Siloxane, chloro

In many cases, these cyclic siloxanes have to be removed from the system by distillation or fractionation, in order to obtain pure products. On the other hand, cyclic siloxanes where n = 3 and n = 4 are the two most important monomers used in the commercial production of various siloxane polymers or oligomers via the so-called equilibration or redistribution reactions which will be discussed in detail in Sect. 2.4. Therefore, in modern silicone technology, aqueous hydrolysis of chloro-silanes is usually employed for the preparation of cyclic siloxane monomers 122> more than for the direct synthesis of the (Si—X) functional oligomers. Equilibration reactions are the method of choice for the synthesis of functionally terminated siloxane oligomers. 

Phenyl and vinyl modified versions of poly(m-carborane-siloxane) were readily prepared using the procedure just described, by introducing the appropriate silane feed into the reaction mix.19 Typically, 1 to 3 mol % di-chloro-methylvinylsilane was added to the di-chlorosilane feed in the syntheses described earlier. The repeat unit of the phenyl modified poly(w-carborane-siloxane) is shown in 5. 

A similar strategy was also applicable for the synthesis of six- and eight-membered siloxanol-ring systems. Hydrolysis of z-PrRSiCl2 (R = Ph, o-Tol) with ZnO and KOH provided the six-membered siloxane rings as a mixture of two constitutional isomers cis-trans-(i-PrRSiO)3 (539, R = Ph 540, R = o-Tol) and Wzr-(z-PrRSiO)3 (541, R = Ph 542, R = o-Tol) which were separated by preparative HPLC. Subsequent reaction with HC1/A1C13 and hydrolysis of the chloro intermediates yielded the same product for both isomers, namely Wzr-[z-Pr(OH)SiO]3 543, implying that isomerization occurs under these conditions (Scheme 75).484... 

Cyclo(alkylperoxyorgano)siloxanes are prepared from the corresponding cyclo(chloro-organo)siloxanes with alkyl hydroperoxide in the presence of ammonia (eqnation 23) . ... 

The first structural report of an alumo-poly siloxane appeared as early as 1966 the molecule (Me2SiO)4(OAlBr2)2(AlBr) has an Si4Al2Ofi 12-membered cycle which is spirocyclically bridged by an Al-Br unit (see Fig. 3).68 Only in 2000 was the corresponding structure of the chloro-derivative (which is iso-typic to the bromo-compond) published.69 In both compounds, all silicon and aluminum atoms are tetra-coordinate with the exception of the spiro-cyclic central bromo(chloro)-aluminum -moiety, which is penta-coordinate with four oxygen bonds. 

PB PBI PBMA PBO PBT(H) PBTP PC PCHMA PCTFE PDAP PDMS PE PEHD PELD PEMD PEC PEEK PEG PEI PEK PEN PEO PES PET PF PI PIB PMA PMMA PMI PMP POB POM PP PPE PPP PPPE PPQ PPS PPSU PS PSU PTFE PTMT PU PUR Poly(n.butylene) Poly(benzimidazole) Poly(n.butyl methacrylate) Poly(benzoxazole) Poly(benzthiazole) Poly(butylene glycol terephthalate) Polycarbonate Poly(cyclohexyl methacrylate) Poly(chloro-trifluoro ethylene) Poly(diallyl phthalate) Poly(dimethyl siloxane) Polyethylene High density polyethylene Low density polyethylene Medium density polyethylene Chlorinated polyethylene Poly-ether-ether ketone poly(ethylene glycol) Poly-ether-imide Poly-ether ketone Poly(ethylene-2,6-naphthalene dicarboxylate) Poly(ethylene oxide) Poly-ether sulfone Poly(ethylene terephthalate) Phenol formaldehyde resin Polyimide Polyisobutylene Poly(methyl acrylate) Poly(methyl methacrylate) Poly(methacryl imide) Poly(methylpentene) Poly(hydroxy-benzoate) Polyoxymethylene = polyacetal = polyformaldehyde Polypropylene Poly (2,6-dimethyl-l,4-phenylene ether) = Poly(phenylene oxide) Polyp araphenylene Poly(2,6-diphenyl-l,4-phenylene ether) Poly(phenyl quinoxaline) Polyphenylene sulfide, polysulfide Polyphenylene sulfone Polystyrene Polysulfone Poly(tetrafluoroethylene) Poly(tetramethylene terephthalate) Polyurethane Polyurethane rubber... 

