56427-21-5Relevant articles and documents
Direct spectroscopic study of unstable molecules with silicon-oxygen multiple bonds: Low temperature matrix stabilization of (CH3)2Si=O and (CD3)2Si=O in the gas phase
Khabashesku, V. N.,Kerzina, Z. A.,Baskir, E. G.,Maltsev, A. K.,Nefedov, O. M.
, p. 277 - 294 (1988)
To continue the IR spectroscopic investigations of intermediates with doublebonded silicon, the silanones (CH3)2Si=O and (CD3)2Si=O have been generated by vacuum pyrolysis of the corresponding 6-oxa-3-silabicyclohexanes and of Diels-Alder adducts of silapyranes with maleic anhydride.The above silanones have first been stabilized from the gas phase in argon matrices at 12 K and studied by IR spectroscopy.Using the dependence of the spectra on temperature and pressure in the pyrolysis zone or in warming-up experiments (to 35-40 K) the following vibrational bands of silanones have been revealed: (CH3)2Si=O 1244, 1240, 1210, 822, 798, 770, 657 cm-1; (CD3)2Si=O 1215, 1032, 1007, 995, 712, 685, 674 cm-1.The limits of thermal ( 850 deg C) and kinetic (5 x 10E-4 torr) stability of dimethylsilanone were determined.By comparison of frequencies found with computed values the band 1210 cm-1 in (CH3)2Si=O (1215 cm-1 in (CD3)2Si=O) was assigned to a Si=O streching vibration.This frequency as well as the calculated force constant (8.32 mdyn/Angstroem) and order (1.45) of the Si=O bond are considered as evidence of significant double bonding in dimethylsilanone.
Selectivity Control in the Tandem Aromatization of Bio-Based Furanics Catalyzed by Solid Acids and Palladium
Genuino, Homer C.,Thiyagarajan, Shanmugam,van der Waal, Jan C.,de Jong, Ed,van Haveren, Jacco,van Es, Daan S.,Weckhuysen, Bert M.,Bruijnincx, Pieter C. A.
, p. 277 - 286 (2017/01/17)
Bio-based furanics can be aromatized efficiently by sequential Diels–Alder (DA) addition and hydrogenation steps followed by tandem catalytic aromatization. With a combination of zeolite H-Y and Pd/C, the hydrogenated DA adduct of 2-methylfuran and maleic anhydride can thus be aromatized in the liquid phase and, to a certain extent, decarboxylated to give high yields of the aromatic products 3-methylphthalic anhydride and o- and m-toluic acid. Here, it is shown that a variation in the acidity and textural properties of the solid acid as well as bifunctionality offers a handle on selectivity toward aromatic products. The zeolite component was found to dominate selectivity. Indeed, a linear correlation is found between 3-methylphthalic anhydride yield and the product of (strong acid/total acidity) and mesopore volume of H-Y, highlighting the need for balanced catalyst acidity and porosity. The efficient coupling of the dehydration and dehydrogenation steps by varying the zeolite-to-Pd/C ratio allowed the competitive decarboxylation reaction to be effectively suppressed, which led to an improved 3-methylphthalic anhydride/total aromatics selectivity ratio of 80 % (89 % total aromatics yield). The incorporation of Pd nanoparticles in close proximity to the acid sites in bifunctional Pd/H-Y catalysts also afforded a flexible means to control aromatic products selectivity, as further demonstrated in the aromatization of hydrogenated DA adducts from other diene/dienophile combinations.
