the atmospheric pressure at measurement (atm), V is the gas volume captured (mL), W is the sample weight (g), R = 0.0082 (gas constant) (L atm mol ‐1 K ‐1 ), and T is the tesmperature (K at measurement) 15…”

“…where p is the atmospheric pressure at measurement (atm), V is the gas volume captured (mL), W is the sample weight (g), R ¼ 0.0082 (gas constant) (L atm mol -1 K -1 ), and T is the tesmperature (K at measurement). 15 Hydrosilylation reaction of PMHS with 5-vinyl-2-norbornene in the presence of H 2 PtCl 6 Polymethylhydrosiloxane (0.9850 g, 0.435 mmol), 5vinyl-2-norbornene (1.8287 g, 0.0153 mol), and 5.5 mL dry toluene were placed into the three-necked flask equipped with a magnetic stirrer, reflux condenser, and thermocouple. Then the catalyst, 0.1M solution of platinum hydrochloric acid in THF (5 Ä 9 Â 10 À5 g per 1.0 g of starting substance), was introduced.…”