Silyl termination

CO species in the adducted triiron complexes, the propargylidene-ketene compoimd has e same structure as compound 5 (ii) desilylation by the substitution of the silyl termin species with the ion originating from H2O or the solvent gives the hydrogen-ketene form. 

Silyl ethers, in silicone chemistry, 22 554 Silyl group, in silylation, 22 691 Silyl-terminated polyurethanes (SPU), 22 39-40... 

Silyl-terminated polyethers, 22 38-39 Silyl-terminated polyisobutylene, 22 39 Simethicone... 

Organolanthanide-catalyzed silylation has recently been developed and is a significant new strategy for the synthesis of piperidines. For example, the diallyl compound 37 was cyclized in 83% yield with 5mol% catalyst in the presence of a suitable silyl terminator (Equation 85) <2005T2631>. 

Silyl-terminated polyether can be blended with epoxy resins to form elastic adhesives at room temperature.9 In this system, small rigid epoxy particles are chemically linked by an elastic poly ether phase. A typical formulation is shown in Table 8.4. Elongation and peel... 

Devroey, D. R. E., and Homma, M., Blends of Silyl-Terminated Polyethers and Epoxides as Elastic Adhesives, International Journal of Adhesion and Adhesives, vol. 21, 2001, pp. 275-280. 

Devroey and Homma, Blends of Silyl-Terminated Polyethers and Epoxides as Elastic Adhesives. ... 

An important further development came from the group of Tietze, who introduced the concept of silyl termination in order to control the regio-selectivity of the final fl-H elimation step in the case of substrates (63) with R = H [20]. An example is the transformation shown in Scheme 17, a key step in an enantioselective synthesis of a cytostatic nor-sesquiterpene [20c]. 

Fu, P.F. Marks, T.J. Silanes as chain transfer agents in metallocene-mediated olefin polymerization. Facile in situ catalytic synthesis of silyl-terminated polyolefins. J. Am. Chem. Soc. 1995, 117, 10,747. 

The stability of the heptaphosphanortricyclene cage is emphasized by its presence as the terminal group in trisodium henicosaphosphide Na3P21, which is preferentially silylated terminally rather than at the middle phosphide atom to give 54 (equation 53)68. 

In cases where stable carbocations can be generated, e.g., tertiary propargylic cations, the rather low nucleophilicity of silylated terminal alkynes is still sufHcient for a coupling reaction. Ring closures have been carried out in this fashion to give the permethylated pericyclynes, which are discussed by L. T. Scott and M. J. Cooney in Chapter 9 of this monograph [8]. 

ANSWER The usual type of sealant for this application is a silicone, polyurethane or a silyl-terminated polyether sealant. However, 1 would also suggest that you consider a flexible two-component epoxy adhesive or sealant. Concrete does not expand or contract very much with temperature changes, and you do not really need a sealant with high flexibility. 

TOF-SIMS spectra of poly(dimethylsiloxane)s having different terminal groups. (A) Trunethyl-silyl terminated, (B) Amide-propyl terminated. (Reprinted with permission from Ref. 51, Copyright 1997 American Chemical Society)... 

Keith, C. Reddy, R. A. Prehm, M. Baumeister, U. Kresse, C. H. Chao, J.L. Hahn, H. Lang, H. Tschierske, C. Layer frustration, polar order and chirality in liquid crystalline phases of silyl-terminated achiral bent-core molecules. Chem. Eur. J. 2007, 13, 2556-2577. 

SCHEME 10.5 Catalytic cycle for [Me2Si(Me4C5)(f-BuN)TiMe]" "[B(C6F5)4] -mediated propylene polymerization using PhSiH3 chain transfer agent to form a silyl-terminated atactic polypropylene prodnct... 

Keith C, Reddy RA, Prehm M, Baumeister U, Kresse H, Chao JL, Hahn H, Lang H, Tschierske C (2007) Layer finstration, polar order and chirality in liquid laystalline phases of silyl-terminated achiral bent-core molecules. Chemistry 13(9) 2556-2577. doi 10.1002/ chem.200600876... 

Nakagawa, Y., et al. (2000). Manufacture of alkenyl-terminated vinyl polymers, their silyl-terminated crosslinkable derivatives, and curable compositions containing them. In Jpn. Kokai Tokkyo Koho 2000038404, Kanegafuchi Chemical Industry Co., Ltd., Japan, 14 pp. 

In studies related to the synthesis of bryostatin natural products, it was shown that stereocontrolled cyclizations could be achieved in silyl-terminated Prins cyclizations (Scheme 5). ° Thus, the syn-P-hydroxy allyl silane (13) reacts with propionaldehyde to provide the cw-2,6-disubstituted 4-alkylidenetetrahydropyran (14) in excellent yield and stereocontrol of the olefin geometry (>95 5). The chemistry was examined by DPT (density functional theory) calculations, which suggested that the cyclization step occurs through a chair-like structure (15). Stereocontrol of the exocyclic double bond is thought to be a consequence of steric and electronic effects, in particular maximization of -silyl stabilization of forming carbocation center (16). 

Fig. 5. Log-log plot of the experimental SAXS curves of hyperbranched polyethoxysiloxane (1) Trimethyl-silyl-terminated of (HBPES) (2) silica sol (3). The set of SAXS curves are normalized at s=lnm ...

Similar to (chloromethyl)trimethylsilane, (chloromethyl)di-methylphenylsilane can be used to prepare alkenes via a Peterson olefination by treating C=0 compounds with Grignard 29. However, due to its propensity for rearrangements under the conditions needed for the elimination step, 1 appears less suited for this task than (chloromethyl)trimethylsilane if the parallel transformation, it was found that if the )3-silylalcohol 31 is treated with magnesium iodide etherate, then the Julia ring-opened homoallylation adduct 32 could be isolated (eq 15). ... 

Sonolastic 150 One-part polyurethane based For use on substrates such as aluminium, concrete, masonry, wood, and stone. It can be used in applications such as wet glazing, curtain wall construction, expansion wall joints, EIFS, panel walls, precast units, aluminium and wood window frames, fascia, and parapets Premium-grade, high performance, silyl-terminated, polyurethane-based, non-sag elastomeric sealant. It is a low-modulus formula, possessing extreme joint movement capability. -1- 100/—50%... 

---