Search results for "Hydrolysis"
showing 10 items of 632 documents
Atomically Precise Alkynyl-Protected Metal Nanoclusters as a Model Catalyst: Observation of Promoting Effect of Surface Ligands on Catalysis by Metal…
2016
Metal nanoclusters whose surface ligands are removable while keeping their metal framework structures intact are an ideal system for investigating the influence of surface ligands on catalysis of metal nanoparticles. We report in this work an intermetallic nanocluster containing 62 metal atoms, Au34Ag28(PhC≡C)34, and its use as a model catalyst to explore the importance of surface ligands in promoting catalysis. As revealed by single-crystal diffraction, the 62 metal atoms in the cluster are arranged as a four-concentric-shell Ag@Au17@Ag27@Au17 structure. All phenylalkynyl (PA) ligands are linearly coordinated to the surface Au atoms with staple "PhC≡C-Au-C≡CPh" motif. Compared with reporte…
Catalytic treatment of rapeseed straw for enhanced production of furfural and glucose for bioethanol production
2021
Abstract Ethanol produced from renewable biomass, such as lignocellulosic feedstock, is one of the most promising future biofuels. In this paper, rapeseed straw was tested as an abundant and cost-effective renewable resource material for the production of cellulosic glucose. Pre-treatment of this material is an important step to improve the efficiency of subsequent cellulose hydrolysis. In this study, we used two pre-treatment methods – hydrothermochemical and ultrasound. Studies have shown that, in the initial hydrothermal pre-treatment of rapeseed straw, Al2(SO4)3 may be used as an efficient catalyst, at least in procedures for obtaining glucose. An increase in the amount of this catalyst…
Transition metal derivatives of low oxidation state phosphorus oxoacids: synthetic pathways and structural studies
1993
Abstract A general synthetic approach intended to rationalize the solution preparative chemistry of transition metal phosphites and hypophosphites is presented. As previously shown for other derivatives containing also tetrahedral or pseudotetrahedral oxoanions, the hydrolytic processes affecting the cationic moieties play a determinant role on the very nature of the final solid. In fact, despite the limited number of donor atoms in the anions, the crystal chemistry of these compounds is quite intricate because of both the variety of possible cationic aggregates and the many ways to interconnect them through pseudotetrahedral anionic groups.
Reactions of Carbonyl Compounds in Basic Solutions. Part 351: The Alkaline Hydrolysis and Reactivity – Structure – Spectra Correlations of (Z)-4-(Sub…
2002
The kinetics of the alkaline hydrolysis and the configuration, conformation and electronic structure were studied using IR, NMR spectroscopy, X-ray analysis and AM1 theoretical calculations for a series of (Z)-4-(substituted benzylidene)-2-phenyl-4H-oxazol-5-ones (1) and compared with analogous results reported for (E)-4-benzylidene-2-phenyl-4H-furan-5-ones (5) and related compounds.
Rapid hydrolysis of benzodiazepines to benzophenones in a microwave oven
1989
Abstract A microwave oven is used to carry out the complete hydrolysis of diazepam to the corresponding benzophenone in only 10 min, at 650 W, with good recovery. The reaction yield is evaluated by first-derivative UV spectrophotometry.
Studien zum Vorgang der Wasserstoffübertragung, 57 Einige Beispiele zur diastereoselektiven Hydrierung von Verbindungen mit prochiralen CC-Bindungen
1979
(1R,2S)-N,N-Dimethylephedriniumchlorid, (1S,2S)-N,N-Dimethylpseudoephedriniumchlorid, (1R,2S)-N-Methylephedrin, (1S,2S)-N-Methylpseudoephedrin und [(2S)-2-Hydroxy-2-phenyl-ethyl]trimethylammoniumchlorid werden mit α- und β-Methylzimtsaure zu 1–4 und 7 verestert und an Raney-Nickel, Palladium, Platin und einer Reihe von Edelmetalltragerkatalysatoren hydriert. Die hydrierten Ester werden verseift und die optische Ausbeute der α- bzw. β-Methyldihydrozimtsaure bestimmt. Die optischen Ausbeuten bewegen sich in Abhangigkeit von der optisch aktiven Hilfskomponente zwischen 68 und 4%. Bei optischen Ausbeuten uber 10% wird die absolute Konfiguration der α- oder β-Methyldihydrozimtsaure von der Konfi…
Preparation and photoactivity of nanocrystalline TiO2 powders obtained by thermohydrolysis of TiOSO4
2013
Nanocrystalline TiO2 photocatalysts were synthesized in mild conditions by thermohydrolysis of TiOSO4 in water at 100 °C and post-calcination treatment at various temperatures. The TiO2 powders were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, specific surface area determinations, scanning electron microscopy and electron paramagnetic resonance measurements. The photoactivity of the samples was tested employing the photodegradation of 4-nitrophenol in liquid–solid regimen and the photooxidation of gaseous 2-propanol. The best results were obtained with the powder calcined at 600 °C for 10 h. Surprisingly, the not calcined sample was the most active for the abatement…
Baeyer−Villiger Oxidation with Potassium Peroxomonosulfate Supported on Acidic Silica Gel
2005
[reaction: see text] Potassium peroxomonosulfate deposited onto silica SiO2 x KHSO5 efficiently reacts with ketones in dichloromethane at room temperature to give the corresponding esters or lactones in quantitative yields. This method avoids hydrolysis of the reaction products. The Baeyer-Villiger reaction is catalyzed by potassium hydrogensulfate present in the supported reagent.
Proteins of Muscle and the Cytoskeleton
1994
The contractile elements of striated vertebrate skeletal muscle, the myofibrils, contain thin filaments, which are 6 nm in diameter and consist mainly of actin, and thicker myosin filaments with a diameter of 16 nm (Fig. 10.1). During muscle contraction, the filaments undergo a sliding movement relative to each other (sliding filament mechanism). This is brought about by the reversible formation of bridges between the myosin molecules and the actin filaments, which bind, change their conformation and then dissociate (bridge cycle). The required energy is supplied by the hydrolysis of ATP. The sliding distance (step size) per molecule of ATP hydrolysed is controversial; the most recent measu…
Metallocenes of Nb and Ta with η2-Se2H, SeH, and Se Ligands – Crystal Structures of [Cp′2Ta(SeH)H2] and [Cp′2Ta(=Se)H·W(CO)5] (Cp′ =tBuC5H4)
1999
The reactions of [Cp#2NbBH4] (1) [Cp# = C5Me5 (Cp*) or C5Me4Et] and [Cp′2TaH3] (Cp′ = tBuC5H4) with elemental selenium give complexes of the general composition [Cp2MSe2H]. These exist in three isomeric forms, A–C, depending on the metal and the chalcogen. [Cp#2NbSe2H] (2) incorporates the novel η2-Se2H ligand (C), which is labile when exposed to light. Solutions of 2(Cp*) can be converted into [Cp*2NbSe2H] (3), which exists in two isomeric forms A or B, along with [Cp*2NbSe3H] (4) and [Cp*2NbO2H] (5). [Cp′2Ta(η2-Se2)H] (6) is the only isomer found for the Ta system. Se abstraction by means of P(OEt)3 gives [Cp′2Ta(=Se)H] (7). Complex 7 can be reduced with Na/Hg and subsequently hydrolysed …