Poly(w-carboranyl-siloxane) elastomers containing a mixture of di-methyl-and methyl(phenyl)-silyl units were synthesised using the Ferric Chloride catalyzed condensation reaction between di-chloro-di-organosilane and 1,7-bis(di-methyl(methoxy)silyl)-/w-carborane. Silica Nano tubes synthesised using i 7situ growth of DL Tartaric acid nanocrystals and concurrent sol-gel hydrolysis and condensation of silane. 

An oligomeric polysiloxane photoinitiator (PSDAP) containing dialkoxy acetophenone moieties, prepared by reacting diallyloxy-acetophenone with penta-methyl-disiloxane and H-terminated dimethyl-silicone in the presence of chloro-platinic acid, has been claimed [87] to be compatible with silicone prepolymers containing methylvinyl siloxane co-units and active in their UV curing. 

Poly(ether.siloxanes) contain a poly(methyl.siloxane) polymer, which may be branched, and poly(eiher)-blocks. Its structure may be linear or comblike. The blocks are connected by Si-O-C- or Si-C- bridges., Si-0-C- linked products can, for example, be produced by reacting branched dimethyl(chloro)siloxy-lerminated poly(methyl-siloxanes) (see Section 4.3.3) with monohydroxy-functional polyCethers. 

The silicon hydrides do not spontaneously add to alkenes either. However, the hydrosilation, or hydrosilylation reaction, of olefins is of significant utility in the preparation of alkyl-subtituted silanes with the use of either radical or transition metal catalysis. The preferred metal catalysts for hydrosilation are platinum complexes. Chloro-platinic acid will catalyze hydrosilations with halosilanes, alkylarylhalosilanes, alkoxy-silanes, and siloxanes that in many cases are quantitative under ambient conditions. Yields and conversions are generally poorer for alkyl,- and arylsilanes. Many other coordination complexes have been found to catalyze the hydrosilation reaction, and these can provide certain advantages, particularly in regiochemistry. Some typical hydrosilation reactions are shown in Table... 

Silylmethyl radical cyclizations are a related class of reactions in which the heterocycle serves a temporary purpose to direct the introduction of a methyl or hydroxymethyl group adjacent to the hydroxy group. Starting from the optically active allylic decalin alcohol, reaction with bromomethyl(chloro)dimethylsilane gives the a-bromosilyl ether. Treatment with tributyltin hydride affords the stereoselective cyclization to a five-membered siloxane62. The siloxane ring is converted either to the a.r-dihydroxy compound, or to the ot-methylated derivative63. 

Mixtures of methylchlorosilanes produced in the reaction of methyl chloride with silicon copper alloys separate well on a column of FS-16 (Dow DC methyl p-chloro-phenyl siloxane polymer) on firebrick at 70 °C using nitrogen carrier gas396. 

Retention data have been listed for374 44 alkyl-chloro and chlorophenylsilanes, 34 linear and branched dimethyl and methyl-vinylsiloxanes, 14 cyclic dimethyl and meth-ylvinylsiloxanes and 6 linear methylphenyl- and ethoxyvinyl-siloxanes. 

These are cross-linked compositions, containing trifunctional (T) or tetrafunctional (Q) silicon units. The simplest are produced from methyltrichlorosilane, by hydrolysis, either directly or after intermediate conversion to methyl-trialkoxysilanes. Smaller amounts of dimethylsiloxane or trimethylsiloxane units may be introduced, as the corresponding chloro- or alkoxysUanes, to increase flexibility of the resin. Curing is brought about by aqueous solvolysis, usually catalyzed by metal salts, leading to highly cross-linked siloxane structures. More typical silicone resins contain mixtures of phenyl- or alkyltriethoxysilanes, mixed with MeSi(OEt)3 and perhaps Me2Si(OEt)2 or MesSiOEt. 

There are two technically important methods by which extended Si/0 systems can be formed from molecular precursors. The first is by reaction of chlorosilanes with oxygen at high temperatures, while the second is by hydrolysis and condensation reactions of chloro- or alkoxysilanes. Chapters 32 and 33 deal with the structural evolution of siloxane structures in such reactions from an experimental and theoretical viewpoint. M. Binnewies et al. compare the stepwise formation of Si-0 networks from SiCU for both the combustion and hydrolysis reactions. The stability and reactivity of intermediate chlorosiloxanes is an important issue in this work. Both the initial process in the reaction of SiCfi with O2 and the growth of larger siloxane cages are investigated theoretically in the contribution of K. Jug. 

In this context we have synthesized ferriomethyl-substituted silanols and siloxanes starting with the ferriomethylhydridosilanes 3a-e [5], generated by nucleophilic metalation of the chloro-methylsilanes 2a-c with the sodium ferrates la,b (Eq. 1). 

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