5906-75-2Relevant articles and documents
Sodiumoxy(aminopropyl)alkoxysilanes - AB2 type monomers for the synthesis of hyperbranched poly(aminopropyl)alkoxysiloxanes and their derivatives
Migulin, Dmitry,Milenin, Sergey,Cherkaev, Georgy,Svidchenko, Evgeniya,Surin, Nikolay,Muzafarov, Aziz
, p. 24 - 32 (2018/02/09)
Based on commercially available aminopropyltrialkoxysilanes, new monosodium salts of organoalkoxysilanes (sodiumoxoaminopropyldialkoxysilanes) with two types of chemically independent functional -ONa and -OAlk groups at the silicon atom were synthesized and characterized. The sodiumoxoaminopropyldialkoxysilanes obtained can be regarded as AB2-type monomers - promising reagents for providing controlled polycondensation and production of functional organosilicon polymers with controlled molecular architectures. Subsequently, polyaminopropylsiloxanes with hyperbranched molecular architectures were obtained by heterofunctional polycondensation of the corresponding AB2-type monosodiumoxoorganodialkoxysilanes. The structures synthesized were characterized using 29Si NMR, 1H NMR, GPC and elemental analyses. The hyperbranched polymer matrices obtained containing aminopropyl organic radicals showed the ability to stabilize silver nanoparticles.
Vinylation of aromatic halides using inexpensive organosilicon reagents. Illustration of design of experiment protocols
Denmark, Scott E.,Butler, Christopher R.
, p. 3690 - 3704 (2008/10/09)
The preparation of styrenes by palladium-catalyzed cross-coupling of aromatic iodides and bromides with divinyltetramethyldisiloxane (DVDS) in the presence of inexpensive silanolate activators has been developed. To facilitate the discovery of optimal reaction conditions, Design of Experiment (DoE) protocols were used. By the guided selection of reagents, stoichiometries, temperatures, and solvents, the vinylation reaction was rapidly optimized with three stages consisting of ca. 175 experiments (of a possible 1440 combinations). A variety of aromatic iodides undergo cross-coupling at room temperature in the presence of potassium trimethylsilanoate using Pd(dba) 2 in DMF in good yields. Triphenylphosphine oxide is needed to extend catalyst lifetime. Application of these conditions to aryl bromides was accomplished by the development of two complementary protocols. First, the direct implementation of the successful reaction conditions using aryl iodides at elevated temperature in THF provided the corresponding styrenes in good to excellent yields. Alternatively, the use of potassium triethylsilanolate and a bulky "Buchwald-type" ligand allows for the vinylation reactions to occur at or just above room temperature. A wide range of bromides underwent coupling in good yields for each of the protocols described.
Oxidation of methylsilenes with molecular oxygen. A matrix isolation study
Trommer, Martin,Sander, Wolfram,Patyk, Andreas
, p. 11775 - 11783 (2007/10/02)
The photochemical and thermal oxidation of 1-methylsilene (2-silapropene) (1a), 1,1-dimethylsilene (1b), and 1,1,2-trimethylsilene (1c) has been investigated in O2-doped argon matrices. All silenes 1 are easily photooxidized in matrices containing more than 1% O2, but trimethylsilene (1c) is the only silene that exhibits thermal reactivity toward oxygen at temperatures as low as 20-40 K. The photochemical reactivity increases from 1a to 1c with increasing number of methyl groups at the double bond and decreasing ionization potential. Key intermediates in both the photochemical and the thermal oxidation of 1 are siladioxetanes 9. These species are labile even in low-temperature matrices and could not be identified spectroscopically, but evidence comes from the observed oxidation products such as a complex between methylsilanone and formaldehyde 8a and the formylsilanols 10. An additional oxidation pathway is observed for 1c with a methyl group at the C-atom of the silene moiety. Here, the primary adduct of 1c and 3O2, triplet-diradical T-21c, can either ring-close to give dioxetane 9c and the products derived of it or produce dimethylvinylsilyl hydroperoxide (22) via H-abstraction from a methyl group.
Formation and homolysis of a mononuclear cobalt-oxygen adduct
Bakac, Andreja,Espenson, James H.
, p. 2273 - 2278 (2007/10/02)
The macrocyclic cobalt(II) complex (H2O)nCo(C-meso-Me6[14]aneN4) 2+ (L2Co2+) binds oxygen to yield L2CoO22+. The rate constants for the binding and release of O2 in aqueous solutions at 25°C have values 5.0 × 106 M-1 s-1 and 1.66 × 104 s-1, respectively. There is no evidence for the formation of a binuclear μ-peroxo complex. The ESR parameters of the oxygen adduct in toluene at 120 K, g∥ = 2.108, g⊥ = 1.96, A∥, = 3.81 × 10-3 cm-1, A⊥ = 2.94 × 10-3 cm-1, are consistent with the formulation of the complex as a 1:1 adduct with the unpaired spin density residing on the oxygen. The laser flash photolysis of L2CoO22+ (λirr 490 nm) induces the cleavage of the cobalt-oxygen bond, L2CoO22+ →hv L2Co2+ + O2.
