1.3- divinyltetramethyldisiloxane

Hydroarylation of alkenes is applied to achieve step-growth co-polymerization of aromatic ketones and ct,c< -dienes such as 3,3,6,6-tetramethyl-3,6-disila-l,7-octadiene and 1,3-divinyltetramethyldisiloxane. Co-polymerization of acetophenone and 3,3,6,6-tetramethyl-3,6-disila-l,7-octadiene is catalyzed by Ru species which has been previously activated by treatment with styrene, and a significantly high molecular weight co-polymer, co-poly(3,3,6,6-tetra-methyl-3,6-disila-l,8-octanylene/2-acetyl-l,3-phenylene), is obtained (Scheme 21 ).166... 

Platinum catalyst preparation a mixture of 1 g of chloroplatinic acid hexahydrate, 12.4 mL (22 equiv) of 1,3-divinyltetramethyldisiloxane (an excess), and... 

Chloroplatinic acid hexahydrate Platinate(2-), hexachloro-, dihydrogen (8) Platinate(2-), hexachloro-, dihydrogen (OC-6-11)- (9) (16941-12-1) 1,3-Divinyltetramethyldisiloxane Disiloxane, 1,1,3,3-tetramethyl-1,3-divinyl- (8) Disiloxane, 1,3-diethenyl-1,l,3,3-tetramethyl- (9) (2627-95-4)... 

Tetrakis(triphenylphosphite) palladium catalyzes addition of HCN to vinyltriethoxysilane, vinylmethyldiethoxysilane, vinyldimethylethoxy-silane, and 1,3-divinyltetramethyldisiloxane to give the corresponding... 

A Review of the Ruthenium-Catalyzed Copolymerization of Aromatic Ketones and 1,3-Divinyltetramethyldisiloxane Preparation of ft-Poly(carbosilane-siloxanes)... 

Step-growth copolymerization of aromatic ketones and 1,3-divinyl-tetramethyldisiloxane is found to be catalyzed by (Ph3p)3RuH2CO. Polymerization occurs by the anti-Markovnikov addition of the C-H bonds, which are ortho to the carbonyl group of the aromatic ketone, across the C-C double bonds of 1,3-divinyltetramethyldisiloxane. 

The reaction, whose scope, limitation and mechanism we are going to review, directly yields a/r-poly(carbosilane/siloxanes) by the (Ph3p)3RuH2CO (Ru) catalyzed copolymerization of aromatic ketones and 1,3-divinyltetramethyldisiloxane, as shown in Figure 4. The key step in this process involves the ruthenium catalyzed activation of an aromatic C-H bond which is ortho to a carbonyl group for anti-Markovnikov addition across the C-C double bond of 1,3-divinyltetramethyldisiloxane. Each time... 

On the other hand, a variety of aromatic ketones have proved to be reactive. Polycyclic aromatic ketones such as anthrone, fluorenone, and xanthone all undergo successful Ru catalyzed copolymerization with 1,3-divinyltetramethyl-disiloxane [12], see Figure 8. It has also been possible to incorporate phenanthrene units, which strongly absorb in ultraviolet and fluoresce, into an fl/l(carbosilane/siloxane) by copolymerization of 2-acetylphenanthrene and 1,3-divinyltetramethyldisiloxane [13]. Initially, the molecular weight of these materials was quite low [12]. 

We have also reacted activated catalyst "[Ph3P]2RuCO" with dimethyldivinylsilane and obtained a 1 1 complex which demonstrates dynamic NMR spectra depending on temperature. This fluxional complex is also capable of catalyzing the copolymerization of acetophenone and 1,3-divinyltetramethyldisiloxane [17]. 

Acetophenones substituted with methoxy or phenoxy groups in the para position had been shown to undergo successful activated Ru catalyzed copolymerization with 1,3-divinyltetramethyldisiloxane [18]. Activated Ru catalyzed copolymerization of 4-acetylbenzo crown ethers with 1,3-divinyltetramethyldisiloxane provides a synthetic route to a/r(carbosilane/siloxane) copolymers which incorporate crown ethers, as shown in Figure 11. Polymeric crown ether/lithium perchlorate complexes have been prepared. Of particular note, the sterically congested ortho C-H bond, which is between the acetyl group and the crown ether ring, is still reactive [19,20]... 

We have previously noted that while terminal C-C double bonds of vinyl-silanes, vinylsiloxanes and styrenes are reactive, internal C-C double bonds are not. This selectivity has been exploited in the activated Ru catalyzed copolymerization of 4-acetylstilbenes with 1,3-divinyltetramethyldisiloxane. As expected, the internal C-C double bond of the stilbene does not react [22], see Figure 12. 

On the basis of the above results, it is surprising that Ru catalyzed reaction between benzophenone which has four potentially reactive ortho C-H bonds and 1,3-divinyltetramethyldisiloxane does not yield a crosslinked material - but rather a low molecular weight polymer as well as a cyclic monomer, as shown in Figure 14. Similar results have been obtained in the ruthenium catalyzed reaction with 4-benzoylpyridine and 1,3-divinyltetramethyldisiloxane. On the other hand, 4-acetylpyridine is unreactive. Apparently once one of the ortho C-H bond in benzophenone or 4-benzoylpyridine has reacted, the second ortho C-H bond in the substituted aromatic ring suffers a significant decrease in reactivity. For this reason, the second ortho C-H bond which reacts is usually in the unsubstituted aromatic ring. The formation of cyclic compounds often occurs competitively in polymerization reactions [26]. 

Similar to Speier s catalyst, Karstedt s symmetrical divinyltetramethyldisiloxane catalyst [1,3-divinyltetramethyldisiloxane... 

Reagents. All reactions were conducted in flame dried glassware under an atmosphere of purified argon. 4 -Piperidinoacetophenone, 4 -morpholinoacetophenone, 4 -piperazi-noacetophenone, 4 -methoxyacetophenone, and 4 -phenoxyacetophenone were purchased from Aldrich. 1,3-Divinyltetramethyldisiloxane and 3,3,6,6-tetramethyl-3,6-di-sila-l,7-octadiene were obtained from United Chemical Technologies. Dihydridocar-bonyltr/5(triphenylphosphine)ruthenium was prepared from ruthenium trichloride (8). 

Based on this hypothesis, we have treated the Ru catalyst with a stoichiometric amount of an alkene such as styrene or vinyltrimethoxysilane. After heating this mixture at 135X for a few minutes, a solution of acetophenone and a,(D-diene were added. In this way, significantly higher molecular weight copolymers were obtained. For example, copolymerization of acetophenone and 1,3-divinyltetramethyldisiloxane with Ru catalyst which had been previously activated with a stoichiometric amount of vinyltrimethoxysilane gave copoly-XII, H/M = 40,600/14,800 with a T = -33°C. Whereas, copoly-XII synthesized without prior activation of the cat yst had =... 

---